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2A3 SET amps. Desire sets in..

friarmac207

friarmac207

Active Member
Hi folks, since getting into tube amps with a Dynaco ST70 and then doing a full rebuild of a Dynaco SCA-35, I've been researching SET amps. I think its time to pick up/build a 2A3 SET. I've been leaning toward a Bottlehead Stereomour kit. I'd appreciate any input/thoughts on that kit from folks who have built and use that amp. I was also considering a WTB in Barter Town to see what may be available. I would be running the amp to Klipsch KG4s, with all the Crites mods/upgrades and a couple tweaks. As always, I ap[preciate any/all input. Thanks, David
 
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I can highly recommend the Stereomour, it's the finest amplifier I have ever owned. It is a beautiful sounding amplifier and a pleasure to build. The only thing you need to be careful of before deciding to go the SET route is make sure you have the right speakers.
 
Good to hear it, marantzfan. From what I've read, my KG4s should be efficient enough, and there are posts around the web from others using them with SET amps. My room is somewhat shallow, too, so I doubt I'd ever be using more than 1-1.5 watts from the amp. My SCA-35, volume straight up at noon, is about as loud as I'd want it in the room. Do you use the Altec 19s with your Stereomour?
 
Sorry I can't help with the Stereomour question except to say that the Bottlehead products seem to have excellent support and I never read anyone say much bad about them.

Just curious, are you planning to get rid of the ST70? I ask because your "If it sounds good, turn it up" signature and SET amps generally speaking aren't 100% conducive. IOW, if you need to sell the Dynaco to fund the Bottlehead I might tread carefully, but if you will keep the Dynaco and want to see what all the SET fuss is about then I'd say the Klipsch would probably be a good match. From what I could glean from a quick search they are 94db which is good for most listening.
Good luck.
 
Thanks, sebrof. I will keep the ST70 for a bit, but its currently not being used-the SCA-35 is just a sweet little amp, and its become the main rig mainstay.
As for the Turn it Up sig, that would be covered by the MAC1900, and the hoarder pile of guitar tube amps that I've amassed! I'm fortunate to live a few hundred yards from my closest neighbors....
 
The KG4s should do reasonably well with 2A3s, as long as the room isnt too terribly large. A larger room will cause it to run out of steam quickly on those. For a 2A3 amp, I usually try and shoot for speakers 95dB 1W/m or more, and something with a rather benign impedance curve, plus no, or a simple crossover. SETs love higher impedance loads, when you get impedance dips it can, and does affect bass performance.
 
I just built a Stereomour a month or so ago, and it is superb for what I listen to which is mostly jazz and classical, but Led Zep sounds good too, so I suspect a good amp is a good amp. I have Econowaves built in Heresy speaker cabs. The detail and realism is a cut above my PP amps. I've never run short of power in my smallish room.

Make sure you have the finest tip on your iron for the boards. I kept swapping tips as the job dictated. I also could not thread the nut on the screws bolting the output iron and the choke to the chassis,but a slightly longer screw solved that.

I also found a typo which has been corrected and they spent a lot of time on the phone making sure I got the power tranny wired correctly. I think it is a great value when you consider the parts cost, etc.

I doubt you'll regret building one.
 
friarmac207 said:
Thanks, sebrof. I will keep the ST70 for a bit, but its currently not being used-the SCA-35 is just a sweet little amp, and its become the main rig mainstay.
As for the Turn it Up sig, that would be covered by the MAC1900, and the hoarder pile of guitar tube amps that I've amassed! I'm fortunate to live a few hundred yards from my closest neighbors....
Click to expand...

What is it about those little Dynacos? Oh I know, it's the Z565 iron, which is possibly the best iron ever wound (according to ears and square waves alike). I have a little ST35 that uses the same iron and it's hard to rotate it out of the main. It gets a lot more play time than my 2A3, but it's strictly a power thing. I like my music very loud at times, and ever since I put my big horns away, the 2A3 just won't get me there. I tweaked up a pair of Paramours a few years back and I think doucanoe is still using them. Take a look at some of the asian uber hi fi design stuff for the 2A3. One thing to remember on any SET amp is power supply, power supply, power supply. Build it about 4 times stiffer than you need and it will be perfect.:D
 
Thank you to each of you for your input. I called Bottlehead yesterday, and after a 20 minute chat with Josh-including a love fest for Portland, Maine record stores we both adore.. Small world- I ordered the Stereomour kit. They say it'll be about a month. I am so excited to bring this amp into being!
And, Jay, is that where that SCA35 gets its mojo? I'm just wading in to the tube pool, and I was thinking it was the 6BQ5 tubes. All I know is that, after re boarding that little beast with Dave Gillespie boards, it is a purely divine little amp. I just don't see it ever leaving the fold. I'm hoping the Stereomour will give the same, SET style, feeling.
Very best to each of you.
David
 
An EML 2a3 meshplate. Doesn't light up as much as the Sophias.

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desire+reality=budget ; at some point that detail comes into the picture because 2A3 amps are all over the map in cost. ;)
 
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