# New LM4562 audio opamps has anyone tried yet



## PinkFloyd

Anyone tried the LM4562 audio opamps as yet and, if so, what do you think of it? If you've got a spare dip8 version I wouldn't mind a try of it.

 Chip details here: http://www.national.com/ds/LM/LM4562.pdf


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## Clutz

Funny you should ask... I've just been reading about it myself. I wish they made a single channel version, cause I'd like to try dropping it into my PPA, though I'd have to lower the gain to get the ultra low distortion and IMD - but I could easily live with that.


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## Polaris111688

It looks pretty impressive. A PSRR of 120dB, and low distortion.

 Clutz, I was just thinking about my current PPA project with that opamp too.


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## Filburt

I will be testing this chip probably next week when they arrive. If you want, I can talk about the results although I don't have the equipment here to do scientific measurements; will have to do that during the winter break if I can. It looks like a good replacement for the NE5532; perhaps better than the AD8599 as the 8599/797 is difficult to work with in terms of actually obtaining the advertised performance.


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## Iron_Dreamer

Wow, the specs on this thing look sick. It'll be interesting to hear your findings, Filburt.


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## Filburt

Quote:


  Originally Posted by *Clutz* 
_Funny you should ask... I've just been reading about it myself. I wish they made a single channel version, cause I'd like to try dropping it into my PPA, though I'd have to lower the gain to get the ultra low distortion and IMD - but I could easily live with that._

 

You'd also need to balance bias currents and whatnot, if you haven't already done so. The "typical" Ib on it is 10nA, which is 2000 times the max rated Ib of the OPA627 (5pA), for example. We've been successful in using a 500nA chip (AD8058) in the PPAS project, so presumably 10nA is doable 

  Quote:


  Originally Posted by *Iron_Dreamer* 
_Wow, the specs on this thing look sick. It'll be interesting to hear your findings, Filburt._

 

Sure, no problem 
	

	
	
		
		

		
			





. I wish this came in single package as well, since I could then test it in the buffer stage of my DAC, but oh well. It will be interesting how it does against some of the other high performance audio op-amps.


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## JahJahBinks

Please see:

http://www6.head-fi.org/forums/showthread.php?t=202491

 It's interesting to see how people react differently in the thread I started compare to this one.


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## Clutz

I saw the previous thread, but I didn't comment cause I hadn't read much about the opamp yet. I have done some reading on it now, and I think it seems promising. Now, I'm not an EE, nor do I have much background in electronics, but I disagree with ATAT in his assessment that PSRR doesn't matter for audio applications. According to Tube CAD, "PSRR refers to the ratio of a circuit's change at its output relative to the disturbance at the power supply that caused it." Hence, a high PSRR improves how resistant a circuit is to power supply noise. I agree that it's current output capabilities are nothing to write home about, and it's slew rate isn't that fantastic - but the OPA627's slew rate is only 55uV/S - granted, that's over twice the slew rate of this new opamp, but I think that demonstrates that there are other factors that are important to having a good sounding opamp than just slew rate. 

 Anyway, there has been quite a discussion of this opamp over at diyaudio, and they seem to like it. A lot of people have said it's made big improvements in their system. That is interesting, but it doesn't necessarily say much - people can hear improvements if they want to. Still, it suggests that we shouldn't write this opamp so quickly. If they made a single channel version, I'd buy a pair and pop them into my ppa.


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## JahJahBinks

The best thing to do is to get one and listen. Because we have agreed in the past that you can't determine its sonic signature based on electrical specs.


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## ATAT

I saw the DIYaudio thead, and it looks interesting, I have a few here I'll try them at some point. PSRR for audio seems not as important as other characteristics since audio power rails are obsessively clean of ripples..

 ATAT.


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## splaz

Couldn't you cut pins off and jumper them around etc. to just use one channel or is there some reason that wouldn't work ?


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## Clutz

Quote:


  Originally Posted by *ATAT* 
_I saw the DIYaudio thead, and it looks interesting, I have a few here I'll try them at some point. PSRR for audio seems not as important as other characteristics since audio power rails are obsessively clean of ripples..

 ATAT._

 

I agree, there are other characteristics are more important - particularly as power supplies get better - that said, if given the choice, I'd rather have greater PSSR all else being equal. Anyway, the THD+N and IMD specs on that puppy are really impressive, and those are two things I would care about for audio. All in all, I agree with JahJahBinks - let's listen to it. Hell, it might be a good cmoy opamp to use with a high impedance headphone - at least for testing. I should think HD580s would be fine with them. 300 ohms instead of 600 - still, not bad though.

