# Audio Op amp sound comparison



## cravenmh (Jan 14, 2009)

The following site gives SQ details on common audio Op Amps. His uses a simple amp circuit and high dollar headphones (talk about nearfield listening).
Yes, the Burr Browns have a laid back sound that helps tame bright tweeters.
Notes on Audio Op-Amps
Good for upgrade ideas on your amps.


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## Mooble (Oct 21, 2007)

I did notice a fairly dramatic difference in op-amps on my Tru, but not for the reasons you might think. I tried the AD823 which he tests. The sound seemed a tiny bit crisper, but the main difference was in volume. The 823 is a very low power chip. I was driving my amp into clipping just to get moderate volume out of it.

I would like to try BB627, but it's a difficult fit to get a Browndog adapter in the space I have.


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## cravenmh (Jan 14, 2009)

I may have an extra pair of new 627's and a Brown Dog, if you want to try the fit. I have most all of those chips, except for the AD843.
If it works. You could just send me $25.00. Half of the going rate.
The AD chips tend to have a snappier sound. The Burr Brown are most all laid back as a family characteristic. Extra good for metal tweeters in my opinion.


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## cravenmh (Jan 14, 2009)

I meant the $25 would be if later, you want to keep them. Don't forget to wear a ground strap on your wrist.


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## Mooble (Oct 21, 2007)

PMed you. If they fit, I'd like to try them.


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## cravenmh (Jan 14, 2009)

I will check on the extra adaptor at lunch time. I definitely have the NIB chips. Sad to think 8 pin DIPS will be obsolete some day. Soldering the SOIC AD8020 chips on the SOIC to DIP adaptor was friggin tedious to say the least. Mike


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## Mooble (Oct 21, 2007)

That's why I haven't gotten around to doing it yet. I'd need a new precision soldering iron. Mine is too clumsy for that kind of work.


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## cravenmh (Jan 14, 2009)

Tiny new tip and a variable temp. Skinny A$$ solder too.


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## vecc205 (Nov 18, 2007)

It's tough to make op amp sound comparisons and say thats how the op amps sounds. It depends where the op amp is being used. Is it driving a heavy resistive load, is it on the input of an amplifier, what source impedance is it being driven from for lowest noise, has the op amp been properly decoupled and is stable etc... An op amp that would be ideal for an input stage of an amplifier may not have the current drive or low distortion at low resistive loads needed to drive say a pair of low impedance phones. Having said that, I have tested numerous op amps AS DROP INS on the input stage of my a600. So I can give an impression of what I thought.

BB2604- I didn't like this op amp in my a600. I thought the sound was clearly colored, it lacked detail, the bass was warm not accurate, though this chip was very laid back and its easy to listen to.

BB2134- I thought this chip was a little nicer than the BB2604. It wasn't as colored to my ears, but thats not to say it was good. Had the typical laid-back sound and tends to the warm side of neutral. Lacked detail but again another easy to listen to op amp. 

OP275- This chip sounds fun at first but to me just didn't sound neutral which eventually gets old. I liked this chip a little more than the Burr Browns because it was more detailed, and the imaging, soundstage etc... were good. 

AD8599- This chip I think has the best mixture of warmth and neutrality. Imaging, soundstage and tonality are all very good. Even though it may not be completely neutral it is not to overly warm as to be distracting. Tight extended bass, warm midrange and smooth highs. This would be one of my top choices.

LM4562- This chip is the most neutral of the bunch to my ears. Great amount of detail. This chip is very accurate and will be for those who want neutrality over anything else. Tight bass, detailed and accurate midrange, highs are a little brighter than AD8599 but not fatiguing. Soundstage, imaging are all excellent. 

My two picks would be the LM4562 and the AD8599 in my amp over the ones I tested to replace the stock LM833's. These are my thoughts that I concluded in my PPI amp. Your results and conclusions may be different but I suggest you give it a try.


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## cravenmh (Jan 14, 2009)

You are absolutely correct. The op amp is one of the first in a chain of components. The list would serve only as a place to start for your desired direction of sound change needs. The impedance reflected back to the opamp would make a difference as well as voltage supply level. It does narrow the field a little.
I'm stocking up on 8 pin DIP chips while they are easy to get. The SOIC's and smaller are taking over. Mike


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## czechm8 (Oct 15, 2008)

Nice read. I have the OPA2134's in my Tru Billet and I've been happy with them. I also use the OPA2227 in a CMOY amp, which is very similar to the 2134, but a lot less power consumption.


