Risson ETA-100

[Junkin8ez]

I picked up on EBAY to mess around with. This thing is frigin' HEAVY!!! Does anyone have a Schematic, info or any paperwork on it?
Under filter cap lid it says "ARGONOT"
Thanks in advance!

[pompeiisneaks]

Sadly I'm finding nothing on the googles. Maybe you need to create the first one Does it look like a form of a marshall in some way? It seems like many of the posts I did find indicate a marshall style circuit?

~Phil

[xtian]

Sure looks Fendery, with the fiber board, doghouse, white Mallory bypass caps, etc.

[sonicmojo]

Interesting amp.

Here's the link I found to Risson amps and Bob Rissi. Definitely Fender heritage.

http://www.rissonamplifiers.com

[Stevem]

Those EL34s are cathode biased?
Those are very large Transfomers for a 50 to 70 watt RMS amp, so I bet its heavy!

[Junkin8ez]

What little info I found out, it takes 2- KT88s OR 6550s
with 3- 12AX7s

I had emailed Risson Amps for some info but no response yet.

[Stevem]

I was guessing 34s because I see pins 1 and 8 going to ground , but with those size Trans 88s seem like a better fit!

[Ten Over]

That amplifier clearly had four big bottles and three little bottles originally. It was almost certainly a 100W amp given the four big bottles, the transformer sizes, and the "100" in the name. There is a high probability that he used 6L6's since this is a U.S.A. amplifier modeled after Fender. There is a bias tap and and bias circuit for fixed bias.

I would strip that thing bare and use the chassis and iron to make a 100W amp of choice.

[Junkin8ez]

That amplifier clearly had four big bottles and three little bottles originally. It was almost certainly a 100W amp given the four big bottles, the transformer sizes, and the "100" in the name. There is a high probability that he used 6L6's since this is a U.S.A. amplifier modeled after Fender. There is a bias tap and and bias circuit for fixed bias.

I would strip that thing bare and use the chassis and iron to make a 100W amp of choice.

Ten Over thanks for the info.
Do you think someone knocked it down to a 50W head by removing the 2 other tubes & sockets ?
Bob Rizzi was the owner/builder of these amps. He did work for Fender so hence the looks.

[Ten Over]

Do you think someone knocked it down to a 50W head by removing the 2 other tubes & sockets ?

Absolutely. Look at the heater wires coming out of the transformer. They were originally twisted and went to the power tube that now has a plastic plug in the hole. One wire managed to make it to the second tube socket when straightened out, but the other had to go to a terminal strip with a new wire continuing on to the tube.

[Ten Over]

I did a search on the ETA-100 and I now believe it originally had 6550's in it.

[Junkin8ez]

I did a search on the ETA-100 and I now believe it originally had 6550's in it.

I actually would not mind keeping it a 50W. I don't plan on playing any stadiums in the near future.

[nworbetan]

A pair of KT-88s can push 100+ watts through speakers if the B+ is high enough and the load is right.

https://drtube.com/datasheets/kt88-sed2001.pdf

Actual mileage may vary, of course. The transformers are the biggest variables as usual.

[Junkin8ez]

A pair of KT-88s can push 100+ watts through speakers if the B+ is high enough and the load is right.

https://drtube.com/datasheets/kt88-sed2001.pdf

Actual mileage may vary, of course. The transformers are the biggest variables as usual.

Thanks!

[Stevem]

If it is reworked to use 6L6 tubes and is applying more then 510 volts on the plates then your gonna need really good 6L6s in there!