Driver for Telefunken RS242 in class A2 - diyAudio
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Old 20th April 2012, 01:09 PM   #1
pebmrb is offline pebmrb  United States
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Default Driver for Telefunken RS242 in class A2

I recently aquired a pair of Telefunken RS 242 DHTs.I thought I would be able to built a simple 6sn7 driver,capacitor coupled and have my first attempt at a nice DHT amp.Unfortunately I didnt realize till after the fact that these tubes are going to draw some grid current if I am to get any decent power out of them.I am now a bit out of my league trying to come up with the best driver for these tubes.The 6sn7 sounded very good breadboarded with the RS242 as long as I kept levels low.I also breadboarded a pair of SV83(6bq5) as driver capacitively coupled to the DHTs which sounded good.I am hoping to get some suggestions on my best options to drive these nice tubes.I dont own any interstage transformers so was unable to breadboard with those.Is capacitive coupling out of the question with class A2?
My normal amp building is generally loosley based on other people's designs and now I am in unfamiliar territory as these RS242s are a bit uncommon.
Thanks in advance
Paul
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Old 20th April 2012, 02:02 PM   #2
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have you tried 6c19s and its two in a bottle western sub 6080/6as7 ?

low Rp low Mu should be able to source alot .

edit what about a matching driver ? RL12p10 looks cool

http://www.jogis-roehrenbude.de/Roeh...10/RL12P10.pdf

http://www.jogis-roehrenbude.de/Lese.../strategos.htm

v4lve .

Last edited by v4lve lover; 20th April 2012 at 02:05 PM.
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Old 20th April 2012, 02:47 PM   #3
pebmrb is offline pebmrb  United States
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Thanks for the suggestions.I will look further into that RL12P10.Ideally I would like to use some 1930s/1940s German tubes to drive the the RS242s instead of the typical tubes,but unfortunately my experience and familiarity lies with the more common audio tubes,but I am sure with a little guidance,I can come up with something special to drive these tubes.I don't read German,but am I to assume that RS282 in the schematic you linked runs A2?Driven by RL12P10?
Thanks
Paul
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Old 20th April 2012, 03:28 PM   #4
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i read RS and i made the assumption you where talking about a Wehrmacht/ kriegsmarine transmitter type tubes

I'd save these and build something bigger whit them .

v4lve
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Old 20th April 2012, 03:51 PM   #5
pebmrb is offline pebmrb  United States
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These RS242 are Wehrmacht/Kreigsmarine tubes,but of low power.About 4 watts audio.You are thinking these might be better suited as a driver for something more powerful?I have seen them used as drivers as well.
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Old 20th April 2012, 07:17 PM   #6
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Quote:
Originally Posted by pebmrb View Post
.....Is capacitive coupling out of the question with class A2?
Thanks in advance
Paul
Yes it is. A2 class operation means that the driver tube must be able to supply DC current into the grid of output tube.

Here is the circuit I have used to drive GU50 into A2.

Click the image to open in full size.
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Old 20th April 2012, 08:38 PM   #7
pebmrb is offline pebmrb  United States
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Thanks for the circuit.I have some of those 6N6Ps and have not had an opportunity to try them.I have heard they are a very good tube.
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Old 25th April 2012, 11:53 AM   #8
pebmrb is offline pebmrb  United States
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Hello
I thought I would give an update on the project and try to get a bit more help.
I have come up with a pretty nice sounding circuit using cheap(non gapped?) 1:1 transformers for coupling a 6sn7 to the power tube.I think I will persue the IT coupling method.Can anyone recommend an good transformer?I know the Lundahl is good but just a bit more than I want to spend at this point,unless I can be coaxed into it of course .Any bargains out there with good quality?Vintage perhaps?
Also,I am considering a pair of Telefunken RL2T2 triodes for drivers and was hoping to get some opinions on that as driver,enclosed is the datasheet.
Thanks
Paul
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File Type: pdf RL2T2.pdf (118.8 KB, 76 views)
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