D3a pentode as driver? History of this tube?

Richard Ellis · 5th August 2009, 08:33 PM

I ran across this schematic of a parallel 2A3 with a D3A as a driver (Redrawn from Audiodesignguide.com)....I can't seem to find any info on this tube!
Most of the more "common" tubes have entire colorful histories associated with their development. This D3A I can't find anything..what was it used for , when did it first come out et al.
_______________________________________Rick....... ...

leadbelly · 5th August 2009, 10:00 PM

Oh come on, you can't tell me that you searched. There's a whole thread about that tube and a PCB for it!

Wavebourn · 5th August 2009, 10:24 PM

$2/each for 6J52P, compare to $20/each for D3A.

kevinkr · 6th August 2009, 04:07 AM

D3A German Post Office pentode, probably developed in the late 1950s. Good parameters when triode connected. Made by Siemens & Halske as well as by Philips (or might have been a relabel?)

I use these in my phono stage where their very high transconductance, low rp, and a mu of 77 triode connected is just about ideal. (Triode connected their internal noise is about equivalent to a 68 ohm resistor.)

They also effectively drive the 300B/50/2A3 and as long as A2 operation is not required will also drive a GM70.

Wavebourn · 6th August 2009, 04:15 AM

Please look at the picture...

Hearinspace · 6th August 2009, 06:33 AM

Lessee, Vp140 @ 27mA with SVCS on top looks fine to me. Hey Wavebourn, gimmee a dozen will ya?

Wavebourn · 6th August 2009, 04:30 PM

Quote:

Originally posted by Hearinspace
Lessee, Vp140 @ 27mA with SVCS on top looks fine to me. Hey Wavebourn, gimmee a dozen will ya?

I don't have them. But I can find a source.

kevinkr · 6th August 2009, 05:48 PM

I might be interested in getting my hands on a few as well if the price is reasonable.

Wavebourn · 6th August 2009, 05:53 PM

Quote:

Originally posted by kevinkr
I might be interested in getting my hands on a few as well if the price is reasonable.

60 Rubles a peace, about $2. Plus shipment from Russia. Let's try to collect info about a group buy, you have my e-mail address.

kenpeter · 6th August 2009, 06:18 PM

Count me for a half dozen. What pinout? D3A or different?

I got a handful of 6CU5, but no curves as Triodes (yet).
Not quite the same thing, is it?

5th August 2009, 10:00 PM	#2
leadbelly diyAudio Member Join Date: Dec 2002 Location: Calgary, Alberta	Oh come on, you can't tell me that you searched. There's a whole thread about that tube and a PCB for it! __________________ Aerodynamics are for people who can't build engines. Enzo Ferrari

5th August 2009, 10:24 PM	#3
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	$2/each for 6J52P, compare to $20/each for D3A. __________________ The devil is not so terrible as his mathematical model! Wavebourn: We Create Creativity!

6th August 2009, 04:07 AM	#4
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	D3A German Post Office pentode, probably developed in the late 1950s. Good parameters when triode connected. Made by Siemens & Halske as well as by Philips (or might have been a relabel?) I use these in my phono stage where their very high transconductance, low rp, and a mu of 77 triode connected is just about ideal. (Triode connected their internal noise is about equivalent to a 68 ohm resistor.) They also effectively drive the 300B/50/2A3 and as long as A2 operation is not required will also drive a GM70. __________________ www.kta-hifi.net

6th August 2009, 05:48 PM	#8
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	I might be interested in getting my hands on a few as well if the price is reasonable. __________________ www.kta-hifi.net

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6th August 2009, 06:33 AM	#6
Hearinspace diyAudio Member Join Date: Jun 2008	Lessee, Vp140 @ 27mA with SVCS on top looks fine to me. Hey Wavebourn, gimmee a dozen will ya?

6th August 2009, 06:18 PM	#10
kenpeter diyAudio Member Join Date: Nov 2007 Location: Dallas	Count me for a half dozen. What pinout? D3A or different? I got a handful of 6CU5, but no curves as Triodes (yet). Not quite the same thing, is it?

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