The OPA2134 'sound'.

[catman]

G'day all, with all my general messing around with different op amps in simple phono stages of late, I think that I do regard the OPA2134 as being the 'best/nicest sounding'.  Having said that though, in all honesty I can't really articulate 'why', but there is indeed something particularly nice sounding about that dual op amp. 

 

Interestingly enough on the Burr-Brown documentation for this particular dual op amp, claims are made for 'superior sound quality', due to the use of a true FET input stage in the OPA2134.  http://www.ti.com/lit/ds/symlink/opa2134.pdf  Ok then, a bit of a blanket statement perhaps but can someone please tell me why a true FET input stage results in 'superior sound quality'?  Perhaps it indeed does, but why?  Regards, Felix.                     

Edited August 13, 2014 by catman

[mwhouston]

Can't answer your question but I can say I have been using OPA2134s for years and years in all sorts of audio gear and for a few bucks each they can't be beat. And I would be willing to bet my left nut that under a subjective sonic review they would stand up to any other OPAMP at any price. After saying that and possibly being left at soprano, I have used the more expensive OPA627. Not sure they sounded better but Mr Tripp got me interested in them and so I built a preamp with them. And just to change it up a little I built the preamp in a Prada mobile phone cardboard box. You think the phone was good the box was even better. I used some really nice caps too. Each module has its own differential PS on board. Still have the preamp.

Edited August 13, 2014 by mwhouston

[hochopeper]

 And I would be will to bet my left nut that under a subjective sonic review they would stand up to any other OPAMP at any price. 

 

 

:S      :eek:

Edited August 13, 2014 by hochopeper

[mwhouston]

:S      :eek:

"Willing" that is. It has to be the left because I lost the other in a bad bet earlier.

[hochopeper]

"Willing" that is. It has to be the left because I lost the other in a bad bet earlier.

An even more ballsy move in that case?

[Addicted to music]

Fets have a high input impedence which is why so many uses them. 

 

The Silicon Chip High Fidelity preamp for 2 channel is based on the OPA2134, and is available via the Altronics franchise.    Good to see so many on this forum liking this opamp.  Any project fired up with the OPA 2134 is going to impress due to the cost.  However for what ever reason I found the 2134 to be boring.  Experimenting with other devices I found all those BB OPA listing such as the 627 to be a complete waste of cash.  The only ones in the OPA that I liked was the ones I obtained free fron the BB site via there R&D program such as the OPA1612 .OPA 1642 and the OPA 827.   The OPA 1612 and the 1642 is to my ears better than the 2134.  The OPA827 is a brighter sounding version of the 627(unity gain) but at a huge cost reduction.  The beauty of the BB OPA "superior sound range"  is that they are highly compensated to suit audio, they are extremely forgiving when you roll them at will and the best is that you can optained them free.

You should try the National LM/LME range or the ADI.  Most ADI range are SOIC so you are going to need an adaptor and be prepared to solder SMD.

[Addicted to music]

@@mwhouston,

 

sreiously you have expensive taste, that PRADA box would have cost more than the parts there and more than the cases you get at Jaycar

[hochopeper]

On a more serious note ... 'Opamp rolling' is a mugs game unless you're checking everything operates correctly before and after with an audio analyser and scope (not just one or the other).

Comparing opamps is really comparison of the complete circuit that its used in and attributing a sonic signature to one component in that circuit is daft. It can be fun but really ... Don't go over thinking it just enjoy the music and learning as you build.

[catman]

G'day all, interesting comments.  I really like the LM4562 as well as it is very low noise (in my circuits), but I still find the OPA2134 to be more pleasant and 'musical' sounding to my ears. 

 

In the end, that does it for me!  Interesting on the 'high impedance' aspect, but again why does that make a difference?  Regards, Felix. 

Edited August 13, 2014 by catman

[Batty]

I have 2 OPA2134s and a pair of OPA627 in my Bugle 2 phono, I replaced the output 2134 with a pair of 627s on an adaptor and found that the bass was improved, left it that way ever since. I also reduced the gain from 60 to 54dB.

[mwhouston]

@@mwhouston,

 

sreiously you have expensive taste, that PRADA box would have cost more than the parts there and more than the cases you get at Jaycar

The daughter bought the phone I just got the box.

[Nada]

Given many audioo connoisseurs rave about discreet circuits free of negative feedback I wonder are there any opamps also free of negative feedback and if so what do they sound like? Cheers.

[Addicted to music]

Given many audioo connoisseurs rave about discreet circuits free of negative feedback I wonder are there any opamps also free of negative feedback and if so what do they sound like? Cheers.

 

I could be wrong and I stand corrected for my ignorance( refer to Hochopeper or Zaph  )  so im going to go out on a limb and left testcle that all typical opamp require a feedback resistor to work, that includes the AD844 that highly praised in these neck of the woods.  I dont believe that any can operate on open loop gain, they are set up to limit there gain for linearisation and stability.

