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Post subject: Silverface Champ overhaul
Posted: Tue Oct 15, 2013 2:15 am
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I have a 79 SF Champ, and even after the speaker upgrade, it sounds a bit lacking in tone to me. There seems to be a lot of Mid & Trebble in the tone, but almost zero Bass (even with Bass set to 10). There is very very little change in tone when turning Bass from min to max. (dead caps?)
Could anyone recommend any upgrades? I'm thinking to the filter circuits (caps etc).
Looking for ideas, what's worked for you etc.

The circuit is all original by the way.


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Post subject: Re: Silverface Champ overhaul
Posted: Tue Oct 15, 2013 3:51 am
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Mike73JM, I recommend:

1.) New 20/20/20 at 475-525VDC cap can, if the can is older than 15-20 years old.

2.) New bypass caps on the 12AX7 cathode.

3.) How old are the 5Y3GT and the 6V6GT tubes? May need replacement. As well as the 12AX7.


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Post subject: Re: Silverface Champ overhaul
Posted: Tue Oct 15, 2013 4:41 am
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Cheers.

1. Where can I get a replacement cap can in the UK?

2. Cool, will look into that

3. The 5y3: unknown. It came with a defective one, which I replaced with an RCA one

The 6V6GT: I changed the original fender tube for an RCA 6V6GTA, but also have
a Brimar 6V6GT on hand


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Post subject: Re: Silverface Champ overhaul
Posted: Tue Oct 15, 2013 5:28 am
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For cap can, look for anyone carrying the CE made brand:

http://www.tubesandmore.com/products/C-EC20X3-525


Or the JJ brand (don't use the 40mfd section -- just the 20/20/20):

http://www.tubesandmore.com/products/C-EC40-20X3-500


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Post subject: Re: Silverface Champ overhaul
Posted: Tue Oct 15, 2013 5:28 am
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Or the TAD brand:

http://www.tubeampdoctor.com/en/shop_Ca ... mount_1335


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Post subject: Re: Silverface Champ overhaul
Posted: Tue Oct 15, 2013 8:47 am
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BMW2002Ti wrote:
Mike73JM, I recommend:

1.) New 20/20/20 at 475-525VDC cap can, if the can is older than 15-20 years old.

2.) New bypass caps on the 12AX7 cathode.

3.) How old are the 5Y3GT and the 6V6GT tubes? May need replacement. As well as the 12AX7.


Solid advice.

As well, don't forget to check the power-rail resistors for drift or signs of thermal abuse.

Arjay

_________________
"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Silverface Champ overhaul
Posted: Wed Oct 16, 2013 12:30 am
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Cool, thanks all for the replies & advice.
New EC cap can ordered & on its way from the US.
Trying to keep the amp as original as possible, so may just try the cap can replacement first & see how that goes.


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