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Old 2nd June 2009, 09:29 PM   #11
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So, no reason, just "after"....
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Old 2nd June 2009, 10:06 PM   #12
McGyver is offline McGyver  Poland
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I heard several times Dynaco ST35 and I liked it very much. It was good enaugh reason for me to do it that way.
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Old 2nd June 2009, 10:08 PM   #13
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Quote:
Originally posted by McGyver
I heard several times Dynaco ST35 and I liked it very much. It was good enaugh reason for me to do it that way.
But it had also a local feedback, from an output tranny to screen grids, it is very significant. More deep global feedback could cause instability on high frequencies.

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Old 3rd June 2009, 04:00 PM   #14
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Default It will sound better if you triode-strap the EL-84s!

Quote:
Originally posted by McGyver
I heard several times Dynaco ST35 and I liked it very much. It was good enaugh reason for me to do it that way.
Hi.

Yes, it is a very good approach to bypass the entire tone-control stages as they surely render the sound "horrible". Likewise, I bypassed the entire line+tone-control stages of my 50-year young stock Dynaco PS-2 preamp.

You have done everything right. But you can still make it sound better by converting the PP powerstage from pentode to triode by simply connect the G2 of each EL-84 to its plate with a 100R resistor. I guarantee you will find it sound more transparent, more airy & more musical.

This is what I have done with my 50-year young stock Dynaco ST-70 which sounded "horrible", "fat" & "slow" like what you just described. Like you, I hate vintage sounds.

I triode-strapped the EL-34 Ultra-Linear PP with a more complex Vg2 level shifter, switchable from triode-UL. Yet I've left it triode-strapped mode for ever since day one of its upgrade. I've also reduced the 20dB global loop NFB to 10dB. This offsets somewhat the reduced O/P power after triode convertion.

Listening is believing. Triode sounds so much more musical than pe tode.


c-J
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Old 3rd June 2009, 04:30 PM   #15
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Sure, if to tie screen grids to anodes less global feedback may be needed.
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Old 3rd June 2009, 04:45 PM   #16
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Yes, I LOVE triode sound. But REAL triode, and not triode-strapped pentode. Especially direct heated triodes are magical. I'm using upgraded ukrainian monoblocks based on 6B4G DHT in PSE, and I love it. And Braun amplifier goes to one of my friends. Maybe I'll install triode-pentode switch. No need to drill, becaude there are 3 unused switches on the frontpanel.
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Old 4th June 2009, 04:52 AM   #17
WBS is offline WBS  Tibet
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Nice work. It is a very clean looking amp.

I would never have guessed it was 50 years old! 50 year old American equipment looks 50 years old.
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Old 4th June 2009, 05:22 AM   #18
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Nice looking amp...

dave
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Old 4th June 2009, 05:52 AM   #19
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Quote:
Originally posted by Wavebourn
Congratulations!
Everything is fine, except what for did you lower feedback?
May be because he doesn't like that "solid statey" sound you get from too much gNFB?
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Old 4th June 2009, 05:53 AM   #20
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Quote:
Originally posted by Miles Prower


May be because he doesn't like that "solid statey" sound you get from too much gNFB?
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