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Something's cooking in my Kustom Kitchen... [message #25469]

Wed, 24 August 2016 18:50

RevDoc
Messages: 7
Registered: August 2016
Location: Eastern Tennessee

Junior Member

(chant away: one of us...one of us...)

I found a sweet deal on my first Kustom, a k150-1 with a 2/12 cab, in remarkably good shape considering the thing is almost as old as me.
Found the source for replacing the bulbs right here on this board along with everything else I wanted to know about it. So thank you, thank you!

I'm naturally curious about its manufacture, can anyone date it for me?
K-150-1 serial 97888
Cab- S- 50966

Amp was clean as a whistle inside with only a single human hair and a tiny spiderweb near the input jacks, and as I'd read about the interesting things one sometimes finds in these cabs, I just had to open it up too.
Sure enough, a pink plastic Easter egg protecting a half-gnawed milk chocolate football awaited someone willing to take out all those damn screws.

I've been having a great time disturbing my neighbors with low frequencies for the past month, and made things more disturbing when I added a SWR 15 to fill out the bottom. (heh...)

I've been thinking about going bi-amp by picking up another head and wiring my P-bass for stereo. Could be fun.

Then last night, bad things began to happen, got a lot of distortion in 3 inputs, with a noticeable loss in volume. The head seemed a bit warmer than usual, and that awful electrical odor was accompanied by the lights starting to dim with each note played. I shut it down, and powered it up this morning to find it working just fine.

Any clue as to what's cooking in there?
Found a local amp tech, but at 75. per hour bench time, it could cost more than I paid for it. although the cab alone was worth what paid for the set.

So I'm not ready to give up on the little guy just yet, but I have no idea what kind of issue I'm dealing with.
Knowledgable opinions would be appreciated.

So, greetings Kustomarians! I'm pleased to be among you.
(now somebody show me the secret handshake...)

RD

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Re: Something's cooking in my Kustom Kitchen... [message #25470 is a reply to message #25469]

Wed, 24 August 2016 19:25

pleat
Messages: 1459
Registered: June 2004
Location: Belding, Mi

Senior Member

If the speakers are original to the amp head then it would be matched to the amp. If you wired a second cab and used both the 2x12 and SWR cab, you were running the amp below the 8 ohms which will make the amp run hot and you may have created your problem. Did you try the amp after a cool down period with just the Kustom cab?

I'll the tech guys chime in on what they think could cause that electrical smell.

Best of luck,

pleat

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Re: Something's cooking in my Kustom Kitchen... [message #25471 is a reply to message #25470]

Wed, 24 August 2016 19:58

RevDoc
Messages: 7
Registered: August 2016
Location: Eastern Tennessee

Junior Member

Thanks pleat,
I ran the extra cab for just a few minutes and later encountered the 'hotness' while using headphones.
I had notice a faint odor some time before plugging in the SWR, but it seemed like normal "old amp working smell"

Additionally,the "to tape recorder" output was not working when I got it and I did notice quite a wide bit of variety in the sound of all the inputs in both channels, I assume that various components ageing in different ways might be the reason for that, but perhaps it was a precursor to a part failure?

I'm wondering what the most common failures are with these amps.

RD

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Re: Something's cooking in my Kustom Kitchen... [message #25472 is a reply to message #25471]

Wed, 24 August 2016 20:03

RevDoc
Messages: 7
Registered: August 2016
Location: Eastern Tennessee

Junior Member

Currently unable to give it a good workout with the 1/12 at volume, but will as soon as the house is empty.

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Re: Something's cooking in my Kustom Kitchen... [message #25474 is a reply to message #25469]

Thu, 25 August 2016 06:16

stevem
Messages: 4778
Registered: June 2004
Location: NY

Senior Member

Using the amp with the added speaker dropped the load on the amp to under 8 ohms , and this assumes that the 2-12" cabinet is still wired for a 8 ohm load !
When you run any solid state amp on a load under its design minimum you cut the amps output power in half and you also make the amp run twice as hot for any given volume level you play it at!!!!!

I am concerned that you said it smelled hot!
These amps have a Thermal circuit breaker in the output section that shuts the amp down once the output transistors get above 182 degrees , and it sounds like you where right on the edge of that when you turned the amp off!!

The inputs on these metal face ( 1971 to 74 ) amps do not have a different tone, the set up a different gain level / volume out of the preamp section on each channel of the amp .
These amps use plug in connectors from board to board and the likely cause of the amps record out Jack not working is the tarnish that forms on these connectors from age .
Many times all that's needed is to unplug them and carefully plug them back in a few times .
Wiping some light oil with a Q tip on the Male pin in each connector will keep tarnish from coming back for a long time!
If you must run that added speaker cabinet than get that recording output Jack working, feed that signal into a poer amp and then into that other cabinet !

If you play the amp up loud thru a 8 ohm cabinet for 45 minute and its solid , then concider yourself lucky that you did no damage with running the two cabinets.
Just note that it's always fully safe to run a solid state amp on a higher impeadance load , you will have the same 50% loss in output watts but the amp will run cooler, not hotter!

[Updated on: Thu, 25 August 2016 06:18]

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Re: Something's cooking in my Kustom Kitchen... [message #25478 is a reply to message #25474]

Thu, 25 August 2016 23:16

RevDoc
Messages: 7
Registered: August 2016
Location: Eastern Tennessee

Junior Member

Thanks stevem,

Sound advice.
You would appear to be correct that I managed to heat it up just below the fail threshold
on the fuse. Cranked it up this morning and I swear it sounds even better than before.
Ran it for about an hour at 50-75% power (any louder and I worry about opening up a sinkhole or something...)
and I'm pleased to report the little fella seems to be in fine shape, at least for this adventure in dumbassery.

Still hoping someone can date the manufacture for me (please)

Thanks!
RD

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