# AD8599 is bloody good



## NelsonVandal

These are only first impressions, but...

 I think we should sing it's praise! I just plugged it in, not burned in, not class A biased, only 9 V supply, no Jung multiloop. I use it in a 2 channel amp with "LISAIII" buffers. It sounds second to none. It has the "Analog snap" but not as grainy as 8397, 8620, 823 etc - very high res. It's as neutral as 744 but more exciting, yet warmer with a fuller mid and less grainy. I'm surprised. I didn't think I liked JFET and/or slow opamps.

 I've seen HiFlight hyping it, and now I know it's for a reason. I know there's other HeadFiers using it. Tell us what you think of it.

 I'll probably build a dedicated amp for this with good parts like OS-CON's etc. I wonder how it sounds class A biased or unbuffered.


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## fierce_freak

I'd certainly be interested in hearing one.


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## mrarroyo

Vorlon1 installed one in his Supermicro IV if memory serves me right. It sounded fantastic.


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## NelsonVandal

First impressions last. It's the best of three worlds - almost. Euphonic as BurrBrown, energetic as the other Analog's, clean as LM4562. I classed A biased it (1.1 mA JFET), but I'm not sure it did anything to the sound. Maybe a little smoother mid.

 AD8397 still has more slam and better bass definition but sounds very harsh and brutally forward in comparison. LM4562 is a tiny bit cleaner but lacks warmth and mid and sound distant. ADA4899-1 has a smoother and cleaner overall sound, but can be a bit "analytic".

 I think I'm going to make a simple CMOY board to find out how it sounds unbuffered. With 60 mA of output current, buffers shouldn't be needed for HD650's.

 The noise level is very low, and it'll make a good companion to IEM's.


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## kanamin

Can I just throw it in my cmoy? lolololol but seriously, can I?


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## TzeYang

Quote:


  Originally Posted by *kanamin* /img/forum/go_quote.gif 
_Can I just throw it in my cmoy? lolololol but seriously, can I?_

 

yesh you can, but no class A bias output unless you add output buffers.

 I suppose using the internal output stage (class ab) should be enough.


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## majkel

Could anyone compare AD8599 to 2xAD825? I tried class A on many op-amps, and the only op-amp I have noticed the difference on was AD825. It was optimal to set 3.5mA but after long listening sessions I realized this change is no improvement. You sacrifice one thing to emphasize something other but it's a fact that modern op-amps don't need such improvements.


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## NelsonVandal

Quote:


  Originally Posted by *majkel* /img/forum/go_quote.gif 
_Could anyone compare AD8599 to 2xAD825? I tried class A on many op-amps, and the only op-amp I have noticed the difference on was AD825. It was optimal to set 3.5mA but after long listening sessions I realized this change is no improvement. You sacrifice one thing to emphasize something other but it's a fact that modern op-amps don't need such improvements._

 

I'm sorry, I only have one AD825. I have compared 825 to 744 in ground channel. I think they both have the "Analog presence or call it snap", not sure which was better. I've compared 744 to 8599 in L/R at 9 and 12 V supply. 8599 is warmer with a fuller mid, but still has the Analog sound to it and same level of details. I haven't tried to optimize it yet (Jung multiloop and higher voltage supply). 744 for sure sounds better at 18 V and in a Jung multiloop, than 9 V and "standard" loop.


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## slowpogo

8599 is a dual chip, so what would mate well with it for the ground channel? The 744? That's what I'm going to try anyway; I have samples on the way...


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## LawnGnome

Quote:


  Originally Posted by *slowpogo* /img/forum/go_quote.gif 
_8599 is a dual chip, so what would mate well with it for the ground channel? The 744? That's what I'm going to try anyway; I have samples on the way..._

 

You could still use it a the ground channel with some changing. I can't seem to find a single version equivalent.

 How many samples does AD let you order?


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## balou

3 different chips, max 2 of each


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## LawnGnome

Quote:


  Originally Posted by *balou* /img/forum/go_quote.gif 
_3 different chips, max 2 of each_

 

Yeah, thats the same limit they let me order. Do they ever let you order more?

 Texas instruments has already let me order over 60 opamps.


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## koike

i guess its the same all over the world.


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## slowpogo

Quote:


  Originally Posted by *LawnGnome* /img/forum/go_quote.gif 
_You could still use it as the ground channel with some changing. I can't seem to find a single version equivalent._

 

Would that be as simple as clipping the leads for either the R or L channel, so you're left with one? Or would it require some ingenuous DIY reworking?


