Just to add to this old thread, I just replaced the OPA827 opamps in the output stage of a low frequency EQ unit that fits between my preamp and my amps, with the new Burson 4th generation discrete opamps (on sale for $68 per pair at PCX). The circuit is a unity gain output stage, and the entire music signal passes through it on its way to the amps.
Wow, the difference is very obvious. Deeper and cleaner bass, and complete removal of the last traces of hardness in the treble. Very smooth sound, but retaining all the detail. The OPA827 was the best IC opamp I'd heard in that position, but the Burson is definitely better.
The Burson operates with 20mA idle current vs the OPA827's 5mA, so that may account for the improved bass drive. I'm impressed. |
So far in opamps the best I have seen for audio is made by Dan Kennedy:
www.diyfactory.com/data/Great_River_Opamp2.pdf
It is built up from discreet components. |
There are advantages of both. Discrete circuits can be made for some special characteristics (such as very high voltage or lowest possible noise for some given source impedance), or customized with features that just don't have enough of a market to interest IC designers.
But there are some things that can be done in integrated circuits that just can't be done in fully discrete circuits, such as extremely high inherent transistor matching and highest possible thermal coupling between devices that need to track to work right. |
Dgarretson, sorry for the late reply.
If you read more about the ASR Emmiter II Exclusive Battery amp, you will find out that its preamp sections runs on high-current batteries heavily bypassed with high-quality capacitors. This amp has 3 extra PS boxes that weigh about 100 pounds.
The Burson discrete opamps and the original OPA627 opamps were compared with the same (close to perfect) power supply.
Specs are just specs...trust your ears. I have trusted mine and do not regret it.
For a discussion on discrete opamps and their superior sound as compared to chip opamps, start here:
http://www.dself.dsl.pipex.com/ampins/discrete/discrop.htm
then take a look at (and listen to samples of) the state of the art opamps used by recording studios that care:
http://www.thelisteningsessions.com/session9.htm
best regards |
Chris - It might "give more harmonic richness/complexity" if you already have rest of the system that you are happy with. I need to spend money on speakers.
Audio always has been neglected an there is only a handful of opamps designed specifically for the audio. Even one mentioned by Undertow (AD843) as great sounding wasn't designed for the audio (no mention of it or any THD data) but rather as fast settling amp to use as buffer for A/D converters or peak capture or sample/hold circuits.
I am afraid that such advances like SACD come to us only because they have absolute copy protection and not for the sound. |
My limited experience with the OPA627 is indeed a bit laid back sound. It sounds clean and "transparent", but altogether it doesn't sound very engaging in the long term. I think a discrete layout (a well designed one of course) would give more harmonic richness/complexity to the sound.
Chris |
Kijanki
Exactly :-) The burr browns get good reps on headphones, they do produce a certain ambience thats nice.. But if your looking for a raw out rock power with detailed sound they are a bit laid back in many designs.. Again going discrete in fact will take about 20 times the Space as an op amp and way more parts and cost! A good op amp based unit is fine, some cases might be just as good as with some Digital equipment and headphones, so op amps have their place no doubt, and cost effective for sure, a comprable discrete circuit in general the parts alone can cost 100 times the single chip, and just wont even be physically useable in many designs easily. If you can fit it go for it! |
Undertow - Burr-Brown is Texas Instruments now. Perhaps sound changed from "Brown" to "Instrumental"? |
OPA627 is a burr brown sound.. Exactly in its name a color "Brown" sound... Just kidding but its DARKer than other opamps... might be the ticket for a cheaper way to make a system that is over excited settle down, but with that goes a lot of strong bass and clarity..
I have used discretes vs. op amps and the burr browns the discrete will kill it if implemented correctly... I like Analog devices Top dog the AD843 best out of all single chip op amps, however very hard to find. |
Chris - I had a friend who believed that DAC IC should have current output to avoid I/V converter inside and be followed by the tube and discrete transistor circuits to avoid opamp. DAC itself has current sources build using monolithic, opamp like, technology - no escape from that.
I don't have enough experience to judge and my system is very modest, but logic tells me that added distortions add dynamics to the sound (distorted guitar vs clean jazz guitar). Yes, Benchmark sounded lifeless to me at first but it doesn't anymore while it still sounds extremely transparent and clean. I got used to this sound - or learned to listen, if you prefer. I read post where somebody asks how to make sound warmer and less detailed - read "exaggerate even harmonics and add a little distortion" (I advised blanket over speakers).
My small class D amp according to some Audiogon members (with better ears and more experience) has some problems with highs and harmonic structure but I think that for the money it is a great bargain.
Stereophile rated A, couple years ago, amplifier that costs $500k. In my opinion review wasn't necessary because any amplifier with that price tag and company still in business will be rated A. Everything is a matter of money and most of the time people ask for the best bargain and synergy in their systems. Opamps, in my opinion, are very good bargain. |
Kijanski, that is a funny phrase --> sometimes it is even true! But of course in general cars are much better now in terms of engineering and performance than those from 40 years ago. But with audio sometimes things from the past are better than the contemporary ones, like some power amplifiers (FM Acoustics, JDF Audio) and DAC's (Wadia 9, Goldmund, Krell). It has to do with execution (of course) but also with the implementation of no compromise discrete layouts only (this is at least my opinion). Personally I don't have anything against OPamps, but usually the sound with OPamps in the analog section of let's say a D/A converter the sound is becoming ultra clean (almost sterile, without the minutest dust or bacteria) and a bit bland/lifeless. This is for example what I think of the sound of the Benchmark DAC (which is a great performing DAC on itself).
