# Attenuator talk



## pabbi1

It is no secret that we all have varying dissapointments with attenuators:

 Grit (rk27)
 Less grit, but... (TKD 2511)
 Unobtanim (rk40 log taper)
 DACT / Goldpoint / DIY (only 23 steps)
 Seiden / Shallco / TKD / Penny & Giles, rk50 ($$$)
 eBay steppers (23 steps, and WILDLY varying quality)

 But, there is something coming in "a couple of months" - Goldpoint tells me they are developing a 48 step attenuator, with remote control capability. No further details, but Arn has heard, and is responding.


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## luvdunhill

A few "out of the box" ideas as well

Audio Consulting - DIY Pot
AVC TVC Transformers | Diy HiFi Supply
intact audio
pure audio transformers
BentAudio.com :: TAP
Promitheus Audio
SOWTER ATTENUATOR TRANSFORMERS TVC VOLUME CONTROL
HIGH QUALITY 24 STEPS TRANSFORMER VOLUME CONTROLS! - eBay (item 120320586938 end time Dec-18-08 03:41:26 PST)
Stevens & Billington Limited Audio transformers TX-102
SAC Thailand


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## cetoole

Fortunately, some of us here are sitting on a small supply of RK40 and AP25 pots. Have you tried LDRs or Broskie's attenuator, pabbi?


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## n_maher

Quote:


  Originally Posted by *cetoole* /img/forum/go_quote.gif 
_Have you tried LDRs or Broskie's attenuator, pabbi?_

 

I've tried Broskie's, it works fine but quite frankly it's a pain in the butt.

 I'm holding out hope that relay based attenuators can make some strides.


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## nikongod

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_I've tried Broskie's, it works fine but quite frankly it's a pain in the butt._

 

Which Version? 

 And did it come with break before make switches?


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## wolf18t

There's the Joshua Tree but still unavailable


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## n_maher

Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_Which Version?_

 

Probably the first, it was when they were first introduced. But the 3-switch setup is what bothered me which as far as I can tell is unchanged. Don't get me wrong, it's a neat idea but I just want one knob.


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## Pars

From across the pond there is also Dantimax.


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## looser101

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Probably the first, it was when they were first introduced. But the 3-switch setup is what bothered me which as far as I can tell is unchanged. Don't get me wrong, it's a neat idea but I just want one knob._

 

X2. Good sounding but such a pain. Even worse at meets when you have to explain how to use it. 
	

	
	
		
		

		
			





 This is NEW from Tent Labs.


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## n_maher

I can never figure out what the heck I need to order from Dantimax to build a simple, rotary encoder controlled balanced attenuator.


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## cetoole

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Probably the first, it was when they were first introduced. But the 3-switch setup is what bothered me which as far as I can tell is unchanged. Don't get me wrong, it's a neat idea but I just want one knob._

 

Yeah, I can see that being really annoying. Maybe not to the same level as dual mono attenutators or 2-3dB steps, but pretty annoying anyways. 

 That Tent attenuator looks cool, as does all of Tent's products, but man, 1-2 more relays would have made it much more appealing to me


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## looser101

Also over the pond. 

HiFiCollective UK

 They also have a TVC.


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## n_maher

Quote:


  Originally Posted by *looser101* /img/forum/go_quote.gif 
_This is NEW from Tent Labs._

 

Given the current dollar/euro relationship that's actually priced pretty well.


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## luvdunhill

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Given the current dollar/euro relationship that's actually priced pretty well._

 

plus, much more compact than alternatives..


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## dsavitsk

Quote:


  Originally Posted by *pabbi1* /img/forum/go_quote.gif 
_(only 23 steps)_

 

I have to say that I find this to be one of the most curious notions in all of DIY audio. Do you guys really use _all_ 23 steps from top to bottom and still find that there just aren't enough? Or, what seems more likely, do you use a small portion of the range, but find the nature of 23 steps means that, within the range you want to use, there are only 4 or 5 steps while you would really like 9 or 10?

 It seems like it would make more sense to just get the gain of the system right in the first place, and then use some mechanism for adding a few steps around the listening range to account for particular recordings, or moods. Use a regular 23, or 12 position switch, but put it in 1 or 2dB increments right around your range. Then add a few large steps at the margins for when you want to test just how loud your amp can go.

 The whole point of DIY (among the other whole points of DIY) is that you can build gear just for you -- you don't need to adhere to manufacturer conventions, or do things how they were always done. Instead, you can figure out what works for you and implement it. The whole notion that one's own amp would need 48dB worth of attenuation simply says that the amp has some design problems.

 My current amp, for instance, uses an attenuator with 12 steps. I only have 6 of them wired up, and in fact have only ever used 3. The reason this works is that it is build for my ears and my source, and so is just right for me.

 And yes, I understand that some people use multiple phones and sources, but in that case, maybe a switch to switch between High Z and Low Z, or some sort of gain adjustment might be useful.

 I might point out, too, that the attenuation method used is a huge step up from a resistive attenuator which throws away signal as heat and mucks with impedance. Resistive attenuators, no matter how well made, are always detrimental. But, a well implemented TVC or AVC actually improves drive capabilities as you attenuate.

 -d


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## luvdunhill

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_I can never figure out what the heck I need to order from Dantimax to build a simple, rotary encoder controlled balanced attenuator._

 

RelVol3 and either Control1 or Control2, depending on whether you want to use a VFD display or not. You can power it with an AC wall wart, or perhaps Standby1 or Standby2 if you want a e24 type functionality.


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## luvdunhill

Quote:


  Originally Posted by *dsavitsk* /img/forum/go_quote.gif 
_IResistive attenuators, no matter how well made, are always detrimental. But, a well implemented TVC or AVC actually improves drive capabilities as you attenuate_

 

well-said.


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## Pars

Quote:


  Originally Posted by *dsavitsk* /img/forum/go_quote.gif 
_<snip>
 I might point out, too, that the attenuation method used is a huge step up from a resistive attenuator which throws away signal as heat and mucks with impedance. Resistive attenuators, no matter how well made, are always detrimental. But, a well implemented TVC or AVC actually improves drive capabilities as you attenuate.