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## koike

just dont connect the leads?
 lol.


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## NelsonVandal

Quote:


  Originally Posted by *slowpogo* /img/forum/go_quote.gif 
_Would that be as simple as clipping the leads for either the R or L channel, so you're left with one? Or would it require some ingenuous DIY reworking?_

 

You can use the other channel in unity gain with 2 resistors as rail splitter à la PINT, and you'll save a TLE2426
	

	
	
		
		

		
			





 . Look at the schematic at Tangent's.


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## slowpogo

I've got the 8599 in my Pimeta L/R w/ discrete buffers, 744 (comp pin) in ground. It sounds amazing!! I really liked the AD744 in L/R, but the 8599 seems to have everything I liked about the 744 and more of it. It's incredibly clear, with a spacious image. The bass has been tightened very nicely over the 744; in rock, I can actually hear the bass instrument now, string scrapes, fret sounds and everything, but the low end is still nice and beefy and tight. With the 744, the bass was fat and wide, but not very refined.

 I'm going to class A bias it next. Really glad I tried it out...


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## majkel

OK guys, so I'll put at least two AD8599's in my CD player to replace some JRC and Mitsubishi stuff. If it sounds better than AD744 for channels (which I find snappy and natural but a bit too sibilant and cold) it should be good, isn't it? 
 Maybe it's a bit off topic but what else would you recommend to place in my CD player? I can use only dual SOIC op-amps. Those of my preference are: AD8066, OPA2604, AD8599, AD8022, AD8620 (not so much), LM4562 (cannot get it), LM6172. For I/V stage I would use a JFET input op-amp because of low input current so AD8066, OPA2604, maybe AD8620. For second stage/filter could be AD8599, LM4562, any of the previous, and output buffer I would see AD8599, AD8022, LM6172. 
 The chips I don't touch any more are: OPA2134, OPA2227, AD823, jellybeans
 2-1 adapter won't work either, unless it is SOIC-SOIC. Are there any such?


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## LawnGnome

I'd say try the AD8066. After some testing with some of the other opamps you mentioned, I find the AD8066 great.

 I find it has a good mix between soundstage, detail, and energy. 

 This is in an x-fi mind you.


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## majkel

@LawnGnome, I agree with your description. I tried single op-amps on the ground channel of my amp and the only I really like are AD825, AD8065 and OPA604. The last one is a bit laid back which only confirms it's Burr-Brown.


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## holland

I've tried an AD8066 in a CMoy, but I hit oscillation issues with 32-ohm headphones and am working on resolving it. I'm concerned about the AD8066 in an X-Fi. With an LM4562 in there, there's 30mV of DC offset on my X-Fi with the caps in place and 180mV without, which kinda sucks. I'm thinking the resistors are too high in value, I will try to measure when I take it out again.

 What is the DC offset you are getting with the AD8066 and do you have the 4 caps in place or not?


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## holland

NelsonVandal, since you seem to be on an AD kick lately, have you tried the AD9632? I've been wanting to try it out, but I always forget to buy it when I place my digikey orders.


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## majkel

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_What is the DC offset you are getting with the AD8066 and do you have the 4 caps in place or not?_

 

When I tried it last time as the only op-amp on the channels side I have never had more than 4mV of offset. It's probably due to oscillations its offset is crazy because FET inputs don't draw significant currents and there is no way to produce such offset. You can use values for the feedback like in the PINT - low noise version, and make the amp DC coupled on the input side. Otherwise you don't allow the offset to be fully compensated. At gains around 5 there are no oscillations on the AD8066 and I don't populate any caps in the feedback loop. However I heard many times AD8066 oscillates when dropped into a CD player as a replacement. I guess the reason is it's intolerance to capacitive loads. Also, in buffered circuits with global feedback loop it gets unstable.


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## LawnGnome

.03V offset.

 The caps are not shorted, and have been replaced with panasonic FM's.


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## NelsonVandal

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_I've tried an AD8066 in a CMoy, but I hit oscillation issues with 32-ohm headphones and am working on resolving it. I'm concerned about the AD8066 in an X-Fi. With an LM4562 in there, there's 30mV of DC offset on my X-Fi with the caps in place and 180mV without, which kinda sucks. I'm thinking the resistors are too high in value, I will try to measure when I take it out again.

