What are your guy's opinion on what make an amplifier quiet from voltage disturbances on the AC line?
Everyone can spout out crap like "big capacitors" but what have you actually done that worked well as opposed to you think should work well?
Everyone can spout out crap like "big capacitors" but what have you actually done that worked well as opposed to you think should work well?
Why do you polite to me, recently?
About op-amp rolling, I agree it is useless if they do not know the op-amp specification, using bad pcb layout, bad decoupling technique. But for line pre-amp with gain around 3x, you should hear the sound difference when using different op-amp.
I design discrete line pre-amp for fun in this forum. People who built it really enjoyed my pre-amp.
It often works like this. Big client says if you come up with an op-amp that does X we will buy several million of them (scale accordingly). Due diligence is done and if the numbers stack up and the process available will do it the opamp is designed and fabbed. THEN they look at secondard applications. So you get the case of ADSL line drivers being repackaged as headphone amps etc.
Pretty sure outside of Muses you can count the opamps designed JUST for audio since 1975 on one hand.
Don't push it! 😉 I'm just guessing you may not be trolling, I'm sick of Mark's stonewalling, maybe you have something constructive to say about what you listen for regards particular amplifier/dac/whatever characteristics, you imply it.
Bill,
You must have a funny hand!
The LME family has single, dual, quad and high voltage parts. Add to that the chips intended to drive 600 ohms, a dead give away audio applications were intended. (I forget the model numbers of the Japanese ones that aimed at the 5532 market.) Throw in the aforementioned 5532 and 5534 and you have a very strange looking hand.
BTY TI lists 65 audio parts http://www.ti.com/amplifier-circuit/op-amps/audio/products.html
So you were probably born too late to be featured in a circus freak show, but do have the advantage of socialized medicine to correct the condition! 😉 (For the humor impaired this has been a friendly jibe!)
You must have a funny hand!
The LME family has single, dual, quad and high voltage parts. Add to that the chips intended to drive 600 ohms, a dead give away audio applications were intended. (I forget the model numbers of the Japanese ones that aimed at the 5532 market.) Throw in the aforementioned 5532 and 5534 and you have a very strange looking hand.
BTY TI lists 65 audio parts http://www.ti.com/amplifier-circuit/op-amps/audio/products.html
So you were probably born too late to be featured in a circus freak show, but do have the advantage of socialized medicine to correct the condition! 😉 (For the humor impaired this has been a friendly jibe!)
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When did the design start on the NE5532? If it wasn't 1975 it was very close to that. Which was my point. Have you spoken to the designers to confirm they were told to design audio opamps or just pulling it out air? I assume latter...
No, unless the original design is very poor, or you put in a completely rubbish op amp for the application, you should hear no difference...
You might be right on the LME series.
However, many of TI's audio newer op-amps are rebrands of another general purpose op-amp. You'll notice many "twins" like OPA211 and OPA1611, where the audio part just doesn't meet the DC specs. There are only a few that seem to be designed for audio-only from the start, like OPA1622. I'm sure johnc124 will correct me if I have the wrong impression 🙂.
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The 5534/2 were almost certainly designed for audio. The LF353/6/7 came out at around the same time and I used them in one of my first preamps for a line stage with a 50k log pot :O) A bit noisier than I would have liked but it sounded ok. These were IMV GP workhorse devices not targeting audio.
But, there are lots of applications that need precision, low noise and reasonably low distortion outside of audio that demand high performance opamps in scientific instrumentation. I think the best modern example of that is LIGO.
My favorite back in the day for TC amplifiers was the LM308A. Quite DC accurate, low power (so low self heating) and relatively cheap. The chopper opamps from Intersil came along, but were 3 or 4x the price and then you had to add the caps (later integrated IIRC).
All the stuff I was designing at the time went into industrial plants (petroleum-chem, mining, food industry etc) so it had to be quite rugged.
There is a life outside of audio for opamps believe it or not!
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IME there are differences (in sound) between various opamps. And huge differences in parametrers, like noise, SR, GBW. And in non-audio parameters, like EMIRR, that potentially may reflect in sound. Differences in sound are not big, but they can be proven even in DBT, if we try hard enough. And no question that applications like microphone preamp or phono preamp need careful choice of parts. So, to me, laughing on "opamp rolling" is not needed and seems to me a bit amateurish.
Once smitten . . .
You may like Gothic Voices as well. They have a bunch of CD’s out.
Gothic Voices - Unaccompanied close medieval harmonies
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Well, in a way - yes. In case I have 2 or more "almost perfect" opamp parts re parameters in a particular design, then I make a final choice by listening, regardless price.
Gee wiz, hope you get over it okay.
Say, Bill mentioned something like dScope or AP needed for really high performance designs.
Found an interesting document on the dScope website entitled: PERFORMANCE CHALLENGES IN AUDIO CONVERTER DESIGN, by Ian Dennis.
A brief excerpt from that for your reading enjoyment:
"The debate as to whether measuring or listening is best will rage forever. But to me, developing high performance audio requires both methods. My own preference, as one who is devoted to transparency rather than any particular ‘character’ in audio equipment, is to use measurement to ‘debug’ the design and to worry about listening tests after that. With experience, I believe it is possible to get a feel for the relative importance of the various measured parameters in terms of audibility – up to a point. Although I know ‘high-end’ designers who don’t possess any measurement equipment..."
My take on that is that they recognize measurements don't exactly correlate with sound quality, and that listening tests are part of the design process. It also recognizes that measurements don't have to some first, it is a preference only to work that way rather than listening first.
Well, I'm still in the listening phase. I'm sure some measurements will probably come eventually though. Why that way? For one thing, I don't have a lab full of measurement equipment, and for another thing, I know how to listen. So, I will work with what I have for now. It can be done that way, is the point.
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