A Superlite 6V6 12watt Amp build

T-Rex

T-Rex

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Hello all, This is the current bench project. It's my build version of a Superlite 6V6 12watt amp. The Superlite's were a spin off from the original 18 watt Marshall 1974, and this one is a spin off from those 18watt spin offs. This build has a P-P 6V6GT power section, cathode bias. Iron is Hammond 272X PT and the OT is 20 OTPP MPS, no choke, tube rectified.

This is a two stage cascaded amp with a High/Low input. It has a TMB tonestack with a fixed NFB. Controls are 1Meg Gain, 1Meg Master, 250K Treble, 50K Middle, 500K Bass. The tone stack is plate feed with the slope resistor at 47K, Treble coupling cap at 390pF, Mid coupling cap at .01uF, and Bass coupling cap is .022uF, all Mullard / Phillips Mustard caps.

Input hits stage 1 which is set up with 100K plate and cathode bypass at 2.7K/ .68uF (typical Plexi values). The signal goes through a 470K resistor/500pF to the Gain pot to stage 2. Stage 2 is set at 100K plate with cathode bypass at 680R/2uF. The signal is tapped at the plate, not the cathode and goes to the tonestack, then FX loop to the PI. I'm ready to look it over once more then apply power to it.







 
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All B+ reservoir filter caps (4 total caps) are 16uF, the dual can cap is F&T. The PI coupling caps are Mustards that are 82000pf's that test out at .9uF, close enough for typical .1uf within a 10% tolerance. The jacks are Cliff, tan resistors are .6watt Dralorics, brown resistors are 2watt metal film Vishays, Belton sockets. Pots are CTS and a couple of Tocos (Tokyo Cosmos).

The power tubes are 6V6GTA Raytheon Made in England black glass. Preamp haven tubes haven't been selected yet.

 
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T-Rex said:
I'm closing this thread and opening a new one. I didnt care for the tone on this build, reworked it into a parallel cascade and didnt like that either. It is now a new build that I call the Stone Cold Bitch. Please check out that thread instead
Click to expand...
I'm curious as to what you didn't like?
 
T-Rex said:
All B+ reservoir filter caps (4 total caps) are 16uF, the dual can cap is F&T. The PI coupling caps are Mustards that are 82000pf's that test out at .9uF, close enough for typical .1uf within a 10% tolerance. The jacks are Cliff, tan resistors are .6watt Dralorics, brown resistors are 2watt metal film Vishays, Belton sockets. Pots are CTS and a couple of Tocos (Tokyo Cosmos).

The power tubes are 6V6GTA Raytheon Made in England black glass. Preamp haven tubes haven't been selected yet.

Click to expand...
I wanted to warn you about fake cliff jacks....
if the jack is stamped "cliff"and is not stamped "UK," it's a fake cliff jack.

1669397097785.png This is the real one, stamped "UK."

1669397162034.png This is the fake cliff jack, there is no "UK" stamped on the plastic.

Watch out for the fake jacks, they are garbage.
 
I know there is a new thread on the amps rebuild, but nice looking build & nice choice of electronic components, hope you get the next go 'round sounding the way you want.
What I wanted to do was offer a few thoughts, if I may.
When using a "plate driven" tone stack, I find that I usually need at least one gain stage (recovery amplifier) after the tone stack, due to the insertion loss incurred when driving the tone stack from a high impedance source.
If the amp is of my own design, I prefer to use a 12AU7's triode to "plate" drive the tone stack because;
1) It can push more current into the tone stack than a 12AX7 can.
2) It has lower output impedance than a 12AX7, so less insertion loss is incurred.
By comparison, a cathode follower provides a "low impedance" source, so less insertion loss is incurred when we use it to drive the tone stack. This is why we can get away without the need of a "recovery amplifier" stage after the cathode follower driven tone stack, even though the cathode follower gives slightly less than unity gain.
Amp Mad Scientist said:
I wanted to warn you about fake cliff jacks....
if the jack is stamped "cliff"and is not stamped "UK," it's a fake cliff jack.

View attachment 87247 This is the real one, stamped "UK."

View attachment 87249 This is the fake cliff jack, there is no "UK" stamped on the plastic.

Watch out for the fake jacks, they are garbage.
Click to expand...
I got caught out with the "fake" Cliff jack sockets about a decade ago, off an Aussie supplier who, without actually stating they were authentic, "implied" they were. Luckily, I only ordered a small amount because, as AMS says, they are garbage.
I'll now take a look at the new build thread. Cheers
 
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