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Old 6th September 2011, 06:36 AM   #251
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Nope, I'm not offended. Hope you're not offended.
I blame Bigun. No reason, it just feels so right...

Was not my intent to pass off phoney circlos...
Just trying to clarify a circuit that I difficulty
wrapping my mind around. It was several days
before I even realized that it performed the
same computation I had been working on...
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Old 6th September 2011, 06:02 PM   #252
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by kenpeter View Post
Nope, I'm not offended. Hope you're not offended.
I blame Bigun. No reason, it just feels so right...

Was not my intent to pass off phoney circlos...
Just trying to clarify a circuit that I difficulty
wrapping my mind around. It was several days
before I even realized that it performed the
same computation I had been working on...
No problem, I think each of the two approach has its own merits, and there is room enough for both.

I suspect your version will appeal more to a number of members of this forum: it is more straightforward, and doesn't include a rather complex servo loop, as the Circlophone.

It is true that in a more complex system, there is more space for things to go wrong.

I took great care in ironing out any potential issue, I tried to leave no stone unturned (or maybe the opposite) to make sure the thing is 99.99% reliable.

But many won't trust the system and will prefer your way of doing things.

I cannot blame them, and generally I prefer this kind of topology too, but I found no way to achieve my goals without adding some complexity.
The result is not very elegant, but it is astonishingly effective, and so far it looks foolproof.
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. .Circlophone your life !!!! . .
♫♪ My little cheap Circlophone© ♫♪
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Old 6th September 2011, 10:57 PM   #253
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Thank you Elvee for sharing with us this beauty. I always respect to intelligent potential and kindness spirit of this site.

I'm planning to build this amp as four channels due to my active speaker requirements. As normally, I'm using balanced signal for each channel. Has circuit any potential to modify input stage to accept balanced signal without referencing to ground? If no, that is not so important at all.

I like to use oldschool parts in new designs, especially TO-3 ones. I got plenty of devices like:

Motorola 2n3773 (Vcbo=160,Vceo=140)
Toshiba 2sd110 (Vcbo=130, Vceo=110, 1mhz, 200pF)
Motorola MJ15003 (Vcbo=140,Vceo=140, 2mhz, 1000pF)
Motorola 2n3055

I think it is easy to maintain 80-100W with a pair of these using proper driver transistors and rails.

I got some choices of DC rails like: 31V, 36.5V, 62V. I think 36.5V a bit low for 80-100W range. As you mentioned in post 182, 31V rails are enough to get 50W. Maybe i have to go with it if I can't bear build a LM338 based regulator for drop 62V to 42V.

Regards.
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Old 6th September 2011, 11:31 PM   #254
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Don't think its that complicated, just needs a well commented redraw of the schematic.
I could take a crack making it easier to read. You want to post latest known good .asc ?
No design changes, just a re-draw....

Last edited by kenpeter; 6th September 2011 at 11:34 PM.
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Old 7th September 2011, 01:43 AM   #255
Bigun is offline Bigun  Canada
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Quote:
Originally Posted by kenpeter View Post
I blame Bigun. No reason, it just feels so right...
what ? me ?

...
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"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.

Last edited by Bigun; 7th September 2011 at 01:48 AM.
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Old 7th September 2011, 02:15 AM   #256
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Here's a sample redraw, based upon Circlophone M.
Models are all still there, just above the screenshot.

During the redraw, I have come to question R19's
purpose? Appears only to bias Q12 into saturation.
Its exactly like this in the original, so I have to ask.
Was this an oops? Intended as a base stopper???

I haven't commented any part of the circuit yet.
Attached Images
File Type: gif CirclophoneM-redraw.gif (44.3 KB, 514 views)
File Type: gif CirclophoneMess.gif (30.0 KB, 447 views)
Attached Files
File Type: txt CirclophoneM-redraw.asc.txt (10.5 KB, 16 views)

Last edited by kenpeter; 7th September 2011 at 02:22 AM.
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Old 7th September 2011, 02:29 AM   #257
Bigun is offline Bigun  Canada
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Quote:
Originally Posted by kenpeter View Post
During the redraw, I have come to question R19's
purpose? Appears only to bias Q12 into saturation.
Its exactly like this in the original, so I have to ask.
Was this an oops? Intended as a base stopper???
I think I asked the same question, only it was R14 when I asked it...unless I'm confused the explanation is here:

♫♪ My little cheap Circlophone© ♫♪
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Old 7th September 2011, 02:42 AM   #258
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PSRR fix for Q12, got it...
I didn't change any reference designators, by the way...

Looking back, the original Circlophone drawing wasn't bad.
It grew slightly less organized as it evolved...

Last edited by kenpeter; 7th September 2011 at 02:58 AM.
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Old 7th September 2011, 12:08 PM   #259
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by terranigma View Post
I'm planning to build this amp as four channels due to my active speaker requirements. As normally, I'm using balanced signal for each channel. Has circuit any potential to modify input stage to accept balanced signal without referencing to ground? If no, that is not so important at all.
Using the (-) input of the amplifier seems risky, as the source impedance would influence the feedback.
This could lead to problems, and I would not recommend it.
If you can be a bit patient, the next PCB version will include a preamplifier with a balanced input.
It is being finalized, and should be available soon
Quote:
I like to use oldschool parts in new designs, especially TO-3 ones. I got plenty of devices like:

Motorola 2n3773 (Vcbo=160,Vceo=140)
Toshiba 2sd110 (Vcbo=130, Vceo=110, 1mhz, 200pF)
Motorola MJ15003 (Vcbo=140,Vceo=140, 2mhz, 1000pF)
Motorola 2n3055

I think it is easy to maintain 80-100W with a pair of these using proper driver transistors and rails.
They are all suitable, and if you aim at 100W the MJ15003 seems perfect.
You don't need other drivers, some of the other transistors may need a higher Vceo if you go for 42V rails.

Quote:
Looking back, the original Circlophone drawing wasn't bad.
It grew slightly less organized as it evolved...
The original drawing is purely graphic, and didn't evolve. The functional versions are messier.
You did a nice cleaning job, thanks for the effort.

Anyway, here is the asc of the graphic version, if someone wants to play with it.
Attached Files
File Type: txt TheCirclophone12.asc.txt (15.4 KB, 37 views)
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♫♪ My little cheap Circlophone© ♫♪
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Old 7th September 2011, 10:33 PM   #260
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Quote:
Originally Posted by Elvee View Post
Using the (-) input of the amplifier seems risky, as the source impedance would influence the feedback.
This could lead to problems, and I would not recommend it.
If you can be a bit patient, the next PCB version will include a preamplifier with a balanced input.
It is being finalized, and should be available soon
My concern is C3, coupling cap at input. My source has DC if it refers to ground, thus requires a cap at input of amplifier which is a compromised solution that I dislike -imho-. If I use balanced as source, then there is no ground referenced signal and there is no DC, then there is no need a cap in signal path. It is fair enough to put a speaker protection at output for possible failures.

I'm a lazy builder, then there is no hurry for me

Regards.

PS: If you ever build/listen an amp based on LME49810's.. can you compare them?

Last edited by terranigma; 7th September 2011 at 10:37 PM.
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