 -d_

 

Aren't transformers, regardless of expense and materials used, still at least somewhat non-linear? Much more so than a resistor? It seems that whenever I see transformers being used, that they are rather expensive, and get more so with silver wire (Kondo?) and probably lots of other stuff I'm not even aware of. Of course I guess we aren't talking about a price comparison with an Alps Blue either


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## luvdunhill

Well, in my case I went from resistive attenuator -> gain stage -> coupling cap, to just a transformer after my gain stage. dsavitsk talks about this in his write-up linked a few posts up... definitely the best exposition on the subject I've seen.


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## pabbi1

Quote:


  Originally Posted by *dsavitsk* /img/forum/go_quote.gif 
_The whole point of DIY (among the other whole points of DIY) is that you can build gear just for you -- you don't need to adhere to manufacturer conventions, or do things how they were always done. Instead, you can figure out what works for you and implement it. The whole notion that one's own amp would need 48dB worth of attenuation simply says that the amp has some design problems.


 And yes, I understand that some people use multiple phones and sources, but in that case, maybe a switch to switch between High Z and Low Z, or some sort of gain adjustment might be useful.

 I might point out, too, that the attenuation method used is a huge step up from a resistive attenuator which throws away signal as heat and mucks with impedance. Resistive attenuators, no matter how well made, are always detrimental. But, a well implemented TVC or AVC actually improves drive capabilities as you attenuate.

 -d_

 

Agree completely - different phones, different sources, different users (at least in my house), and then IFF something should get _sold_, well, what is good for me rarely translates, or guarantees a bad transaction.

 I really like the TentLabs solution - and, since my skills lag everyone else, is the 4 input for balanced? If so, fabulous. That said, JT (from what I have heard) is a bit finicky on source - would this seem to be also?

 Finally, I simply prefer a 48 step resistive to 23 step resistive - especially where it is true I only use 5 spots or so on a stepper, it is not always the exact 5 spots preferred. 

 Besides, I struggle enough making amps work, much less dialing in their gain to match the attenuation. 
	

	
	
		
		

		
		
	


	




 We'll see what Goldpoint comes up with - maybe it is not mechanical resistive at all.


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## JamesL

It seems as the tentlab's volcontrol has 4 separate pairs of unbalanced RCA inputs, each sharing the same relay circuit, so I don't think it would work for balanced stereo.

 I could be wrong though, and it wouldn't hurt to ask them directly.

 The RelVol3 + VolControl(1-3) sold at dantimax I think would be a good alternative for a balanced attenuator though.


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## rogerlike

Quote:


  Originally Posted by *pabbi1* /img/forum/go_quote.gif 
_
 Grit (rk27)
 Unobtanim (rk40 log taper)
_

 

Isn't the Rk40 the same as the RK27, just a motorised version? (or "motorized" for my American friends ^^ )


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## nikongod

Quote:


  Originally Posted by *rogerlike* /img/forum/go_quote.gif 
_Isn't the Rk40 the same as the RK27, just a motorised version? (or "motorized" for my American friends ^^ )_

 

nope.

 Its a totally different beast. In any type of cage-match the RK40 takes the RK27 and makes it its female dog. sadly the RK40 has not been built for quite a few years, and is accordingly hard to come by.


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## cetoole

There is also the issue of different levels in the music. I have some albums which are +/-10 dB hotter than other albums, which, considering the fact that there is even more variation in the sensitivity of my various headphones, means that there is no way I could make 23 steps work to my satisfaction.

  Quote:


  Originally Posted by *Pars* /img/forum/go_quote.gif 
_Aren't transformers, regardless of expense and materials used, still at least somewhat non-linear? Much more so than a resistor? It seems that whenever I see transformers being used, that they are rather expensive, and get more so with silver wire (Kondo?) and probably lots of other stuff I'm not even aware of. Of course I guess we aren't talking about a price comparison with an Alps Blue either 
	

	
	
		
		

		
		
	


	


_

 

What, you mean fancy stuff like cobalt laminations? Yeah, transformers can get pricey.

 Rogerlike, the Alps RK40 is much larger than the RK27, and better made. Also, it is black, thus the nickname, Black Beauty.


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## rogerlike

Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_nope.

 Its a totally different beast. In any type of cage-match the RK40 takes the RK27 and makes it its female dog. sadly the RK40 has not been built for quite a few years, and is accordingly hard to come by._

 

D'oh

 RK27 Motorised = Blue Beauty
 RK40 = Black Beauty

 I think? This is what I get for trying to discuss something I know nothing about


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## n_maher

Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_nope.

 Its a totally different beast. In any type of cage-match the RK40 takes the RK27 and makes it its female dog. sadly the RK40 has not been built for quite a few years, and is accordingly hard to come by._

 

Indeed the RK40 is superior in everyway to the RK27. I once happened upon 4 of them about to make a poor helpless RK27 their lunch.






 Now, about Doug's point about gain matching. Part of the issue for me is that the source material that I listen to varies wildly and levels can be all over the map. I've had several instances where switching between CD's resulted in a 50% volume difference. No way a 6 or 12 step adjustment is going to be able to cope with that. I also use several different sources that each have a different output level, further muddying the waters. Finally, I've got amps that I use for both speakers and headphones where when listening to headphones I might hover in the 9 to 10 o'clock position and require fine adjustment but when I switch to speakers I'm in the 3 to 4 o'clock range. 

 And don't autoformer type attenuators still require a switch and have a limited number of positions?


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## luvdunhill

Quote:


  Originally Posted by *rogerlike* /img/forum/go_quote.gif 
_D'oh

 RK27 Motorised = Blue Beauty
 RK40 = Black Beauty

 I think? This is what I get for trying to discuss something I know nothing about _

 






http://cgi.ebay.it/Potenziometro-vol...05126001r14920


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## rogerlike

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Indeed the RK40 is superior in everyway to the RK27. I once happened upon 4 of them about to make a poor helpless RK27 their lunch._

 

wow, that is awesome. OK now carry on...


