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Post subject: Fender silverface aa371 ciruit design question
Posted: Tue Mar 05, 2019 8:32 pm
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Joined: Tue Mar 05, 2019 5:55 pm
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I am new to this forum so please forgive me if this is not the correct place to ask this question.

I am in the process of repairing / recapping my 1971 fender Fender Bassman amp. At first I did not know the year or what schematics went with it so I did a lot of studying of the different models’ schematic prints.

In the process of comparing prints to my board I found the tube cathode bypass caps in the first two stages of my AA371 amp’s (bass input jacks) are 1uf 25v. And 5uf 25v. All the other bassman amps back to the aa165 apparently have 25uf 25v caps for all cathode caps.

Curious as to how this affected my amp’s audio after further research I found a video that explained how different value caps attenuated the input signal based on the frequency.

So here is my reason for the post. According to the info, the smaller the cap the more it blocks lower frequencies and allows higher frequencies. . The larger the cap the lower the frequency it passes.

So this noted, and if this is correct, I’m wondering why did Fender put the small caps on the bass inputs (low frequencies) and the large caps on the normal (guitar) inputs (high frequencies). To me this is backwards. I’m considerjng replacing them with 25uf caps.

Anyone on the forum have expertise with these amps and if so have any input on this subject? I know very little about tube amps and hope someone can enlighten me. In the mean time my Fender is down but not out and I’m in he process of bringing it back to life.


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Post subject: Re: Fender silverface aa371 ciruit design question
Posted: Tue Mar 19, 2019 1:06 am
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Joined: Fri Feb 05, 2010 4:31 am
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Location: Province de Québec, Canada
Welcome to the forum

No answer yet ?

Wrong sub forum, post on a vintage guitar amp , not in bass amp sub forum. Expert are there.

In the real life, Bassman is use as a guitar amp not a bass amp :lol:


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