hey, new here. just picked up this old 70's solid state amp.
says wildcat bass on the front and on the blue plate it says model number rb-4c / serial number 124
wondering if anyone out there has any information about these or someone i could email for specs couldnt come up with anything on google.
Never seen.
It's *very* old, certainly one of the first SS amps.
The output transistors have 1966 date codes.
They are Germanium and impossible to get today.
Does it work?
wow really 1966? if you nees any better pics of any specific parts lmk i can take them asap.
when i first got it the chassis was hot.(tested with volt meter before i touched it because the guy warned me of it(got it for free)). so i wired in a socket from an old power supply for the 3 prong plug. and that fixed the chassis being hot.
it works great and sounds reallyyy good, except channel 2 doesn't work im pretty sure its missing a 700uf 50v capacitor.
im already liking this forum! the other forum i posted on i just harassed about me getting shocked.
any ideas on how many watts this thing is putting out?
Probably around 50W, maybe more.
Looks very well made, but parts are expensive or unavailable, so take care of it.
Specially avoid shorts in the speaker cable.
I had a few notes about them in my collection. They were a product of Stereson Amplifiers and Accessories from Clearwater, Florida. Made from late 1960's to maybe mid 1970's. Not fisrt solid-state amps by a long shot but in the second generation. At least some of the amplifiers they made tried to ride with the Kustom fame, copying their "tuck-n-roll" upholstery.
its very cool to hear what people have to say about this unique amp.
it seems pretty well built but looks like its been opened up a few times and some joints resoldered but all is well and sounds pretty good besides the scratchy volume.
any ideas on where to get a matching (or close to matching) 700uf 50v capacitor?
heres a little sound clip with my les paul using bridge pickup(l500xl)
http://www.filedropper.com/rec20120519184016
Go for a 1000uFx50V cap.
should i? would that make channel 2 sound any different from 1?
hmm...tried it out with a cap i had laying around 800uf 100v. channel 2 still doesnt work :'(.
so should i sell this amp or do you think i should salvage it for parts. im planning on building a fender champ and a few other tube amps. and i could use most of the resistors and caps.
but i really dont wanna salvage it maybe i should sell it and someone can fix it and have a super cool rare unique clean sounding amp.
found a loose wire going to one of the input jack resoldered and im getting some sound but its really really faint.
hard figuring these types of things out without a schematic/layout.
You can sell it for $20, if any. Serious.
Keep and use it as-is. The day it stops working, it's done.
Buy new parts, these are 40 years old.
And repeat it, use it as is.
You can play a club date with it, you can not do that with the Champ.
Besides, it sounds incredibly clean.
If you want distortion, add a good pedal.
yea it is really clean i kinda like the sound.
i'll just try to fix it maybe keep it for awhile, post it on craigslist and if someone wants to give me 100 bucks for it its theres.
but i'd like to get a pedal and nice cab and try it out see how it sounds then.
you think i can replace all of the 700uf 50v caps with some newer axial maybe 1000uf 100v?
IF the original circuit used 50 Volt rated Caps then anything over that voltage is fine,,, just don't go below it.
Uf Value is a matter of how much you want to spend???? :duh
I doubt you will hear an earth shattering difference between 700uF and 1,000uF. 8|
All that really matters is that the ***Voltage rating of the capacitors is above the working DCVoltage*** present on the rails.
Observation?
Sounds like you don't really want to keep it any way so you choose chum.
I'd keep it if it sounds good to your ears otherwise a waste of time trying to fix it.
I keep stuff like that for spare parts. :tu:
Phil.
I wouldn't advice going overboard with the capacitance. Too much of it and the inrush will begin to blow fuses. Use caps that have equal or higher voltage rating than the caps you are replacing. For capacitance, get something that's in the ballpark of the old part.
If the old one was, say 500uF, don't use a 1000uF cap but maybe a 470uF, 520uF, or 560uF.
As for unobtanium germanium transistors. If they die replace with silicon and reconfigure the bias circuit. You probably won't notice much difference except for a huge improvement in reliability. R.G. Keen has written some good stuff about this issue concerning Thomas Organ solid-state Vox amplifiers. The good news: The information is for most parts interchangeable since you likely find a very similar design from these amps.
