Fender AA165 Bassman filter cap values?

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Yoda
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Fender AA165 Bassman filter cap values?

Post by Yoda »

Hello all,

I have a 1964 Bassman with the AA165 circuit, I'm replacing the filter caps but need to know what the correct filter cap values are, both capacitance AND voltage.

I believe the correct capacitance values are as follows, but I still need to know what the voltages are for each:
-1 x 8 uF
-3 x 22 uF
-2 x 100 uF

Thanks.
sluckey
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Re: Fender AA165 Bassman filter cap values?

Post by sluckey »

IAW the schematic...

-1 x 8 uF @ 450
-3 x 22 uF @525
-2 x 100 uF @ 350
Yoda
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Re: Fender AA165 Bassman filter cap values?

Post by Yoda »

Thank you, that's exactly what I was looking for.
Stevem
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Re: Fender AA165 Bassman filter cap values?

Post by Stevem »

Also what is the deal with the 220K resistors off of the output tube plates on this model Bassman as I do not think those where ever used again on a Fender?
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ToneMerc
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Re: Fender AA165 Bassman filter cap values?

Post by ToneMerc »

Stevem wrote:Also what is the deal with the 220K resistors off of the output tube plates on this model Bassman as I do not think those where ever used again on a Fender?
Wrong amp Stevem, you have the AA165 confused with the transitional AB165 which has the funky feedback loop in the PI.

TM
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ToneMerc
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Re: Fender AA165 Bassman filter cap values?

Post by ToneMerc »

sluckey wrote:IAW the schematic...

-1 x 8 uF @ 450
-3 x 22 uF @525
-2 x 100 uF @ 350
Actually it's:

-1 x 8 uF @ 450
-3 x 20 uF @525
-2 x 70 uF @ 350


When I recapped my AA165, I used F&T caps:

1 x 10 uF @ 500
-3 x 22 uF @500
-2 x 80 uF @ 450

TM
Yoda
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Re: Fender AA165 Bassman filter cap values?

Post by Yoda »

ToneMerc wrote:
sluckey wrote:IAW the schematic...

-1 x 8 uF @ 450
-3 x 22 uF @525
-2 x 100 uF @ 350
Actually it's:

-1 x 8 uF @ 450
-3 x 20 uF @525
-2 x 70 uF @ 350


When I recapped my AA165, I used F&T caps:

1 x 10 uF @ 500
-3 x 22 uF @500
-2 x 80 uF @ 450

TM
The AA165 schematic says 100uF/350v, not 80uF. How much difference would that make anyways?
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ToneMerc
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Re: Fender AA165 Bassman filter cap values?

Post by ToneMerc »

Yoda wrote:
ToneMerc wrote:
sluckey wrote:IAW the schematic...

-1 x 8 uF @ 450
-3 x 22 uF @525
-2 x 100 uF @ 350
Actually it's:

-1 x 8 uF @ 450
-3 x 20 uF @525
-2 x 70 uF @ 350


When I recapped my AA165, I used F&T caps:

1 x 10 uF @ 500
-3 x 22 uF @500
-2 x 80 uF @ 450

TM
The AA165 schematic says 100uF/350v, not 80uF. How much difference would that make anyways?



http://diagramasde.com/im2/90906_bassma ... hempdf.jpg


http://ampwares.com/schematics/bassman_aa165.pdf

My AA165 matched the above schematic and it was 70uf/350V caps that I removed. I replaced them with 80uf caps.

I would say it would depend on the tolerance on those caps and how you are running the amp when pushed hard. If they were replaced with higher value 100uF caps, one "might" be able to detect it in how the amp responds in feel. In theory, the blueprinted stock capacitance is only around 35uF on the plates, whereas a couple of 130uF caps would put you around 65uF.

TM
Yoda
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Re: Fender AA165 Bassman filter cap values?

Post by Yoda »

Should the resistors on the filter cap board be replaced as well? And if so, with NOS carbon comp resistors or with metal film or other?
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ToneMerc
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Re: Fender AA165 Bassman filter cap values?

Post by ToneMerc »

Yoda wrote:Should the resistors on the filter cap board be replaced as well? And if so, with NOS carbon comp resistors or with metal film or other?
If they are with tolerance, I would leave them. Did you replace the cathode and bias electrolytic caps as well?

TM
Yoda
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Re: Fender AA165 Bassman filter cap values?

Post by Yoda »

ToneMerc wrote:
Yoda wrote:Should the resistors on the filter cap board be replaced as well? And if so, with NOS carbon comp resistors or with metal film or other?
If they are with tolerance, I would leave them. Did you replace the cathode and bias electrolytic caps as well?

TM
Not yet, I will be ordering new Sprague Atoms to replace all electrolytics soon.
Yoda
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Re: Fender AA165 Bassman filter cap values?

Post by Yoda »

I just picked up some NOS GE-JAN 12AX7WAs and Amperex 5751s to put in this Bassman once it's recapped. Just curious how well the 5751s will work in V1, V2, and V3, since the dealer who sold them to me said they were the same thing as 12AX7s but looking online it seems they have a gain factor of 70 vs 100 for the AX7s. I do want to get as much drive as possible out of this Bassman so perhaps I made a mistake picking up the Amperex 5751s.

I'm also considering using the GEs in V1-V3 and putting one of the 5751s in V4 since the tube chart calls for a 12AT7 in the phase inverter position and the 5751 is roughly equivalent to an AT7.
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