Chris |
Dgarretson - Jeff Rowland used batteries in his preamps but now he "switched" to switching power supply (SMPS) in Capri. It should be easier to filter out high frequency than 120Hz and also to make stronger supply within same dimensions (and SMPS are load and line regulated) but unfortunately manufacturers use SMPS technology to make it cheap instead of better.
Somebody said that there are two types of fools in this world: One says "it is old and therefore good" while the other says "this is new and therefore better" |
Chris - This is difficult to answer. Example of Capri shows what is possible. The real question is what you can buy for the difference. It might be better to buy Capri for $3,500 instead of discrete preamp for $10k and spend $7k more on speakers. Benchmark DAC1 praised by many uses $0.50 opamps (NE5532).
I agree with you that it might be better to get discrete circuit if money is no object but even then you might not beat opamps in offset drift to eliminate caps from the signal path.
Problem with opamps is that they are not designed in general for the audio. First opamp really designed for audio was NE5532. It was about 25 years ago and Benchmark claims that it performs better than OPA627. Now National Semi. came with LM4562 but many claim that NE5532 has better midrange.
I was surprised with Rowlands selection of 180MHz amplifier and even more surprised when I checked datasheet - It is an audio amp. It has 180 MHz bandwidth but its full power bandwidth is only 800kHz (Capri swings 7V rms = 20Vp-p). Distortions start to climb-up starting from 10kHz so it was probably necessary to spike-up bandwidth to avoid distortions and any phase shift at 20kHz. |
I have not tried Burson discrete op amps, but IME the sonic performance of monolithic op amps is very much dependent upon the quality of the power source. Typically the same build-to-cost considerations that lead manufacturers to use inexpensive op amps, also leads them to cheap out in the power supply. Therefore few people hear op amps at their best. Executing op amps together with batteries and well engineered discrete DC regulation circuits is a different animal. And if this is done correctly, then monolithic op amps may have the advantage insofar as there less is less metal, solder joints, etc. to add degredation. Moreover, at Burson's price point it is unlikely that he uses top-quality piece parts. |
Kijanki, I understand the technical difficulties of making discrete layouts and the costs that it will generate. But we are audiophiles and we are only interested in sound quality, not technical specifications. So do you think the best OPamps with the best specifications ever sound as good (= musical) as the best discrete layouts? Or even better?
Chris |
Casouza - Jeff Rowland uses, in great sounding Capri linestage, fully differential high speed op-amps OPA1632.
OPA1632 has:
0.00002% THD
0.00005% IMD
1.3nV/SQRT(Hz) noise
180MHz bandwidth
discrete amp like that is not a trivial task (layout!). Can you imagine the cost? |
HI.
I replaced the original OPA 627 opamps in my ASR Emmiter amplifier with Burson discrete opamps. The improvements were major and all across the board: clean, more tuneful bass, amazing midrange purity, clean treble, more dynamics, a deep and wide soundstage and specially a more musical delivery.
I could not hear a downside. My only complaint is that Burson does not make a tube based opamp.
Highly recommended, though it requires a bit of DIY skill (one needs to find a suitable nearby signal ground point and solder a ground lead there).
The Burson opamps have worked flawlessly for about 18 months and do not become too hot (the OPA 627 needs a heatsink and stays too hot to touch). |
>Yes - quality op amp packages can have outstanding performance. The only reason to use discrete components is for building output side of power amps. This is because of the high heat.
You get better thermal tracking and lower cross-over disortion with transient signals when the bias diodes are on the same die as the power transistor.
You could use the ONSEMI Thermal Traks, but parallel LM3886 or other power op amps work well and make for a decidedly clean board layout.
The Rowland Model 10 ($8K MSRP) is six LM3886s per channel. |
Don't forget that discrete components(capacitors/resistors/rectifiers/transistors/etc.) have advanced in materials, manufacture and design over the years also. Much of what is considered "High-End" now days not only is built with discrete components, but is hard-wired(point to point) as well. OP amps are quite impossible to avoid when considering digital equipment though(unfortunate, in my opinion). |
To take a slightly more concrete example rather than a theoretical one, I have not yet heard a phono stage based on op amps that could equal a discrete-component design for refinement and sonic magic. I'm thinking of the best phono stages I've heard, the Audiomat 1.5, the Ensemble Fonovivo, the SimAudio Moon LP5.3. The op amp designs cost less, and it shows in their sound.
I haven't heard the Burson, though. It certainly intrigues me, and it's not too high-priced. |
I have not seen the data to compare the above two - but generally it is accepted that a high quality OP amp can achieve better measured performance (S/N etc.) than discrete. Whether you like the sound of it or not is another matter -as measured performance is not the holy grail for many. |
Is the Burr Brown OPA627 better than the Burson discrete OPamp?
Chris |
Yes - quality op amp packages can have outstanding performance. The only reason to use discrete components is for building output side of power amps. This is because of the high heat. |