 What do you think?


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## PinkFloyd

So, is anyone going to send me one of these buggers? I'll either pay or swap for something (chips etc.) NS don't want to send me samples


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## ezkcdude

Quote:


  Originally Posted by *Filburt* 
_Sure, no problem 
	

	
	
		
		

		
		
	


	




. I wish this came in single package as well, since I could then test it in the buffer stage of my DAC, but oh well. It will be interesting how it does against some of the other high performance audio op-amps._

 

I read that single and quad versions will be available in early 2007.


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## ozshadow

I honestly do not put much faith in spec sheets but choose to rely more on hearing the actual opamp. Take the 2107 opamp. Spec-wise, you would not think much of it, but everyone that listens to it enjoys it. AD8620/10's compete with OPA627's and are in the same ballpark spec-wise, but sound completely different. Maybe these specs matter more for alternative applications other than audio amplifiers, but for audio amps, just get it and listen then decide. It's like opening Christmas presents, no matter how big the box is or how nice it's wrapped, you never know what you are gonna get til you open it !


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## Magsy

I got a few, try signing up and choosing the European Distro, not the US.
 You do have to be a little more persuasive than normal though. (I cannot find them for sale yet here in the UK, so...
	

	
	
		
		

		
			





 ) 

 I have 3 SOIC only, if you cannot get anywhere I can send you one mounted on a Bdog but I would need it back as I have a use for it.

 I'm probably going to drop a pair into a HP Dac this week, unfortunately I left my HD580 behind by mistake and I won't be home till the end of the week. I only have E3C's with me
	

	
	
		
		

		
		
	


	




 I'm hoping they will pretty good unbuffered with the HD580!


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## adfinni

Quote:


  Originally Posted by *ATAT* 
_I saw the DIYaudio thead, and it looks interesting, I have a few here I'll try them at some point. PSRR for audio seems not as important as other characteristics since audio power rails are obsessively clean of ripples..

 ATAT._

 

 Yup the guys at diyaudio who have tried them in their marantz cd63/67 CDP's have been very impressed, especially compared to an opa627/opa132 combo. Mine should be here in the next few days


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## PinkFloyd

Quote:


  Originally Posted by *JahJahBinks* 
_Please see:

http://www6.head-fi.org/forums/showthread.php?t=202491

 It's interesting to see how people react differently in the thread I started compare to this one. _

 

In what respect? In a "wooohooo I was first to lay eyes on it look at me" kind of stylee or a "that pink guy stole my thunder cause he's more popular than me"? Bollocks man, the Rickmeister was giving the heads up on this chip a while ago It's nothing new, I was just interested to find opinions on how it sounds..... looks like I'll have to go and "BUY" one and form my own conclusions, as usual, not even so much as a PM offering to send me one in exchange for the usual AD8620 (or similar) ..... plenty of them here too (AD8620) and quite a few BUF634.... so come on guys, it's a fair exchange


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## JahJahBinks

well, if i say you should use search button before posting then I am being too anal right?


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## PinkFloyd

Quote:


  Originally Posted by *JahJahBinks* 
_well, if i say you should use search button before posting then I am being too anal right? 
	

	
	
		
		

		
		
	


	


_

 

You're right, I should have used the search button, I'll do that from now on in.


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## JahJahBinks

no, I already said I was being too anal.


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## PinkFloyd

Quote:


  Originally Posted by *JahJahBinks* 
_no, I already said I was being too anal._

 

Missing out on the LM4562 scoop was a fate worst than life for me, I retire to my hole in the ground promptly.


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## Pars

Check this thread out http://www.diyhifi.org/forums/viewto...t=lm4562#16654

 That said, most that have tried them seem to like them. I have a pair in my Rotel RCD-855 currently, but I haven't listened enough to form an opinion.

 Chris


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## Andrea

I look forward to having some amp where to use these 
	

	
	
		
		

		
		
	


	






 Btw, I think that a 10 nA Ib shouldn't even require that you balance the input impedances ...right?


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## Filburt

Quote:


  Originally Posted by *Andrea* 
_I look forward to having some amp where to use these 
	

	
	
		
		

		
		
	


	






 Btw, I think that a 10 nA Ib shouldn't even require that you balance the input impedances ...right? 
	

	
	
		
		

		
		
	


	


_

 

 Quote:


  Originally Posted by *Filburt* 
_The "typical" Ib on it is 10nA, which is *2000 times* the *max* rated Ib of the OPA627 (5pA)_

 

10nA is 10000pA; that's a big difference from a lot of the JFET-input op-amps people use in their PPA.


