[andyr]

Hello Andy

The AD825 are for audio and have a 41mhz bandwith, 125 v/us slew rate, with 12 nv/hz noise at 10khz.

The AD826 are for video and have a 50mhz bandwith, 350 v/us slew rate, with 15 nv/hz noise at 10khz.

Some was prefered the sound of the AD826.

Bye

Gaetan

Thanks, Gaetan, 

From the specs, surely it seems the AD826 should be better for audio ... except for the higher noise figure?  (And, as far as noise is concerned, the signal in each of the 3 channels of my active XOs passes through 3 AD826s, yet with CD selected and my GK-1 turned up full (but no CD playing), I can put my ear against each driver and basically don't hear any noise!  (A real tribute to the AKSA products, IMO!  ) )

Regards,

Andy

[gaetan8888]

I'm using them in my CDP and while I agree about the transparency and soundstage, there's a certain amount of edginess in the top-end that I don't like all that much. They've been in there for nearly a year now and I'm quite used to them but based on my initial impression, I'll be replacing them audio-gd discrete component op-amps [similar to Burson devices]. Going back to what Hugh, gaetan and others have said, distortion seems a likely culprit.

Jules

Hi jules,

Why did you pick the audio-gd discrete-component opamp over the Burson "opamp"?  I have heard people comment on a harsh top-end with the Burson buffer and I wondered whether the Burson opamp replacement would sound as harsh?

I'm interested in trying out a "discrete opamp" replacement for the opamp used in the GK-1 phono stage.

Regards,

Andy

Hello Andy

Which opamp are used in the GK-1 phono stage ?

Thank

Bye

Gaetan

[andyr]

Hello Andy

Which opamp are used in the GK-1 phono stage ?

Thank

Bye

Gaetan

Sorry, don't know, Gaetan (Hugh scrubs the markings off them!). 

Regards,

Andy

[rabbitz]

I've used the LM4562, AD825 and OPA2134 on CD player outputs and my preference is in that order. I hated the AD826 but could have been fakes. I also hate the OPA627 even though it is loved.

It's a very good opamp (very neutral) and did a little buffer comparing it against a Nelson Pass B1 and a Burson. In fact I preferred it to the Burson which sounded overblown in comparison and it was almost as transparent and neutral as the B1. It bettered the B1 in extension and dynamics in a system (uses a tweaked AKSA 55N+) that goes down to 30Hz and I think that's due to the high output impedance of the B1.... mine's capless and 330R but the suggested B1 uses caps and is 1K. Used in a system >40Hz and the B1 wins but the LM4562 is not shamed.

To me, the LM4562 was a pleasant surprise and is my choice for CD player outputs.

[gaetan8888]

Hello

I'm interest in high end op-amp for best transparency, soundstage and sweet musicality, because I will use an old Onkyo receiver, I will take out it's amp circuit, and also replace the phono and line stage MJM4559 Ic op-amp by the best opamps.

So I would use those op-amps for the line preamp and phono preamp section of this receiver.

Thank

Gaetan
 

[kyrill]

Gaetan

try these forums out http://www.audioasylum.com/index.htm
 for instance digital general  http://www.audioasylum.com/audio/digital/bbs.html

[essoess]

I'm always suspicious of this, because in my experience very low distortion usually means mostly higher order, which sounds clean but sterile.


Hugh

Yes, that's the LM4562! Still one of the best monolithic opamps.

[andyr]

I'm always suspicious of this, because in my experience very low distortion usually means mostly higher order, which sounds clean but sterile.

Hugh

Yes, that's the LM4562! Still one of the best monolithic opamps.

Sorry sos ... how can it be sterile yet "still one of the best monolithic opamps"?

Secondly, can you explain what a "non-monolithic" opamp is?

Regards,

Andy

[BillB]

I built a really simple single stage preamp using a 4562 and I absolutely loved it. Worth the time to try at least, just a few resistors and caps:



Very musical and not sterile at all...even with Solens. 

[AKSA]

Thanks Bill,

I'm getting interested......   

Hugh

[JoshK]

THe DEQX I own is revamped in AU by the manufacturer by replacing multiple opamps for the LM 4562

The sound is not sterile but very very transparent and dare i say musical for a digital device.

Speaking of the devil, my DEQX is Oz bound for upgrades to HDP-3 status which includes tearing out all the old opamps and replacing with LM45462s.  Initial reports confirm what you are hearing, that it is a big improvement.  Of course, there is more going on in the HDP upgrade so it won't be an apples to apples comparison for me. 

[BobM]

I've used the LM4562 in my DAC output (Zhaolu) and found it to be a bit sterile as well. Very transparent, for sure, but somewhat mechanical in nature, no matter what I did to try and give it some additional "musicality". Overall the AD2107 seems to fill that void for me better than the LM4562.

