Classic amp topologies made with submini tubes

[thomasha]

Hi,
yes, they similar, but Z-vex uses the american versions. The socket is a problem indeed, I'm using IC's sockets so far.
The clean headroom in the nanohead is very reduced, as it only uses one triode in SE, it will only output 1/4W or so.
These one has two triodes in PP and a real Pi, not self-split like the Superfly. It's louder, something like 1W, like the load line shows. I'm redesigning the amp to obtain more headroom, and max. power from these tubes and the SMPS
The 12ax7/12au7/ecc99 amplifier is better, and the JTM1 clone will be one of my next projects, but i'm kind of a miniaturizing maniac, addicted to sub-miniature tubes. 

[mrsmash23]

@thomasha

Hello, any updates on your JCM800 project? Or even any news about JTM1 project?  Thanks in advance!

[thomasha]

Hi,
after some soldering I finished the board, take a look:



After some testing, there was a lot of noise in the preamp, using only the PI and power stage it was nice and clean.

I'm drilling an old enclosure to test how the circuit behaves.
If it works like the first build, the proximity with the enclosure removes the SMPS noises.
Cheers,
Thomas

[frequencycentral]

Wow Thomas! That's a lot on a small PCB...hope it works out.

Rick

[thomasha]

Hi!
unfortunately that board was very noise... back to project....

The SMPS near the first stage was a horrible layout idea. I'm thinking of reducing it to 3 tubes, same as the little 1W marshalls and use a cathodyne PI. (more space, less heat)

And make a separate board for the SMPS, with a cooler, or heatsink the fet. The best fet I could find was the IRF644, but it still gets really hot after one hour playing...a better low ESR capacitor and inductor are in to buy list.

Just thinking of it's worth dropping the electrolytic capacitor for 2 film capacitors...easier to find at least.

Well, I made another video of the first build:

I salvage this same kind of speakers yesterday, I think this amp needs a brother, I just need to find a nice wood piece for it...

Thomas

[thomasha]

Hi all,
new video, this time with a real speaker!

Cheers
Thomas

[thomasha]

Hi,
I made another prototype, this time using 3 tubes. The PI is now a cathodyne, and the B+ is 234V.

This should fit in a 1590b box.

Cheers,
Thomas

[Taylor]

I'm enjoying your submini tube odyssey! Cool build. I started this thread but never got my Superfly working back then. Maybe I'll try to resurrect it one of these days, as my building skills have improved somewhat in 6 years.   

[thomasha]

Hi,
this was already posted elsewhere, but for completeness, here is the final version of that amplifier in the video above!







and I made a small doc. if someone is interested.
https://dl.dropboxusercontent.com/u/10420127/RussianJTM.pdf

cheers,
Thomas

[Digger1770]

That is one of the coolest things I have ever seen!

[ASchmalex]

Hi,
this was already posted elsewhere, but for completeness, here is the final version of that amplifier in the video above!



cheers,
Thomas

That is very cool, sounds nice too!
Wonderful and inspiring build!

[deadastronaut]

cute-ist amp ever...sounds cool too. 

[thomasha]

Hi,
made a new video of this amplifier:

and this:

cheers,
Thomas

[deadastronaut]

ha ha i just saw that on youtube..

cool..

[Jarno]

Fantastic build!

[thomasha]

Another one to the list:







same schematic as the previous one, but using the 6111 and 6112 tubes, that required some changes.
I used a prototyping board this time.
Cheers

[tonyharker]

Did you change the bias on the tubes or use the same as the Russian ones?

[thomasha]

changed the cathode resistor to 1k.
Current for both output triodes is 8mA at 220v, roughly the 1.8W max. dissipation.

[Cozybuilder]

Wow, that is one great looking sub-mini tube build Thomas! 

[runmikeyrun]

Awesome!!!


Ham fisting my way through one build to the next since 2003.