Tone*L*u*x Op amps

[boji]

If you have not dug around tonelux's site, this is a cool read I wanted to share:

http://www.tonelux.com/opampinfo.html

What do you think of his "divide and conquer" method?

Also it's so cool to see his breadboard design testing mess- makes me think of more than a few of you, working hard to realize your ideas!

 

[tv]

These breadboards actually look clean and tidy.
You should see my ratnests. (but I'm not going to show them).

 

[JohnRoberts]

API was noted for using discrete circuitry and high headroom (high rail voltage) designs.

Paul continued that by making his own SMT DOAs at API and today at Tonelux.

Making a DOA specifically for audio is not very cost effective but a nice touch for esoteric markets.  Many off the shelf ICs are even better than needed for audio and using a better part than is needed is not much of a compromise.

Some of the newer ultra performance opamps require a little more care in application, but only because they are so high performance and a little touchy about terminations.

JR

 

[ppa]

API was noted for using discrete circuitry and high headroom (high rail voltage) designs.

Paul continued that by making his own SMT DOAs at API and today at Tonelux.

Making a DOA specifically for audio is not very cost effective but a nice touch for esoteric markets.  Many off the shelf ICs are even better than needed for audio and using a better part than is needed is not much of a compromise.

Some of the newer ultra performance opamps require a little more care in application, but only because they are so high performance and a little touchy about terminations.

JR

a DOA designed like an IC sounds like an IC, but a DOA designed like a discrete amp sound like a discrete amp.
When a my customer (one of the firsts) tested a my APP2055 said me: your DOA sound totally different from the IC opamps, is the type of sound that is different!

Pier Paolo

 

[JohnRoberts]

API was noted for using discrete circuitry and high headroom (high rail voltage) designs.

Paul continued that by making his own SMT DOAs at API and today at Tonelux.

Making a DOA specifically for audio is not very cost effective but a nice touch for esoteric markets.  Many off the shelf ICs are even better than needed for audio and using a better part than is needed is not much of a compromise.

Some of the newer ultra performance opamps require a little more care in application, but only because they are so high performance and a little touchy about terminations.

JR

a DOA designed like an IC sounds like an IC, but a DOA designed like a discrete amp sound like a discrete amp.
When a my customer (one of the firsts) tested a my APP2055 said me: your DOA sound totally different from the IC opamps, is the type of sound that is different!

Pier Paolo

The terms "operational amplifier", "integrated circuit", and even "discrete operational amplifier" , have very specific meanings.

A "DOA designed like a discrete amp" is actually still a discrete circuit, not a discrete opamp, so it should sound like what it is.

In my experience ICs do not have specific sound characters. Most ICs are not even used for audio circuits. One could argue that if we go back to the earlier days of integrated circuits, they had performance limitations compared to similar circuits fabricated from discrete devices, that may have inferred a characteristic sound. Back in the not so good old days there were notable differences between different engineer's implementations using the same raw parts. Probably more so than today since ICs have done a lot of catching up since then. Modern IC devices today, are certainly linear, quiet, and powerful enough for 99.9% of audio applications. It is easier now for less skilled engineers to get good results.

The linearity and precision delivered by the new generation IC opamps is difficult to match in even a "cost no object" DOA design, due to the inherent benefits of integrated circuit device matching, thermal tracking, etc.

About the only intrinsic limitations of IC opamps, is that you can't easily incorporate a large value inductor into the input long tail pair, or operate from higher than nominal process voltages (40V or so).  These limitations are not game stoppers or reasons to expect inferior sound quality.

Like anything else, they are tools that can be well applied or not.

JR

 

[ppa]

The terms "operational amplifier", "integrated circuit", and even "discrete operational amplifier" , have very specific meanings.

A "DOA designed like a discrete amp" is actually still a discrete circuit, not a discrete opamp, so it should sound like what it is.

the 90% of solid state discrete amps are formed by a discrete operational amplifier with some components added for the feedback network and , if used , a servo DC, because, for audio use, many amps have a large amount of overall negative feedback applied, so it's necessary using a discrete operational amplifier section in these amps.
At this point, it's possible designing a DOA using the same criterias used for the operational amplifier section used in the audio amps. Obvius, I referred to this operational amplifier section of the discrete amp when I said  " DOA designed like a discrete amp".

(    I'm an electronic engineer with several years of experience (more than 10) in the analog field (from DC to microwaves) and I know the specific meanings of these terms. I've not said:  " DOA designed exactly
like a discrete amp" but " DOA designed like a discrete amp".      )


Pier Paolo

 

[ppa]

In my experience ICs do not have specific sound characters. Most ICs are not even used for audio circuits. One could argue that if we go back to the earlier days of integrated circuits, they had performance limitations compared to similar circuits fabricated from discrete devices, that may have inferred a characteristic sound. Back in the not so good old days there were notable differences between different engineer's implementations using the same raw parts. Probably more so than today since ICs have done a lot of catching up since then. Modern IC devices today, are certainly linear, quiet, and powerful enough for 99.9% of audio applications. It is easier now for less skilled engineers to get good results.

The linearity and precision delivered by the new generation IC opamps is difficult to match in even a "cost no object" DOA design, due to the inherent benefits of integrated circuit device matching, thermal tracking, etc.

About the only intrinsic limitations of IC opamps, is that you can't easily incorporate a large value inductor into the input long tail pair, or operate from higher than nominal process voltages (40V or so).  These limitations are not game stoppers or reasons to expect inferior sound quality.

I have not never said that the IC opamps sound bad, I tried to say that a DOA, if designed to fully exploit the possibility of a discrete amplifier, sounds different from an IC opamp, and, again, I was referring at the operational amplifier section.   :-*


Pier Paolo

 

[gridcurrent]

API was noted for using discrete circuitry and high headroom (high rail voltage) designs.

The power supply voltage specifications for the 2*5*2*0 are hardly high rail voltage (bipolar 12 to 20 VDC).  API's famed high headroom is due to the inclusion of step-up output transformers.  Quad/Eight and Sontec were noted for their high headroom operational amplifiers (bipolar 28 VDC).

 

[JohnRoberts]

Thanks for the clarification...

I had made the logical leap myself that the high headroom they were noted for, was created rail voltages on discrete circuitry. I never spent any time under the hood of one.

A ASSume the 2*5*2*0 similar to a 2520?

J*R*