Kasino Club output impedance?

[xtian]

I have this amp on the bench, a Kasino Club L-50 like this:



It uses a pair of RCA 36892 transistors for output power. I cannot find anywhere what speaker load this amp will be happy with. The four speakers are currently wired in series (three 16R and one 8R speaker!) giving a load of about 32 ohms DCR. I wonder if that's totally wrong for this solid state amp.

The sound is currently good, though it does not sound like it's putting out anywhere near 50 watts clean--though the speakers could be horribly inefficient.

[Leo_Gnardo]

Gadzooks, a speaker load nominally 56 ohms, it's a wonder you could get more than a couple watts out of that amp. Most solid states of the time could run 8 ohms no problem, some 4 ohms. I think somebody monkeyed with it in the past all right. Maybe wired it that way to guarantee the amp wouldn't overheat & self destruct. "Meh, those rock musicians are deaf, they'll never know! All they want is distortion anyway." Sure would be good to scare up a schematic.

[xtian]

LG, I think these schematics are a close match:

https://music-electronics-forum.com/...ad.php?t=12852

The power amp schematic is in post #2.

Does that help? Still see no spec for output impedance.

[Leo_Gnardo]

Looks like the standard Kasino/Kustom power amp of the time, 50ish watts to 4 ohms. (Kasino was Kustom's downmarket brand, they just leave off the tuck n roll cab covering. Perfectly good amps, if you like that sort of thing.)

I'm still guessing something went awry - maybe Guitar Johnny popped a speaker back in the 70's and all the tech could come up with was an 8 ohm version. So he wired 'em in series because in parallel, the 8 would hog current and perhaps blow prematurely or drive the amp into overheating. Nothing about that schemo leads me to think it needs to drive a 64 or 56 ohm load. I'd find a compatible 16 ohm speaker & wire them parallel. If you want to hedge, go series-parallel for 16 ohms. Bound to be better than series wired.

[vintagekiki]

http://www.vintagekustom.com/FUDforum/index.php?t=rview&th=2812&goto=15901

http://www.vintagekustom.com/FUDforum/index.php?t=thread&frm_id=2

http://www.vintagekustom.com/FUDforum/index.php?S=b7ba9f31726f56b39fb1bd3fba64e2ea&SQ=0&t=sear ch&srch=Kasino+Club+Speaker+ohms
... The amp is designed to run a total of 8 ohms ...

[Leo_Gnardo]

Hm, well there ya go. Now, how to make 8 ohms out of 3x16 and an 8... Maybe it originally had 8 ohmers in series parallel.

Thanks vintagekiki, you've been on a tear this week!

[xtian]

As suggested, I wired series/parallel, ended up with ~9 ohms DCR, all speakers in phase. And as expected, the amp is MUCH louder.

Thank you, gentlepersons!

[Leo_Gnardo]

As suggested, I wired series/parallel, ended up with ~9 ohms DCR, all speakers in phase. And as expected, the amp is MUCH louder.

Thank you, gentlepersons!

Kiki's DA MAAAN! Bump up his rep power, I just did. Well deserved!

[vintagekiki]

Hm, well there ya go. Now, how to make 8 ohms out of 3x16 and an 8... Maybe it originally had 8 ohmers in series parallel.

Underline I think so too

Kustom Semiconductor Information 2.pdf says substitute for RCA36892 is transistor 2N3055. That is a 15 amp 115 watt transistor, which says that the amplifier can output 50 - 60W with voltage +/- 40V at 8 ohm

As for speaker resistance, opinions are divided.
They vary between 4 and 8 Ohm. Given the supply voltage, it is difficult for one pair of RCA36892 to withstand operation at 4 Ohm.

Question:
Can you identify by the speaker sticker whether all 4 speakers have the same Kustom Part NO or different.
Can by visual inspection of 8 ohm speaker see if it has been repaired.

Old Kustom speaker

https://www.talkbass.com/attachments/serial-jpg.3493175/


Kustom speaker wiring

http://schems.com/bmampscom/kustom/Kustom%20Speaker%20Configurations.pdf
https://docs.google.com/file/d/0B1FxxpOmGO8vOU04cFdKeDZTa2c/

[xtian]

Sorry, I've zipped up the package, so I can't photo the speakers. They're silver, stamped steel, square magnets. One is def different, same package but different rubber stamped lettering. None of them showed ohm ratings.

Anyway, my client is a "I picked this up for $20 at a a yard sale" guy and doesn't want to spend much money--I've probably already exceeded his budget by identifying and fixing the speaker wiring!

[Leo_Gnardo]

Anyway, my client is a "I picked this up for $20 at a a yard sale" guy and doesn't want to spend much money--I've probably already exceeded his budget by identifying and fixing the speaker wiring!

Funny t'ing, some people, just because they pick up some prize at a fire sale price, don't want to spend more than a couple bucks fixing it up. Call it the "distorted perception of value." Meh, it's just a piece of junk, and I'm not going to make a fortune selling it no matter what happens. So fix it if you can. I'll buy you a six pack of Pabst Blue Ribbon. That's part of the reason I ask crustomers to set a "do not exceed" price, sometimes while we're on the phone having an initial discussion. They don't want to spend beyond 40-50 bucks, I do what I can to diplomatically avoid taking any further steps.

Those speakers are probably cheapie CTS or Eminence. Used to be able to buy them surplus from McGee Radio in Kansas City for a couple bucks apiece.

[xtian]

He's also one of those clients to live in the hills, so I can never reach him on his mobile. I'll hear from him when he comes off the mountain for supplies.