 What is the DC offset you are getting with the AD8066 and do you have the 4 caps in place or not?_

 

I use AD8066 in a Xenos OHA-REP but without buffers and a LMH6642 as ground channel. There's no stability problems with any load - 16, 32 or 300 Ohms. It sounds very good, very detailed and fairly smooth. I like it better than the Mini3. The DC-offset is low. I use SMD ceramic 0.1 uF and tantalum 4.7 uF from rails to ground in close proximity to the power pins. There's also some electrolytics in there - 3x330 uF from rail to rail and 330 uF from rail to ground. I even abuse the opamps with JFET class A biasing (6 mA).


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## majkel

It all seems like screwed up gorund channel. First you have to verify its around half of the supply voltage. Also, when you rail the ground channel on the output with the capacitors, you're killing it's bandwidth. I strongly recommend no railing caps and no decoupling the supply voltage to the ground. You can decouple the op-amps by putting a cap between V+ and V- on the supply. No capacitances on the output side of the ground channel! It only makes sense on ground channel built with no feedback loop, like discrete AB, or RC divider. When it's active, like in a PINT or PIMETA, no railing. Also, it's a weird idea to put the RC divider instead of resistors alone on the input of PIMETA ground channel driver.


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## holland

How would you find the AD8599 vs AD8066? I'll have to buy some AD8599 and give it a try. I *really* like the sound of the AD8066, when it's working.

 I dropped the AD8066 into my X-Fi last night, 30mV offset as expected, but didn't have time to listen. I would really like to get that down to < 5mV, but I didn't have the time to analyze the circuit.

 Majkel, were your comments to me regarding my CMoy? Virtual ground is fine. I have no input caps, and the circuit stabilizes when I adjust the volume to half. I'm thinking I just need to balance the input currents to tighter tolerances, as input resistance seems to affect the circuit stability.

 Let's see, in CMoy terms. C1 is replaced with 1K resistor. R2 is 100K, R3 is 1K, R4 is 5.1K, no R5. Caps on opamp, V+ to ground, V- to ground, V+ to V-. Queiscent current is fine @ 15mA. When I plug in the 32-ohm headphones it jumps to 60mA till I adjust the volume to half. 100 ohm headphones and higher have no issues, haven't tried 16 ohm nor anywhere between 32 and 100. AD8397 has no problems in said circuit. DC offset is always < 5mV under all conditions for the AD8066 in said circuit.


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## NelsonVandal

Quote:


  Originally Posted by *majkel* /img/forum/go_quote.gif 
_It all seems like screwed up gorund channel. First you have to verify its around half of the supply voltage. Also, when you rail the ground channel on the output with the capacitors, you're killing it's bandwidth. I strongly recommend no railing caps and no decoupling the supply voltage to the ground. You can decouple the op-amps by putting a cap between V+ and V- on the supply. No capacitances on the output side of the ground channel! It only makes sense on ground channel built with no feedback loop, like discrete AB, or RC divider. When it's active, like in a PINT or PIMETA, no railing. Also, it's a weird idea to put the RC divider instead of resistors alone on the input of PIMETA ground channel driver._

 

The capacitors goes from rails to virtual ground/input ground and not to output ground. I don't know much about electronics, but I can't see how this could effect the bandwidth at all. There's ofcourse no capacitors from OG to VG or from rails to OG. Decoupling caps from rails to ground is used in "all" amps, and it's recommended in "all" opamp data sheets. Why shouldn't there be decoupling caps from rails to ground?


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## NelsonVandal

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_How would you find the AD8599 vs AD8066? I'll have to buy some AD8599 and give it a try. I *really* like the sound of the AD8066, when it's working._

 

I never compared them head to head, but I've used them in the same amps but at different times. The impressions are from memory and compared to other amps/opamps. These amps have discrete buffers that may influence the tonality. I find AD8066 to be a very "fun" opamp. It's fast, detailed, has great sound stage, it's just a tiny bit grainy and sibilant. What I don't like is the lack of "body". I would like a warmer more pronounced lower mid. I think AD8599 is warmer in tonality, yet it is detailed and fast.

 Right now I'm building a pocket JISBOS and after that, I think I'll try to make some kind of PINT with AD8599/AD825. Since I'm using HD650's most of the time, I think there's enough current to use them unbuffered. I'll write some impressions when it's finished. I also have to complete my LISAIII clone.


