OPA-Earth & OPA-Sun, Discrete Opamp diy kits

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#21
nelsonvandal said:

Aren't most of them class A up to a certain load? It has been popular to force monolithic opamps to class A operation by applying a resistor or active current source from output to negative (or sometimes positive) rail. I thought the world of doing this until I did this tweak live, and I heard no difference at all. Placebo is a miracle drug.
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Biased in class A and designed in class A are different things leading to different results, because reduced crossover distortions and no crossover distortions at all are totally different things.
AFAIK only CA3140 was designed with class A output stage, but it has very noisy input stage.
 
#22
I tried to make some measurements yesterday, but I had some problems. The results are not worth to be published, I am sorry.

And I contacted Samuel Groner. He is interested to test this OPA-chips, but not to publish the results, as long as it is not clear, if this are unauthorized copies.

Here the problem with my measuring system: when I connect the outputs to the inputs of the system box, I dont get a proper square wave. And I did not find a calibration function.

An externally hosted image should be here but it was not working when we last tested it.


Franz
 
#23
Our OPAs are first.
Check below links please, although these links all are Chinese, but you can have a look of the pictures and the post date, we sale OPA(HDAM) begine Jul of 2005, they sale HDAM begine at Reb of 2006,
Except OPA(HDAM) , in these links can see there clock, Feg modules, all these products ,we have sale begin 2005-2006 year.

These days, I don't wish to said about these thing, but some guy do some tenebrous action in web and hurt us,.


http://bbs.audio-gd.com/dispbbs.asp?boardID=2&ID=2270&page=101

http://bbs.audio-gd.com/dispbbs.asp?boardid=2&replyid=2683&id=2683&page=95&skin=0&Star=2

These links pictures have deleted, but the words said our OPA(HDAM), date is at 2005 years.

http://bbs.audio-gd.com/dispbbs.asp?boardID=2&ID=1967&page=108

http://bbs.audio-gd.com/dispbbs.asp?boardID=2&ID=593&page=137

http://bbs.audio-gd.com/dispbbs.asp?boardID=2&ID=664&page=135
 
#25
I'll chime in here with my own particular brand of nonsense. I recently purchased two dual Earth modules and two dual Sun modules from a guy on eBay. He didn't say they were made by Burson and he didn't say that they weren't. He told me that someone purchased them for him directly from Burson. That is kluster number one. I e-mailed Burson with the numbers silkscreened on the PCB's. He said they were not his and that they were counterfeit. They look like they should work and I would know. I have a studio full of pro audio gear. I have discrete opamps from known pro audio manufacturers. Many of them. I don't care who designed these as long as they work and they sound good. If these are FET-based (and that is what they appear to be), then they probably won't drive my beloved output transformers. But that's alright. I plenty of other gear which will do that. Ya' see, we do both. Or anything. Or everything. If I want ultra-clean, I go to Mil-Media or Grace Design. If I want character, I go to vintage API or Purple Audio or Quad-Eight. What really gets me is the smoke and mirrors approach of "manufacturers" like Burson. Oh, we don't do that. Oh, here buy this and try this and let me know what you think. Are you out of your mind? I don't buy any audio box that costs over 1000 dollars without hearing it first. And if I don't like it, it goes back. So I took a chance and purchased these opamps unheard. I can live with that. I'm pretty certain this dude at audio-gd designed these. But who cares? Either they work and sound good or they don't. I need to identify an expendable box into which I can install these and have a listen. Small-minded losers selling vapor-ware. Good luck with that. This here internet will put an end to that non-sense. You can't get away with crap like that anymore.
 
#26
tubemooley said:
I'll chime in here with my own particular brand of nonsense. I recently purchased two dual Earth modules and two dual Sun modules from a guy on eBay. He didn't say they were made by Burson and he didn't say that they weren't. He told me that someone purchased them for him directly from Burson. That is kluster number one. I e-mailed Burson with the numbers silkscreened on the PCB's. He said they were not his and that they were counterfeit. They look like they should work and I would know. I have a studio full of pro audio gear. I have discrete opamps from known pro audio manufacturers. Many of them. I don't care who designed these as long as they work and they sound good. If these are FET-based (and that is what they appear to be), then they probably won't drive my beloved output transformers. But that's alright. I plenty of other gear which will do that. Ya' see, we do both. Or anything. Or everything. If I want ultra-clean, I go to Mil-Media or Grace Design. If I want character, I go to vintage API or Purple Audio or Quad-Eight. What really gets me is the smoke and mirrors approach of "manufacturers" like Burson. Oh, we don't do that. Oh, here buy this and try this and let me know what you think. Are you out of your mind? I don't buy any audio box that costs over 1000 dollars without hearing it first. And if I don't like it, it goes back. So I took a chance and purchased these opamps unheard. I can live with that. I'm pretty certain this dude at audio-gd designed these. But who cares? Either they work and sound good or they don't. I need to identify an expendable box into which I can install these and have a listen. Small-minded losers selling vapor-ware. Good luck with that. This here internet will put an end to that non-sense. You can't get away with crap like that anymore.
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Short question, mate: did you test them?
 
#27
Franz Gysi said:

I don't know, who is copying from who! When I look in web.archive.org, I cannot say who was the first, Burson or Audio-gd.

But: audio-gd seems to be more innovative, as he announced the OPA-Moon, Class-A output! BTW: I ordered some moon's and will measure it later.

Why are there no audio opamps with Class-A output by design from the big semiconductor manufacturers available?

Thermal issues?

Franz
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1. I do not know what Burson has to do with these OPA amplifiers.
Not more than Nelson Pass power amplifier has to do with Mark Levinson Power amplifier.
Is Mark Levinson latest power amplifier a clone of Nelson Pass Aleph?

