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View Full Version : Old Caps/Old Tubes-their respective noises

kbphx
02-27-2006, 03:20 PM
Is there an audible difference in tone/response for an amp with worn out tubes vs. caps in need of replacement? I'm currently helping a friend troubleshoot a silverface Deluxe Reverb that gets a bit 'farty' when you dig into the strings, and has dropped a bit in output. Shouldn't be a speaker prob, as it has a reasonably new RI Jensen.
Damon
02-28-2006, 12:38 AM
This is where it helps to have a couple known good backup tubes on hand. Pop 'em in and if the tone doesn't change, it's something else.

If it's weak filter caps, there's likely to be a noticeable background hum.
Blue Strat
02-28-2006, 07:07 AM
This is where it helps to have a couple known good backup tubes on hand. Pop 'em in and if the tone doesn't change, it's something else.

If it's weak filter caps, there's likely to be a noticeable background hum.

What Damon said. Trial and error is often the most effective troubleshooting technique.

If the electrolytic caps are over 15 years old, don't waste time wondering about them, replace them!
SarasotaSlim
02-28-2006, 07:18 AM
It helps to have another healthy Deluxe to compare things with. Like putting them back to back so you can use the speaker from the other amp to see if maybe the RI Jensen is farting when you use it with a known good working Deluxe and then using the other Deluxe with the speaker from the good amp etc.
donnyjaguar
02-28-2006, 10:27 AM
If the electrolytic caps are over 15 years old, don't waste time wondering about them, replace them!

I just have to disagree with this. I'm running a pair of Eico HF20 amplifiers on my hi-fi. Both are using the original capacitors (1957/1958) and they test perfectly fine. That's nearly 50 years old. In my experience the typical failure mode of these things is internal resistance which causes one of two things: (1) internal heating and rupture (2) main fuse to blow.

BTW, if you ever come across an Eico HF20, or two, I would grab it. In my opinion, and others, this is the best sounding low-powered tube hi-fi amplifier ever made. (although admittedly not the best looking!)

DJ