Risson Guitar Amp

[CJ]

on the bench,

Risson ETA-100

 

[CJ]

got a bigazz Plush OP 4000 output transformer,

couple of PhillipsECG 6550's

 

[Matador]

Is that a JCM800(ish) clone?

 

[Brian Roth]

Wow! Plush amplifiers? I remember that brand from my youth and time working in the service dept. at a music store when I was in college. I can't recall the name for the type of upholstery on the cabinets....Kustom "tuck and roll" was similar but quite different. The Plush upholstery was like the seats in the booth at a diner.

http://www.plush-amps.com/P-cat9.jpg

http://www.plush-amps.com/cat_pages.htm#da_cat_2

Slogan "The Plush Rush".

Bri

 

[CJ]

Kind of like a Marshall with one input jack feeding a gain stage and another jack coming after that. I drew a schematic, none online, will post tomorrow.

There is so much gain that you can make it sound like a fuzz box.

You could put wheels on those Plush cabinets and enter them in a car show.

https://risson.com/artists/

 

[CJ]

there is a simple effects loop that does not require extra parts other than a few resistors,

the power tube B+ comes after the choke,

the gain was so high on the 1 + 2 jack that a 10 mv p-p signal was used.

 

[rock soderstrom]

I don't think I've ever mentioned this before, but I admire your schematic drawing skills, I wish I could do it as nicely. I think I will sample your style with an app.

 

[NoisyIndividual]

there is a simple effects loop that does not require extra parts other than a few resistors,

the power tube B+ comes after the choke,

the gain was so high on the 1 + 2 jack that a 10 mv p-p signal was used.

You forgot to designate HT C on the pre-amp tube Anode resistors, other than the first one.

Just saying, but I suspect you would like to know that.

 

[CJ]

got the B and C added, thanks!

also edited 2.2 K screen drop in supply to 1 K 5 W as the 2.2 K i stuck in there got mighty hot.

 

[CJ]

dual trace shots, on the transformer, primary vs secondary,

 

[CJ]

sq wave

 

[CJ]

weird telephone company input jack,

apparently Ben Risso worked at Fender and when they shut down, he took home some surplus parts and made amps.

 

[NoisyIndividual]

I can't see the bias pot in there, but I think I would be modifying it to loss of wiper means full bias, rather than no bias at all as in the schematic.

 

[CJ]

Oral history for Risson amps>

 

[Rusan]

Too cool, CJ! I became close friends with a guy in1990 who'd just moved to Arkansas from L.A., and he always talked about how badly he missed his Risson that he had to sell and leave behind. He couldn't believe I'd never heard of them, because they were fairly common there, and both he and the other guitarist in his band played 'em. I've still never seen one in real life, and this is the first time I've seen anything online about them.

It made no sense to me when he'd say Bob "Rissi" without an N and then "Risson" with an N. I thought it was just his accent (that was rather unusual to me), because around here in these parts our Southern twang is rather extreme, to say the least. It all makes sense now!

Thanks for posting the schematic! Like Rock, I'm amazed by your stellar schematic drafting skills. My own hand-drawn schematics are about as easy to understand as my aforementioned speech.... maybe even less so.

 

[map2112]

there is a simple effects loop that does not require extra parts other than a few resistors,

the power tube B+ comes after the choke,

the gain was so high on the 1 + 2 jack that a 10 mv p-p signal was used.

Nice schematic especially the signal levels and voltage notation.

But schematic looks odd around the effects loop jacks to me; Is the top effects jack actually the “out” and the bottom one the “in”, and perhaps the lower jack is a switching jack to break the loop if something is plugged into the effects in / lower jack?

 

[Rob Flinn]

What is the purpose of the double diodes on the H.T rectifier ? I notice that you have missed out some parallel resistors with these diodes on your circuit diagram. Do the resistors with the diodes provide some sort of power supply sag ?