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## nikongod

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_And don't autoformer type attenuators still require a switch and have a limited number of positions?_

 

yes, but they way they attenuate is different. 

 Rather than just throwing signal away (slipping the clutch to get something with 1 highish gear going...), they act like many gears in a transmission. I dont think that the fact that there are switches in the signal path is that big of a deal: the problem is that there are resistors in the signal path wasting signal. 

 I think another important thing is that he runs an output transformer (or auto-former) in most of his amps. This also counts for a LARGE amount of "total gain" reduction in open-loop tube amps. With multiple output taps, you could get by with an attenuator with only a few positions and a variety of headphones.


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## n_maher

Ari,

 I'm not at all concerned with the switch being in the signal path, my thought was more running along the lines of the fact that with a TVC or whatever you're still limited to using a mechanical switch and the affordable versions of those are generally limited to 24 positions.


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## pabbi1

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_Potenziometro volume stereo Alps RK40 100Kx2 Log. su eBay.it Componenti elettronici passivi, Elettronica ed ElettricitÃ*, Audio, TV, Elettronica_

 

Well, the good news is that there are still 5 of them... too bad they are $400 for the bunch... well, IF he ships to the US, as my Italian is a little rusty. Still tempted to get a couple.


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## luvdunhill

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_you're still limited to using a mechanical switch and the affordable versions of those are generally limited to 24 positions._

 

I'm using relays.

 there there is something like this, dual mono:







 or this 2-deck, 24 position switch for $20






 I paid around $30 for a 4-deck version of the same switch. Ari has posted a lot of great links in other threads for decent switch vendors.

 I still prefer the flexibility of relays though..


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## cetoole

Gosh darn, $75+ship for an RK40? I had no idea these got so expensive. Do those of you who have tried both feel that they are of similar quality to the CP2511? I was planning on using one of my 50k RK40 for volume control on my 300B project, and maybe another for a 'stat amp.


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## pabbi1

Well, the TKD cp2511 just don't sound as good to me as the cheap smd Taiwan attenuators (when they are well behaved). Could be any number of things, but I just won't use them again. While the sale at PcX helped, I might rather take a shot on the rk40 for almost the same money. Oh, they still kick the snot out of the rk27, but anymore, that isn't saying much.

 To date, nothing has bested the Goldpoints, including a DACT CT-2(?), and not sure why I have wasted so much time and money not just sticking with them, as, in the end, it has not saved me anything.


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## JamesL

For those who've tried it, how do you feel about the noble ap25? They're only a little more expensive than the RK27's, but I haven't seen much of it around here.


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## cotdt

My experience is the same as dsavitsk, 23 steps is more than enough if the gain is set properly. Most headphones, and even speakers, need pretty similar voltage gain. Actually for the majority of headphones you don't need voltage amplification at all.

 If 23 steps really isn't enough, you could always add a pre-attenuation switch (AKA "gain" switch) like I did for a Beta22 I built for amb's gallery.


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## luvdunhill

Quote:


  Originally Posted by *cotdt* /img/forum/go_quote.gif 
_my experience is the same as dsavitsk, 23 steps is more than enough if the gain is set properly. Most headphones, and even speakers, need about the same voltage gain._

 

did you read his post? you're saying the exact opposite of what he was arguing...


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## cotdt

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_did you read his post? you're saying the exact opposite of what he was arguing..._

 

I just reread his post and not sure what you mean. We're both saying that 23 steps is enough. He argues for basically using 1dB steps in the region where you typically listen to headphones, which has its drawbacks. I'm saying that you can instead just set a low gain on your headphone amp, or use a pre-attenuation switch. I mean, who listens to headphones that need +-20V voltage swing anyway?


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## luvdunhill

Quote:


  Originally Posted by *dsavitsk* /img/forum/go_quote.gif 
_My current amp, for instance, uses an attenuator with 12 steps. I only have 6 of them wired up, and in fact have only ever used 3. 
 -d_

 

I thought his point was 24 steps is way more than anyone would need.


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## cetoole

I was considering getting an attenuator from that other site, pabbi, which I see you are also getting some from. I held off because I recalled how dissatisfied I have been with these big volume increments. I was hoping you would say the TKD CP2511 were almost as good, though if the RK40 is, I will be happy, as I still have the three I bought from the JBL tent sale a few years ago. I mainly use Nobel AP25 pots in my builds, but that is more because I picked up a sack of them surplus for $2 each, so didnt see the point in buying RK27 pots.

  Quote:


  Originally Posted by *cotdt* /img/forum/go_quote.gif 
_I mean, who listens to headphones that need +-20V voltage swing anyway?_

 

Besides people with 'stats, 'trets, or piezos? Ortho heads take a pretty good amount of drive.


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## pabbi1

To be fair, they seem to be settling down a bit (I do believe in burnin), but these sounded better. I was also hoping the TKD would be the end of the road, except I am itching to try the TKD 2P65S, as an end of the road for me, knowing I am NOT going rk50.

 I am going with the DACT as a known quantity, for $100 less than the equivalent Goldpoint, but was going Goldpoint or with the TKD IFF the design warrants it - hopefully it will. In fact, the TKD were purchased for the new thing, but the crap attenuators in the Bijou forced my hand.


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## cetoole

How about Penny & Giles rotary faders? Those are infinitely adjustable right? Shallco also makes some good attenuators, up to something like 45 steps, IIRC.


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## nikongod

Quote:


  Originally Posted by *cetoole* /img/forum/go_quote.gif 
_Besides people with 'stats, 'trets, or piezos? Ortho heads take a pretty good amount of drive._

 

The electrostatics/piezo's do need more than 20v swing, but I think its safe to assume that since they will need a dedicated amp they can be considered separately. They still get by with less then 60dB of range.

 orthodynamics dont take much more voltage than "cone and coil" dynamics. You may wind up shooting yourself in the foot with output impedances... but we are just talking about voltage swing 
	

	
	
		
		

		
		
	


	




 even if you consider the effects of highish output impedance on a low-impedance headphone you will probably still find you dont need 60db of control range to cover most dynamic (non-K1000) headphones.

