Replace OP amps. Completely pointless, or not?

[antcollinet]

Indeed... I wonder how many of today's (or yesterday's) op-amp rollers know that it's perfectly possible to build an op amp that is fully discrete...

Aren't typical "audiophile" op amps fully discrete? Isn't this part of the nonsense?

Model 992Enh Discrete OpAmp

 

[mhardy6647]

Aren't typical "audiophile" op amps fully discrete? Isn't this part of the nonsense?

Model 992Enh Discrete OpAmp

well, depends on how hard-core the audiophile, methinks.
The really serious ones would go discrete and point-to-point -- of course.
I mean, everybody knows how much the harmonic and textural purity of those poor fragile, feeble music signals suffer when forced through those little flat traces on a PC board.

 

[Ricardus]

You already know this, and many others who write in the thread. But for those who read the thread and wonder. Basic regarding OP amps in this video. What they can be used for and how they are constructed:

The EEV Blog guy did an amazing video on opamps maybe 6 or 7 years ago. I'll see if I can find it.

 

[JSmith]

EEV Blog guy

Yes Dave is always informative and amusing. I'd imagine you mean #600;

JSmith

 

[RayDunzl]

About the highest signal levels I've seen, even in pro gear, is about 4 volts which would result from tone controls being turned all the way up.

Higher here at home:



Benchmark DAC 2 balanced output

DAC2 Texas Instruments LME49860 output stage opamp spec

Feeding Krell KCT preamp

PS:

The DAC2 opamps aren't socketed but I've never felt a need to swap them.

 

[Deleted member 46664]

Higher here at home:

Those are maximums.... But what are the running normals?

I'm betting it's closer to 1 volt in operation.

Most power amps are designed to clip on 1 volt inputs.

 

[MakeMineVinyl]

Those are maximums.... But what are the running normals?

I'm betting it's closer to 1 volt in operation.

Most power amps are designed to clip on 1 volt inputs.

Current power amplifiers are designed with 29dB of gain, so that 1 volt = 100 watts. Amplifiers with lower or higher power will require correspondingly less or more voltage drive to achieve rated output.

 

[RayDunzl]

Current power amplifiers are designed with 29dB of gain, so that 1 volt = 100 watts. Amplifiers with lower or higher power will require correspondingly less or more voltage drive to achieve rated output.

Yeah...

An example.

An amp series:

I sport a pair of the little baby of the series.

 

[Deleted member 46664]

Current power amplifiers are designed with 29dB of gain, so that 1 volt = 100 watts. Amplifiers with lower or higher power will require correspondingly less or more voltage drive to achieve rated output.

Maybe so ... but that's just dumb. So now you need pre-amps with more or less output to match an amplifier.
That totally defeats the notion of standard line levels that allow us to mix and match devices freely.

Amplifier gains should be varied so that 1v p/p input brings it to the edge of clipping.

 

[MakeMineVinyl]

Maybe so ... but that's just dumb. So now you need pre-amps with more or less output to match an amplifier.
That totally defeats the notion of standard line levels that allow us to mix and match devices freely.

Amplifier gains should be varied so that 1v p/p input brings it to the edge of clipping.

THX came up with this standard, and we, like most amplifiers manufacturers, are following it. I don't consider it dumb or great for that matter; its just the way amplifiers are manufactured now.

 

[Deleted member 46664]

THX came up with this standard, and we, like most amplifiers manufacturers, are following it.

I guess I'd better read up on this one .... got a link to the documents?

 

[MakeMineVinyl]

I guess I'd better read up on this one .... got a link to the documents?

I'm sure the Google machine will give you lots of results. This is not a new standard by any means; I don't know when it took affect, but its been there for years.

 

[Deleted member 46664]

I'm sure the Google machine will give you lots of results. This is not a new standard by any means; I don't know when it took affect, but its been there for years.

Not helpful ... I did find a bunch of places where they said the standards are not publicly disclosed.
ROFL ... makes perfect sense to me... NOT.

 

[Ricardus]

Yes Dave is always informative and amusing.

I would pay good money to see The EEV Blog guy fight Mr. Calrson in an MMA style cage match.

 

[Cbdb2]

Even the ancient 741 and 301 can get within a couple volts of the rails; I have yet to see any op amp which cannot do this, especially current designs. If a designer chooses to use lower voltage rails, well that's a design issue and choice of op amp is not going to cure a compromised design from the start.

Changing op amps is a solution in search of a problem. Personally, I've had better sonic results by changing the on/off power switch on my gear.

Guitar pedals are a compromise that can't be helped, and other devices that use batteries. If you've only got 8volts (a 9v battery after some use) an OA that hits the rails can add usable headroom. (Not to mention battery life changes with different OAs.)
Fet input vs BP often can't be swapped. Some OAs can drive 200ohms some can't. Some are unity gain unstable. That 741 dosnt have sufficient slew rate. Sometimes stability issues from swapping OAs, even with similar specs.
Different OAs will have different input offset Vs and Is changing output offsets. (and if its a high gain circuit that offset can cause early clipping.) There are more.

 

[Angsty]

Aren't typical "audiophile" op amps fully discrete? Isn't this part of the nonsense?

Model 992Enh Discrete OpAmp

I have good examples of both philosophies. Bryston eschews the use of any integrated op-amps in their phono preamps - I have a BP-1.5 with fully discrete op-amp circuitry. Sutherland fully embraces op-amps in his designs as a way to drive more production consistency and put greater focus on other areas of concern, like power supply management. I have the Sutherland Insight. Both design approaches produce great results.

 

[Cbdb2]

And what are the odds, in an audio circuit, of either of those chips having to produce 24volt peak to peak signals?

Virtually all line level devices operate at about 1 volt p/p ....

You should have said home audio circuit. And what if I add 10db at 60hz?
Pro gear runs 10db hotter and has to handle large dynamic range.

 

[sq225917]

Neurochromr 686 needs 2.4v to reach max power at standard gain, more at lower gain settings.

 

[Deleted member 46664]

You should have said home audio circuit. And what if I add 10db at 60hz?
Pro gear runs 10db hotter and has to handle large dynamic range.

True ... I should have.

The standard line levels are defined ... HERE

 

[Sokel]

Since there is a thread about op-amps,let's ask here.It's not about rolling,its about the relation between the op-amps and (excessive) current.Doesn't matter the application,what makes me wonder is the following:
Feeding a LME49720 based circuit with 50mA ,-+15V operates just fine giving approximately .04mV dc offset.When I feed it with 200mA all else been the same I get .0 dc offset.Can anyone explain without be (too) technical?And,is this an optimal way to go?