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## Andrea

Yes but it's only 5 times the 2 nA of the OPA2227.

 Also... in my Zero Audiocraft amp, one not designed for bipolar op-amps, the 350 nA Ib of the LT1361 resulted in "just" 100 mV (constant with every volume setting - the amp had input caps) of DC offset. Now, if you divide by 35...


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## Andrea

No, sorry... 4 times 'cause it's 2.5 nA


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## Filburt

Quote:


  Originally Posted by *Andrea* 
_Yes but it's only 5 times the 2 nA of the OPA2227.

 Also... in my Zero Audiocraft amp, one not designed for bipolar op-amps, the 350 nA Ib of the LT1361 resulted in "just" 100 mV (constant with every volume setting - the amp had input caps) of DC offset. Now, if you divide by 35..._

 

You can't use an OPA2227 in the PPA without careful balancing of bias currents, either. Your Zero Audiocraft amp is topologically dissimilar and doesn't use the same value resistors that people often use in their PPAs. The higher value resistors used in the default configuration (http://tangentsoft.net/audio/ppa/amp...chematic7.pdf), coupled with Ib in the nA or even uA range, can make for rather substantial offset at the input if you don't break from the default configuration and have the bias currents balanced to cancel it out.


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## Andrea

I see, it's the Jung Multiloop thing (I forgot).

 One thing is for sure - you could comfortably use the LM4562 (and AD8599 and such) in a Xenos 0HA-REP ! (preamp position) That's a cheap way to get to use this chip, worth mentioning I guess? But I wouldn't do it without changing the LMH6642's with the quite a bit better sounding LMH6654's too. Well at least you could get both chips with a single order from National


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## Andrea

Btw, one idea just hit my mind -- my incoming "mSEEDS LABS Faith AMP" should also be well suited for trying the LM4562? (I guess I'll ask Mr Yang)


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## ATAT

Quote:


  Originally Posted by *Andrea* 
_I see, it's the Jung Multiloop thing (I forgot).

 One thing is for sure - you could comfortably use the LM4562 (and AD8599 and such) in a Xenos 0HA-REP ! (preamp position) That's a cheap way to get to use this chip, worth mentioning I guess? But I wouldn't do it without changing the LMH6642's with the quite a bit better sounding LMH6654's too. Well at least you could get both chips with a single order from National 
	

	
	
		
		

		
			



_

 

How? that statement doesnt even seem to make sense to me.. especially on a buffered design. 

 You could replace the *buffers* without balancing Ib, but if you replace the preamp you'd probably get some issues (unless its already balanced, which I dont think it is, since it uses FET inputs..) AND you'd want a coupling capacitor on the input to prevent changing input impedances from ruining your balancing or drawing from the source..


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## PinkFloyd

Jesus Christ whatever happened to virgin rolling of op amps ? Roll that person in and, if it sounds good it is good! As much as I like reading spec sheets, 9 times out of ten your ears are the best judge, honestly they are.... roll her in and ignore the armchair enthusiasts speculation, see how she sounds with your own lobes..................


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## ATAT

Heh.. I rolled in a bipolar opamp into my PPAv2 once.. my cheap 'phones didnt stand a chance..


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## IEATTEFLON

Tried them in a cmoy built around tangents cranky opamp guide. It was nothing special to my ears. AD8620 still trumps it for musicality.


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## Filburt

Quote:


  Originally Posted by *PinkFloyd* 
_Jesus Christ whatever happened to virgin rolling of op amps ? Roll that person in and, if it sounds good it is good! As much as I like reading spec sheets, 9 times out of ten your ears are the best judge, honestly they are.... roll her in and ignore the armchair enthusiasts speculation, see how she sounds with your own lobes.................._

 

I imagine the people who talk to me regularly will note that I use a variety of chips that aren't exactly well known in these parts. However, I do use datasheets to help me in selection, and I've been pretty successful with it as well.

 IEATTEFLON - Wow, definitely different tastes there! I find the 8620 to be pretty unpleasant.


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## IEATTEFLON

Quote:


  Originally Posted by *Filburt* 
_Wow, definitely different tastes there! I find the 8620 to be pretty unpleasant._

 

Yes but I think we both agree that the opa2107 is superb.


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## Andrea

Quote:


  Originally Posted by *ATAT* 
_How? that statement doesnt even seem to make sense to me.. especially on a buffered design. 

