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FDP Forum / Fender Amps: Vintage (before 1985) / ‘72 Bronco - Misbuilt?

Leftee
Contributing Member
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VA

Oct 10th, 2018 09:54 AM   Edit   Profile  

I just did a cap job on this recent acquisition. The V1b cathode bypass cap was 2uF, not 10. It looks original. It’s a white Mallory like the rest.

Anyone else seen this?

Silverface

Lawndale CA

No Chops but Great Tone ©
Oct 14th, 2018 05:28 PM   Edit   Profile  

Yep, and it's correct. The CBS export versions used a 2/25 in this position. They were attempting to reduce gain and distortion caused by excessive bass. Raising the value will increase gin slightly along with bass response.

You can experiment with anything from no cap to roughly 33uf - no cap might somewhat sterilize the sound - higher values can cause speaker flabbiness - so just watch the volume.

When I found modded Champs with extra holes already drilled I've installed a toggle switch that flips between and 8uf and 25uf for slightly different voicing. (I don't drill vintage amps).

If you read rob Robinette's website pages he does a good job of showing the signal path and effect of various parts on the sound.

Leftee
Contributing Member
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VA

Oct 15th, 2018 05:27 AM   Edit   Profile  

Thanks!

So I’m guessing this amp went to Canada. It is 120v. I went to a 10/25 when I did the cap job on the amp.

I wonder if this particular situation is also why the original speaker is not toast.

Pinetree
Moderator Emeritus
(with many stars)

NW Pennsylvania

Oct 20th, 2018 10:17 PM   Edit   Profile  

One of my (mid-70's) Champs is an Export version (you can tell be the serial number) and has this.




Leftee
Contributing Member
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VA

Oct 21st, 2018 07:10 AM   Edit   Profile  

I might order a 2/25 with my next AES order and put this one back to it’s original config. I did save all those Mallorys, as well.

Years ago when I worked on amps I never changed these. Just the cap can.

FDP Forum / Fender Amps: Vintage (before 1985) / ‘72 Bronco - Misbuilt?




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