4P1L as First gain stage or in Pre-Amp..?

Alastair E · 6th July 2011, 06:46 PM

Just thinking out loud....

Ive seen good stuff written about this little Russian D.H. Tube wired as triode...

I'm wondering how it would be to use as a gain-stage rather than driver/O/P stage, maybe with MOSFET on top....

Any thoughts....?

tomchr · 6th July 2011, 08:57 PM

I'm thinking along the same lines. A grounded cathode stage has pretty high output impedance, though. One might have to add a cathode follower or similar to be able to drive interconnect cables.

~Tom

andyjevans · 6th July 2011, 09:42 PM

I've never used this tube but I can supply a quote from someone who has regarding microphonics:

"Mark's tube dampening (solder coil+silicon) - first reports - I tried this technique - somewhat different. Instead of silicon (fear of corrosion) I used liquid urethane spray (for PCB masking). It claims to resist hot solder, and is definitely neutral (good for protecting polished copper). First applied a solder coil, then 3-4 coats of urethane. The tubes were soviet 4P1L DH pentodes driving my 6B4G PP amp. They have a long, 1-1.5 microphonic resonance, sometimes very audible on piano passages. Tubes run very hot (as hot as a typical EL84). So far no problems with urethane layer or the tube itself. With the coil, the sonic signature changed. The 1kHz ringing is very well muffled down. But there's ANOTHER resonance, somewhere in 200-300Hz area. Not the original bug shifted downwards - this is something completely new, although nowhere as loud, and decays quickly. It's not a problem with piano, - sometimes it interferes with male vocals. But still - definitely worth trying. With the 2-tube driver, I found the less fatuguing option to have 1 stage dampened, second untreated, - just marginally better than both stages dampened. BTW, the coil need not be too big - in my case, covering 1/3 of available glass (one layer) was as effective as covering the whole length"

Wavebourn · 6th July 2011, 10:43 PM

I had an experience with 4P1L tubes. They are very nice tubes for drivers and output stages when triode connected, better than 2A3. They are easy to parallel for more power. About 1.5K output resistance and great linearity without any feedback. But for an input stage I would use some smaller tube, like 6J4P, 6J5P, 6J9P in triode mode.

Tony · 7th July 2011, 12:56 PM

anyone for 3Q5GT's?

artosalo · 7th July 2011, 02:09 PM

What would you like to do with it ? Line stage ?

I have some experience as PP-UL output stage. I just built a 15 W amplifier with two 4P1L and Hammond 1608 (no the best OPT, I know).
It performed very well.

tomchr · 7th July 2011, 06:26 PM

Quote:

Originally Posted by Wavebourn

But for an input stage I would use some smaller tube, like 6J4P, 6J5P, 6J9P in triode mode.

Are you aware of a Russian DHT tube that's more suitable for an input stage?

~Tom

Wavebourn · 7th July 2011, 06:34 PM

Quote:

Originally Posted by tomchr

Are you aware of a Russian DHT tube that's more suitable for an input stage?

This one fits better than 4P1L:

tomchr · 7th July 2011, 09:27 PM

Eh.... I think something went wrong with the link. Would you repost?

~Tom

Wavebourn · 7th July 2011, 09:55 PM

Quote:

Originally Posted by tomchr

Eh.... I think something went wrong with the link. Would you repost?

It works:

Ëîêòàëüíûå ëàìïû 2Æ27Ë, 2Ï29Ë, 4Æ1Ë, 4Ï1Ë, 10Æ1Ë, 10Æ3Ë, 12Æ1Ë, 12Æ3Ë, 12Ï17Ë » Ñäåëàé ñàì óñèëèòåëü Hi-Fi

6th July 2011, 06:46 PM	#1
Alastair E diyAudio Member Join Date: Feb 2004 Location: South Wales	4P1L as First gain stage or in Pre-Amp..? Just thinking out loud.... Ive seen good stuff written about this little Russian D.H. Tube wired as triode... I'm wondering how it would be to use as a gain-stage rather than driver/O/P stage, maybe with MOSFET on top.... Any thoughts....? __________________ Das Beste Oder Nichts

6th July 2011, 10:43 PM	#4
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	I had an experience with 4P1L tubes. They are very nice tubes for drivers and output stages when triode connected, better than 2A3. They are easy to parallel for more power. About 1.5K output resistance and great linearity without any feedback. But for an input stage I would use some smaller tube, like 6J4P, 6J5P, 6J9P in triode mode. __________________ The devil is not so terrible as his mathematical model! Wavebourn: We Create Creativity!

7th July 2011, 12:56 PM	#5
Tony diyAudio Member Join Date: May 2003 Location: Palatiw, Pasig City	anyone for 3Q5GT's? __________________ http://www.electronicslab.ph/forum/i...?topic=32688.0

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6th July 2011, 08:57 PM	#2
tomchr diyAudio Member Join Date: Feb 2009 Location: Greater Seattle Area	I'm thinking along the same lines. A grounded cathode stage has pretty high output impedance, though. One might have to add a cathode follower or similar to be able to drive interconnect cables. ~Tom

6th July 2011, 09:42 PM	#3
andyjevans diyAudio Member Join Date: Sep 2003 Location: London	I've never used this tube but I can supply a quote from someone who has regarding microphonics: "Mark's tube dampening (solder coil+silicon) - first reports - I tried this technique - somewhat different. Instead of silicon (fear of corrosion) I used liquid urethane spray (for PCB masking). It claims to resist hot solder, and is definitely neutral (good for protecting polished copper). First applied a solder coil, then 3-4 coats of urethane. The tubes were soviet 4P1L DH pentodes driving my 6B4G PP amp. They have a long, 1-1.5 microphonic resonance, sometimes very audible on piano passages. Tubes run very hot (as hot as a typical EL84). So far no problems with urethane layer or the tube itself. With the coil, the sonic signature changed. The 1kHz ringing is very well muffled down. But there's ANOTHER resonance, somewhere in 200-300Hz area. Not the original bug shifted downwards - this is something completely new, although nowhere as loud, and decays quickly. It's not a problem with piano, - sometimes it interferes with male vocals. But still - definitely worth trying. With the 2-tube driver, I found the less fatuguing option to have 1 stage dampened, second untreated, - just marginally better than both stages dampened. BTW, the coil need not be too big - in my case, covering 1/3 of available glass (one layer) was as effective as covering the whole length"

7th July 2011, 02:09 PM	#6
artosalo diyAudio Member Join Date: Feb 2010	What would you like to do with it ? Line stage ? I have some experience as PP-UL output stage. I just built a 15 W amplifier with two 4P1L and Hammond 1608 (no the best OPT, I know). It performed very well.

7th July 2011, 09:27 PM	#9
tomchr diyAudio Member Join Date: Feb 2009 Location: Greater Seattle Area	Eh.... I think something went wrong with the link. Would you repost? ~Tom

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