 You could replace the *buffers* without balancing Ib, but if you replace the preamp you'd probably get some issues (unless its already balanced, which I dont think it is, since it uses FET inputs..) AND you'd want a coupling capacitor on the input to prevent changing input impedances from ruining your balancing or drawing from the source.._

 

Sorry, it was left more implicit than it should... the Xenos has balanced input impedances for the preamplifier op-amp (since it's designed for either the NE5532 or the OPA2134). That's one of the reasons why I could safely use the AD8397 in it, with a 2 mV DC offset (constant with the volume too, even in the absence of the input coupling caps)


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## Andrea

Quote:


  Originally Posted by *IEATTEFLON* 
_Tried them in a cmoy built around tangents cranky opamp guide. It was nothing special to my ears. AD8620 still trumps it for musicality._

 

Thanks a lot for reporting.

 Btw, I truly like the AD8620 a lot. I find it not just highly resolving (meaning: within the boundaries of "natural sounding"), but also lively and warm&musical in tonality at the same time; a great feature I think.


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## Andrea

Quote:


  Originally Posted by *PinkFloyd* 
_Jesus Christ whatever happened to virgin rolling of op amps ? Roll that person in and, if it sounds good it is good! As much as I like reading spec sheets, 9 times out of ten your ears are the best judge, honestly they are.... roll her in and ignore the armchair enthusiasts speculation, see how she sounds with your own lobes.................._

 

Sound advice


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## n_maher

Where are folks even finding this chip available? I did a quick search at Digikey and it looks like they'll be carrying it, but 0 DIP chips available at this time. Sorry I'm no use to you Pink 
	

	
	
		
		

		
		
	


	




.


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## JahJahBinks

Can you request samples from National?


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## NelsonVandal

Yes you can, I'm gonna get mine in a couple of days.


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## NelsonVandal

Xenos OHA-REP with LM4562/LMH6654
 Just switched OPA2134 for LM4562 and 2xLMH6642 for 2xLMH6654 from National. I was really going to try AD8620 after Andrea's recommendations, but it's delayed from Analog. I'm going to let it burn-in for a while now. My first impression is that the congested Xenos-sound seems to be gone. The highs are clearer and more open, and not synthetic like the LM6171 seems to be. The mid is still a bit prominent though but more transparent and intimate. I can't really evaluate the bass because it's the weak part in my old cans, but it's definately not worse. I'm going to try it out with my Senn's later. It plays really well with my modded Philips SHP895 in a way the original Xenos never did. I might even regret bying those Sennheiser HD650. Yeah if did this mod a month ago, I wouldn't have bought them.

 I'm smiling right now!

 Is there anybody out there who has tried LM4562 yet? How does it compare to AD8620?


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## adhoc

Just ordered my samples for my ZL (they charge shipping), will let you all know how they pan out in my setup.


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## pddjsteve

I bit, I ordered one to try in the pimeta.


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## Filburt

I'm still trying the 4562 with various things *shrug*

 I do prefer it to the AD8620, although that's not saying much, as I think the AD8620 sounds pretty lousy.


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## Magsy

Quote:


  Originally Posted by *Filburt* /img/forum/go_quote.gif 
_I'm still trying the 4562 with various things *shrug*

 I do prefer it to the AD8620, although that's not saying much, as I think the AD8620 sounds pretty lousy._

 

It seems to have a slightly strange sound. At first it seems great but after a while it leaves you wondering if something is wrong because it sounds more open and airy than any other opamp I have tried - un-natural? It is a little too clean and sterile maybe?

 It has to rank quite highly though, I wish I could merge LT1364 and LM4562 into one


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## Andrea

Quote:


  Originally Posted by *Filburt* /img/forum/go_quote.gif 
_I'm still trying the 4562 with various things *shrug*

 I do prefer it to the AD8620, although that's not saying much, as I think the AD8620 sounds pretty lousy._

 

You always say the AD8620 sounds not to your liking but never precisely say why and how.

 I've yet to try the LM4562 but judging from what I've read so far I doubt it could become a favorite of mine. Me really likes the likes of the AD823 sound.


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## Andrea

Quote:


  Originally Posted by *Magsy* /img/forum/go_quote.gif 
_It has to rank quite highly though, I wish I could merge LT1364 and LM4562 into one 
	

	
	
		
		

		
		
	


	


_

 

Mmmmmm, LT1364, I like that. You have just inspired me a tasty idea for my Xenos... i.e. do LT1364 + AD9631


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## Andrea

Err, no, I think I'll do LT1361 + LMH6654


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## Xakepa

So is it similar to BB or to 823/8620 line?

 Could I run it at +-12V and plug in into (completely unbalanced) PIMETA?

 I could call some friends from Maine IEEE chapter to see if I can get some samples overnight...


