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Old 30th January 2012, 01:26 AM   #3271
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Is there any reason to try adding a swamping resistor across my DX4 TP1 / F4 combo? I can think of a few cases (transformer coupled amp maybe?) that this might make sense, but not sure if it is worth trying in my case.
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Old 30th January 2012, 02:01 AM   #3272
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well - you can do that with some intention ........

but - which one ?
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Old 30th January 2012, 03:42 AM   #3273
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Quote:
Originally Posted by Zen Mod View Post
well - you can do that with some intention ........

but - which one ?
Better sound? Better low end bass? Sanity that I tried something?
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Old 2nd February 2012, 12:15 PM   #3274
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Can we play with harmonic distortion character (2nd/3rd ratio) of F4 by putting P3 (200 Ohm) over R3 and R4 (source resistors of JFets), like we do in case of F5 ?
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Old 2nd February 2012, 02:39 PM   #3275
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presumably not , at least not in same amount - just because that's buffer stage - without voltage gain
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Old 2nd February 2012, 04:32 PM   #3276
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The output devices are recommended to be Vgs matched +/- 0.02V -- but the gm of the two halves may be different -- in which case adjusting the source resistors on the MOSFETs may have some benefit -- but you've got 3 on each side so it will be a real headache!
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Old 6th February 2012, 06:45 AM   #3277
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Proper answer to my question can be found in the Nelson article
http://www.firstwatt.com/pdf/art_sweet_spot.pdf page 14 -15.
Yes you can change amount of distortion by trimming value of Jfet source resistors.
But change is not so dramatic in absolute numbers. So Zen Mod is right about it.

Last edited by Dzius; 6th February 2012 at 06:47 AM.
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Old 6th February 2012, 09:50 AM   #3278
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Quote:
Originally Posted by Dzius View Post
Proper answer to my question can be found in the Nelson article
http://www.firstwatt.com/pdf/art_sweet_spot.pdf page 14 -15.
Yes you can change amount of distortion by trimming value of Jfet source resistors.
But change is not so dramatic in absolute numbers. So Zen Mod is right about it.
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Old 8th February 2012, 01:46 AM   #3279
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Not being willing to read 51 pages of blurbs, I'll just ask--
1. Are Cs 1 and 2 signal-coupling capacitors?
2. If so, what is the load impedance for filter-point calc?
3. Can the cap-value be changed to create a hi-pass filter in the audible range for a speaker that requires one? That speaker is a Vandersteen 5A that needs a filterpoint between 50 and 100 Hz.

Thanx much in advance to the much-more-knowledgable-than-I (and that doesn't take much) who answer.
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Old 8th February 2012, 05:16 AM   #3280
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1. sort of , but not exactly
2. it's not constant vs. frequency
3. read #2
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