Schematics and layouts..? Heck, if you really need them just spend a few hours to sketch them out. With these kinds of amps it's still humanly possible without a microscope and without having to spend weeks into the process. If you choose to take that path then post the sketches here (or to the Internet in general) so that in the future there actually will be some information and technical documentary about these amps to help other guys like you.
yea i think im going to gut it and build a fender tube amp into the head, maybe a Princeton?
i just pick up today 2 Sunn 2000s heads and 1 sunn 2x15 cab and a 1979 Fender Bassman combo 4x10. (pics for proof)
so im all set with amps right now so I'll probably set it a side till i feel like building something. lol
(http://i50.tinypic.com/280r5si.jpg)
(http://i48.tinypic.com/nvqgy0.jpg)
Quote from: teemuk on May 21, 2012, 01:46:29 PM
I wouldn't advice going overboard with the capacitance. Too much of it and the inrush will begin to blow fuses. Use caps that have equal or higher voltage rating than the caps you are replacing. For capacitance, get something that's in the ballpark of the old part.
If the old one was, say 500uF, don't use a 1000uF cap but maybe a 470uF, 520uF, or 560uF.
As for unobtanium germanium transistors. If they die replace with silicon and reconfigure the bias circuit. You probably won't notice much difference except for a huge improvement in reliability. R.G. Keen has written some good stuff about this issue concerning Thomas Organ solid-state Vox amplifiers. The good news: The information is for most parts interchangeable since you likely find a very similar design from these amps.
Schematics and layouts..? Heck, if you really need them just spend a few hours to sketch them out. With these kinds of amps it's still humanly possible without a microscope and without having to spend weeks into the process. If you choose to take that path then post the sketches here (or to the Internet in general) so that in the future there actually will be some information and technical documentary about these amps to help other guys like you.
yea i could get a sketch of it and upload it here. pictures of the wiring too would help others. i no how had it is to do something without a layout or schematic. but it will be a little bit (few weeks) got lots of projects right now.
thanks for all the input everyone!!
Why wreck it? If you don't want it give it to somebody who can be bothered restoring it. As for "parts" - it's 50 years old and there isn't anything in there that you can't buy better new, and a lot that is simply useless once it is pulled apart.
Why don't you have a go at tracing the circuit? A bit like servicing an unknown stereo amp you seem to have two similar preamp boards to compare, and two similar output stages as well. Tracing one of the preamps should give you most of the other one, and ditto for the two output stages (which are likely to be identical).
If you are going to be doing any work on this I'd apply some heatshrink to the mains socket inside to avoid accidentally "shaking hands with beef"; and the "ground" switch certainly needs cleaning up (if you haven't done so already).
It appears to have two power trannies, one for the low voltage to supply the preamps and driver, and the bigger one to power the output stages.
The small tranny down between the heatsinks suggests that this uses an old style transformer-coupled driver. I'll attach a circuit of an amp that I think used a similar driver/output stage arrangement to give you the idea.
I'm guessing that the board mounted vertically in the middle will combine the two input channels and feed the driver; that transistor mounted on the back plate will be a class-A driver for the output stages; and the missing fuse holder may go some way to explaining why one channel isn't working.
It's going to need a few new electros, but frankly I think this would be a poor choice of metalwork for a valve/tube build.
QuoteI think this would be a poor choice of metalwork for a valve/tube build.
Fully agree.
A tube chassis is thin (say 2 in deep) , has small parts inside, has a 4 to 6 in free space on the other side for tunes, transformewrs and large caps and on its surface has the sockets which jopin the inside and the outside world.
An SS Chassis is 4 to 6 in thick, has *everything* inside and nop free space outside because it does not need it.
ASbsolutely incomptible.
Better donate it to some poor bass player or whatever.
jm2c.
Quote from: Roly on May 23, 2012, 03:32:44 PM
...and the missing fuse holder may go some way to explaining why one channel isn't working.
I'm with Roly. I'd try to fix it or give it away/sell it to someone who wants it. No point in tearing it apart when it is almost fully functional and quite rare.