Just because two different sources are selling same sort of stuff, does not make any of them be fakes.
I do not get the logic ...


2. Why almost no chip op-amps are Class A? Thermal issues?
Yes, this is one reason, I would say.
One 8 pin DIP plastic capsule can only take like 0.5-0.7 Watt max.
Suppose the recommended upper voltage is 36 VDC (2x18).

700 mW / 36V = max 20 mA.
And one Class A output stage need several mA for previous driver stage(s).
The Class A operation of output stage would only be like 10-15 mA
Per chip!!!
Suppose one dual 8 pin op-amp = 5 mA per amplifier. (OPA2134 / OPA2228 TL072)

In many loads these would simply go into Class AB anyway.
And one amplifier designed for Class A but operating into Class AB
will perform worse than one designed for Class AB in the first place
Especially in the 2 regions where the transistion from Class A to Class B takes place.


The max 0.5 Watt per capsule, is the reason I prefer single opamps.

2 x OPA134 = 2 x 0.5 Watt heat sinking
1 x OPA 2134 = 0.5 Watt heat sinking
So, for same power output two OPA134 (single) will work at lower inside transistors junction temperature.
And probably do a better job. Especially when comes at higher level of output power.
Closer to the limit of SOA, Safe Area Operation.
 
#28
KSTR said:
What I don't like about them (Sun & Earth) is that one of them seems to be 1:1 copy of another commercial discrete opamp replacement, the Burson amp (or vice versa, which appears to be rather unlikely, but I just don't know). There is a thread about the Burson amp here where schematics are shown (and some measurement), from a french forum.
http://www.diyaudio.com/forums/showthread.php?threadid=127559
(see first dozen of replies).

- Klaus
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Why would you just assume that the Sun & Earth opamps are copies of the Burson and not the other way around. Just because Audio-gd is in China it does not preclude that he is copying someone else. From what I have read on this forum Audio-gd seems to know his stuff and is quite innovative. While Burson's response to the request from the french poster for a datasheet was "measure it yourself" and only providing the usual hyperbole on their website about how discrete op-amps are better than IC's with out a shred of evidence to the contrary.
While it is true that there is rampant coping of intellectual property in China there is also innovation. There is a huge audiophile community in China and many audio manufacturers in china that do not export to the rest of the world. Some are copies of things in the west and some or not. To me China is like Japan was in the 60's and 70's. With 1.3 people and growing wealth, it is only a matter of time before more innovations will be revealed to the rest of the world. I believe this is already happening.
 
#29
Sze said:


While it is true that there is rampant coping of intellectual property in China there is also innovation. There is a huge audiophile community in China and many audio manufacturers in china that do not export to the rest of the world.
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These circuits are all basicly, as the JE990, out there free for anyone to make. To be fair none of these discrete op-amps would substitute for any of the claimed IC's. They have poor DC performance, low Aol, and way too much power consumption.

BTW, I found a great audiophile store in Shenzhen, looked as good as any in Akihabara.
 
#30
there are a number of DSL driver op amps that have >10mA Iq - some with current programming pins to select the bias

I'm pretty sure some of these will be Class A output to +/-20 mA - enough to run Class A for any consumer line level signal processing

these chips typically have exposed copper pads for several W dissapation on regular PCB - I've extracted more than 6W from the TPA6120 by clamping the thermal pad to a Cu heat sink

really high performance could be had by building smt composite op amp modules with the best input op amps (opa627, AD743, AD797, LT1115... ) driving a parallel pair of the Class A output DSL op amps biased to Class A push-pull at any current level you're willing to heat sink

I show a couple of circuits for Class A output bias for monolithic op amps in:

http://www.head-fi.org/forums/f6/ad8397-class-188758/index2.html#post2264079
 
#32
Re: Specs?

QSerraTico_Tico said:



And may I ask how DC performance, Aol and power consumption relate to sound quality?
😕
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They basicly claim they are drop ins for ANY op-amp, they actually did not specify only for audio. But if you relied on 250uV offset and 1uV/C so you could dispense with a servo you might have problems.
 
#33
jcx said:
there are a number of DSL driver op amps that have >10mA Iq - some with current programming pins to select the bias

I'm pretty sure some of these will be Class A output to +/-20 mA - enough to run Class A for any consumer line level signal processing

these chips typically have exposed copper pads for several W dissapation on regular PCB - I've extracted more than 6W from the TPA6120 by clamping the thermal pad to a Cu heat sink

really high performance could be had by building smt composite op amp modules with the best input op amps (opa627, AD743, AD797, LT1115... ) driving a parallel pair of the Class A output DSL op amps biased to Class A push-pull at any current level you're willing to heat sink

I show a couple of circuits for Class A output bias for monolithic op amps in:

http://www.head-fi.org/forums/f6/ad8397-class-188758/index2.html#post2264079
Click to expand...

AD8397, that's my guy! I have to show that to him tomorrow. He got a free USB powered headphone amp for walking through some problems with the customer.
 
#34
scott wurcer said:


BTW, I found a great audiophile store in Shenzhen, looked as good as any in Akihabara.
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I was in Tokyo many years ago, wish I had pickup some of those large Cerifines or Blackgates that were prevalent in the Akihabara stores back then. Who knew that most of them are now unavailable today.
 
#35
Re: Re: Specs?

scott wurcer said:


They basicly claim they are drop ins for ANY op-amp, they actually did not specify only for audio. But if you relied on 250uV offset and 1uV/C so you could dispense with a servo you might have problems.
Click to expand...

Sorry it does not answer my question.

One of the very few things I learned from the Blow Torch thread was that high Aol was not advantageous for good sound. But maybe I wrong, too many smoke-curtains in that thread.
 
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