| Live with a VERY slight sputtering/frying noise? [message #8258] |
Thu, 15 February 2007 03:49  |
Ubehebe
Messages: 2
Registered: February 2007
Location: Darwin, California
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Junior Member |
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My first post here, so who knows what it will look like.
A little background first. I purchased a cosmetically dead-mint SC 150 at a guitar show in Costa Mesa for $200 three weeks ago. One heck of a deal I think. Gray-sparkle nauga is perfect except for one tiny nick. Not discolored. Everything works: bright switch, verb, trem, pots all clean without static, original speakers. It looks like it was in a closet for 40 years. BUT it did have a TREMENDOUS hiss in the main channel. I bought it knowing that I would have to have this fixed.
After no little research, I decided on a VERY well-known amp tech here in SoCal. I chose him because everyone else “thought” they could fix it, but had no direct experience with vintage Kustom amps.
Sure enough, he found a bad transistor, the first one in the pre-amp. (Pardon me if I don’t get all the technical terms completely correct here; I know just enough about amp circuitry to get myself in trouble but not enough to attempt a repair like this). He said that it had been replaced one time before with a germanium transistor with the wrong bias and the wrong type.
He replaced the transistor with a silicon transistor of unknown type and VOILA -- hiss, she is gone. Completely utterly gone. Crank it up to 10 and it has less noise than my 4X10 Fender deville.
He also went through and cleaned all the pots and scoped everything else out: caps, etc. No other problems. Had him specifically check the caps and pilot light, as these have been mentioned here on this site as problem areas. He said they were fine. Total cost: $150.
Amp now kicks pass, sounds great, nice and loud, etc., etc. Sounds absolutely killer, in fact, exactly like I remember my old SC 150 sounding like, an SC 150 that is now no longer with us because of a long story. I am happier than a Klam, well almost.
But now when I turn on the amp, I get this VERY SLIGHT sputtering/popping/frying noise that is not varied by volume. It’s always there. It is not a hiss. That is gone. This slight frying/popping noise was probably there all along and covered by the hiss.
But when I say it is slight, I mean it is slight. You have to stick your ear right up to the speakers to hear it, and once you crank the volume up, say, to one or two, just the noise of the guitar is enough to cover it up without playing anything. It is buried and gone.
With a single coil PUP, the noise is buried at any volume level.
Even at very low volume level (one maybe) with a very quiet humbucker, you would be hard pressed to pick it out. As a comparison, the hum of my Fender 4X10 Deville at say 4 on up is WAY louder than this noise. If you were playing very very softly and were miking the Kustom, you might have to gate it.
How loud is it? Just enough to hear, but really not enough to interfere with even the quietest guitar passages. And even on the lowest volume setting possible, a guitar note easily covers it and makes it unnoticeable.
Here’s my question: Is this pretty much a normal noise for an old Kustom? Does anyone else have this noise? Should I live with it?
If memory serves me, I could almost swear that my original SC 150 had this noise when I bought it new. I have read the board here with interest, and I assume that this is maybe/probably caused by aged tantalums.
I have a feeling that the problem is so minor that the amp tech will gladly replace transistors or caps or whatever, but not for free. Because it sounds like the parts are cheap but it takes a considerable amount of time. I want the amp to be perfect, but I’m not sure that I want to pay $300-$400 in labor to get rid of this noise.
Or is the noise a harbinger of bad nasty things to come? Will it just get louder and louder so that I will need to get it fixed in the next year or so if I keep using the amp as much as I have been over the past coupla days since it has been fixed.
I LOVE THIS AMP!!
What say the rest of the Kustomaniac Kommunity?
Thanks for any help anyone can give.
Irv
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| Re: Live with a VERY slight sputtering/frying noise? [message #8265 is a reply to message #8259] |
Thu, 15 February 2007 11:54  |
chicagobill
Messages: 2023
Registered: April 2003
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Senior Member |
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Irv:
Welcome to the board!
I believe that the noise you are describing, is commonly known as "thermal noise". This can easily be missed in a shop environment with a lot of white background noise, but will stand out in a studio or quiet home or bedroom. It can be caused by any number of components, such as transistors, resistors or capacitors.
Unfortunately there is no simple test to find the problem part or parts. Heating or cooling sometimes will cause the bad part to show up, but this as you mentioned will take time to pursue. There are a few of us tech types here, and we have all been down this road before. And if you ask each of us, we will all have found different solutions to the problems.
This problem rarely if ever goes away on it's own, and often will get worse (louder). If you can live with it for now, play the amp and see what happens to the noise. Also see if there are any other things that pop up as you use the amp. If the amp hasn't been used a lot before you got it, there may be a few other age issues that may not turn up until the amp has been run for a while. If the amp gets bad enough, then take it in and have it serviced.
Again, Welcome to the board.
Bill
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| Re: Live with a VERY slight sputtering/frying noise? [message #8268 is a reply to message #8265] |
Thu, 15 February 2007 14:37 |
Ubehebe
Messages: 2
Registered: February 2007
Location: Darwin, California
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Junior Member |
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Thanks to everyone for their help so far. I have been playing the SC 150 again all morning. I just can't tear myself away from the amp. It sounds sooooooo good!
For the first time I plugged my effects in, and the tiny slight buzz from them is more than enough to completely cover up the sound of someone frying eggs three houses away, so there is no reason to repair it now 'cus I can't hear it! That’s how small the sound is. And I don't use many effects -- just a compressor, Rat, digital echo and very rarely a chorus.
I think I was just being too anal about the noise. It really is insignificant. I will use the amp for a while, as suggested, and see if it gets louder.
Yup, you're right about other issues surfacing. I have a small buzz in one of the speakers that I didn't notice before. It’s a speaker issue not electronic. I can make it go away by touching the speaker cone. Probably wasn't there before until someone (me) played the amp at volume for the first time in 30 years. Slight, but enough to warrant getting it fixed, so I pulled the speaker and will run it over to Orange County Speaker, which is fortunately only 15 minutes away from me and is a semi-famous speaker repair company. Here's the address if anyone needs speakers repaired: http://www.speakerrepair.com/. Can't recommend them too highly. Just the best.
The amp guy I used is Jerry Blaha at ampcrazy.com. His big store on Sunset near the Hollyweird Guitar Center has closed, but he does repairs out of his house now. He certainly knows what he is doing after so many years in the biz. And he says he has worked on many vintage Kustoms. He pointed out some differences between mine and other models. Like the pilot light on mine doesn’t have a resistor, I think he said.
Even though he has repaired amps for half of the rock industry, he doesn't have a 'tude like some other L.A. amp techs and luthiers who shall remain nameless. Doesn't matter if you're Jimmy Page or just another old guy with some crazy amp, he takes the time to explain everything he will do and does do. Very highly recommend him to those out there in the SoCal area who don't have the electronic expertise of others on the board.
As I said, until I called Jerry, the indifference I met when calling around to get the Kustom repaired was disappointing. “Why do you want to get THAT repaired? It’s solid state, you know.” But Jerry recognizes the special sound of Kustoms and was just great.
Thanks to everyone for their help. I’ll be lurking if not posting. Won’t have that much time to post because it takes away from me playing my new-old Kustom!
Irv
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