Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: J Rindt on March 11, 2012, 03:23:38 pm

Title: AC15 Build
Post by: J Rindt on March 11, 2012, 03:23:38 pm

Have any of you guys built an AC15 of some type or another.?
I have a Chassis and cabinet from an old Crate V18 that I thought I could use for an AC15 donor.
Do not think I have ever seen a layout for this amp, and was wondering what you guys did.
Not sure if anybody makes a turret board for this amp, or if it is more a matter of using turret strips to make the circuit.
Any ideas/help would be appreciated.
Thank You

Title: Re: AC15 Build
Post by: archaos on March 11, 2012, 03:51:10 pm

I've never built an AC15. Yet I've already built 2 x AC30s from scratch : one using an Hoffman board, the other à la JMI (turret strips).

If I were you, I'd build a turret board for that amp, it's far better : you can design the circuit like do Kevin O'Connor or Merlin Blencowe (with galactic grounds), & it's neat-looking (attached the guts of my 5E3).
Turret strips look vintage but are messy IMO.

Title: Re: AC15 Build
Post by: birt on March 11, 2012, 03:58:55 pm

this is an AC15 with a 12AX7 preamp and an EF86 preamp (EF86 values but i used a 6AU6)

(http://a4.sphotos.ak.fbcdn.net/hphotos-ak-snc7/5163_93040214077_745844077_1833831_800115_n.jpg)

Title: Re: AC15 Build
Post by: tubenit on March 11, 2012, 06:02:48 pm

http://www.el34world.com/Forum/index.php?topic=6642.0 (http://www.el34world.com/Forum/index.php?topic=6642.0)


AND  .........take a look at these.  You may find this very useful to draw up a schematic and layout.

http://www.el34world.com/Forum/index.php?topic=5048.0 (http://www.el34world.com/Forum/index.php?topic=5048.0)

http://www.el34world.com/Forum/index.php?topic=1890.0 (http://www.el34world.com/Forum/index.php?topic=1890.0)

http://www.el34world.com/Forum/index.php?topic=4996.0 (http://www.el34world.com/Forum/index.php?topic=4996.0)

http://www.el34world.com/Forum/index.php?topic=575.0 (http://www.el34world.com/Forum/index.php?topic=575.0)

With respect, Tubenit

Title: Re: AC15 Build
Post by: tubenit on March 11, 2012, 06:15:55 pm

http://media.photobucket.com/image/AC-15%20layout/fabiomayo/VoxAC15-30Layout2007-08-17b.gif (http://media.photobucket.com/image/AC-15%20layout/fabiomayo/VoxAC15-30Layout2007-08-17b.gif)

from a google search

Tubenit

Title: Re: AC15 Build
Post by: tubenit on March 11, 2012, 06:38:45 pm

This looks like a decent layout.

Tubenit

Title: Re: AC15 Build
Post by: J Rindt on March 11, 2012, 09:28:32 pm

Thanks for the ideas/photos so far.
I can probably use some type of "generic" turret board. Something like you would see in a Hiwatt.....kind of long and narrow.
Thanks Again

Title: Re: AC15 Build
Post by: tubenit on March 13, 2012, 05:44:03 am

I drew this up thinking it could be an interesting idea.  You'd have an AC15 tone using a 5879 (less microphonic) instead of a EF86.
AND you could switch in a HoSo56 tone.   It also has switchable active FX loop.

Could be a cool amp?  Not sure about the coupling caps after the LTPI. I put down .047 but would probably build it myself using .033.

With respect, Tubenit

Title: Re: AC15 Build
Post by: moonbird on April 16, 2012, 12:43:18 am

Tubenit -

A very interesting spin on the AC15. What PT voltage does this design want? I am looking for AC-30 kind of chime and articulation for country tunes. Probably looking for a poor man's top-boost circuit I suppose. Will this design deliver that you think or could something be added?? If I wanted reverb, I presume I could add your "single 12AX7" verb design from the 56T at the effects loop. Thanks very much for posting this!!

Title: Re: AC15 Build
Post by: tubenit on April 16, 2012, 05:17:33 am

If I were building it, I'd want a PT that was 275-0-275 and had 150ma.  You might be able to use a 300-0-300 with a 5Y3GT?
Just check the tube data for an EL84


With respect, Tubenit

Title: Re: AC15 Build
Post by: J Rindt on April 16, 2012, 11:36:53 am

Tubenit.....
In your previous 2 links, are they of the same schem.? I ask, because I cannot open the second schem that uses the Microsoft Schedule Plus program.
Thank You

Title: Re: AC15 Build
Post by: balcorn80 on April 16, 2012, 01:22:52 pm

Quote from: J Rindt on April 16, 2012, 11:36:53 am

Tubenit.....
In your previous 2 links, are they of the same schem.? I ask, because I cannot open the second schem that uses the Microsoft Schedule Plus program.
Thank You

Download Jschem or PCBExpress to open the .sch files. I just learned about these programs last week, and have already started putting my hand-drawn schematics into electronic form(even I have a hard time reading my chicken scratch) plus it makes it easy to make any changes between your paper/electronic schematic and what actually worked for you. Just a suggestion.

http://dhost.info/jschem/ (http://dhost.info/jschem/)


http://www.expresspcb.com/expresspcbhtm/Download.htm (http://www.expresspcb.com/expresspcbhtm/Download.htm)

Title: Re: AC15 Build
Post by: J Rindt on April 16, 2012, 02:10:14 pm

10-4
Thank You