 1v (RMS) will make virtually any dynamic headphone play at stupid volume levels (including orthodynamics). The fact that the amp can swing 20v is barging rights and overhead. Is it worth adding more active parts to get a few dB of extra voltage headroom? I certainly agree there is a point below which your "headroom" is Inadequate, but once you pass that point... When you view active parts as distortion generators as well as voltage/current manipulators more is not necessarily better.

 The fact that the amp has unity gain (or is an attenuator) does not detract from its ability to pass large signals. There are buffers designed to pass at least 20v. The nelson-pass/first watt F4 comes to mind.


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## fishski13

pabbi1,
 i think you ought to try a ground-shunt - 2 deck for unbalanced, and 4 deck for balanced. i can send you the BOM from Mouser and schematic i used for my attenuators in my Bijou. 23 positions is more than enough for both my HD650 and K701 with 1 dB steps over the critical range. 

 i have a good line on some D9 Electroswitches at 1/2 price, but they're a bit "industrial" in turn-over force. definately not "consumer grade".


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## nikongod

why not a straight shunt with 2 decks?

 2*100K plus a 10-K-ohm attenuator should skim offf extra gain plenty well.


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## fishski13

Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_why not a straight shunt with 2 decks?

 2*100K plus a 10-K-ohm attenuator should skim offf extra gain plenty well._

 

straight shunt??? got a schematic? how do you deal with 4 channels with only 2 decks?


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## fishski13

something like this, in Fig. 2:Kit Upgrades ?


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## nikongod

link

 davistk posts a good schematic.

 Considering the problems getting the attenuation of a pot EQUAL for both legs (not +-2db, equal is +-0dB, which matters for balanced wiring) and the unavailability of good 4-deck pots....


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## luvdunhill

this will be available soon, and is a solid design:

diyAudio Forums - PoorSerbianMan Lightspeed - Page 1


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## fishski13

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_this will be available soon, and is a solid design:

diyAudio Forums - PoorSerbianMan Lightspeed - Page 1_

 

i need to keep tabs on this one. 

 i would like to try building a Nelson Pass pre-amp, and see if i can find a DAC design that would be comparable to my BM DAC1.


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## fishski13

Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_link

 davistk posts a good schematic.

 Considering the problems getting the attenuation of a pot EQUAL for both legs (not +-2db, equal is +-0dB, which matters for balanced wiring) and the unavailability of good 4-deck pots...._

 

thanks!


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## luvdunhill

Quote:


  Originally Posted by *fishski13* /img/forum/go_quote.gif 
_i need to keep tabs on this one. 

 i would like to try building a Nelson Pass pre-amp, and see if i can find a DAC design that would be comparable to my BM DAC1._

 

better keep an eye on this thread then, as they will go quick:

Pass DIY: Store


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## fishski13

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_better keep an eye on this thread then, as they will go quick:

Pass DIY: Store_

 

thanks, i see that. i wouldn't mind trying to design a PCB as well.


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## BrianDonegan

Quote:


 That said, JT (from what I have heard) is a bit finicky on source 
 

Please explain...


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## n_maher

Quote:


  Originally Posted by *BrianDonegan* /img/forum/go_quote.gif 
_Please explain..._

 

I think he's referring to the lower-than-typical impedance that the JT presents to the source, which with tube output gear is definitely below the standard 10x multiplier (desired input impedance = source output impedance x 10). From what I've read the JT load is as low as 2k.


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## BrianDonegan

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_I think he's referring to the lower-than-typical impedance that the JT presents to the source, which with tube output gear is definitely below the standard 10x multiplier (desired input impedance = source output impedance x 10). From what I've read the JT load is as low as 2k._

 

Ah, I always forget about high output-impedance gear... 
	

	
	
		
		

		
			





 Makes sense.


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## n_maher

Quote:


  Originally Posted by *BrianDonegan* /img/forum/go_quote.gif 
_Ah, I always forget about high output-impedance gear... 
	

	
	
		
		

		
		
	


	




 Makes sense._

 

Yeah, I think I've seen some tube stuff measured in Stereophile with output impedances in the 500ohm range which might not play so nice with the JT. Or at least that's what the technically minded folks tell me. I'm just a round hole cutter tech.


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## pinkfloyd4ever

to fishski and luvdunhill: The B1 can definitely be built on protoboard, as many have done. Heck it can even be built with neither protoboard or PCB as seen here


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## pabbi1

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_I'm just a round hole cutter tech._

 

Gonna have to call BS on that one.


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## dsavitsk

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Yeah, I think I've seen some tube stuff measured in Stereophile with output impedances in the 500ohm range which might not play so nice with the JT_

 

600 ohm is standard, and common, and 2K is too low for the next stage. In fact, 2500 Z out is not uncommon -- anything where the output is taken from the plate of a 6dj8 fits that description.

 I've built sources with a Z out in the 7 or 8K range. You (hopefully*) won't find commercial gear like that, but pushing short cables and an easy (250K) load it was fine.



 *I wouldn't have thought I'd find a pot being sold as a generic volume control in the 2K range either, at least not without a big warning -- live and learn.


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## n_maher

Quote:


  Originally Posted by *dsavitsk* /img/forum/go_quote.gif 
_*I wouldn't have thought I'd find a pot being sold as a generic volume control in the 2K range either, at least not without a big warning -- live and learn._

 

Doug, 
 In fairness to the Twisted Pear guys the JT is sold as a DIY module and as such I think the burden of deciding whether or not it's use is applicable is on the end user. Now if they tried to hide the fact that it's a low impedance attenuator that'd be one thing but it's always been out in the open.


