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1969 kustom k100c8 [message #26231]

Mon, 24 July 2017 18:11

Wil Muny
Messages: 1
Registered: July 2017

Junior Member

I have just acquired a 1967-1971 kustom k100c-8 4x10 combo amp. What is the wattage and ohm rating for the amp itself, and the speakers? Why do the speakers pop loudly when powered on, and off? Should the speakers be wired series/parallel, or parallel series? When I turn my power switch on to the left, the amp hums loudly, but when I switch it on to the right, it does not hum, Why is That? Is it supposed to take the trem/vib about 5-10 minutes to warm up before it starts working? Is there any way to figure out exactly which year model it is?
I realize that I have alot of questions, and I sure,do appreciate any advice that I can get. I've wanted one of these amps since I was a kid, and now that I finally have one, I want to restore it completely to its former glory. Thank you.

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Re: 1969 kustom k100c8 [message #26232 is a reply to message #26231]

Tue, 25 July 2017 06:06

stevem
Messages: 4774
Registered: June 2004
Location: NY

Senior Member

All 100 series amps need a 8 ohm load to output there 50 watts of clean power.

The speakers are a 8 ohm if original and should be wired series / parallel for the best tone, although if you do not want the amp to sound as brite you could wire then parallel/ series.

The loud pop at turn on and turn off plus your Trem/ Vib not working right way are part of a common age issue with all amps of electrolytic type capacitors going bad and needing to be replaced.

The lack of Hum/ buzz with the on/ off switch in one position is as it should be, but can be a shock hazard.

You can date your amp by the white stamping on the mounting lip, or the magnet of the speakers,they are CTS brand speakers I would guess so you should find a series of numbers that start of with 137, this is the CTS manufacture code.
The next four numbers will be for eaxample 3669 , which would be the 36th week of 1969, making the whole amp itself date to 1969.

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Re: 1969 kustom k100c8 [message #26233 is a reply to message #26231]

Tue, 25 July 2017 11:43

chicagobill
Messages: 2006
Registered: April 2003

Senior Member

Welcome to the place.

The speaker code that Steve mentioned is called the EIA date code. The correct format is YYWW. The first two digits are the last two digits of the year and the second two digits are the week of that year. So Steve's example would be 6936.

The power switch is designed to function as a "line reverse" switch as well as the power switch. It connects a capacitor from the metal chassis of the amp to one side of the power line. When the capacitor is connected to the neutral side of the line, hum is reduced and there is less of a chance for being shocked when touching your guitar strings while standing barefooted on a concrete floor or while touching the ground of another amp or microphone.

If you unplug the cord from the wall and turn the plug 180 degrees and plug it back into the wall socket, when you turn on the amp the hum will be less when the power switch is turned on in the opposite from before. So don't always expect the hum to be less only in one switch position. It will depend upon how the cord is plugged into the wall socket.

Modern specifications use a grounded three wire ac cord which eliminates the need for the line reverse function of the switch.

Again, welcome to the place.

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