Blackface twin rectifier diodes

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Blackface twin rectifier diodes

Postby strangedays on Mon Oct 09, 2017 11:03 am

Hi,I was was wondering If there are any benefits in terms of sound improvement by changin the rectifier diodes in a blackface twin and in vintage amps in genearal.'i've rearely found posts about them so i presume they're not a part subjected to leake or age in particular like many other components,but who knows ,maybe their mantainence could be more important than i think.
Thank you.
Cheers.
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Re: Blackface twin rectifier diodes

Postby OldSchoolDave on Mon Oct 09, 2017 2:15 pm

In my experience, those diodes work until/unless they fail completely.

YMMV,
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Re: Blackface twin rectifier diodes

Postby stratele52 on Mon Oct 09, 2017 3:00 pm

OldSchoolDave wrote:In my experience, those diodes work until/unless they fail completely.

YMMV,
Dave



+1, no need to replace them.

News filter caps may improve tone.
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Re: Blackface twin rectifier diodes

Postby JJman on Mon Oct 09, 2017 11:45 pm

Selenium rectifiers are said to be risky but they are likely to be there only on the older stuff.
-If it says "Vintage" on it, it isn't.
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Re: Blackface twin rectifier diodes

Postby stratele52 on Tue Oct 10, 2017 8:16 am

JJman wrote:Selenium rectifiers are said to be risky but they are likely to be there only on the older stuff.



There are no selenium rectifier on this amp or any Fender amps.

Where do you see that ?
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Re: Blackface twin rectifier diodes

Postby eolon on Tue Oct 10, 2017 10:42 pm

stratele52 wrote:
JJman wrote:Selenium rectifiers are said to be risky but they are likely to be there only on the older stuff.



There are no selenium rectifier on this amp or any Fender amps.

Where do you see that ?


Fender used selenium rectifiers in many early amps, including the 1959 Bassman, Tremolux, and Vibrolux.
...just FYI:

Best Regards,

e
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Re: Blackface twin rectifier diodes

Postby pdf64 on Wed Oct 11, 2017 7:57 am

I don't think that selenium diodes were ever used in Fender HT supplies, rather just the bias supplies of fixed bias tweed amps.
High voltage, high current selenium diodes were big; and likely expensive. Lossy too, so little advantage over tube rectification.
Not sure about the brown era amps, ie whether some of those may have had selenium diodes in their fixed bias supplies.
But it seems a safe bet that BF era onwards, all solid state diodes were silicon.
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Re: Blackface twin rectifier diodes

Postby stratele52 on Wed Oct 11, 2017 10:15 am

eolon wrote:
stratele52 wrote:
JJman wrote:Selenium rectifiers are said to be risky but they are likely to be there only on the older stuff.



There are no selenium rectifier on this amp or any Fender amps.

Where do you see that ?


Fender used selenium rectifiers in many early amps, including the 1959 Bassman, Tremolux, and Vibrolux.
...just FYI:

Best Regards,

e


1959 Bassman use tube rectifier, no rectifier for bias, same for Tremolux
Vibrolux use tube rectifier, bias, I don't know
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Re: Blackface twin rectifier diodes

Postby stratele52 on Wed Oct 11, 2017 10:16 am

pdf64 wrote:
But it seems a safe bet that BF era onwards, all solid state diodes were silicon.



+1
BF , Silverface and all other more new amps
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Re: Blackface twin rectifier diodes

Postby pdf64 on Wed Oct 11, 2017 3:07 pm

stratele52 wrote:1959 Bassman use tube rectifier, no rectifier for bias, same for Tremolux
Vibrolux use tube rectifier, bias, I don't know

See p2 of http://schems.com/schematicheaven.net/manu/fender/bassman_5f6a_schem.pdf
There's fixed bias applied to the power tube control grids, and bias supply rectifier is labelled 'SEL. RECT.'
I'm sure that you know that and it's just a communication breakdown :lol:
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Re: Blackface twin rectifier diodes

Postby stratele52 on Wed Oct 11, 2017 3:42 pm

I did not look ( at layout ) to find wich bias diode is it because the post is about BF Twin Reverb
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Re: Blackface twin rectifier diodes

Postby Naked Clarke on Thu Oct 12, 2017 3:53 pm

stratele52 wrote:I did not look ( at layout ) to find wich bias diode is it because the post is about BF Twin Reverb


"There are no selenium rectifier on this amp or any Fender amps."

But you were so certain before!
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Re: Blackface twin rectifier diodes

Postby strangedays on Wed Oct 18, 2017 7:07 am

Thanks a lot everyone for reply,
Cheers.
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