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## pabbi1

I will stand up and admit I was rather harsh on the TKD - as a believer in burn in, it would have been better had I waited a week to bag on them. They are actually quite nice, no grit, and very smooth action. Worth the $85 (on sale), and maybe the $99.


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## Pars

Quote:


  Originally Posted by *pabbi1* /img/forum/go_quote.gif 
_I will stand up and admit I was rather harsh on the TKD - as a believer in burn in, it would have been better had I waited a week to bag on them. They are actually quite nice, no grit, and very smooth action. Worth the $85 (on sale), and maybe the $99._

 

Yes, I like the TKDs alot. I thought they were still around $65 not on sale?


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## pabbi1

PartsConnex has a Log A version that is $99. ThlAudio quoted me a price, but not sure if it was 1x or 2x, and then there is shipping... if there is another source for Log A cp2511, I am all ears, and better for cp65s, which I really want to try, especially now... well, pending price.


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## BrianDonegan

Quote:


  Originally Posted by *n_maher* /img/forum/go_quote.gif 
_Doug, 
 In fairness to the Twisted Pear guys the JT is sold as a DIY module and as such I think the burden of deciding whether or not it's use is applicable is on the end user. Now if they tried to hide the fact that it's a low impedance attenuator that'd be one thing but it's always been out in the open._

 

I guess you have to weigh it against the wide ranging output impedance you get from a pot or stepped attenuator. JT's output fixed at 750R. If you don't mind high output impedance, you can always choose R values that will raise the input impedance but maintain fixed output Z. Perhaps this would be a valuable offering for "tubies." The current config was targeted at our solid state gear (and most other).


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## Pars

Quote:


  Originally Posted by *pabbi1* /img/forum/go_quote.gif 
_PartsConnex has a Log A version that is $99. ThlAudio quoted me a price, but not sure if it was 1x or 2x, and then there is shipping... if there is another source for Log A cp2511, I am all ears, and better for cp65s, which I really want to try, especially now... well, pending price._

 

I personally like the std. CP2511 log curve much better than the Alps curve, so I won't be paying additional to get the Log A curve from Partsconnexion (CP2508?). Both of my TKDs came from Percy Audio.


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## dsavitsk

Quote:


  Originally Posted by *BrianDonegan* /img/forum/go_quote.gif 
_I guess you have to weigh it against the wide ranging output impedance you get from a pot or stepped attenuator. JT's output fixed at 750R. If you don't mind high output impedance, you can always choose R values that will raise the input impedance but maintain fixed output Z. Perhaps this would be a valuable offering for "tubies." The current config was targeted at our solid state gear (and most other)._

 

If there is a way to configure it to have a highish Z in, then I have no complaints. I think the design is pretty cool. Well, I do have one complaint, which is that it takes a little digging to find the input impedance -- the only place I found it was in the third post of the design thread, which seemed like a long way to go to find this. This seems like the sort of thing that should be right up front, perhaps with instructions on how to increase it.

 In addition to tube gear with a high Z out, this matters for coupling caps. You need a huge cap into 2500 ohms, and a decent one, if you can find one, costs more than the pot. I think a lot of commercial gear is going to come up short in this regard


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## fishski13

nikongod and dsavitsk (a.k.a. The Crusher), 
 thanks guys!!! i re-wired my Balanced Bijou with only one 2 deck attenuator. it sounds/works great, and sooooo much cheaper 
	

	
	
		
		

		
			





.


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## nikongod

Quote:


  Originally Posted by *fishski13* /img/forum/go_quote.gif 
_nikongod and dsavitsk (a.k.a. The Crusher), 
 thanks guys!!! i re-wired my Balanced Bijou with only one 2 deck attenuator. it sounds/works great, and sooooo much cheaper 
	

	
	
		
		

		
		
	


	




._

 

Glad you like it 
	

	
	
		
		

		
		
	


	




 Before you know what hit you you'll be reducing global feedback to just enough to keep output impedance low and give good linearity while tweaking the attenuator resistors to put you back in your listening range.


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## DouglasQuaid

Any way to remove the detents on a black beauty? It's probably a really nice pot, but the fact that it acts like a stepped attenuator but isn't as good as one bothers me a bit. BTW, I had an ebay stepped attenuator go bad on me.


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## n_maher

Quote:


  Originally Posted by *DouglasQuaid* /img/forum/go_quote.gif 
_Any way to remove the detents on a black beauty?_

 

Yes, you can, but you have to disassemble part of it. I'll leave it up to you as to whether or not that is worth it.


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## digger945

Just wanted to say thanks for the info on the AVC. 
 I think this is what I'm gonna go with, either the Intact or Slagleformer.

 Bump for any new info.


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## digger945

Well an email back from John Chapman is suggesting I use a Goldpoint for my balanced needs.
 Turns out autoformers are a pain to configure for a balanced amp.
 I will see what Dave Slagle at Intact Audio says about his products before looking into building my own.


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## Bosk

Sorry to dig up an old thread but I have a quick question.

 I'm using a DAC-AH and T-amp with my PC as source and am currently bypassing the cheap volume pot on the T-amp and using the PC to control volume. 
 Will this give me superior sound quality or would a stepped attenuator be better?

 I was thinking that the best volume pot is no volume pot, but I know there are disadvantages of using Windows to control volume also.

 Cheers.


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## MoodySteve

It's generally considered a bad idea to lower volume in the digital domain - doing so is changing the 0s and 1s.

 Try upgrading the pot - I think a stepped attenuator is a big step up from a 'cheap pot.' Have you tried the ubiquitous Alps RK27?


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## Bosk

Quote:


  Originally Posted by *MoodySteve* /img/forum/go_quote.gif 
_It's generally considered a bad idea to lower volume in the digital domain - doing so is changing the 0s and 1s.

 Try upgrading the pot - I think a stepped attenuator is a big step up from a 'cheap pot.' Have you tried the ubiquitous Alps RK27?_

 

Not yet, I figured that I'd try it without any pot and just buy an eBay stepped attenuator if folks suggested I buy a volume control.