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## cravenmh (Jan 14, 2009)

I use my Sennhauser 600 phones as my reference. My room is not good enough to use my home gear for ref. I built a META 42 using the old Elentec 02 buffers. (unobtanium now).


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## manina (Mar 29, 2008)

vecc205 said:


> My two picks would be the LM4562 and the AD8599 in my amp over the ones I tested to replace the stock LM833's. These are my thoughts that I concluded in my PPI amp. Your results and conclusions may be different but I suggest you give it a try.


Are these any easy fit? Do you need to change other pieces or just the op-amp?

While I understand some adjustments may be needed to obtain the top performance, I'm looking to an op-amp that can work even without changes - a plug and ear will be really welcomed


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## cravenmh (Jan 14, 2009)

Ray at TIPS would have alot more experience than I. Check your voltage supply to the op amp as they have a +/- volt range. Choose a single or dual channel after checking the specs on the current part #. A nice gold legged socket makes trying different op amps a breeze. Just plug it in. Some super high freq. op amps need a small ceranic cap. across the pins. All is explained at the site listed above. Even has a section on biasing op amps into Class A operation. Quite easy to do. Building the headphone amp was a great experience. $8.00 for a board. You can even try different input caps. Film vs. Electrolytic, etc. It sounded so good, I sold it to a friend that kept begging. Using close tracking quality pots for level control can be rewarding too. I see some cheezy looking $0.50 pots on $200+ amps.


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## vecc205 (Nov 18, 2007)

manina said:


> Are these any easy fit? Do you need to change other pieces or just the op-amp?
> 
> While I understand some adjustments may be needed to obtain the top performance, I'm looking to an op-amp that can work even without changes - a plug and ear will be really welcomed


Depends what op amp they are replacing. I used gold plated dip sockets. The AD8599 would need an soic to dip converter because they only come in SOIC. Just make sure not to exceed the supply rails of the op amp. Make sure they are pin to pin compatible which they should be if your swapping a dual for a dual a single for a single etc... If you can tell me the op amp your replacing or the amp you have I may be able to help you more.


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## vecc205 (Nov 18, 2007)

Most amps use ceramics on the power supply pins for decoupling. I don't think it is necessary to go changing other parts it might actually cause the circuit to perform worse unless your sure.


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## cravenmh (Jan 14, 2009)

Source for low quantity. parts, adaptors, sockets, film caps, etc. for the above tweaks. No min qty's and good prices. Paypal a plus. He put the OpAmp list together. A good guy that is not trying to get rich on every sale.
Tangent’s Parts Shop


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## vecc205 (Nov 18, 2007)

To cravenmh or anyone else interested in headphone amps, I was looking at using the topology shown on the data sheet for this buffer. I may make a pcb if I have the time.

LME49600 - High Performance, High Fidelity, High Current Audio Buffer


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## cravenmh (Jan 14, 2009)

The BUF634 by Burr Brown was the only one that I was aware of. Looks good.
Yes, I love my Senn 600's. Feels like a pair of woman's legs over my ears. Covered in velor.


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## smellygas (Feb 21, 2008)

cravenmh said:


> I may have an extra pair of new 627's and a Brown Dog, if you want to try the fit. I have most all of those chips, except for the AD843.
> If it works. You could just send me $25.00. Half of the going rate.
> The AD chips tend to have a snappier sound. The Burr Brown are most all laid back as a family characteristic. Extra good for metal tweeters in my opinion.


That's pretty cheap. Just make sure you didn't get counterfeit OPA627's. If you got them off ebay, they're probably fake.

Otherwise, I swapped out a bunch of different op amps, including the 2134, LM4562, a few AD's, and the OPA627x2's, in my single opamp headphone amp, and yes I thought it made a difference. My test was not blinded. I have not been able to find a single BLIND listening test of opamps in a headphone amp circuit anywhere, and I doubt one exists. In theory, changing the opamp in single-opamp headphone amp could make a difference. Why? Because the opamp is actually driving a transducer (rea: low impedance) almost directly. However, will it make a difference when it's just feeding a signal to a high-impedance audio component? I doubt it. Interestingly, the Benchmark DAC1, which is a very well-known renowned "benchmark" DAC, with extremely good measurements, uses very very cheap opamps. I think the 5532's. Take it for what it's worth.

SG


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## cravenmh (Jan 14, 2009)

I get all my op amps factory direct. I work for a huge corp and I just have purchasing buy them for me at the corp. discount. Not going thru Newark. Never off ebay. They are still in TI wrapping and yes I did pay more that $25.00.


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