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The U-6V6

tubelectron

tubelectron

Super Member
The U-6V6

Same idea as my U-KT120, but compact version and using a 6V6GTA tube :

It started also years ago as a mono blocks prototype :

bkjFJb-U-6V6-proto-30-05-2020.jpg


But it now takes shape - each mono block uses the same chassis format as my Micro-Amp Stereo project :

7C5gQb-P1170021.jpg


Lateral faceplate :

x9CgQb-U-6V6-lateral-plate.jpg


The parts and faceplates for the Micro-Amp, U-KT120 and U-6V6 arrived today, so these three projects will be able to move forward ! :cool::cool::cool:

Wait and See... ;)

T
 
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Selmerdave said:
Around 5W output or is it triode? What are the potted outputs you're using?
Click to expand...

It's an Ultra-Linear, cathode bias operation, with 2WRMS nominal output expected.

The output transformers are of an unknown Chinese provenance. It's a friend of mine who brought them from there as samples.

upload_2023-6-11_1-28-45.png

So I encased them and invented an obscure improbable brand for the fun... ;) These are 5K/8R, possibly 10-15WRMS transformers.

upload_2023-6-11_1-30-48.png

After a test on the prototype, they proved to be classic but fine output transformers...

The power transformer and the choke are French Army 60s surplus, from the brand LMT (Le Matériel Télephonique).

T
 
OK : resurrecting the thread ! Nearly three years later... :rolleyes: Pour la bonne cause ! ;)

First, I modified the mounting of the meters, from upwards (at R) to underneath (at L) : nicer presentation...

D1zaXb-P1250780.jpg


The chassis are ready for wiring :

U1zaXb-P1250781.jpg


The workstation is ready for starting tomorrow (Sunday) :

p2zaXb-P1250784.jpg


Schematic principle - I wonder about the usefullness of a Triode / Pentode switch... :idea: :crazy:

kMzaXb-SCN-20260820-195405.jpg


T
 
Some people like triode mode, some don't. I have pentode/triode switches on one of my stereo amps, and a pair of mono blocks. I wasn't impressed with triode mode at all. I just left that option out of a single ended amp I built.
 
Lavane said:
Some people like triode mode, some don't. I have pentode/triode switches on one of my stereo amps, and a pair of mono blocks. I wasn't impressed with triode mode at all. I just left that option out of a single ended amp I built.
Click to expand...

Yes @Lavane - thanks ! :cool:

I have too been disappointed by all my attempts on Guitar amps by the Triode/Pentode switch : it lowered the power as expected, but provided a dull, lousy sound in clean and anemic in overdrive. So you confirm in Audio - at a lesser extent - what I noticed on Guitar amplification...

OK - I forget that T/P idea and stay in P ! ;)

T
 
Nice work so far.
What did you use to bore rhe holes for sockets and the meter?
I found Fortner bits meant for wood working work very well with aluminum if you have a drill press. They leave a nice clean bottom too if your not cutting all the way through thicker aluminum to recess a knob, or need to relieve some of the chassis for a potentiometer. I just set my drill press for a slow speed. Then slowly start cutting the hole a little at a time using something to help with cooling the bit like a light oil. Cut, brush away filings, add a bit of oil, cut some more, rinse and repeat. It makes for much cleaner holes than a step drill bit.
 
You mean this, @Lavane :

1788126552442.png
I never used this kind of bits with my drill press, I must confess - but I should, so I note it ! :cool:

Personally, I still use the good old GreenLee punches : I have an assortment of suitable diameters...

T
 
tubelectron said:
You mean this, @Lavane :

View attachment 3827009
I never used this kind of bits with my drill press, I must confess - but I should, so I note it ! :cool:

Personally, I still use the good old GreenLee punches : I have an assortment of suitable diameters...

T
Click to expand...
Yup. As long as you go slow and keep brushing the filings away and using a cutting fluid or just 3-IN-1 oil like I do the bits stay sharp. I have bits from 1/4"
to 4". The 4" Forster bit is kind of big though. Ive only used it on wood.
I used it to make a hole for a vent in a guitar head amp cabinet.
In the second picture I had to counter sink holes on the thick aluminum front panel so I could get the nuts on the selector and volume pot. The Forstner bit left a nice clean bottom on those counter sunk holes.
 

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