MAD Stealth-5, finally finished

[soundbrigade]

This project started ages ago, when I studied various projects found on mapletree Audio Design's website. Back then the major thing was the 5W pushpull monoblocked amp called Stealth as it was all black - metal canned tubes.
I had gotten the OP trannies from Erik Andersson, the guy behind Audio Innovation and the power transformer was wound by a local company. I think tubes came from AES or maybe OldRadioParts. However I changed the metal 12A6 to glass-canned 12A6 as the metals behaved funny (vlf oscillations).
The project as it started is presented on my site: http://www.pastisch.se/tubes/stealth5.htm, but that was the beginning. A year ago I started modify the amp to allow two pair of line inputs and an iPod dock. This job took me a long time to finish, though the last bits (90% of the job) was done in an afternoon, followed by two days of faultfinding . I had cut the wires to the power inlet and forgotten about that, Some wires around the volume pot was broken and the last fault was found minutes ago - swapping a 12SJ7 with a 12SC7 ...
Most (all) parts are what can be obtained from local companies selling electronic components and no money are spent on high end snakeoiled stuff. The speaker connectors are cheap ones from a car sparepart dealer.

Some pics:


Placing the tubes in two curves:


Marking the tube sockets help keep some order in the chaos:


Let's modify the sh*t:


Almost there (missing screws to the PSU):


But how can I miss this:


To be honest, though there are loads of various projects lying around, this is at the moment the only work amp I have.

PS The "5", means 5 Watt/channel.

[katabatic]

Magnus--

Love the removable paper 'socket pin reminder' sheets -- never saw or thought of that before. It wins the 'Nifty-Idea-of-the-Day' award!!

George

[soundbrigade]

When looking at the schematic, in this case a standard design (Williamson?), everythings looks reallys mart, but when starting to assembling the amp linke I have done, things tend to be very complicated after a while and counting the pins on the sockets may lead to problems.
I have been using this "technique" when it came to simple SE-amps, else I have tried to use breadboards.

[burnedfingers]

Have you tried VT-268's or 1634's in place of the 12SC7's?

Nice job by the way

[soundbrigade]

Nope, but thanks for giving me an idea ....

However I am to rebuild my SIPP 6L6 (6P3S-E) and I need 12ATs (got 'em) wired ... oh, sh*t, look at the drawing I thought maybe 6SC7/12SC7 could do the job instead, or 12SL7.

My new idea for 6L6PP

[EWBrown]

I'm in process of building its baby brother, 12A6 & 12SL7 version of teh Clementine, wth 250-260V B+ (same as for the 1626) and 500 ohm RK for V2 and V3, and 7.5K OPTs (TF103-48) and two chokes in the PSU filter string. With these values, the SEP output should be about 3.4 WPC.
If it sounds , then it's an easy matter to change it back to a 1626 Darling.

No Pain, No Gain

Back to the MAD man amp....

Should you decide to have NFB, it is a simple matter of injecting it back into the top of R5, through an appropriate value resistor, from the 8 ohm output.

/ed B