Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Planobilly on December 19, 2016, 10:52:39 am

Title: Best replacement for a 70uf filter cap Twin Reverb AC568
Post by: Planobilly on December 19, 2016, 10:52:39 am

Hi guys,

The 70uf cap is not made any longer as far as I can tell. JJ makes a 80uf and so does F&T.

Any suggestions?

Also has anyone converted  the AC568 back to a Blackface?

Thanks,

Billy

Title: Re: Best replacement for a 70uf filter cap Twin Reverb AC568
Post by: sluckey on December 19, 2016, 11:37:24 am

Hoffman sells a couple brands of 100µF/350V caps that are ideal for that.

Title: Re: Best replacement for a 70uf filter cap Twin Reverb AC568
Post by: Ed_Chambley on December 19, 2016, 03:39:45 pm

With SS rectifier of the Twin, Sluckey's suggestion will work just fine.  Yes, I have "Blackfaced" this circuit.  Really, CBS had not changed a whole lot.  If I am not mistaken, you will still have the 85 watt so when done it should be just like a pre 1968.


A lot of these had the EV speakers installed and will hold a clean quite well.

Title: Re: Best replacement for a 70uf filter cap Twin Reverb AC568
Post by: Planobilly on December 19, 2016, 07:39:53 pm

Thanks Guys,

It looks like I am the first person to work on this amp. Everything is original. There is very little in this amp that changed from the AB763. I had a couple of 80 uf caps in stock so I only need the 20 uf ones. I have some 100 uf also.