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Hoffman Amps Forum image Author Topic: Vox AC15 layouts  (Read 99491 times)

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Offline bnwitt

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Vox AC15 layouts
« on: July 30, 2012, 06:04:35 pm »
Has anyone in here built a Vox AC15 with a layout they like and can share.  I have a set of AC15 trannies and I need to get the VOX sound for my recently "risen from the grave" recording studio.  I sold off all of my hand made amps a while back when I no longer had time to record and now that I have a little time I need to rebuild my amp line.  A 5E3, BFDR, Marshall 18 watt and JCM800 2204 are already underway in head versions.  I just need to get going on the AC15.
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Offline bakerlite

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Re: Vox AC15 layouts
« Reply #1 on: July 30, 2012, 07:32:13 pm »
I mailed you the original vox layout,
Unbuilt by me but vox made a few.
Hth
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Bakerlite

Offline bnwitt

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Re: Vox AC15 layouts
« Reply #2 on: July 30, 2012, 08:35:27 pm »
Thank you sir. :worthy1:  I'll turn it into a single chassis turret board layout and share with everyone when I'm done.

Barry
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Offline tubeswell

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Re: Vox AC15 layouts
« Reply #3 on: July 30, 2012, 09:24:56 pm »
Here's a(nother?) version (courtesy of Fabio Mayo):

(Image removed)

« Last Edit: August 03, 2012, 03:06:14 am by tubeswell »
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Offline bnwitt

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Re: Vox AC15 layouts
« Reply #4 on: July 31, 2012, 12:02:08 am »
TW,
Who is Fabio Mayo?
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Offline tubeswell

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Re: Vox AC15 layouts
« Reply #5 on: July 31, 2012, 12:19:02 am »
I'm under the strong impression Fabio could be the guy who produced that picture, or it could be his 'pen name'. (Its a nice tidy picture, and I didn't want to appear rude by not acknowledging the author). Is that any help/use? :-)
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Offline Tyrannocaster

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Re: Vox AC15 layouts
« Reply #6 on: July 31, 2012, 06:38:35 am »
That might have elements of an AC15 in it but it's no AC15. I'd like to find a decent layout of an AC15, too; Google is not my friend in this case.

Offline bnwitt

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Re: Vox AC15 layouts
« Reply #7 on: July 31, 2012, 02:07:14 pm »
TW,
I did a little googling and he is/was someone who was building a hybrid AC15/AC30 looking for feedback on his layout on Ampgarage and a couple other websites.  There is no evidence that layout is correct or that it was ever built but thanks for sharing it.  It does look nice. :smiley:

Tyrannocaster,
I am working on a single chassis layout with the actual AC15 1960 schematic and layout from the Stephen Grosvenor service guide book and will share the new layout in both PDF and Visio format when I am done.  It may take a little while as I just got an 80 megawatt PV system design dumped in my lap.

Barry
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Offline topbrent

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Re: Vox AC15 layouts
« Reply #8 on: July 31, 2012, 03:32:28 pm »
The Brown Note Foxy 18 has all the essential EF-86 VOX AC15 DNA plus a few nice extras. 
« Last Edit: July 31, 2012, 04:35:01 pm by topbrent »

Offline phsyconoodler

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Re: Vox AC15 layouts
« Reply #9 on: July 31, 2012, 03:43:10 pm »
The ceriatone 'creme brullee' is an AC15 with an EF86 preamp.Very nice tone.I'm building one now.
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Offline kagliostro

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Re: Vox AC15 layouts
« Reply #10 on: July 31, 2012, 04:31:14 pm »
Hi Bnwitt

here a very well documented build with all you can desire to know

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



instead here there is the Service Manual of the AC15HTVH1 Handwired (Layout inside)

http://www.el34world.com/charts/Schematics/files/Vox/Vox_AC15HTVH1_handwired.pdf

Ciao

K
« Last Edit: July 31, 2012, 05:07:50 pm by kagliostro »
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Offline Tyrannocaster

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Re: Vox AC15 layouts
« Reply #11 on: July 31, 2012, 05:34:30 pm »
I like that Foxy 18 layout but I really wish the Brown Note site posted schematics too and not just layouts. I like to see the electrical design of what I'm building. Apparently there are a lot of people out there who just build from layouts, which I can't even begin to understand on a design that you don't know. Who wants to have to draw his own schematic from a layout to see what tweaks they did?

