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Kasino U100-P - Reverb [message #26173]

Tue, 30 May 2017 15:03

mindofone
Messages: 3
Registered: January 2016
Location: Texas

Junior Member

I've been digging into a Kasino Club U100 PA amp recently. The biggest issue (among several) is that the reverb doesn't work. Much to my surprise, once I opened it up - there is no reverb tank. I can't find any photographic evidence that any other Kasino U100 were supplied with tanks (or perhaps the amps are common sources for reverb tanks transplanted into other amps).

Anyone with an original, un-molested Kasino Club that has a reverb tank?

Also, after replacing the two large power filter caps, the amp continued to produce a fair amount of white noise. From others suggestions, I replaced the four PET8002 (equivalent) transistors on the PC803 Reverb board with 2n3904s. As expected, the noise floor dropped dramatically. Although not as much as I would ideally like.

Next I replaced the PET8002 (equivalent) transistors on the PC900 power board with 2n3904s and the two 2n4249 transistors with more modern 2n3906s. Even more reduction in hiss (I think - tough to make an unbiased, scientific measurement. After doing all that work, I'm hopeful there is now even less hiss Smile

Anyone looked at making some sort of discrete low-pass filter for these amps to eliminate the white noise that is apparently inherent in the design (or at least the original parts selection)?

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Re: Kasino U100-P - Reverb [message #26174 is a reply to message #26173]

Tue, 30 May 2017 17:50

chicagobill
Messages: 2006
Registered: April 2003

Senior Member

The reverb tank was mounted by two aluminum cross bars that connected to the top edges of the chassis, so that it hung down into the center part of the chassis. If you look at the top edge of the chassis you should find the 4 holes where the cross bars connect to it.

As for the noises, you're talking about a 40 year old amp. Modern transistors are much quieter now, so if you continue to replace the old ones, you can reduce the noise a bit more, but don't expect total silence from an older design.

As for a low-pass filter to remove the noise, it can be done, but it will alter the high frequency response of the amp's audio signal as well.

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Re: Kasino U100-P - Reverb [message #26175 is a reply to message #26174]

Wed, 31 May 2017 05:49

mindofone
Messages: 3
Registered: January 2016
Location: Texas

Junior Member

Thanks Bill. Good to know there was actually a reverb tank at one point! Agree about this being a 45 year old amp (!), and my expectations for dead silent operation isn't high, but then again, this isn't my first 45 year old solid state guitar amp, and this just seems to be more noisy than most.

I will try some different output filters on this guy. Interesting there is no output filter cap on the power supply.

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Re: Kasino U100-P - Reverb [message #26176 is a reply to message #26175]

Wed, 31 May 2017 08:25

stevem
Messages: 4773
Registered: June 2004
Location: NY

Senior Member

Many 45 year old SS amps like Sunn's used a high end and low end frequency limiting phase inverter transformer to drive the main output stage which Kustoms stopped using with the 1968 and up models.

Along with the new direct coupled amps came more hiss.

When all is well with these 68 and up Kustoms even with good as manufactured Transistors the noise floor should not be a issue unless your recording off of the RCA jack on the rear of the amp.

Fact is the more coupling caps you have in the signal chain, the more steps of phase change takes place and before you know it the nice natural tone of a guitar you may like is gone, or the amp is on the edge of oscillating and sounds Nasle as hell like the early Mesa amps!

Add more stuff / circuits to your amp if you like , but for me be it a SS or tube amp I will live with a less then great noise floor thank you!

[Updated on: Wed, 31 May 2017 08:27]

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