 

There is a ADI 4627-1 brz cost Approx $20-30 each single device, its a typical device in competition with the OPA 627/ OPA 827.  If you have used the AD825 and you wanna go better the ADI 4627-1 brz is the one I like.  Many on Head fi have used this and have confirmed the SQ is more detailed than some of the discrete devices such as the Audio gd however I have never done the comparision.

 

Again if you intend to experiment, like Hochopeper stated in his post no8 that you really need a CRO, MM and a analyser to ensure what you are doing doesnt run into oscillation and the device self destruct, always follow the manufacturer spec sheet and adhere to the correct set up so you dont roll at will and get expensive smoke.

Edited August 14, 2014 by pchan

[Nada]

Thanks.  I will leave it to Chris then

[hochopeper]

Nada, this isn't my area of knowledge ... I don't know the answer.

I know what to do and where to look but it isnt something I could answer categorically with only a few minutes research. I've got friends that are experts at analogue and line level design and I mostly leave IV and phono and amplifier design to them and just watch the process and know some of the pitfalls and traps for young players and stick to DSP stuff that I am more comfortable with.

Cheers,

Chris

[catman]

G'day all, an interesting point on the feedback network.  As far as I know a feedback network is a part of every typical op amp amplifier circuit.  Interestingly enough reading that Burr-Brown documentation, high value feedback resistors worsen the noise performance of the op amp and should be minimised as much as possible for noise reasons.  That's interesting and probably explains some of my less than ideal noise observations with the OPA2134.  Regards, Felix.  

[WINEDS]

I have always liked the op249

 

http://www.analog.com/en/all-operational-amplifiers-op-amps/operational-amplifiers-op-amps/op249/products/product.html

[hochopeper]

A good resource that I have been meaning to spend more time reading is -

http://www.analog.com/library/analogDialogue/archives/39-05/op_amp_applications_handbook.html

[niss_man]

Here is a link to the great opamp shootout. 

http://www.diyaudio.com/forums/everything-else/245455-ultimate-opamp-shootout-where-you-get-decide.html

 

As a result of this I decided to purchase an LM4562 (to put into my dac) which to my ears and the majority who did this blind test was the best of the lot. including opa134.

Results are at post #226

 

Simon

[Addicted to music]

Here is a link to the great opamp shootout. 

http://www.diyaudio.com/forums/everything-else/245455-ultimate-opamp-shootout-where-you-get-decide.html

 

As a result of this I decided to purchase an LM4562 (to put into my dac) which to my ears and the majority who did this blind test was the best of the lot. including opa134.

Results are at post #226

 

Simon

Doesn't surprise me, the LM4562 is found in the OPPO105. I have never had the LM4562, but no matter what Ive tried the LME 49720 find it's way getting deployed. There is something about the Bipolar inputs of National devices.....

[mwhouston]

The other places I have extensively used the humble OPA2134 is in portable headphone amps. I made quite a few of these over the years based on the CMoy schematic. They sound excellent, will drive low impedance phones, you can run them on 27V (3X9V batteries) and are easy on batteries. All I have made are all sold. I don't even have one for myself. The small prototype brd. has a differential PS on it also. This one used Russian PIO caps. Mil-spec chip socket, snubbed PS, silver soldered and silver plated wire-wrap wire as hook-up wire. I employ my "safe on" socket and switch arrangement where unless there is a plug in each socket and the power switch is no current flows.

Edited August 16, 2014 by mwhouston

[TMM]

Any opamp worth it's salt should be acoustically transparent unless it is used in a very demanding application - unusually high gain or unusually high output current, like driving some 32ohm headphones.

Interestingly enough on the Burr-Brown documentation for this particular dual op amp, claims are made for 'superior sound quality'

Touting sound quality in the datasheet makes it sound 300% better.

It's quite funny how the diy audio crowd rave about the opamps marketed towards audio and shy away from the ones that aren't.

[catman]

G'day all, one thing that I've noticed from my own DIY work is that the OPA2134 seems to draw more current in normal operation.  Yes the case gets a lot warmer than op amps like the NE5532 and the LM833.  I am reliably informed that this is quite normal with the OPA2134.  Regards, Felix. 

[A9X]

Any opamp worth it's salt should be acoustically transparent unless it is used in a very demanding application - unusually high gain or unusually high output current, like driving some 32ohm headphones.

 

Yep. Show me that you can actually hear the difference between two modern types in the same application without knowledge of which you are listening to.

[statman]

Given many audioo connoisseurs rave about discreet circuits free of negative feedback I wonder are there any opamps also free of negative feedback and if so what do they sound like? Cheers.

AFAIK the transconductance op amps AD844/OPA861 used as dac outputs are free of neg feedback. George should know for sure. They sure dont have that closed in sound I hear with every other opamp i've heard.