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## NelsonVandal

I totally agree with Magsy. Impressive but after a while I found it over-spacious and unnatural. Very fun with my Philips, just strange with my Senn's. I bet you came to this conclusions using Sennheiser's, Magsy.


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## Andrea

So it's decided, the LM4562 won't go inside my Xenos.

 IMO, anyway, the above mentioned LT chips are a must hear for those who really like the AD823 like me (beware that they're bipolar input though).


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## Magsy

Andrea: I have read many of your posts (and there are a lot!) and I think we share similar tastes. I've loved the LT1364 for a long time, I find others which better it in some ways but I always come back because it is a great all rounder.It is the opamp which makes me sing along most!!I haven't heard the AD823, so I'll have to get some to try!

 NelsonVandal: Yes, it is weird with HD580! I have HD650 for Xmas and was hoping it might sound better with LM4562..


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## Andrea

Glad about that!

 Yes btw, I should moderate myself in terms of post count 
	

	
	
		
		

		
		
	


	





 Have you tried the LT1361, also?


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## Andrea

OK I guess I'll do LT1361 + AD9631, and in case I should not be happy with the latter, I can always switch back to the trusty LMH6654.


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## NelsonVandal

No Andrea, don't moderate yourself. We need the oppinion from someone who dares and have the energy to try.


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## Andrea

Curiosity won me, too. 
	

	
	
		
		

		
		
	


	




 I replaced the AD823 with the LM4562 and from a brief listening, with John Mellencamp first and Jayhawks soon after, I'm not regretting it one little bit.

 Granted, there was no revolution anywhere, but a subtle yet useful improvement. I expected the vague mids NelsonVandal had hinted at, but I didn't get them. I expected a sterile tonality, but I didn't get it. I also expected a too airy sound, but it's not there. 
	

	
	
		
		

		
		
	


	




 What's left is pretty neutral and musical if you ask me -- even with the LMH6654 that might possibly not be the best match to the LM4562 on earth.

 Specifically, I hear a bit more (always welcome) midrange body than with the AD823; the bass seems perfect, and a bit stronger, the treble is even clearer, guitar plucks are (even more) lifelike and detailed, the midrange feels neutral and not distant or lacking focus. There isn't too much warmth, but no dullness either. 

 It's to be noted that my CD player has a rich tonality and a good midrange presence to start with -- and the interconnects I'm using certainly don't take away from these features.


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## Andrea

Quote:


  Originally Posted by *NelsonVandal* /img/forum/go_quote.gif 
_No Andrea, don't moderate yourself. We need the oppinion from someone who dares and have the energy to try._

 

Just read this (thanks for the encouragement btw) -- oh well, there you have it ^^^


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## adhoc

Quote:


  Originally Posted by *Andrea* /img/forum/go_quote.gif 
_Granted, there was no revolution anywhere, but a subtle yet useful improvement. I expected the vague mids NelsonVandal had hinted at, but I didn't get them. I expected a sterile tonality, but I didn't get it. I also expected a too airy sound, but it's not there. 
	

	
	
		
		

		
		
	


	


_

 

Sounds like I'm in for a treat; my LM4562s should arrive anyday now.


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## NelsonVandal

Hm, maybe a should give it another go. I thougt it was such a big change in tonality to OPA2134 which is exaggerated in the mids/midbass, and AD8620 changed it all back to "normal". Maybe I should try it in the Xtra, because it's a bit too fat-sounding and lacks soundstage and speed. I doubt burning it in will change all this.

 Please give some more impressions after further listening. Are you listening with HD650?


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## Andrea

I do like a "ripe" midbass and lower midrange... The LM4562 may not have the most bloom in this part of the spectrum, but then again those AD chips don't, as well... If only there was something like a improved OPA2134 from BB... (I don't consider the OPA2107 to be so, at least for a 12V supply)


 When I manage I'll say some more about my liking of the all-LM amp. Yes btw, it's with the HD650 I'm listening to it.


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## NelsonVandal

I hope the answer to our prayers will be OPA2827. Supply from 8 - 36 V.


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## NelsonVandal

Shouldn't it be possible to use DC/DC step up converters in these kind of small amps to boost the voltage?


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## Andrea

Some more listening. I think I like the LM4562 more than the AD8620 (that somehow it resembles, to me) with the LMH6654. I delivers a slightly nicer midrange, better bass, perhaps better treble.

 In short, it all sounds quite good. Yet...still not perfect. I'm positive that chips like the AD9631 and the AD8397 would pair with the LM4562 better and give out what now is missing... a bit of "3" flavor, especially. I'm not kidding... the 'numbers' are a key to an effective pairing of different op-amps I've realized. 
	

