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What size chassis it that, Tom? With the GXSE15 and the XPWR005, and as much space as you've left between the transformers, it must be at least 12" wide.

That's my "standard" 12 x 8 x 3. I'm sure everything could be
squeezed onto a smaller chassis, but I like that size.

The minimum chassis size could be 10X6X2 inches , but then that would be a bit of a "squeeze" job to get everything to fit in, and on, the chassis neatly, and leave enough working room under the chassis, especially with the larger-sized "6L6" PT and OPTs.

I like the 12 X 8 X 3 chassis, it is a very useful, and "universal" chassis size for all but the largest (like ST70) stereo power amps.

/ed B

This is probably my densest 12x8x3 ... a push-pull 6V6 with
Russian tubes ... the amp went back to Russia!

I've started a "Chubby Clementine" build, got all of the chassis metalworking completed and all of the iron, input RCAs and speaker binding posts, power switch, fuse, and pilot light mounted on the chassis top, only the power cord enters through the back of the chassis.

Still have to load up the PC board, I already have the three octal sockets and the four PSU caps soldered - this was a ciritical part of getting everything to fit through the necessary seven chassis top holes

Since this is another of my oddball-sized "dumpster" chassis, which has slightly less than 1.5 inches internal depth, I had to get somewhat "creative" in order to accomodate the four PSU electrolytics - and since a picture is worth (at least) a thousand words, I'll save any detailed descriptions until after the unit is completed, and photographed.

I am planning to use 6.3VAC for the filaments, rather than rectifying it, the 6SL7 and 6L6GCs should be very happy with AC filament power.

OPTs are Edcor GXSE10-8-5K and the power trannie is a one-of-a- kind USA made prototype from Musical Power Supplies, and is essentially a slightly pared down PA774 same secondary AC voltages, just a little less maximum B+ current capability. I also have two Hammond 156R chokes (same as C3534s) under the chassis - they are a tad taller than the under chassis space, so some more "creativity" will be forthcoming. I tried fitting them in on the back panel, but I ran into spacing problems with the transformer mounting screws The PSU will have CLCLCRC topology.

This is definitely going to be a very "different" looking Clementine, I guarantee it

/ed B in NC

The filament rectification on the Clementine board is intended as a
double to power the 12 volt 1626 and 12SL7 tubes in a Darling build,
so no need for 6L6's.

Looking forward to the pics ... sounds interesting!

If one were to use 12SL7 and two 12V6GTs then the filament voltage doubler could be used. In triode mode, about 1.5-2 W rms per channel, depending on the B+ voltage.

/ed B

I finally completed "Chubby Clementine" today, using a NOS Tung-Sol 6SL7 and two of the Russian 6L6GCs. OPTs are the Edcor GXSE10-8-5Ks, and the power trannie is an oddball MPS prototype, 300-0-330 @ 120 mA and two 6.3VAC @ 3A filament windings, one of which is also tapped for 5VAC

It sounds amazingly good, and after four hours running, it sounds a bit better than on initial power-up, seems to have smoothed out and developed more low and high freq response - the caps and OPTs had to break in.

The B+ at the OPTs is 370VDC, and each 6L6GT is drawing about 55 mA, 27.5VDC across the paralleled 1K 2W cathode resistors. PD is running just about 18.9W, or 63% of the tubes' max 30W PD rating. The 6SL7 B+ is 320 VDC, and it is running at about 1.15 mA, each triode.

Its power supply is a bit beefier, I used 4 X 180 uF / 500V caps, and two Hammond 156R (C354 equivalents) in the filter string - I replaced the 100 ohm series resistor with the second choke.

This is the "triode mode" circuit, I may try the "ULtra" mod later on, should be a relatively easy mod to perform, even with the board wiring directly soldered, with no terminal strips.

Photos coming soon...

Now, what to do with the second Clementine board...