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## majkel

So, when you have the ground channel like in the Cmoy "classic", then it's OK to decouple anything to the ground. The resistor values I would use as follows: potentiometer - 10k logarythmic is OK, R1 - 4.7k both are OK, R2 - no part here, R3 - 1k, R4 - 4.7k, C2 - use 820 ohms resistor instead. R5 - 0 ohms (nothing but wire) is OK. Such circuit will prevent you from going into high offset with nasty op-amps. 
 Regarding PIMETA it's ground architecture is actually OK as I looked at it again, however I would do it a different way, with one powerful ground. 
 In the PINT there is the RC voltage divider I was talking about. C7 should be both removed, and C2 should be one capacitor connected to supply rails. Otherwise most ground channel op-amps will oscillate without heavy compensation. So it's probable that people building such amps find some good op-amps nasty. The circuit is bad, not the op-amp. It's much better to build low noise version of the PINT.


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## NelsonVandal

Quote:


  Originally Posted by *majkel* /img/forum/go_quote.gif 
_So, when you have the ground channel like in the Cmoy "classic", then it's OK to decouple anything to the ground. The resistor values I would use as follows: potentiometer - 10k logarythmic is OK, R1 - 4.7k both are OK, R2 - no part here, R3 - 1k, R4 - 4.7k, C2 - use 820 ohms resistor instead. R5 - 0 ohms (nothing but wire) is OK. Such circuit will prevent you from going into high offset with nasty op-amps. 
 Regarding PIMETA it's ground architecture is actually OK as I looked at it again, however I would do it a different way, with one powerful ground. 
 In the PINT there is the RC voltage divider I was talking about. C7 should be both removed, and C2 should be one capacitor connected to supply rails. Otherwise most ground channel op-amps will oscillate without heavy compensation. So it's probable that people building such amps find some good op-amps nasty. The circuit is bad, not the op-amp. It's much better to build low noise version of the PINT._

 

So you say PINT, PIMETA, Mini3, LISAIII, M3, B22 etc has a faulty ground because of capacitors going from rails to virtual ground, or being a compromise because of the TLE2426? When I have time and energy, I'll try to compare using caps from rail to rail or from ground to rail. I think I've tried it once and found a better sound when I had electrolytics from rails to ground, not only from rail to rail, but I think I had small ceramics from rail to ground all the time. I just made a 3 channel JISBOS, and thought about what you've said and I only use capacitors from rail to rail. This is the best amp I've ever heard, but I'm not sure how much the "cap thing" has to do with it.


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## TzeYang

nelson, you just finished the 3 channel Jisbos?

 Did you stick an opamp at the ground channel?

 Really looking forward to it, please do post some pics.


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## NelsonVandal

Quote:


  Originally Posted by *TzeYang* /img/forum/go_quote.gif 
_nelson, you just finished the 3 channel Jisbos?

 Did you stick an opamp at the ground channel?

 Really looking forward to it, please do post some pics._

 

No I use 3 JISBOS. Since they are closed loop with low output impedance, I don't think there's any need for an opamp. It's not finished yet. I'm running it from wallwart, but I'm going to squeeze it in a C1201 with 10 AAA's. It distorts at 6 V and doesn't sound good enough at 9.6 V, but I think it sounds OK at 12 V, maybe just a little bit better at 24 V and I haven't tried it with higer supply voltage. It's very easy to breadboard, and there's no need for PCB's. I'll take some pictures of it and start a new thread when It's finished.

 The current draw is crazy. When I fired it up I had a current draw of 160 mA, with only 2 channels running! I later lowered the bias, but I can tell you it's still hot in many ways.


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## NelsonVandal

Majkel, I've changed the caps in my ADA4899-1 amp like you suggested. All caps going from rail to rail and none to ground. It's still stable. Still the same extreme clarity and uncolored sound signature.

 Maybe it's the old placebo thing, but the amp might sound better now with a wider soundstage, and just maybe there's more bass impact. Maybe it can play louder without distortion as well. Nothing seem to have changed to the worse. But after tweaking things, you hear what you want to hear. I'm going to give it some time, and if I like it this way, I'm going to start redoing my other 3 ch amps this way.

 Thank you for enlightening me, Majkel!


