Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: phsyconoodler on February 22, 2011, 06:52:06 pm

Title: AC15 CC1 mods
Post by: phsyconoodler on February 22, 2011, 06:52:06 pm

Is anyone familiar with mods to improve the overdriven sound of the AC15 CC1 combo amp?

  I don't really want to jump in and start changing stuff without a possible plan.It sounds a bit ratty when driven hard.Not like an 18 watt Marshall at all.
  There are a bunch of Youtube clips but no real guide to what mods were actually done.Or at least no schematic guide anyway.

Anyone who has any info on where to get a hold of some of these possible mods?

cheers!

Title: Re: AC15 CC1 mods
Post by: VMS on February 23, 2011, 11:56:26 am

Here is a couple pages of mods:

http://meyer-repair.blogspot.com/2011/01/vox-ac15-custom-classic-upgrad.html (http://meyer-repair.blogspot.com/2011/01/vox-ac15-custom-classic-upgrad.html)

http://www.guitarpug.com/2008/06/vox-ac15cc-mod-guide/ (http://www.guitarpug.com/2008/06/vox-ac15cc-mod-guide/)

If you have different speakers, try those with the amp.

Other thing that is mentioned on those mod pages is the removal of the bright cap.

Title: Re: AC15 CC1 mods
Post by: phsyconoodler on February 23, 2011, 05:55:51 pm

Yeah those mods have been around and they do indeed help,but it's the 'soldano mod' that interests me and info on it is rather vague.

Thanks for the input!

Title: Re: AC15 CC1 mods
Post by: jojokeo on February 24, 2011, 12:55:46 am

p, did you see the schematic in one of those links? They used 100k load resistors w/ 1k5 w/ 22uFs on both V1 stages' cathodes (these could be tweaked especially the cap values). It appears that the output of V1a only goes through a 470pF cap (seems a bit small) to the TB Vol (w/ that bright cap) and the B+ filter cap has a .01uf smoothing cap accross it (seems a bit much or simply remove it?).
After going through the tone stack they are still reducing the signal by half (seems like a lot) before going into the pi section. That's going to reduce a lot drive going into there. Also check out C15/4n7 & R23/220k going accross the outputs of the pi - (what is that - a type of conjuctive filter?) before going into the power tubes. Lastly w/ a 120r Rk on the el84s, they're running those tubes pretty hot.

Title: Re: AC15 CC1 mods
Post by: jojokeo on March 02, 2011, 01:20:18 am

saw this tonight - maybe it'll help?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200582152215&ssPageName=ADME:B:SS:US:1123