	
	
		
		

		
			








 So if I keep the LMH6654's in the new 0HA-REP I'll use the LT1361 for preamp; if I keep the LM4562 instead, one of the two above mentioned chips. I think.


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## Andrea

I was just one step away...

 So now I've the AD9631's too in the Xenos. Still have to listen, but one thing I can tell for sure: powered with 12V, they don't run cool 
	

	
	
		
		

		
		
	


	




 The top of the amp gets a bit warmer than even with two AD8397's inside. I think I'll keep the voltage a little lower, i.e. 9V for now, and maybe 10V later.


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## Andrea

I'm left absolutely SPEECHLESS. 
	

	
	
		
		

		
		
	


	







 This is IT. The sound has suddenly turned heavenly, breathtaking, perfect. 
	

	
	
		
		

		
		
	


	




 And what do I care if it gets a little bit warm, when it sounds this good. I'll keep 12V (previously I was overly cautious, I believe).


 The first two songs of Beth Orton's Central Reservation, like all of an usual favorite, Rainy Day Music by Jayhawks, suffice to prove that this is the most perfect sound my HD650 has ever delivered. 
	

	
	
		
		

		
		
	


	






 edit- forgot to say that I've made the AD9631's to work at unity gain by removing the 1K resistor going to ground. This way the overall gain is perfect for my needs, and perhaps the AD9631 is even more fine tuned(?)


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## NelsonVandal

This is weird. The AD8397 went out from my Xenos. I'm never going to get used to the Analog-sound. It's harsh and fatiguing, a nasty colouration. I don't even bother to burn it in. I'm using LM4562 again. But this time with output buffers bypassed. It sounds good. I hope it's just not a honeymoon, because now my PCB is starting to wear out. There's still some treble colouration, like I said before like Kodacolor or Fujichrome, like the sun always shining. Still a bit hollow and larger than life in the mids. But... this is more fun than both Analog and (cheap) Burr-Brown.

 In the specs it says "Easily drives 600 ohm loads". I'm not sure if I need output buffers. Maybe i should go for Sijosae's discrete buffers.


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## NelsonVandal

PS. Xtra with bypassed input stage sounds just as clear and fun but with less colourations. To my ears that is.


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## NelsonVandal

Silly not to think of it before. The Xtra acts as a buffer now since the input stage is bypassed. Xenos with Lm4562 plays better through Xtra than straigt out with bypassed buffers.


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## Andrea

If you want to hear how good the LM4562 can be in the Xenos, try it with the AD9631's


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## NelsonVandal

OK Andrea, they're quite expensive and I don't have the guts to order more free samples from Analog. Where did you get yours? Are you sure it's not that harsh and fatiguing "Analog-sound"? I don't want the amp to be brighter. I find LM4562 a bit thin and bright. Do you find AD9631 neutral, bright or warm in toanlity? To my ears the LMH's seems to be too bright. Do you think it's sane (and safe) to try sijosae's discrete buffers?

 The board is a bit messy because I have nothing appropriate to clean it with.


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## Andrea

The AD9631 counterbalances the LM4562 very well, with its full and comparatively warm sound, without apparent treble aggressiveness.

 Although the Xtra with the same op-amp sounded still more transparent thanks to the discrete buffers. 
	

	
	
		
		

		
		
	


	




 I say "sounded" 'cause now I've the AD8620 in the Xtra and it's there to stay. 
	

	
	
		
		

		
		
	


	






 For the AD9631 I got two samples from AD. Beware that it warms up a little. You may want to try the THS4051. It's another chip that goes very well in the Xenos (wish I could compare them) and it has much of the typical BB sound. Note that the specified minimum supply voltage is +/- 4.5V.


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## NelsonVandal

Andrea, now I'm awaiting your review - which amp's the best - your modded Xenos or modded Xtra?

 Your comments about LM4562 in Xtra supports Magsy's and mine impressions of the "hollow, not very neutral, LM-sound", I think.

 You really should try bypassing those damned things (input opamps), they all seem to colour the sound.


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## Andrea

Think of it, I do like the OPA2134 
	

	
	
		
		

		
		
	


	




 I think I'll leave it in, and buffer it with two AD8057's, in the new amp. If I'm not happy enough, I'll replace it with an LT1361.


 At the moment, the Xtra is the better sounding amp. But I'm a bit perplexed about these AD9631. After all, the LMH6654 may have sounded more transparent/clear, without the hotness...


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## Andrea

I don't know, perhaps a strange moment, or maybe that I used an unfamiliar record...


