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C3g & D3a [message #31879] Sat, 06 May 2006 08:49 Go to next message
Damir is currently offline  Damir
Messages: 1005
Registered: May 2009
Illuminati (2nd Degree)

Received some of those German "postroehren", SQ gold pin pentodes. D3a is mentioned before like possible good driver. C3g is a very interesting tube, too, inside and outside shields, loctal socket, low noise, linear. Nice triode - connected curves; with OP, say, Uak=182V/Ugk=-3V/Ia=12mA we`d have ยต=40 and rp~2k6. Looking good for the (300B) driver, RIAA stage input tube, etc. Must try it soon and report.
But, 6 of 15 D3a was defective right from the box, white getter = air inside the tube through barely visible crack between the pins...
The best thing is, those quality tubes can be (still) found relatively cheap.
Some informations and pictures from the Web:

http://www.jacmusic.com/nos/C3g-C3m-info.html
http://www.tubecollection.de/ura/postroehren.htm
http://www.jogis-roehrenbude.de/Roehren-Geschichtliches/Behoerden/Post/C3g.htm

And detailed "Telefunken" data:
http://frank.pocnet.net/sheets/128/c/C3g.pdf

Re: C3g & D3a [message #31880 is a reply to message #31879] Sat, 06 May 2006 23:19 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)

Sweet! Bad about the cracked ones but it sounds like a good find in spite of that.


Re: C3g & D3a [message #31881 is a reply to message #31880] Mon, 08 May 2006 11:23 Go to previous messageGo to next message
Damir is currently offline  Damir
Messages: 1005
Registered: May 2009
Illuminati (2nd Degree)
Fortunately, I bought those tubes from reliable German company, and they promised to exchange the defective ones.
If someone needs the source for these tubes, I`ll E-mail the details.

Re: C3g & D3a [message #31911 is a reply to message #31879] Sun, 25 June 2006 16:53 Go to previous messageGo to next message
dividebytube is currently offline  dividebytube
Messages: 5
Registered: May 2009
Esquire
glad to see someone use a pentode as a driver. I've found them to be simple to implement and very involving sound-wise.

Re: C3g & D3a [message #31914 is a reply to message #31911] Mon, 26 June 2006 18:38 Go to previous messageGo to next message
Damir is currently offline  Damir
Messages: 1005
Registered: May 2009
Illuminati (2nd Degree)
Hey, welcome to the forum and feel free to present some of your projects, make a suggestions, etc. Yes, we "believe" in pentodes here, too - you mentioned EF86 and "Neumann" on your interesting DIY pages.
Friend of mine is in (expensive) constant search for EF86 and EF806S - not just for the mikes, but even "Matchless" guitar amp...
German engineering at that time was something...and those pentodes, especially "postroerhren" and "SQ", gold-pins types.
For example, I found the comparison of the prices of some tube types in Germany (TFK, Valvo, Lorenz, Siemens), about 1955.; in the well regarded "Das grose Roehren-Handbuch" by Ludwig Ratheiser":
-ECC81 - 14DM
-ECC82, ECC83 - 13 DM
-EL34 - 18 DM
-EL156 - 21 DM
-GZ34 - 12 DM
-E180F - 30 DM
-C3g - 42 DM

Re: C3g & D3a [message #31915 is a reply to message #31914] Tue, 27 June 2006 06:04 Go to previous messageGo to next message
dividebytube is currently offline  dividebytube
Messages: 5
Registered: May 2009
Esquire

I've mostly played around with the EF86, making two triode-connected EF86 preamps. Very detailed sound, yet not overly harsh or bright. I'm building a new one (once the metal work gets in) for someone else using onboard regulation, chokes, etc...

I've also become interested in the EF40, EF12 and want to start using them. I also had some good sound out of a SE 300B amp using an SV83/EL84 - that was a budget version of a Loesch design.


Re: C3g & D3a [message #31916 is a reply to message #31915] Tue, 27 June 2006 06:42 Go to previous messageGo to next message
Damir is currently offline  Damir
Messages: 1005
Registered: May 2009
Illuminati (2nd Degree)
Unfortunatelly, I have just 2-3 EF86, of different makers, of course, and didn`t try DIY with them, they are now (almost) scarce and expensive.
But yesterday I get another 15 pcs of C3g and 4 pcs D3a (another 4 was broken ).
Nice looking projects, I`m glad when I "found" someone who actually built something

Probably you know this, but besides many old tube books on-line, there is a big pentode test on Pete Millett`s DIY pages.
I like those cheap and "odd" tubes...


Re: C3g & D3a [message #31917 is a reply to message #31916] Tue, 27 June 2006 07:56 Go to previous message
dividebytube is currently offline  dividebytube
Messages: 5
Registered: May 2009
Esquire
there are some new EH EF86s coming out - still priced at $15ea - but I'll be checking them out to see how they match up sonically. They almost look like Mullard or Telefunken solid-plate copies.

anyways - I'm looking forward to getting some c3g and d3a tubes

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