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## majkel

NelsonVandal, you wellcome! However, I don't want anybody to generalize my thoughts. I would have to look at certain designs and comment each one separately. I'm not an expert, I'm still developing in this "business". My only comfirmation is what people say about my amps after listening to them, so it makes me assured I'm going my own and right way. I share some of my ideas and maybe publicize something later on. 
 So, coming back to the topic of railing, etc. - it depends on the design. You need to understand the whole circuit and see how the blocks are working together.

 What I don't like in PIMETA:
 1) Using TLE2426 as a rail divider you choose it's sound signature which I actually don't know. I prefer simple resistor divider.
 2) I don't think it's a good idea to use unbuffered ground for op-amps referencing and buffered for headphone out. These way the negative feedback information for the op-amps is screwed up. 
 3) Ground channel efficiency is lower than the sum of channel efficiencies. It's a mistake for me, may be not that heavy. 
 BTW, what is JISBOS? Could anybody give a link to it? Just wanna know what we are talking about.


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## NelsonVandal

Quote:


  Originally Posted by *majkel* /img/forum/go_quote.gif 
_NelsonVandal, you wellcome! However, I don't want anybody to generalize my thoughts. I would have to look at certain designs and comment each one separately. I'm not an expert, I'm still developing in this "business". My only comfirmation is what people say about my amps after listening to them, so it makes me assured I'm going my own and right way. I share some of my ideas and maybe publicize something later on. 
 So, coming back to the topic of railing, etc. - it depends on the design. You need to understand the whole circuit and see how the blocks are working together.

 What I don't like in PIMETA:
 1) Using TLE2426 as a rail divider you choose it's sound signature which I actually don't know. I prefer simple resistor divider.
 2) I don't think it's a good idea to use unbuffered ground for op-amps referencing and buffered for headphone out. These way the negative feedback information for the op-amps is screwed up. 
 3) Ground channel efficiency is lower than the sum of channel efficiencies. It's a mistake for me, may be not that heavy. 
 BTW, what is JISBOS? Could anybody give a link to it? Just wanna know what we are talking about. 
	

	
	
		
		

		
		
	


	


_

 

1) So you think the TLE adds it's own sound signature when used this way. I never thought of that. Interesting.
 2) So the ground buffer shouldn't be in the feedback loop? Like using two separate loops, one for the opamp and one for the buffer?
 3) I don't understand this, please explain.

 JISBOS "single channel discrete buffer board with jfet input stage and bjt output stage"
http://headwize.com/ubb/showpage.php...d=6711&fpage=1
 I was never happy with any opamp, and I think the best sounding amps I've made or heard are buffers only amps. The problem with the buffers I've used are high output impedance because they're open loop. JISBOS are closed loop. The problems with JISBOS are high voltage supply and high current draw that makes them hard to use portable, and I want my amps to be portable.


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## majkel

3) ... L is one BUF34, R is another BUF634, 250mA max. each. To fully take the advantage of this efficiency you need 500mA in the ground channel. You have BUF634 again, so 250mA instead. 

 OK, so I saw this JISBOS buffer - it's OK but I wouldn't agree that amps without feedback will sound better. My thinking is totally different, I even fed back the diamond buffers. There are many advantages:
 - full output offset voltage control
 - low output impedance (you realized that)
 - hight damping factor (read: transducer control)
 Of course, you have to obey a couple of rules to prevent the circuits from oscillations. The stages have to be fast, especially buffers. When it's not, you have to limit the badwidth. When ground channel is active and with feedbck loop - it has to be output only, no railing. 

 JISBOS for me is a typical buffer intended for dual supply voltage circuits, so in this case you should rail both supplies to the ground. I'm not sure it will work well in a tripath architecture without feedback loop. How will you control ground voltage on the output of the ground buffer? Again - when you have dual supply, you don't have to play with ground channel anymore and you have to rail all capacitors after the voltage sources/stabilizers to the ground. You also decouple op-amp supply pins symmetrically to the ground. It's a different matter - if I've understood you well.
 2) ... this time I don't understand 
	

	
	
		
		

		
		
	


	




 Build a single buffered/unbuffered efficient voltage follower for the rail divider and that's it. It will have 100% negative feedback loop.


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## NelsonVandal

JISBOS is not an open loop buffer, it's supposed to be 100 % negative feedback.

