Has Anybody converted an VOX AC15 Combo to Point to Point?

[Platefire]

A friend recently got one of these and was asking me about converting it to Point to Point with a board. He lives about 30 miles away so I haven't seen the amp yet. Has anyone here maybe have done this before that could tell me the ins and outs of such a conversion. Thanks, Platefire 

[shooter]

Can't help there but my 1st 5 builds were all point to point n the one thing that stands out more than anything, layout is way harder than turrets or PCB!!, it was about impossible for me not to wind up with a techs nightmare of wires.  anyway fwiw.

[kagliostro]

Ciao Platefire

M.Huss refers to this construction way as a PtP



I dont think to that as a real PtP, to me a real PtP is this way of construction



and despite this metod can have some advantages, I think that disavantages are more and I don't like it very much

stated that my preferred constructions arrangements are Turret Board and Eyelet, a metod that I consider

good (but difficult to be implemented) is the metod that our friend Darryl masterfully uses



To which method do you refer ?

Franco

[shooter]

Wow, that last one is a work of art! very nicely done!
 

[Platefire]

Thanks Kagliostro for the pixs. I assume those are AC15's but not for sure since I haven't seen one before. Looked like about the right tube configuration. The first two pictures look like vintage and the last one looks like a modern PCB conversion to P to P. I guess a more appropriate question is in the current production AC15, is there room to build the circuit on a turret board or the best way--old style point to point as shown in all three pixs?  Platefire

[sluckey]

I've never done the specific conversion you are speaking about but I'm familiar with the various old AC15 circuits. There are several versions. And I've built a couple AC15s. I think you need to get the amp in hand, pull the chassis, take some pics, and post them here. Don't commit to the conversion until you see what you are up against ***AND*** have decided which version to shoot for. This project could be straight forward or it could be a shoehorn challenge. Meanwhile, find out exactly which model your friend has and do some google research.

Oh, BTW. That first pic is an old Sunn amplifier.

[kagliostro]

No those aren't AC15 only examples of kind of arrangement of PtP circuits

here is a complete documentation about cloning an AC15 (exactly as original) but it isn't a PtP montage

http://members.ziggo.nl/jheijer/AC15.htm

Vox used a kind of board often used in GB




May be this tread is of your interest

http://charliehall.proboards.com/thread/593/again-ac15-replica-build

at this days you can find that boards only with 18 positions x 2 instead the near 40 position x 2 used on the original



K

[Platefire]

Thanks! I've been doing some AC15 research also and came across some of the same info. I have text-ed my friend to get a model number and some pictures. No use going any further until we know exactly what we are dealing with. Thanks, Platefire

[kagliostro]

I think near all the old AC15 are made in the same manner, the new AC15 (on PCB) may be different also in circuitry

Doug has a large database of Vox schematics and you can control there for circuitry differences on the new models

K

[Platefire]

I haven't got pictures yet but did learn it is a model C1. I couldn't find any Vox produced schematics identified as "C1" even on Doug's database but I found one that is a reverse engineered schematics.

[kagliostro]

Here some photo of the inside (chassis is different from old models)

http://www.harmonycentral.com/forum/forum/guitar/acapella-28/1428176-

Looking to the images seems that in a conversion it will be a good thing to follow something like the two board sistem

recently used by Doug  on his Blues Junior conversion

http://i45.tinypic.com/2utqbkh.jpg

http://i346.photobucket.com/albums/p433/oddjobpeters/P1090512.jpg~original

http://www.planetz.com/wp-content/uploads/2011/03/2010-12-15-AC15C1-004.jpg

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In my archive I've this complete version of the AC15C1 schematic from the same author

http://www.mediafire.com/view/qkg2679xlt7fidq/AC15C1_Schematics_(Rev_2).pdf

Franco

[Platefire]

The pixs of this amp have been sent but I'm having trouble with my e-mail account and can't open the stupid e-mail 
Really I think it will be the same PBC layout as whats already been posted.


I talked to him on the phone and he said he's not interested in reverb or tremolo, just wants the basic amp. That may would simplify it somewhat. I did notice the op-amps in the preamp section and wouldn't know how to handle that! Maybe doing away with the verb and trem would do away with the SS stuff. Platefire

[PRR]

voxac15c13.gif.jpg

That's a very sweet snippet, suitable for most any bias-trem amp where you do not want to add a tube to make the shake.

"Vcc" should be a small positive voltage; however I think you could just replace Q2 with a switch.

[Platefire]

OK, here are the actual pictures. He is not interested in reverb and tremolo. So with using the existing tubes can that be brought forth? or possibly returning to vintage original AC15 tube configuration without using all 12AX7?

[kagliostro]

or possibly returning to vintage original AC15 tube configuration without using all 12AX7?

I think that as to semplify your life, and if there is no interest on reverb and tremolo, you can simply build

Doug's version of the AC30 only with two final tubes instead of four and an adequate cathode resistor and add the crossline MV (or a LarMarr if you prefer)

http://el34world.com/Hoffman/files/Hoffman_AC30.pdf

Or, arrange a bypass for V2a+V2b so from the Top Boost channel you can obtain also the Normal channel and use V1a as oscillator for tremolo, reuse the input Jack of the normal channel for the switch between normal and TopBoost

Only you must find a new occupation for the reverb pot on the faceplate (may be a RAW control on the TS  or a Presence ?)

Franco

[Platefire]

Kaglilstro, sounds like a good plan following Doug's AC30 but using an AC15 power section. Just looking at the pictures, it appears that tube sockets are PBC mounted. I haven't done this type of conversion before but it appears to me new solder-able tube sockets would have to be installed? Also the issue of the power supply without a rectifier tube and the diodes supply that will be removed with the main PBC boards.  Really hard to tell much without the amp in hand. Platefire

[kagliostro]

Just looking at the pictures, it appears that tube sockets are PBC mounted. I haven't done this type of conversion before but it appears to me new solder-able tube sockets would have to be installed?

ask and you shall receive 

Doug has just invented a solution for this problem 

He invented the solution few days ago for a Blues Junior conversion, but why don't apply it also in a Vox AC15c1 conversion ? 

http://el34world.com/Forum/index.php?topic=17845.0









Note the position of the PS, I think the AC15C1 is large enoug to do that

the board that Doug sell for the AC30 is 3.125 x 10 inches long, add the space for the PS and I think there is further free space on the chassis

I think also that you can ask Doug about the small socket Board for the AC15C1 and a modified Turret board with PS incorporated for the whole circuit
(may be this will be a thing that Doug can resell to other interested on this kind of conversion)


Oh, one other thing, if you extract the two PCB from the amp intact, your friend can resell it and pay a part of the conversion with the proceeds


---


Elsewere you could clone the AC15HW/AC30HW layout (if you search is possible to find documentation, but not as good as Doug's documentation)

http://mastershine.de/VOX/?page_id=809 <-- (on the link click on the small image and you see the whole version)




Franco


p.s.: I really love the job Doug is doing with the Blues Junior conversion 

[Platefire]

After looking at the Blues Jr. operation by Doug, that's definitely the pattern that would have to take place. Even Doug said it was super labor intensive. Just seeing all the work required to bring the AC15 around is daunting!
   My friend is a great amp tech and regarding trouble shooting and mods has way more experience than me. He just has never built something from scratch or done a major work over like this. I have had more experience in builds than him. He has talked about taking it on himself but I'm not sure he comprehends the major task this would be.
So I'm trying to decide rather to take this on or just be support for him on his first major project  I would think this is not a good first time project even with experience. Platefire