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previous: aron OK, Here's a ridiculous question - ... -- 4/24/2000 11:41 PM

Re: old Fender Amps - make noise?

4/25/2000 4:07 AM
Reverb	Re: old Fender Amps - make noise? Greetings Aron, With all respect to other opinions, I say that the sound you describe is most definitely not normal and can be eliminated. I used to work at an audio repair shop, where I worked on tube amps, solid-state amps, keyboards, and mixing boards. Of course, tube amps were my personal favorites, and I have built numerous amps of my own design since that time. You are correct that many old Fender amps do make this noise when "whacked" on the top of the cabinet, but they should not do so. I have found that the problem can usually be traced to these sources: 1. A bad component on the eyelet board (which can be hard to find) such as a coupling cap, filter cap, or plate resistor. 2. An intermittent tube which becomes microphonic when the cabinet is hit. 3. A bad ground somewhere (check pot grounds and solder connections on brass grounding plate). 4. A conductive eyelet board. Many Fender amps are over 30 years old, and over time they absorb moisture. Eyelet boards become slightly conductive (or very conductive in the worst cases), but they can often be "restored". In many cases, you can remove the bottom board (the one without the eyelets), and sand it with 80 grit sandpaper on both the top and bottom sides. This will break any conductive paths on its surface which may be leaking to the chassis or adjacent components. These conductive paths cause all kinds of odd noises, including the noises you describe. Sanding the eyelet board can cure many otherwise incurable noises. As part of my job as an audio repair guy, we gave each repaired tube amp a "cooking" period. This was a period of time (at least 4 hours) of having the amp turned up to full volume with nothing plugged in and listening for odd noises. If we heard anything, the amp was disassembled and the problem fixed BEFORE IT LEFT THE SHOP. Sure, it was a pain at times, but I never had a tube amp returned the entire year I worked there - and that included a lot of amps. The noises you describe could be caused by many other sources, such as an intermittent socket or cold solder joint, but I listed the four most common sources I have found. I hope this information proves useful for you, and best of luck with your amps now and in the future! Ampage Rules! Reverb

4/25/2000 4:07 AM

Reverb

Re: old Fender Amps - make noise?

Greetings Aron,

With all respect to other opinions, I say that the sound you describe is most definitely not normal and can be eliminated.

I used to work at an audio repair shop, where I worked on tube amps, solid-state amps, keyboards, and mixing boards. Of course, tube amps were my personal favorites, and I have built numerous amps of my own design since that time.

You are correct that many old Fender amps do make this noise when "whacked" on the top of the cabinet, but they should not do so. I have found that the problem can usually be traced to these sources:

1. A bad component on the eyelet board (which can be hard to find) such as a coupling cap, filter cap, or plate resistor.

2. An intermittent tube which becomes microphonic when the cabinet is hit.

3. A bad ground somewhere (check pot grounds and solder connections on brass grounding plate).

4. A conductive eyelet board. Many Fender amps are over 30 years old, and over time they absorb moisture. Eyelet boards become slightly conductive (or very conductive in the worst cases), but they can often be "restored". In many cases, you can remove the bottom board (the one without the eyelets), and sand it with 80 grit sandpaper on both the top and bottom sides. This will break any conductive paths on its surface which may be leaking to the chassis or adjacent components. These conductive paths cause all kinds of odd noises, including the noises you describe. Sanding the eyelet board can cure many otherwise incurable noises.

As part of my job as an audio repair guy, we gave each repaired tube amp a "cooking" period. This was a period of time (at least 4 hours) of having the amp turned up to full volume with nothing plugged in and listening for odd noises. If we heard anything, the amp was disassembled and the problem fixed BEFORE IT LEFT THE SHOP. Sure, it was a pain at times, but I never had a tube amp returned the entire year I worked there - and that included a lot of amps.

The noises you describe could be caused by many other sources, such as an intermittent socket or cold solder joint, but I listed the four most common sources I have found.

I hope this information proves useful for you, and best of luck with your amps now and in the future!

Ampage Rules!

Reverb

Replies:

aron Great reply!Thank y... -- 4/25/2000 4:57 AM