SSS Power Transformer 100W Design

[ToneMerc]

Let's get some chatter going about the ideal power transformer for a 100W version. I would imagine the CF PS would be the most demanding, so whats on your core wish list?

TM

[Colossal]

TM,

What kind of plate voltages? Total current will be higher with all those lovely tubes. How about an accessory tap or two?

[topbrent]

I thought the 100w versions used the iron from a twin reverb?

[M Fowler]

My SSS project is using P-TM-P100 for power and Hammond 1750W 2k 100w OT and Choke P-CF22699. Standard Twin Reverb reverb-driver.

Mark

[boldaslove6789]

I thought the 100w versions used the iron from a twin reverb?

AFAIK, SSS #1, #2, and #4 all used Fender Twin Reverb Iron (Pwr, Output, Verb trafo, and Choke).

Although #4 may have a MM Iron (Jelle might know more)

[dcribbs1412]

Wondering if PT would need a higher bias voltage
say like 100-150V instead of the Twins 60V supply.

My SSS project is using P-TM-P100 for power and Hammond 1750W 2k 100w OT and Choke P-CF22699. Standard Twin Reverb reverb-driver.

Mark

Hi Mark
you have any voltages yet?

Darin

[ToneMerc]

Wondering if PT would need a higher bias voltage
say like 100-150V instead of the Twins 60V supply.

Darin

That's why I asked. Depending upon which driver config there are clones that have 150V bias settings. I might try the MM power with a CC and driver. That seems to be the easiest to implement.

TM

[M Fowler]

Wondering if PT would need a higher bias voltage
say like 100-150V instead of the Twins 60V supply.

My SSS project is using P-TM-P100 for power and Hammond 1750W 2k 100w OT and Choke P-CF22699. Standard Twin Reverb reverb-driver.

Mark

Hi Mark
you have any voltages yet?

Darin

No voltages yet I haven't had the time I lately to work on much.

Mark

[toner]

blackface twin iron? so they only had 4ohm taps, thats annoying

[M Fowler]

I do have a Heyboer 100w Fender type PT that has the extra 6v tap for the relays it was from a special order David Root had going.

But I wanted to use a standup PT to give me some more interior chassis space.

Mark

[dreric]

I've been hoarding a few parts. I have a PT from a Fender PS160 and I've been thinking that it would work for a 2 x 6550 build.

Also, the chassis is one of rj's mega size. Near as I can figure it's the right size for a SSS and a ODSR build. Unfortunately rj seems to be on hiatus right now.

Eric

[Max]

so they ... [OT of SSS100W #001 - #004 - Max] ... only had 4ohm taps...

Yes - AFAIK this is correct - see the attached picture of SSS #003. But as you can see on the attached picture of the back of SSS #001 Alexander Dumble and/or Henry Kaiser obviously liked the sound of the SSS 100W #001 combo loaded with this 8 ohm speaker connected to this 4 ohm OT. And AFAIK all the 1st, 2nd, 3rd, transition and 4th generation ODS combos with a Fender 4 ohm OT are loaded with an 8 ohm JBL, Altec or EVM speaker (see the attached data sheet of a 4th generation ODS e.g.).

picture of SSS #001: http://personalpages.manchester.ac.uk/s ... 74-O-1.jpg
picture of SSS #003: http://personalpages.manchester.ac.uk/s ... __2jpg.jpg

Although #4 may have a MM Iron (Jelle might know more)

On the attached pictures - AFAIR once posted by Tom (Structo) in another thread - you can see the transformers of SSS #004.

BTW: On the back of all the SSS 100W amps AFAIK you'll find the values for the power consumption and for the fuse. So you might be able taking these into account thinking about the specs of the PTs in the original SSS 100W amps #001 - #004?

Cheers,

Max

[dcribbs1412]

Wondering if PT would need a higher bias voltage
say like 100-150V instead of the Twins 60V supply.

Darin

That's why I asked. Depending upon which driver config there are clones that have 150V bias settings. I might try the MM power with a CC and driver. That seems to be the easiest to implement.

TM

Maybe a PT with 690V-700V 450-500ma, 6-7A 6.3V and 150V bias tap?
TM here's some info I read from other threads.

Darin

No problems with the bias supply I came up with though. I used a 20mA 120VAC source, a BR34 bridge rectifier and a 47uF 250V cap on the raw driver cathode bias and another 47uF 100V on the driver grid bias. I inserted a 56K resistor ahead of the standard HAD 10K bias pot/22K tail and get minus 175 to 180V raw bias. With 310V on the driver plates I get minus 44.3V on the cathodes and minus 45.8V on the driver grids. I do use the 150K driver grid resistors as shown in Bill's schematic, and also changed the 100K 2W cathode resistors to 51K. Works fine.

According to what I've heard, the set-up in an SSS is similar...but uses a 12AX7 instead of a 12BH7 as a cathode-follower/driver. Plan on a bias supply of -150 volts...with a B+ of around 500. If you work the circuitry right, you can take the -150 off the bottom of a 650 volt PT (think MusicMan), leaving the remaining 500 for the B+. Cathode resistor on cathode-follower/driver S/B 100k if you want an exact clone. My version is different.

[Max]

On this schematic of SSS #002 with a driver / inverter configuration https://tubeamparchive.com/download/file.php?id=22111 you find these Fender part numbers of all the transformers noted:

Rev: 022921
PT: 022756
Choke: 022699
OT: 022889

And even if this schematic shouldn’t be correct – as some members here suspect AFAIR – I doubt that its author wasn’t able to read and to note what was written on the transformers. But I admit – you never know.

Cheers,

Max

[ER]

Stiffening up the secondary reflection is a common method for tweaking an amps tone (especially 6l6s). Kimock runs 16 ohm cabinets on an 8 ohm tap, and for what it's worth before his sss amps came along Stevie Rays vibroverbs had a 2 ohm super reverb OPT hooked up to an 8 ohm EVM 15L.

Typically this will give you less power and bring the midrange forward (attenuation at the frequency extremes). Another important factor is the effect this has on the feedback/presence values, you may not be hearing what HAD intended without the proper-improper load.

Sakuma-san say's it like this;
'It is only after much cut-and-try that I find my best matching point for audio. The tube manual is like a telephone book. It gives perfect numbers. It is useful to make it possible to speak with a girl- but we cannot see her beautiful face from the mere telephone number."

-E