Re: Hello JamesD, really enjoyed your posts

Posted by Gary P (A) on December 6, 2003 at 08:54:12

In Reply to: Re: Hello JamesD, really enjoyed your posts posted by JamesD on December 5, 2003 at 06:34:05:

Hi James,

I'm another person that is envious of Lynn's writing and comunication skills.

In response to your comments,

"The other question I have is, given good dynamic balance, then we have good even order harmonic dist. cancellation ? so do we need to engineer the harmonic distortion profile for ?best? sound? I believe we do but I?m not sure how to do that in this sort of amplifer? I say this as I have noticed a tendency towards an over clean sound from this type of circuit that I associate with very low distortion ss circuits and this correlates to having the odd harmonics at a higher level than the even harmonics in the distortion profile. Again any views would be much appreciated for discussion.

Speculation ? does Gary Pimms 47PP amplifier have this characteristic? I think it might. I put together an ECL82 PP partial feedback amplifier and it was super clean and had this type of distortion profile. Keeping the partial feedback and running the output stage in triode mode brought back the ?niceness? of the ECL 82?"

I think your thoughts on the distortion profile might be correct.

I'm still learning about how the 47P-P amp is working. Something is going on in the distortion area that I haven't figured out yet. Second harmonic is higher than it should be for a fully balanced circuit. I suspect it might be in the front end as the screen's are not bypassed/bootstrapped to the cathodes.

What could be considered a plus is the harmonic profile is more like the prefered decending order with the second harmonic higher than the third untill the amp gets near full power (3.75 watts). At levels up to 1.5 watts the odd harmonics are lower than the even harmonics. As the amp gets near clipping the odds overtake the evens.

This is a case where I want to know where the even second harmonic is comming from. It might also be a case where after the source of the second harmonic is known, it gets left unchanged in the current setup if the higher second harmonic with the prefered decending order sounds better than lower overall distortion with a higher percentage of odd's.

Here is what the distortion performance looks like for the current setup of the 47P-P amp.

Gary

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Follow Ups Full Thread

Topic - Hello JamesD, really enjoyed your posts - Lynn Olson 21:39:33 12/02/03 (22)

Re: Hello JamesD, really enjoyed your posts - JamesD 06:34:05 12/05/03 (15)

Re: Hello JamesD, really enjoyed your posts - Gary P 08:54:12 12/06/03 (2)

Just a quick thought... - JamesD 00:01:11 12/07/03 (1)

Found the Diyaudio thread but incomplete data... - JamesD 03:51:11 12/07/03 (0)

Assorted Thoughts - Lynn Olson 14:21:20 12/05/03 (11)

Like Bas, I love the recollections! - James D. 04:14:30 12/07/03 (0)

Better Math - Lynn Olson 21:01:31 12/05/03 (0)

Mo' Thoughts - Lynn Olson 15:50:06 12/05/03 (8)

An aside your thoughts suggested... - JamesD 05:16:45 12/07/03 (7)

Here's another one ... - Lynn Olson 17:34:23 12/11/03 (2)

Re: Here's another one ... - JamesD 12:39:27 12/14/03 (1)

Unusual behavior from grounded-grids ... - Lynn Olson 14:59:23 12/14/03 (0)

It boils down to a pentode CF driving a GG triode - Lynn Olson 13:56:45 12/07/03 (3)

Re: It boils down to a pentode CF driving a GG triode - JamesD 08:27:07 12/09/03 (2)

Setting up the bias - Gary P 12:00:45 12/10/03 (1)

Re: Setting up the bias - JamesD 03:50:58 12/11/03 (0)

Hi Lynn..yes finally someone else I like to read.... - Bas Horneman 08:02:53 12/04/03 (3)

Argh... Bas, how could you do this to me? - JamesD 06:36:51 12/05/03 (2)

Not really pressure James...you would be suprised how - Bas Horneman 13:53:58 12/06/03 (1)

I agree! - JamesD 04:17:07 12/07/03 (0)

12B4A? - keto 22:30:07 12/03/03 (0)

Hmm , interesting schematic - IslandPink 07:33:54 12/03/03 (0)

Follow Ups

Re: Hello JamesD, really enjoyed your posts - Gary P 08:54:12 12/06/03 (2)

Just a quick thought... - JamesD 00:01:11 12/07/03 (1)

Found the Diyaudio thread but incomplete data... - JamesD 03:51:11 12/07/03 (0)

You can not post to an archived thread.