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FDP Forum / Fender Amps: Vintage (before 1985) / TR Blackface: Sound problems. Can you help me?



Feb 4th, 2016 04:54 AM   Edit   Profile  

Hello everybody

I own a '67 TR blackface . The amp sounds awful from 1 week ago..
I checked valves and they are OK.

It could be fault of capacitors? . The original Mallorys were replaced 13 years ago...

Please, listen the sound clip and let me know your opinions.

In case of fault capacitors, which are the best to replace in my '67 TR? I have not idea, Sprague,Mallory,FT,...I have understood that capacitors have influence in the sound .. I'd like get a very similar sound to original.

Finally, what site do you recommend to buy them?

I'm living in Europe.

Sorry for my bad english!

Greetings from Spain

Sound clip: http://www.ivoox.com/10312641

(This message was last edited by josepc at 04:38 AM, Feb 22nd, 2016)

Contributing Member

American Patriot

I'm on guard these days.
Feb 4th, 2016 08:42 AM   Edit   Profile  

Not sure what the problem might be but the F&T caps are being used a lot these days.
Could just be a bad tube. I'd substitute them one at a time in case one is bad. Check all of your connections including speakers and guitar cord.



Feb 4th, 2016 09:21 AM   Edit   Profile  

Thank you BbendFender;

I've checked tubes and they are OK.
Connections seem be OK.

Are you listened the sound clip?

It seems to me caps filter problem..


Steve Dallman
Contributing Member

Merrill, Wisconsin

Age is just a number...mine is big
Feb 4th, 2016 11:24 AM   Edit   Profile  

That sounds like at least one bad filter cap. That dissonant, atonal tone is because the hum which is not being filtered, is mixing with the signal. The result is the sum and difference of the two signals...hum and audio.

This is what a ring modulator does.

A cap has likely opened up. If it had shorted, it would have shut the amp down.

(This message was last edited by Steve Dallman at 01:31 PM, Feb 4th, 2016)



Feb 4th, 2016 12:17 PM   Edit   Profile  

Steve, I'll need replace one damaged cap only, or all at once?

The complete cap set was installed 13 years ago..

Contributing Member

So. Cal. USA

Feb 4th, 2016 12:27 PM   Edit   Profile  

I would replace all of the filter caps as well as the bias cap. 10-15 years is a normal life.

I've been using the F & T caps lately. I'm not sure who would have them in Europe. If you want to have them shipped use the link from FDP sponsor Antique Electronics Supply at the top of the page.



Feb 7th, 2016 04:48 PM   Edit   Profile  

I agree with Hammond101 and would replace all filter caps, bypass caps and bias cap with F&T. The F&T's are made in Germany, so they should be easy to get in Europe.

Contributing Member

So. Cal. USA

Feb 8th, 2016 10:30 AM   Edit   Profile  

Finding the Bypass caps in 25/25 or 25/50 will be difficult in F&T brand. I use Sprauge for these.



Feb 10th, 2016 11:11 AM   Edit   Profile  

I use Spectrol/Vishay 22uf@35v for the bypass caps. Dependable and not too expensive.


(This message was last edited by slider313 at 12:55 PM, Feb 11th, 2016)


Redondo Beach CA

No Chops but Great Tone
Feb 11th, 2016 07:52 PM   Edit   Profile  

Bypass caps rarely fail. I rarely need to replace them at 30-40 years. Filter caps are another story, and that sounds like the issue here. I would replace the bias cap as well, but not the bypass caps unless they test bad.

I'm curious though - how did you know the tubes were OK? A tube swap its the only reliable method unless you have access to a very exotic tester,

I no longer use ANY Sprague caps, after cutting a 40uf cap open and finding a small Chinese cap inside the big blue can. I use F&T, NTE, K&D - all hold up fine and are a fraction the price of Atoms.

Are you replacing the caps yourself? If so, do you know all the safety rules to follow? If not, PLEASE take it to a tech! Also, after a cap job voltages may change, so you'll want to at minimum check the bias setting and rebus if necessary. You'll be dealing with high voltages during the whole process so please, be sure you know exactly what you are doing.



Feb 22nd, 2016 02:37 AM   Edit   Profile  

Silverface thank you for your advice...

I took amp to a tech, and he said me no replace caps. Only one cap had put down, and so amp sounds bad.. He said no need replace caps now,I can wait 5 more years. He affix put down cap.

Another question: He told me power transformer needs replace (??). He recommended replace cause noises and poor sound.

I am afraid of replacing transformer, the amp loose original Fender Blackface sound and spirit, but he said me amp will sound alive,intense,...

What is your opinion about this?

Maybe it would be better set out this question in a new post?


Way Out East

Feb 22nd, 2016 03:25 AM   Edit   Profile  

You'll need to ask your tech if there is something actually wrong with the transformer, or if it's just his personal opinion that the original one is not very good...

If there is something wrong with it, that it's actually "broken" somehow, I think you should consider getting a replacement.
You probably want the amp to sound as good as it can. I don't think much of the blackface spirit lies in the power transformer...
As long as the replacement is made for a Twin and supplies the right voltages, you'll be fine.

(This message was last edited by Lynxtrap at 05:27 AM, Feb 22nd, 2016)



Feb 22nd, 2016 05:14 AM   Edit   Profile  

Tech says power transfer is not broken. But amp has noises and buzz and the sound is not alive. No filter caps problem. As well as reverb has background noise also.


Way Out East

Feb 22nd, 2016 06:15 AM   Edit   Profile  

If there is nothing wrong with the transformer, I find it hard to believe it would cause noise and buzz.
Aged resistors and capacitors are more likely to cause those kinds of issues.



Feb 23rd, 2016 08:27 AM   Edit   Profile  

Well tech said power transformer is old, and it vibrates moving the chasis and buzzing


Way Out East

Feb 23rd, 2016 01:45 PM   Edit   Profile  

That might cause noise, but I don't know about "poor sound"...

You could try putting rubber bushings or grommets around the screws, between the transformer and the chassis. Also make sure all the screws are tightened really well, including those going through the transformer.

Also ask yourself how much the noise bothers you, after the faulty cap is replaced of course. If the amp sounds fine to you, it IS fine.

FDP Forum / Fender Amps: Vintage (before 1985) / TR Blackface: Sound problems. Can you help me?

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