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Chip Amps Amplifiers based on integrated circuits

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Old 17th July 2017, 11:24 PM   #3361
alexwey is offline alexwey  Australia
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lehmanhill
I thought maybe it's a fuse or a resistor and missed the simplest explanation. Thank you.
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Old 18th July 2017, 07:22 PM   #3362
suburra is offline suburra  Italy
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Originally Posted by Joseph K View Post
Jokes apart: thank you, Marco, you know I value much your opinion.

But If I may choose, I think I would rather be a Janitor. And even at that, I could only be a Vice-Janitor, given that this is Dario's thread and achievement, principally.

I'm serious about this Janitorship: while I had always enjoyed enormously the beautiful,democratic and creative atmosphere in this thread (due to all of you, and the righteous governance of Dario..), still
technical projects like this, where things can explode and take out paper cones... need some less democratic and more technocratic maintenance, appunto, a Janitor

Ciao, George --- alias F. Joseph K

(hmmm.. does it not look like an F word??)
George,

If we ( me for sure ) are reached this point, is thanks to Dario and his FE.
His continue input gave me the spark for continuing believe in this project!

Ciao
Marco
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Old 19th July 2017, 05:33 PM   #3363
Spartacus is offline Spartacus  United Kingdom
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Originally Posted by Joseph K View Post
I'm serious about this Janitorship: while I had always enjoyed enormously the beautiful,democratic and creative atmosphere in this thread (due to all of you, and the righteous governance of Dario..), still
technical projects like this, where things can explode and take out paper cones... need some less democratic and more technocratic maintenance, appunto, a Janitor
I think the great strength of this amplifier is that it has received attention of a number of different people with different methodologies. The result is it has outstanding technical specifications as well as much care in the selection of parts. Many amplifiers are optimized in just one of these areas.
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Old 20th July 2017, 07:58 AM   #3364
ClaveFremen is offline ClaveFremen  Italy
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Can anyone confirm that J1 is the same on new boards?
Hi Jac,

yes, J1 is the same on all board revisions.
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Old 20th July 2017, 03:16 PM   #3365
Spartacus is offline Spartacus  United Kingdom
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Dan, yes, it is on my list. These days I will have again an amp in original config.
Aso would be nice to see what the others are capable of: ADA4898, OPA627 etc.

But some good information is already out there:

fet/cmos opamps tested similarly:

New Audio Op Amp - OPA1622

bipolar opamps :

New Audio Op Amp - OPA1622

OPA827 & OPA1641

Distortion and Source Impedance in JFET Input Op Amps

Ciao, George
Thanks, interesting reading. Great to learn new things!

How true do you think it is to say that using opamps such as the ADA4627 and OPA827, we are as close to perfection as we can get with this topology? Where are the remaining weaknesses?
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Old 20th July 2017, 03:57 PM   #3366
Joseph K is offline Joseph K  Hungary
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Wov, Dan.. I think this is a question appropriate for mr. Caldwell himself..

But I can point out little things: not all parameters of these amps are perfect; In fact what regards bandwidth & precision, there are already today opamps that are more performant (but not FET input). Noise vise bipolar opamps are the king for low impedance applications; then there are opamps with monster output drive capability (like OPA1622 - also with enhanced stability for capacitive loads)
Also integrated circuits today are going in a direction of miniaturization and power economy; this is not properly the direction most desired for us poor audio-piles.
Even if.. even if the new model of the muse opamp series had just been released, so we are good for the next week.. )

But really, I would gently prod You to ask this same thing from Johnc124. Would be very curious of his response..
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Old 20th July 2017, 04:29 PM   #3367
UnixMan is offline UnixMan  Italy
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Originally Posted by Spartacus View Post
How true do you think it is to say that using opamps such as the ADA4627 and OPA827, we are as close to perfection as we can get with this topology? Where are the remaining weaknesses?
the only "weakness" that I can think of is perhaps the max output power and, even more so, the max current. This is a relatively serious limitation for the FE, while for the "Full-Evo" with double pump is much less of a problem.
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Old 20th July 2017, 04:45 PM   #3368
Joseph K is offline Joseph K  Hungary
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Ah, ok, I have totally misunderstood the original question, pardon..
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Old 20th July 2017, 11:35 PM   #3369
lehmanhill is offline lehmanhill  United States
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Originally Posted by UnixMan View Post
the only "weakness" that I can think of is perhaps the max output power and, even more so, the max current. This is a relatively serious limitation for the FE, while for the "Full-Evo" with double pump is much less of a problem.
Looking at it that way, I don't disagree, but it's only a weakness for low sensitivity speakers and in the lowest two octaves. Most speakers 20 cm (8") or less are fine with the FE power output. Even bigger speakers are fine as long as they have moderate sensitivity.

Still, it is a weakness and the double pump is a good answer.

Jac
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Old 20th July 2017, 11:36 PM   #3370
lehmanhill is offline lehmanhill  United States
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Ah, ok, I have totally misunderstood the original question, pardon..
I was thinking along the same lines as you were and am enjoying your response.

JAc
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