 Yesterday evening I had the impression that the Xtra with LM4562 was more transparent in that it had more "breath" in the mids, but now I think that the Xenos with LM4562 and AD9631 just sounds more coherent and full bodied. The Xtra had a bouncy bass that was enticing at first, but the Xenos's bass is truer, more realistic. What's for sure is that I've moved the Xenos to the HD485 setup, and the 'phones are sounding fantastic, better than they ever did... 
	

	
	
		
		

		
			





 And now that the Xenos isn't on top of the Pioneer integrated (which I must keep powered since I'm using its rec output) anymore, it looks like I overestimated the warming up, even.


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## picklgreen

You can get them directly from national semiconductors.


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## Andrea

These AD9631's are super, indeed. Lot of resolution and extension, without any harshness in the treble, lots of grip on the bass (wow!), and that lovely full bodied midrange that I just can't live without. These are for me 
	

	
	
		
		

		
		
	


	




 LM4562 and AD9631 could really be the ultimate setup for this amp.


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## pddjsteve

Quote:


  Originally Posted by *Andrea* /img/forum/go_quote.gif 
_These AD9631's are super, indeed. Lot of resolution and extension, without any harshness in the treble, lots of grip on the bass (wow!), and that lovely full bodied midrange that I just can't live without. These are for me 
	

	
	
		
		

		
		
	


	




 LM4562 and AD9631 could really be the ultimate setup for this amp. 
	

	
	
		
		

		
		
	


	


_

 

My LM4562 arrived on friday and I popped it in my Pimeta. Sounds good! I think I am going to pick up a 3rd AD9631 and see how they fare in the buffer positions.


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## Andrea

Quote:


  Originally Posted by *pddjsteve* /img/forum/go_quote.gif 
_My LM4562 arrived on friday and I popped it in my Pimeta. Sounds good! I think I am going to pick up a 3rd AD9631 and see how they fare in the buffer positions._

 

That'd be interesting. Note that in my Xenos here they're configured as unity gain followers, with a 1K feedback resistor with a capacitor of unknown value in parallel. Plus there are 6.8 ohm series output resistors, outside the feedback loop. This should optimise the transient response of the chip, and perhaps guarantee its stability driving reactive loads, as far as I understand. But it's not necessarily true that leaving out the R's and the C and just connecting the output to the inverting input would sound worse(?).


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## Andrea

Oh and the Xenos also has two dedicated .1uF (or so) bypass capacitors on the power lines of the buffers.


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## pddjsteve

Quote:


  Originally Posted by *Andrea* /img/forum/go_quote.gif 
_That'd be interesting. Note that in my Xenos here they're configured as unity gain followers, with a 1K feedback resistor with a capacitor of unknown value in parallel. Plus there are 6.8 ohm series output resistors, outside the feedback loop. This should optimise the transient response of the chip, and perhaps guarantee its stability driving reactive loads, as far as I understand. But it's not necessarily true that leaving out the R's and the C and just connecting the output to the inverting input would sound worse(?)._

 

Well, I know the AD9631 works well in the unity gain ground channel position of the pimeta, but that was followed by the buffer and not directly by the load. I modified a couple of DIP sockets to connect pin 2 and 5 to make it unity gain (just like if I was going to use the opa551 instead of buf634), not sure if I'm going to need to swap the piece of resistor lead I soldered in with a small cap or not. The ground opamp has a 10pf cap between 2 and 5 fro bandwidth limiting. I do have a resistor in series outside the feedback loop, 75 ohms for a built-in ER4P->ER4S adapter.

 If it doesn't end up working, I might just toss them on a single-to-dual browndog and see how I like having AD9631 in all 3 channels in the opamp position. All I've really done is modify a couple of sockets so far, so no GREAT loss if it doens't work. If it does, then whee. 

  Quote:


  Originally Posted by *Andrea* /img/forum/go_quote.gif 
_Oh and the Xenos also has two dedicated .1uF (or so) bypass capacitors on the power lines of the buffers._

 

Hmm. This might be the biggest problem I come up against. I'd have to mess with the board and not the sockets.


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## Andrea

It's a little risky to use the AD9631 for the preamplifier job in the L-R channels of the Pimeta, you'd surely get lots of DC offset unfortunately.

 I wouldn't know if the AD9631 actually performs better than the BUF634 buffers in high bandwidth. Certainly it beat all the other op-amps I tried for output drivers in the Xenos amp!


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## pddjsteve

Quote:


  Originally Posted by *Andrea* /img/forum/go_quote.gif 
_It's a little risky to use the AD9631 for the preamplifier job in the L-R channels of the Pimeta, you'd surely get lots of DC offset unfortunately.