/ed B

EWBrown wrote:I finally completed "Chubby Clementine" today, using a NOS Tung-Sol 6SL7 and two of the Russian 6L6GCs. OPTs are the Edcor GXSE10-8-5Ks, and the power trannie is an oddball MPS prototype, 300-0-330 @ 120 mA and two 6.3VAC @ 3A filament windings, one of which is also tapped for 5VAC

It sounds amazingly good, and after four hours running, it sounds a bit better than on initial power-up, seems to have smoothed out and developed more low and high freq response - the caps and OPTs had to break in.

The B+ at the OPTs is 370VDC, and each 6L6GT is drawing about 55 mA, 27.5VDC across the paralleled 1K 2W cathode resistors. PD is running just about 18.9W, or 63% of the tubes' max 30W PD rating. The 6SL7 B+ is 320 VDC, and it is running at about 1.15 mA, each triode.

Its power supply is a bit beefire, I used 4 X 180 uF / 500V caps, and two Hammond 156R (C354 equivalents) in teh filter string - I replaced teh 100 ohm series resistor with the second choke.

This is the "triode mode" circuit, I may try the "ULtra" mod later on, should be a relatively easy mod to perform, even with the board wiring directly soldered, with no terminal strips.

Photos coming soon...

Now, what to do with the second Clementine board...

/ed B

6550's

Doktor Brown, are these the same 6P3S tubes you sent me or a newer 6L6GC type? I assume mine are rated at 20W, basically a GA:
http://www.tubes.ru/techinfo/HiFiAudio/6p3s.html

These tubes are quite wonderful. Mine are by far the brightest blue tubes I've used, with perfect 6L6 specs and the best linearity. They pulse to the music, too!

I think you would be pleased with the ULtra mod. Other than the low gain, it is a poor man's 300B SET amp.

Shannon

The Russki tubes I am using in this amp are the larger sized 6L6GCs, the 6P3S was loosely described as being like a "6L6GA" or "6L6GB" at the time, they are more like beefy 6V6s in appearance. I'll have to unearth some of them and try them out in Chubby Clemmy.

The tubes I used are significantly "fatter" then the 6P3S and have a "coin" base. They are marked as 5881/6L6WGC SOVTEK Made in Russia. Same tube that I used in the Champzilla / uglytron 6SL7 / 6L6GC / 5AR4 SE guitar amp.



the two big electrolytics marked "C1+C2 and C3+C4" are J/J 32+32 uF.

I'll post a "real" photo in a day or two...



/ed B

Ok - I do see the guitar guys raving on those 5881-style coin base Russkie tubes. I'll have to grab some.

BTW, missing that early winter in NH?

Shannon

Those Russki 5881/6L6WGCs are definitely pretty nice, I got a set of 8 which were pretty closely matched - probably just luck of the draw, all were in the same manufacturing lot - at a silly cheap price a few years ago, before I moved here. I still have five of them left, so they'll get some good use during my winter "building season".

The 6550 idea sounds good, I was considering the same thing, I have a couple of spare 6550Cs not being gainfully employed. I may try them out in teh 6L6WGC build, just to hear the dirfference, then the next one, I'll kick up the B+ around 430VDC, and try the "big dawwg" tubes

/ed B

EWBrown wrote:... I'll kick up the B+ around 430VDC, and try the "big dawwg" tubes

The 500V caps are pretty dang handy!

I only had one on hand, from my boxes of pulls, otherwise I would have used them myself.

Shannon

My supply of 180uF/500V (the blue ones) caps is running low, I got them years ago at a local (in Milford NH) antique/junk shop, which I discovered through fee-bay. They had bought the leftover parts from a defunct solar power company (No, it wasn't Solyndra, this was years before that debacle).
I also bought a large quantity if SS rectifiers, and assorted power resistors, all on the cheap.

I still have a dozen or so 180/450V (the black ones) caps from the same source.

Just goes to show, you never know what strange places one might find tube amp parts

Similarly, I've seen speaker "zip cord" wire and cheap RCA interconnects and adapters at the local grocery store, next to the lightbulbs and airconditioner filters

/ed B