• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

First DIY Tube Kit Recommendations

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S

sparton175

Member
Joined 2021
#1
I've had the opportunity to pick up a few pairs of vintage speakers recently, Dynaco A-35s and Akai SW-180s. I'm enjoying them on my SS amps that I own now but I'm interested in trying speakers with some tubes. I currently have a DarkVoice for my headphones which I love but I'd like to try a stereo tube speaker amp. I've seen a number of kits out there for DIY tube amps but I'm not sure which one would be best for my application and price point. I'd like to use this with my record player and with my phone via either Bluetooth or RCA and I'd like the best kit I can buy for $300 or less shipped to the US. I don't need a headphone output for this amp and I don't need any crazy high wattages to drive these speakers.
 
#2
The output transformers really determine the sonics of a tube amp and unless those are really efficient speakers, a low power , hence low cost if you want decent sonics may not cut it. Used console amps may be still affordable, if you rebuild it yourself and can find one.

Diy PCB's from George at tubelab.com can be an affordable start for a nice amp , but you would have to go else where to say a glassware for an affordable phono preamp. George has a nice forum on this site.
 
#8
 
#9
For me these kit would be competing against the off the shelf offerings like the Nobsound 6P1, APPJ PA1501A, TubeCube 7, and FX Audio P1. Just to give some additional context. I know whatever I end up getting won't be the best and will for sure not be my last tube amp, this is just to get my feet wet and get these speakers up and running. If this wouldn't be ideal I can buy or build a solid state amp.
 
#10
The third one on your list (13W*2) is very similar to the one Xraytonyb built. Watch all his videos on the build, there's 5 or 6. See if it would suit you. Tony does a few mods and the amp does fairly well in bench testing. The single-ended amps are OK if you have fairly high efficiency speakers but for most "normal" speakers I think a push-pull amp would be better. EL84 tubes are dead cheap too. I've bought NOS Russian ones
for as little as 10 bucks US each. The gain/phase splitter tubes in the 13W*2 amp can be swapped out for ECC85/6AQ8 tubes or with a little work changed over to 12AT7 tubes.
I have a push-pull EL84 amp in my workshop powering a pair of Triangle BR02 speakers and it's plenty loud enough.

S.
 
#17
The speakers need at least 20 WPC and more is really appropriate. PP EL34 and 7591 designs will do the job. Too bad Scott LK72B kits are no longer being offerred.

That $300 figure is completely unrealistic. Suitable Edcor O/P transformers for the 7591 cost $85 each.

Now for the practical solution. More than 1 good sounding system has employed SS power amplification and tubed preamplification. $300 will get a nice DIY control center with a phono section and buffered volume control done. The provided tweaked RCA phono setup will drive modern recording devices, should that tickle your fancy.
 

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#20
The little miracle should put out closer to 25W if used as a pentode amp and the provisions are on board to do so complete with zener shunt for the screens. I haven't build the prototype up yet. Everything is here except for 9 pin ceramic sockets. PSA the plastic ones will smell like fertilizer for at least 2 weeks so if you don't like VOCs spring for the ceramic ones...

The MA-1 modular amp would be much better, but it'll cost more like 500$ at least. Works with over 40 different output tubes (so far) though.
 
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