AC15HW1 Schematic

[jhawk]

Anyone have the AC15HW1 schematic/layout? From the pictures I've seen it doesn't seem to be an over-complicated build. Also wondering how difficult it would be to add an effects loop.

[Stevem]

It is not hard to add a loop, but it should be of the buffered type which calls for one more preamp tube.
Also note that time delay type effects like chours , reverb and echo do not sound that great when the distortion of a output stage is applied after the effect.
In light of this I myself have never found them to be of much use, but try a amp out first that has it already and let your ears be the guide!

[jhawk]

Truth be told I'll likely never run it loud enough for the output tubes to get really distorted. I'll be running it clean mostly, just as it's barely breaking up.
And silly question--if I got rid of the normal channel on this amp, would I free up an extra tube?

[jhawk]

Can anyone weigh in?

[Long Distance Call]

Based on what I read in the description of the AC15HW1, it might be something like this:

NORMAL Channel: Either a Vox AC30 Normal channel with added bright Switch. Or an AC15 or AC.34 - EF86 channel (with the bright switch) and a paralleled 12AX7 instead of the EF86.

TOP BOOST Channel: Vox AC30 Schematic

HOT/COOL Switch: Tone controls are lifted from ground a bit.

Phase Inverter: AC15 or AC30 Schematic

TONE CUT: AC15 or AC30 Schematic

MASTER VOLUME with BYPASS switch - 1Meg Pot with switch

Half power Switch - Pentode/Triode Switch

Tubes:
3 x ECC83/12AX7
2 x EL84
1 x EZ81 (rectifier)

[Masco]

Would like to give credit, but I have no idea of the drawing source...

[86'd]

Truth be told I'll likely never run it loud enough for the output tubes to get really distorted. I'll be running it clean mostly, just as it's barely breaking up.
And silly question--if I got rid of the normal channel on this amp, would I free up an extra tube?

Yes you would free up a tube, however, putting in a SS rectifier frees up the rectifier tube holder, which is a simpler mod, unless you are dedicated to having tube "sag" in your sound.

Also with a post PI MV mod the ability to drive the PI harder by the pre amp opens up a lot of sonic possibilities, as would power scaling or VVR and since these amps are cathode biased they adapt well to the latter.

The present AC15HW1 specification uses 2 similar triodes in the pre amp so adapting one circuit, say the TBM channel, with a switch-able bypass on the tone stack can mimic the "normal" channel leaving you scope to fit an internal FX loop buffer using the double triode formally serving the normal channel.

If clean is really your thing and you are building from scratch the EF86 tube really is worth the adventure to build in (IMHO). Why else did Vox go to so much trouble to making mod kits and adding "Top Boost" to later ACs to retrieve that elusive chime after dropping the EF86 from early production.

Hope that helps.

[10thTx]

Lots of info (schematic/layout) and help here:

http://el34world.com/Forum/index.php?topic=17184.0

http://home.comcast.net/~seluckey/amps/VAC15/ac15.htm

With respect, 10thtx

[andyfromdenver]

i'm surprised no one has linked the service manual.
All thine questions answered within.
http://www.blueguitar.org/new/schem/vox ... dwired.pdf

it's a cool circuit and I really like the amp.

I believe assembled in Asia, all metal film resistors (except where higher watt), except thoughtfully placed carbon comp plate resistors. I thought that was a nice touch.

[andyfromdenver]

*delete*

meant to add to previous post.

[sluckey]

The Vox AC15HTVH is not the same as the Vox AC15HW1.

I believe this is the correct schematic/layout...

[andyfromdenver]

Cool.
OP, for your consideration then.

[LuciMan]

Would like to give credit, but I have no idea of the drawing source...

I guess it's from here: nikplayer.com

I found it when I started digging into the VOX amps made from 2000 till today.
In the meantime I came to the conclusion to built up the real AC15 (& AC30) from the sixties.

Cheers

[TimmyP1955]

If you are speaking of the fawn colored Vietnam made amp, it's one of my favorites. The only thing I would change is to put shields on V2 and V3 (which I have done to ours - makes 'em more stable). And make sure to use the later layout, with the EL84's grid stoppers right on the sockets instead of on the board.

I prefer the Celstion Blue for clean and the Greenback for dirty.

[amptone]

AC15HW1.pdf

Official schematic