 I wouldn't know if the AD9631 actually performs better than the BUF634 buffers in high bandwidth. Certainly it beat all the other op-amps I tried for output drivers in the Xenos amp!_

 

Yeah, I am not too sure about that either. I played with tangent's offset calculator after reading the cranky opamps article he has and got the AD8058 offset down really low, but I think I was having trouble getting the AD9631 to a decent value. Then again, the offset in practice with the 8058 was even lower than calculated, so I might give it a shot and just measure first, then test with cheap phones. If it turns out to be too high, I won't bother.


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## Andrea

And, out of curiosity, how did you like the AD8058?


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## d-cee

i tried ordering these through the samples program from national's website and they said they will review it within 24 hours and let me know

 it's been more than 24 hours... how long did everyone else have to wait for theirs?


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## pddjsteve

Quote:


  Originally Posted by *Andrea* /img/forum/go_quote.gif 
_And, out of curiosity, how did you like the AD8058?_

 

I had to toss the ad8058 back in to give it another listen. I can't decide whether I like the ad8058 or the lm4562 better. The immediate difference I could notice was the 8058 has a bit more bass. The detail seems to be about the same. I've noticed a bit more turn-0n thump with the 8058. Offset was between 10-12 mV at my normal listening levels, 15-17 at closer to full volume (I played with the multiloop resistors and am using lmh6321 in the pimeta buffer position). I don't know if I can get into more without further listening.

 And yeah, blindly tossing the 9631 in the buffer position just resulted in warm buffers and a whole lot of DC offset.

 Just for kicks, I left the same resistor values in as the 8058, and tossed the 9631 on a 2xsingle->dual browndog... cool to the touch, DC offset was less than 10mV, so I went for it - sounds GREAT at first listen.

 Don't take my words as gospel, though - for all I know it's a fluke. I really don't COMPLETELY know what I'm doing


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## izquierdaste

FYI lme49710 is now available at digikey. It is the single version of this opamp. Other forums seem to be pretty excited about the lm4562, so it could be interesting for resolution lovers.


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## ericj

Quote:


  Originally Posted by *d-cee* /img/forum/go_quote.gif 
_i tried ordering these through the samples program from national's website and they said they will review it within 24 hours and let me know

 it's been more than 24 hours... how long did everyone else have to wait for theirs?_

 


 I paid $12 for my 'free' samples and was approved in seconds. got my samples a couple days ago, haven't tried them. 

 You might try again, and be prepared to shell out $12 for three of 'em - which is a good deal. Usually I'm against 'abusing' the free sample system, but you can't actually buy these anywhere yet.


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## izquierdaste

Both the single (lme49710) and dual (lm4562) are available at digikey for about $5 each. (Perhaps my last 2 posts make me sound like a digikey shill, but I'm not.) I just want to hear people's opinions on these.


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## ericj

Ah, so they are. I was placing a digikey order about 10 days ago and they showed 0 stock with a lead time of several weeks. I guess they overestimated.


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## d-cee

Quote:


  Originally Posted by *ericj* /img/forum/go_quote.gif 
_I paid $12 for my 'free' samples and was approved in seconds. got my samples a couple days ago, haven't tried them. 

 You might try again, and be prepared to shell out $12 for three of 'em - which is a good deal. Usually I'm against 'abusing' the free sample system, but you can't actually buy these anywhere yet._

 

i actually didn't end up having to pay anything for them. after they were approved (friday) they arrived monday

 how good is that!? i've had them in my Zhaolu D2.0A ever since and loving it

 i've heard others had to pay for shipping, but for some reason i wasn't asked for any payment details, and they arrived before i even checked their status


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## supermite

Quote:


  Originally Posted by *izquierdaste* /img/forum/go_quote.gif 
_FYI lme49710 is now available at digikey. It is the single version of this opamp. Other forums seem to be pretty excited about the lm4562, so it could be interesting for resolution lovers._

 

Thanks! Gonna try it soon. I love the LM4562!


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## ezkcdude

Quote:


  Originally Posted by *supermite* /img/forum/go_quote.gif 
_Thanks! Gonna try it soon. I love the LM4562!_

 

Did you ever get around to this?


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## splaz

Looks like the guy's banned ezk.


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## joe_cool

Quote:


  Originally Posted by *ezkcdude* /img/forum/go_quote.gif 
_Did you ever get around to this?_

 

I installed 6 LME49710s in a DAC replacing NE5534s. I got exactly the result I wanted: more resolution without changing the sound signature.


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