 I guess there's no harm in doing that, and if I prefer it without the pot just desolder it out.


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## lacrossebowe8

I would love to find a remote relay attenuator for a decent price. There is one design on diyaudio but I have not heard back from the builder when I emailed him. 

diyAudio Forums - New project : R-2R Attenuator With Remote Control V2 - Page 1

 There is also welborne, but that is expensive, esp. for balanced. There are the dantimax ones too but they appear to have little documentation. Are there any others to consider?


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## MoodySteve

^^^ I was discouraged by the 500mA current draw of that attenuator. That's more than almost any headphone amp.


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## lacrossebowe8

Wow that's huge. Why would it need so much?


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## nikongod

Quote:


  Originally Posted by *lacrossebowe8* /img/forum/go_quote.gif 
_Wow that's huge. Why would it need so much?_

 

its running relays and a few other things. they draw LOTS of current to run. The good news is that the power supply for the relays are (sort of, there is something of a debate elsewhere on this: you are as right as he is wrong. he can say the same for you...) not in the audio circuit so you can use a cheap regulated wall-wart to supply the relay's on the boards and build the audio PS the way you want. build the wall-wart into the amp and never think about it again. if you like the idea of that thing, use it.

 The melos uses 600ma to idle the output stages. (300ma each) More if you use russian tubes.

 A dynalo uses about 500ma between both channels.
 A dynahi uses "whoa my gosh" on 1 board.

 A couple others (b22/millet hybrids/M^3) can be made to run into the few hundred ma ranges per channel.


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## lacrossebowe8

I see. I may try it. Its cheap at least!


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## pabbi1

Noble alert - for real? Worth it?


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## spritzer

These look like split pots (think Stax) but other then that they should be excelent. I would certainly take a Noble pot over an Alps RK27 any day.


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## digger945

Recieved both stereo and balanced DACT attenuators in the mail today.
 These things are much smaller than I expected, and the rotary switching detents have a very smooth action (read quality).
 I'm getting anxious to use them now.


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## pabbi1

Yes, I got one balanced DACT 50k as well, and will order another. VERY nice action.


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## digger945

I think I'm gonna order a couple more stereo as well
	

	
	
		
		

		
		
	


	



 Just finished adding some Molex connectors and terminals to the mouser order.


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## 22906

Quote:


  Originally Posted by *DouglasQuaid* /img/forum/go_quote.gif 
_Any way to remove the detents on a black beauty? It's probably a really nice pot, but the fact that it acts like a stepped attenuator but isn't as good as one bothers me a bit. BTW, I had an ebay stepped attenuator go bad on me._

 

Dude your sig is kind of misogynist... pretty funny though.


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## MoodySteve

I hope this doesn't mean what I think it may...

 With my CDP connected to my ß22, I can hear the characteristic light hiss of Johnson noise; it gets louder as I turn the volume up UNTIL I approach the end of its range, where it's very nearly shorting the input to the output. At this point, the noise basically vanishes.

 Does this mean that all the noise I'm hearing is from the pot?


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## Bojamijams

Sorry Steve, I can't answer your questions but on the topic of attenuators I have another q.

 I couldn't find anything with attenuators in the wiki's so I ask here.

 Do all attenuators exhibit the trait of where they operate 'best' in only a certain range? For those that do exhibit that trait, is the 12 o'clock position always 'best'?

 Where I'm going with this is.. should gain be set so that with the given headphones the volume on your amp is near 12 to assure you have the best sq?


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## m1abrams

Quote:


  Originally Posted by *Bojamijams* /img/forum/go_quote.gif 
_Sorry Steve, I can't answer your questions but on the topic of attenuators I have another q.

 I couldn't find anything with attenuators in the wiki's so I ask here.

 Do all attenuators exhibit the trait of where they operate 'best' in only a certain range? For those that do exhibit that trait, is the 12 o'clock position always 'best'?

 Where I'm going with this is.. should gain be set so that with the given headphones the volume on your amp is near 12 to assure you have the best sq?_

 

if you mean step attenuators they do not exhibit this trait. Potentiometers do exhibit something similar to what you describe but the issue is only at low volume. Basically at low volumes they tend not to track well, ie left and right channels have different volumes. More expensive ones have less issue.

 It is best to select a gain so that you do not have the pot set to a very low setting. However shooting for right at 12 is not needed, in fact shooting for the up end of the pot is probably better to go for. Easier to do if you know exactly what headphones you will always use with the amp.


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## Bojamijams

I seem to like low z cans (ones in sigs and I'm sure I'll get a grado rs-1 at some point soon too) so I was thinking of building this with a gain of only 2. But then if I ever want to run the HD800 I'll be screwed. Maybe. 

 Do you think it'd be better to just build it at gain of 5 and that way I'm relatively covered for low and high z? Or build a relay that switches from 2x and 8x gain?


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## les_garten

Quote:


  Originally Posted by *cetoole* /img/forum/go_quote.gif 
_Fortunately, some of us here are sitting on a small supply of RK40 and AP25 pots. Have you tried LDRs or Broskie's attenuator, pabbi?_

 

When you said that, you sounded like Newman Hoarding Victoria's Secret Catalogs!

 .


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## MoodySteve

FYI, it appears that an eBay seller in Germany has a small lot of Alps RK40s in stock.

eBay My World - familygate

 I see only linear in his listing now, though I swore I saw log earlier today (edit), but I have not purchased from him myself.


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## K3cT

Quote:


  Originally Posted by *MoodySteve* /img/forum/go_quote.gif 
_FYI, it appears that an eBay seller in Germany has a small lot of Alps RK40s in stock.

eBay My World - familygate

 I see only linear in his listing now, though I swore I saw log earlier today (edit), but I have not purchased from him myself._

 

Would it be advisable to use a Linear attenuator like that in place of the usual Logarithmic one?


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## spritzer

You would have to "fake" the log curve but it can be done.