Bob

[Occam]

Oddly, I consider myself fortuneate in having a less elegant, prior implementation of Bob's dac, the Zhaolu 2.0. Because my Zhaolu 2.0 provides balanced outputs, it uses a typical app note implementation of each phase of a channel feeding its output to an op amp (which provides the balanced outputs) and after, the 2 phases combined in another op amp to provide single ended outputs. [This is the same topology as found in the SB Transporter]

I use the single ended outputs, which allows me to tune the subjective results by using different opamps for dac filtering and balanced to single ended output. For the dac chip (CS4398) output filtering I use 1 dual OPA2107/channel (each phase served by its own amp in the dual), and for the balanced to single ended combining and output to the external world, one dual LM4562, with each of its amps serving its own channel. In total, 3 dual opamps for the analog section of the DAC for both channels.

In reality, this topology is no more complicated than that in Bob's Zhaolu 2.5. My 2.0 has an additional opamp per channel, as each phase, gets its own amp, rather than both phases of a channel filtered and combined in a single opamp, and then buffered. But most importantly, it allows me to use different monolithic opamps for the filtering and single ended output functions, and get what I want subjectively. (nor do my choices compromise objective measures)

This also leads me to the sad conclusion that audio reproduction is far more 'additive' than I'd like from a superficial intellectual perspective. I've not evaluated the newer Zhaolu 3.0 which provides single ended outputs from a single opamp per channel, combining phases, filtering and output in one stage. Perhaps the LT1028, or the new SiGe opamps from TI. But I've yet to encounter a monolithic opamp that 'does it all'.

FWIW,
Paul

[jholtz]

Hi Guys,

I've sold my Zhaolu 2.5C with a Zapfilter and moved on but tried a lot of different opams before going to the Zapfilter and couldn't find one that sounded good to me while I owned it.


So, that brings me to my question. Have any of you played with HDAM opamp replacements? Audio-gd sells them and they get very good reviews on the Head Fi forum. http://www.audio-gd.com/enweb/pro/diy/OPA.htm

Jim

[gaetan8888]

Hello

I did only try the OPA627 last year and it was a very sweet and precise op- amp with a 3D tube sound.

There was a web site where a guy test somes op-amps for the distortions spectrums, but I've forgot where was that web site.

There is few discrete op amp schematic thread in the diyaudio forum.

I've look at the HDAM opamp web site, they are more affordable than some others discretes op-amps.

Bye

Gaetan
 

[VYnuhl.Addict]

Hello

I did only try the OPA627 last year and it was a very sweet and precise op- amp with a 3D tube sound.

There was a web site where a guy test somes op-amps for the distortions spectrums, but I've forgot where was that web site.

There is few discrete op amp schematic thread in the diyaudio forum.

I've look at the HDAM opamp web site, they are more affordable than some others discretes op-amps.

Bye

Gaetan
 

Gaetan,

 
    I think your referring to Doug Selfs site where he goes through most of the popular opamps, AD797,opa2134 etc.. I wholly agree on the Opa627 though, it sounds very very close to a tube with very subtle differences that really take alot of listening to seperate, the only area I have found strongly better Opa627 vs tube is the soundstage width, its huge and surprisingly not clinical from this Op. There are steps to get the absolute best out of it, but out of the box its quite good. The ad744/ad811 almost completely caused me to abandon opamps for anything musically related, then I dragged back out this trusty old bugger with a new approach ..



Colin

[gaetan8888]

Hello Colin

I know that page of Doug Self, but there is a more complete analyse with spectrum analysis, from S. Groner, done in 2008, I just founded it on my hard disk and traced it on the web, here is the document link;

http://www.sg-acoustics.ch/analogue_audio/ic_opamps/pdf/opamp_distortion.pdf


Btw, this weekend it's the Audio Show in Montreal at the Sheraton in downtown, I will be there.

http://www.salonsonimage.com/en/visitors/index.html


Thank

Bye

Gaetan

[gaetan8888]

Gaetan,
 
I wholly agree on the Opa627 though, it sounds very very close to a tube with very subtle differences that really take alot of listening to seperate, the only area I have found strongly better Opa627 vs tube is the soundstage width, its huge and surprisingly not clinical from this Op. There are steps to get the absolute best out of it, but out of the box its quite good. The ad744/ad811 almost completely caused me to abandon opamps for anything musically related, then I dragged back out this trusty old bugger with a new approach ..

Colin

Hello Colin

You mean pushing the OPA627 into class A ?

As an example, Thorsten Loesch, in his revised Analogue Addicts Phono Preamplifier, push the Op-Amp output to operate as single ended class A emitter follower, he connect a 6K8 resistor from the output to the positive supply.

Thank

Bye

Gaetan

[bhobba]

Thanks Bill,

I'm getting interested......   

Hugh

High Hugh.

Yes it does look interesting.  Certainly interesting enough to try.  Like I said read reports that in class A and output buffered with a transistor sounds really sweet.

Thanks
Bill

[VYnuhl.Addict]

Hi Gaetan,


     Yes Class-A is correct, I originally used the resistor trick a long time back, found that even a simple Bjt,Led,resistor current source sounded much better, also a drawn current of 5ma,a buffer and nested feedback really improved this chip for a voltage gain stage.



Colin