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Old 16th March 2004, 09:56 AM   #1
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Default DIY Single Ended Triode Designs

i was hoping some of you out there could share your impressions and recommendations for some diy single ended triode projects (i am and have been using only solid state up to this point, but now have 96db efficient speakers, so i figure its time to try this route) . preferable not kits, but if you have run across a particularily outstanding (and hopefully not too expensive) kit, i'd be all ears to that as well. thanks.
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Old 16th March 2004, 10:20 AM   #2
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If you have 96db speakers a 2A3 amp would suffice.

And as Joe Roberts said in his article in Sound Practices "I Never Met A 2A3 Amp I Didn't Like"

Many would agree. So do a search for 2a3 se amp and choose one.

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Old 16th March 2004, 10:39 AM   #3
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funny that you mention that as i was just about to add the postscript that solid state diy has left me somewhat miserly (i don't fancy for instance spending $4-500 on a pair of 300b's alone). so. . . actually any simple tube designs that anyone out there feels are a good introduction to the world of valves would be appreciated. (simple not only for ease of construction, but i still very much prefer the least amount of parts in the signal path) thanks.
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Old 16th March 2004, 10:51 AM   #4
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A pair of matched Sovtek 2A3 from triodeelectronics will set you back $64.90

The Sovtek happen to be some of the best sounding as well...

The JE labs 2a3 is appertenly good sounding. Think it is a lot like the Sun Audio 2a3. Then there are ofcourse the kits from Welborne ...the DRD kits that are getting rave reviews..or at least a lot of happy owners...
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Old 16th March 2004, 10:53 AM   #5
Mike L. is offline Mike L.  United States
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There is an article on a DIY single ended pentode amp in the new issue of audioXpress. It is very simple and inexpensive; intended for a first time builder.

Mike L.
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Old 16th March 2004, 12:48 PM   #6
Previously: Kuei Yang Wang
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Default Re: DIY Single Ended Triode Designs


Originally posted by jesserparker
i was hoping some of you out there could share your impressions and recommendations for some diy single ended triode projects
Well, looking at the other stuff further down, I'd recommend a 2A3/45 Amp. If yu carefully select the Mains transformer you could also later convert to 300B's.

I'd recommend (purely on other peoples comments at this time, but people who have compared) the James 6123-HS Output transformer as an affordable choice that can be used with 45, 2A3 & 300B Outputs.

If you use a Mainstransformer with 380V + 380V AC and at least 200mA DC plus several Heater windings (James should have one that matches the Outputs) plus a nice Filter Choke you would have the basics to make an RC/LC coupled 300B Stereo Amplifier or a DC coupled 2A3/45 Amplifier.

Start using the sovtek 2A3 (which is not much more expensive than most decent Pentodes/Tetrodes), Sovtek 5U4 or the like and russian 6S45PE or 6S4PE or WE417A/5842 or 6Z9P/6688/E180F triode connected as drivers in a DC coupled Circuit like that I recommended to Arnold Cruz on a while back and you will have an excellent little Amp.

Click the image to open in full size.

(note - +B should read 468V!!!)

Audio Asylum Comments on Finished Amp

Audio Asylum Comments on the design reasoning

The Sovtek 2A3 will actually work as "pseudo 45" with a 5K load and will work VERY WELL under these conditions (and last to the next Iceage BTW) or you can change two resistors (the 5k1 to 3k1 and the 43R to around 27R) to acommodate the 2A3 with 60mA current and a 2k5 Load.

In fact, if you wanted to, you could make the Amp fully switchable, simply switch 8k2 in parallel with the 5k1 and switch the output transformer tap, then adjust the resistor marked 43 Ohm (which should be adjustable anyway) to establish the correct bias.

To use a 300B simply change the Amp to RC/LC coupled, self bias 1k cathode resistor and 3k5 or 5k load from the Output transformer with the 68uF & 22uF caps retained as is, suitable +B dropper for the Driver Valve and cathode RC combo.

Anyway, I hope this points you along a possible route to get something to have fun with for a long time.

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Old 16th March 2004, 02:18 PM   #7
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Default 2A3 schematic

This one works quite well and is fairly easy to build. Though not shown on the schematic, a 1K grid stopper right at the grid pins on the driver is highly recommended...

Roscoe's DC 2A3/45 amp

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Old 17th March 2004, 04:49 AM   #8
SHiFTY is offline SHiFTY  New Zealand
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I have been trying to build a good sounding single ended triode amp for a while, and have come to the conclusion that you need to drive it with something really grunty. Also a good power supply with a choke sounds better.

I have tried 1/2 6SL7, 1/2 6SN7, cascaded 6SN7 (300B driver!) 6SL7 SRPP (angela SRPP) and I am now using a 6SL7 cathode follower (angela easy 2A3)

I have found they are all too distorted except the cathode follower... It sounds a bit too "clean" and "dry" but it has details, slamming bass and a good amount of power. I found the other configurations were syrupy- great with vocals but a distinctive SET sound I wasn't too keen on.

There is a thread
on this.

However I am no expert, just an experimenter!

And the sovtek 2A3 (or the 6.3V version, 6B4G) is a good tube to use, but very dull to llook at. You can't see the glow! Maybe the Full music mesh plate 2A3 is more your style...

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Old 17th March 2004, 03:30 PM   #9
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Based on advice from members on this forum, I changed the driver for my 2A3 from a 6SL7 SRPP (Angela) to a CCS loaded ECC99 running at 20mA. I think it made a pretty significant improvement to the sound.
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Old 18th March 2004, 08:26 PM   #10
AKSA is offline AKSA  Australia
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Has anyone here ever done a 6C33C in SET?

Any comments on operating point/sonics?

Aspen Amplifiers P/L (Australia)
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