 I don't say that a no feedback amplifier is better. I think it has to do with complexity. Using just a buffer is less complex, fewer degrading components. I've found out that every transistor in a diamond buffer adds it's own sound signature, and I think that 20 or so transistors in an opamp must degrade the sound even more. I'm no fanatic. I use diamond buffers in a multiloop fashion with opamps most of the time.

 I've also found out (or at least I think I have) that JFET's have a unique sound signature. They're a bit grainy and seem to add something in the mid that makes them sound warmer. Since most of the opamps suitable for audio has JFET input you have to cope with a grainy sound.

 Have you ever heard diamond buffers without opamps? To me it was a revelation. Opamps for sure are degrading the sound. If they weren't, why would we still be arguing about what opamp is the best?


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## majkel

Maybe I'll try pure diamond buffers in a hybrid amplifier I'm planning to build but constant orders and other activities delay the start. Regarding JFETs alone - I actually don't understand why people like to use them. Is it any better than BC550/BC560 in the input stage? Op-amps, yes, each one sounds different, that's why it only makes sense when you find a unique op-amps combination giving overall good sound. Designs based on one op-amp type will never sound so great.


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## kvant

Quote:


  Originally Posted by *majkel* /img/forum/go_quote.gif 
_My thinking is totally different, I even fed back the diamond buffers. There are many advantages:
 - full output offset voltage control
 - ..._

 

Majkel, could you please elaborate a bit on this? Are you saying you have some kind of diamond buffer with a feedback without an opamp to hold zero DC on output? Thanks.


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## majkel

I cannot provide a schematic ATM 'cause I'm in the office but imagine a diamond buffer acting as a buffer of the op-amp in the non-inverting voltage amplifier. You just wire the feedback from the DB output instead of the op-amp output. If the resistors are chosen correctly to compensate the offset current then you have the offset controlled by the op-amp. 
 Another solution which I don't like is adding a DC servo - it's a kind of "DC only" feedback loop.


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## kvant

Quote:


  Originally Posted by *majkel* /img/forum/go_quote.gif 
_...imagine a diamond buffer acting as a buffer of the op-amp in the non-inverting voltage amplifier. You just wire the feedback from the DB output instead of the op-amp output._

 

I see, so there is an opamp the audio goes through. I misunderstood that yesterday. Similar to PIMETA, for instance. Am I right?


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## majkel

Yep. The diamond buffer alone is still a diamond buffer, however I saw pretty crazy diamond buffer designs with more than 10 transistors including current mirrors.


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## majkel

Post after post, I know, but I'm in need to revive this thread. 
	

	
	
		
		

		
		
	


	




 AD8599's have landed in my CP player, after kicking out LM4562's. So, first stage is OPA2604, second stage is AD8599 and the third stage is NJM4580. The last one works in the Technics proprietary Class AA circuit which is kind of smart application but let's leave it know.
 My question is: how do AD8599 and AD8022 differ from each other sonically? I know both from my circuits but I was surprised ater placing the AD8599 in my CD player because of a different effect than in my headphone amp. Is it just supply voltage or instability in the amp? Actually, what I have got in the CP player is more like the AD8022 in the amp but with much better instruments imaging.


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## majkel

Quote:


  Originally Posted by *Shopper* /img/forum/go_quote.gif 
_Does the AD8599 sound better than the LM4562 in your CD player?_

 

Yes, it does. LM4562 sounded worse than the stock M5219 by Mitsubishi. I obtained huge, deep and enormous bass, colorless, recessed midrange and weird sound in overall. There is one feature I've recently cared much about: it's sonic source image. It has to be stable and well defined both in width and depth - with the LM4562 I lost it, with AD8599 alone it has grown to big dimensions but after replacing preceding op-amps for OPA2604, the spatial definition is even better than before the upgrades.

 Regarding the AD8599 alone, I got the same results in the amp as NelsonVandal obtained in his and described in another thread - warm presentation with slightly recessed mids.


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## majkel

My concern now is what I'd obtain by replacing the AD8599's or the NJM4580's in my CDP with the AD8022's? Actually I'm leaning towards replacing the latter due to better electrical parameters however I'm afraid the AD8022 might destroy the spatial order and make the sound too bass-light and colored. I will try after the Christmas.