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## pabbi1

Anyone tried the AudioNote:

Audio Note 100K Audio/Log Taper Stereo Volume Control

 May OJ this, or back to the trusty TKD (more on that later) for the new SS thingy I built - and really like.


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## spritzer

Some news on my end, I got the shipment of these pots which I had custom made for me. 4-gang, 50K with specs equal to or better then the RK27. Also smaller and sounds pretty good in my BH.


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## pabbi1

JUST got a deal on a 2P65CS - now I just have to get an RK50 to see what's what...


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## fishski13

i just bought a TKD CP2511 yesterday. i'm getting fed up with the noise on my PEC pots (understatement). yesterday, my PEC on the B22 just went bad, the PEC in my M3 went from bad to worse, and i found out the PEC in an am i built for a friend is bad now - bad pot day. the only quiet PEC i have is in my Bijou, but then again it's only been in service a week. i'm tempted to try to crack one open to see if i can get at the tracks/wipers for a squirt clean.


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## pabbi1

Sad, as those PEC were all the rage a year ago... and the CP2508 have been fabulous for years.

 Also got a CP2511 as a backup in case the CP65 won't fit (fat chance), but got both for $210, which works any way I look at it. Finally, a decent 42 step attenuator, at a price I can justify.


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## Lil' Knight

Quote:


  Originally Posted by *spritzer* /img/forum/go_quote.gif 
_Some news on my end, I got the shipment of these pots which I had custom made for me. 4-gang, 50K with specs equal to or better then the RK27. Also smaller and sounds pretty good in my BH._

 

Looks nice. Any more info (price?) about this?


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## spritzer

Nice score on that 2CP65 Al.  I've got some 4CP2508's incoming and some 4CP601's which should be a fun comparison. 

  Quote:


  Originally Posted by *Lil' Knight* /img/forum/go_quote.gif 
_Looks nice. Any more info (price?) about this?_

 

Nope since these can only be bought in batches of 100 at a time and the price is always a personal quote. So yes, I did buy 100 of them. :tongue_smile:


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## nattonrice

With the rate you churn stuff out that's not gonna last the year


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## spritzer

Hehe


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## K3cT

Quote:


  Originally Posted by *spritzer* /img/forum/go_quote.gif 
_You would have to "fake" the log curve but it can be done._

 

I guess that will not be a possible option for B22 as Ti will kill me if I add resistors in between the pot and the boards.  

 That said, how do you potentiometer aficionados say about this TKD CP2511 pot here? It seems to be popular but first hand anecdotes will be very welcome. A local store has the 50K log Black Beauty but for the asking price, I might as well use a Stepped Attenuator...

 EDIT: Perhaps I spoke too soon. I'm reading through this thread now.


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## nikongod

Quote:


  Originally Posted by *K3cT* /img/forum/go_quote.gif 
_I guess that will not be a possible option for B22 as Ti will kill me if I add resistors in between the pot and the boards. _

 

The shunt resistor goes in parallel to one of the sections of the pot if you are trying to make a linear taper pot work like an audio one.

 On that note, the pot is nothing but a resistor or 2 between the source and the board.


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## pabbi1

Quote:


  Originally Posted by *K3cT* /img/forum/go_quote.gif 
_That said, how do you potentiometer aficionados say about this TKD CP2511 pot here? It seems to be popular but first hand anecdotes will be very welcome. A local store has the 50K log Black Beauty but for the asking price, I might as well use a Stepped Attenuator..._

 

Long time fan, and used them in the Bijou (balanced, so x2), and just bought another. It is my current choice for best available at a reasonable price, well, or reasonable for the topologies we are talking about. I have this intense curiosity for how much better the 2p65 is over the cp2511, but just never could quite look at the cp601. *Tthink* I have a new build worth a killer pot, and not very likely to build SE ever again, so... but the 2511 is years ahead of the rk27. Just a better resistor, akin to Riken or Takman vs Xicon (though I use Xicon a LOT - just can't use them for everything).

 Really wish someone could report on the Audio Note - at $30, that might be the interim step for something not quite up to a $75 pot, but deserving more than a rk27.


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## K3cT

Quote:


  Originally Posted by *nikongod* /img/forum/go_quote.gif 
_The shunt resistor goes in parallel to one of the sections of the pot if you are trying to make a linear taper pot work like an audio one.

 On that note, the pot is nothing but a resistor or 2 between the source and the board._

 

Ah, OK. I foolishly thought that the process involved adding resistors between the B22 board and the potentiometer. :redface: Thanks for the correction, man. 

  Quote:


  Originally Posted by *pabbi1* /img/forum/go_quote.gif 
_Long time fan, and used them in the Bijou (balanced, so x2), and just bought another. It is my current choice for best available at a reasonable price, well, or reasonable for the topologies we are talking about. I have this intense curiosity for how much better the 2p65 is over the cp2511, but just never could quite look at the cp601. *Tthink* I have a new build worth a killer pot, and not very likely to build SE ever again, so... but the 2511 is years ahead of the rk27. Just a better resistor, akin to Riken or Takman vs Xicon (though I use Xicon a LOT - just can't use them for everything).

 Really wish someone could report on the Audio Note - at $30, that might be the interim step for something not quite up to a $75 pot, but deserving more than a rk27._

 

Much appreciated! How would you compare the CP2511 with the famed Black Beauty? 

 And if my understanding is correct, this CP2511 one is smooth and doesn't go "click click click" when you turn the knob right?


----------



## Lil' Knight

Quote:


  Originally Posted by *K3cT* /img/forum/go_quote.gif 
_And if my understanding is correct, this CP2511 one is smooth and doesn't go "click click click" when you turn the knob right?_

 

Yes. Very smooth.


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## spritzer

Quote:


  Originally Posted by *K3cT* /img/forum/go_quote.gif 
_And if my understanding is correct, this CP2511 one is smooth and doesn't go "click click click" when you turn the knob right?_

 

It's an option when the pots are ordered so depending on the source, they might be stepped


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## pabbi1

The 25xx (11 or 08) are exceptionally smooth, with no fake steps. It is also the most neutral pot I have found (my Acoustic Dimensions is a stepped attenuator).

 I personally prefer it over any ALPS or Noble (still better than Alps) pots, save for the RK40 (unobtainium) and the RK50, which I have not yet had the pleasure (at $580 each). 

 My dislike for the rk27 (or rh27) knows no bounds, like a belt sander grinding away the last 1% of resolution - heck, maybe the last 5%. It is ok in some places, but a 'good' amp deserves better. Oh, it could that be the most widely faked part in all DIY, so who knows if half are even what they are supposed to be.


----------



## spritzer

Quote:


  Originally Posted by *pabbi1* /img/forum/go_quote.gif 
_The 25xx (11 or 08) are exceptionally smooth, with no fake steps._

 

25xx are smooth and 25xxS are stepped. Just look at the data sheet. 

  Quote:


  Originally Posted by *pabbi1* /img/forum/go_quote.gif 
_...so who knows if half are even what they are supposed to be._

 

It's easy enough to check, by looking at the trace. I had to open one up just to be sure and it was authentic.


----------



## pabbi1

Good to know about the 'S' - learn something new every day. Still, the 2511 isn't talked about nearly as much as it should be - maybe folk think $75 is excessive for a pot?

 Dunno - maybe the fake rk27 sound better?


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## K3cT

Thanks for the helps so far guys, I really appreciate it. I've dropped Michael Percy and Partsconnexion an E-mail for quote requests so we will see. I'm honestly not financially ready to invest in an expensive Stepped Attenuator now so this will do for the time being.


----------



## pabbi1

thlaudio web site pages is for sure closer, maybe even cheaper, especially on shipping.


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## K3cT

Thanks for the heads up Pabbi. It appears that they only have the "S" version available for the 2511. I seem to have a preference for the smooth one but I'm open to suggestions.


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## pabbi1

Just changed out a (wretched, awful, putrid) rh2702 with a TKD 2511 - just stunning the difference. Let me start with the proviso that not every amp needs a better attenuator, buit, for those that do, TKD is the cheapest EASY upgrade (yeah, leaving all the digital attenuators aside for the moment, as they are not easy for me). The new amp is complete, well, except for that linear instead of audio taper thing... but the incoming 2cp65 is audio taper...


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## fishski13

cool.  the TKD 2511 for my B22 should hopefully be here soon.  the PEC from the B22 now sits in my recently finished B1 buffer.  the noise on this particular PEC "cleans up"  with a few rotations and hopefully won't be noticeable through 89dB speakers. 

  
  Quote: 





pabbi1 said:


> Just changed out a (wretched, awful, putrid) rh2702 with a TKD 2511 - just stunning the difference. Let me start with the proviso that not every amp needs a better attenuator, buit, for those that do, TKD is the cheapest EASY upgrade (yeah, leaving all the digital attenuators aside for the moment, as they are not easy for me). The new amp is complete, well, except for that linear instead of audio taper thing... but the incoming 2cp65 is audio taper...


----------



## fishski13

i have the TKD in the B22.  nice pot and well balanced from top to bottom.  more detailed and focused than the PEC, with a blacker background, and less "diffuse" sounding.  the PEC has a more mid-range emphasis that i miss.  the TKD has the best bass i've ever heard from any of my HP set-ups.  tade-offs i guess.  but the TKD is miles ahead of the PEC with respect to tone and timbre in the B22.  it can groove too.  jesus, it's just conductive plastic fer christ-sakes 
	

	
	
		
		

		
		
	


	




. 
   
  i'm going to pick up another TKD for my M3 to bring to CanJam.


----------



## K3cT

I ended up with the TKD after all. Let's hope that I made the right choice.


----------



## slowpogo

I use the TKD in my Millett Hybrid Max.  I didn't directly compare it with the Alps or any other pots...but I think my Max sounds as good as it possibly can, between the TKD and using Black Gate NX caps, Riken output resistors, etc.
   
  I prefer a smooth volume control to steps, and the stepped attenuators are big enough that they can thwart the typical enclosure plans of many projects, like the Max, M3, PPA2, etc.  The TKD can still be made to work...makes it an obvious choice to me.


----------



## Beefy

Sorry to resurrect such an old thread, but this does seem like the perfect place......
   
  So I bought a TKD 2CP2511 50k pot for my Crack build, and I need a sanity check. Resistance across input (pin 1) to gnd (pin C) is a constant 43kohm regardless of pot rotation, which makes perfect sense. But the resistances across the input and gnd to the output (pin 2) while turning the pot are baking my noodle.

 When moving from minimum volume up, pin 1 to pin 2 *increases* in resistance from 43kohm to a maximum of 59kohm at about 1/3 of the pot travel, then drops steadily to 10ohm. Pin 2 to pin C jumps very fast from 10ohm at minimum volume to about 3kohm in the first few degrees of rotation, then moves steadily up to 43kohm for the remainder of the rotation.

 Clearly, these TKD's don't behave like normal pots, and there is a PDF on their website explaining that their rotary faders are 'ladder' circuits. Is this the full explanation for what I am seeing, or am I just going nuts?

 Useful references: datasheet and an explanation of their ladder curve.


----------



## jdkJake

I bought one for my EHHA and noticed the same thing when I buzzed it out. So, either that is the expected behavior or we are both going nuts!
   
  I guess either is possible at this point.


----------



## hukkfinn

Is Bourns in the running at all?  Seems they use carbon instead of conductive plastic.  Thoughts?
   
  http://www.bourns.com/data/global/pdfs/PDB24.pdf  (one example)


----------



## hukkfinn

I'm gonna post an answer to my own question that I found from Mr. Wright:
   
  http://www.diyaudio.com/forums/solid-state/153841-potentiometer-overview-alps-penny-giles-tkd-vishay-more-whats-your-fav.html#post2012779


----------