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## majkel

What I could accept is:
 - deep and powerful bass with good low end
 - good focus/imaging of sound sources
 - dark to neutral presentation
 - move soundstage closer to me or leave it untouched
 - can stand +-10V supply
 - dual op-amp in SO8 package


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## Earwax

Quote:


  Originally Posted by *majkel* /img/forum/go_quote.gif 
_ 
 What I don't like in PIMETA:
 1) Using TLE2426 as a rail divider you choose it's sound signature which I actually don't know. I prefer simple resistor divider._

 

Hi majkel, 

 I replaced the TLE2426 with a resistor voltage divider in my pimeta a long time ago and I though the change opened up the sound a bit. Even so, I left the amp aside for a long time, something about it still bothers me, most likely the BUF634s. The easiest change seems to be to put in LMH6321s instead. 

 You've mentioned the TLE2082 in the past and I think that's a great chip (along with it's brother TLE2072). 
 To get back to the topic of this thread, how do you think the AD8599 compares to the TLE2082? It looks like it wants higher voltage, maybe a drawback for portable use.


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## majkel

Earwax, 

 TLE2082 is a very good Cmoy chip, with low power consumption and accepting high supply voltage range. AD8599 is for sure darker and warmer, should be hissing less but I don't know how low you can go with the supply voltage. AD599 is higher class but might be more demanding. Ask NelsonVandal for more details or just try it.


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## majkel

Yepp and they both sound different from each other. I loved TLE2082 for a long time for its bass and soundstage. Overall, it's slightly metallic-bright.


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## NelsonVandal

Quote:


  Originally Posted by *Earwax* /img/forum/go_quote.gif 
_To get back to the topic of this thread, how do you think the AD8599 compares to the TLE2082? It looks like it wants higher voltage, maybe a drawback for portable use._

 

I think AD8599 sounds good with 9 V supply. I've not done any extensive listening tests below this, but there's no obvious distortion at 6 V.


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## majkel

Could anybody tell the sonic differences between the AD8599 and the LT1364? 

 I replaced the NJM4850ED's for the AD8022's in my CDP, much good happened, and now I'm thinking about fine tuning the sound. What I will do at the time of the next CDP disassembly will be replacing the transport oscillator for low jitter 5ppm quartz and placing the Nippon ChemiCon ??? (forgot the type) 'lytics in place I put the Jamicon's last time. The Nippon's give a denser, fuller sound, however the Jamicon's have been still an upgrade compared to the stock 'lytic on the digital section supply. Oncoming low jitter master clock for the DAC is another story... If the Nippons and oscillators fail to deliver sonic nirvana, there is still some op-amp rolling possible.
 My concern now is - what could I obtain when placing the LT1364 in the stage that I currently have the AD8599? It's a differential amplifier/filter, so the op-amp behavior might be different from a single-ended application. Another problem is that the PCB copper paths are fragile and easily burn off while soldering, so I haven't got many trials left. 
	

	
	
		
		

		
			





 There are already some wire bypasses on the board, actually.


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## majkel

OK, great thanks! This is probable that the AD8599 and the AD797 are similar to each other. I listened to the AD8599 just once but it sounded like a warmer AD797. I guess I don't need more midrange color - it's already done by the OPA2604 and the AD8022. Also, I don't want to decrease amount of bass but on the other hand I'm expecting to have more bass from the Nippon capacitors, they are dark, warm and colorful at the same time which I like. They also smooth out the highs, so too much of this effect might sound mellow.


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## luvdunhill

probably a stupid question, but is there a single version of the AD8599?


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## NelsonVandal

No, not to my knowledge.


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## majkel

Use 2x AD797, should be even better, less offensive, more neutral.


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## NelsonVandal

Soon, there'll be a single version - AD8597. They show a simplified shematic of it now. I was right. It is a folded cascode bipolar input amp
	

	
	
		
		

		
		
	


	




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## Bilavideo

This is Bill from the Future. The AD8599 is an amazing chip. I'll leave it to brighter minds to explain what it actually does, but listening to this chip I feel pulled into the sound, which is dynamic, vivacious and sparkling. It isn't just detailed; it's alive.


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## HeadphoneAddict

It's a good opamp for me. I have the AD8599 in my modded Stax SR-001 Mk2 and it sounds wonderful, with tighter more extended bass and treble sparkle and extension too, getting rid of the midrange boost too. In my iBasso D10 the AD8599 sounds very good too, but that circuit is more picky about what I use for buffers when then AD8599 is in it, otherwise the sound can be thinner and brighter than I like (but perfect for Senn IE8 and HD600).


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