I'm sort of looking around for what my next build will be and I always liked the AC15 & 30 but I don't have any EF86s and they seem to be kind of expensive as well as microphonic. There are other pentodes, though.  :icon_biggrin:

Offline phsyconoodler

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Re: Vox AC15 layouts
« Reply #12 on: July 31, 2012, 07:03:34 pm »
Layouts are easy for me.I just don't go beyond the tube's limits and it's rather easy to choose the right transformers and parts.Looking at a schematic and then doing a layout is time consuming and unnecessary if you have a good layout.
  I only go back to the schematic if a layout is obviously wrong.e.g. super champ layout.Wrong!
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Offline bnwitt

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Re: Vox AC15 layouts
« Reply #13 on: July 31, 2012, 08:27:56 pm »
The ceriatone 'creme brullee' is an AC15 with an EF86 preamp.Very nice tone.I'm building one now.

No offense but I wouldn't say the Creme Brulee is an AC15.  It lacks a lot of the AC15's controls and has no trem.  I am currently  focused on building an exact (circuit wise) AC15 model for use in my recording studio.  I will probably design this amp in a C channel Marshall 18 Watt style chassis layout and a 20" Marshall head style cabinet layout.  Then make up my mind if I want a combo or head.  I'm hoping to get my 5 holy grail amp tones in as little cubic feet as possible.  So I may have 5 heads and 3 cabinets.  A 1x12" Celestion Blue cab, a 1x12" Jensen Alnico cab and the 4X12 Celestion Vintage 30 Cab I already have.  I wish it was a 1X12" but oh well.  The other option is to have 5 small combos which will take up more room but make switching between amps easier.  Below is just the beginning of a layout.  I'll probably redo the 2 board sections completely into one logical board that lays out components to work with the tubes on the bottom of the C Channel chassis.

Kagliostro,
Thanks a bunch for those links.  Awesome.

Barry
« Last Edit: July 31, 2012, 08:48:36 pm by bnwitt »
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Offline kagliostro

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Re: Vox AC15 layouts
« Reply #14 on: August 01, 2012, 03:48:33 am »
WoW Barry

Really an impressive plant  :thumbsup: :thumbsup:

Many thanks for sharing

K
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Offline bnwitt

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Re: Vox AC15 layouts
« Reply #15 on: August 01, 2012, 10:17:04 am »
Kagliostro,
That PDF is just the working file with components loaded in to a working format.  I am sure everything will get moved around to properly line up with the chassis layout.  We're going from a dual chassis layout to a single chassis layout so changes are needed.  I'm going to be tightening up the circuit card component spacing as well.  This AC15 will be more like a Marshall layout on a turret board.  Hopefully it will be a lot easier to build and trouble shoot.  I will most likely redo the schematic as well to match the chassis tube order to the left to right schematic order.  It will take a little while to get it all done.

Barry
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Offline phsyconoodler

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Re: Vox AC15 layouts
« Reply #16 on: August 01, 2012, 10:56:34 am »
Hmmm...a one chassis AC15 is not an AC15 either.No offense.The tone is obviously what we want here.The way you lay it out to get that tone is whatever you want it to be.
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Offline kagliostro

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Re: Vox AC15 layouts
« Reply #17 on: August 01, 2012, 12:56:34 pm »
Barry if you want to redraw the layout I think you have your reasons

---

maintaining the single chassis choice

have you think to use the original layout with the tubes in two rows and arrange it in a single chassis ?

this way you semplify your life because there is no need to rearrange the component disposition

or there are particular reasons and you need to have all the tube in a single row ?

Oh, I see, probably you are building a combo, not a head amp, is this the reason ?

K
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Offline bnwitt

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Re: Vox AC15 layouts
« Reply #18 on: August 01, 2012, 01:05:42 pm »
Pyscho,
I can never figure you out.  Hoffman layouts of Fender amps are sacriligous but an AC15 with only half the circuits is OK. :l2:  I love ya man and I accept you as you are.  Regardless of the layout, my amp is going to have every single circuit component an original 1960 AC15 has but in a layout that won't catch on fire or be impossible to work on.  That's my goal.  I'm sure it will sound just like the original.  52 years have passed and I imagine Mr. Denny would do a few things differently today as well.

Kagliostro,
I will be doing a combo and an head layout.  On the head, I may run the tubes in two rows.  Whatever makes the connections the shortest possible routes and renders a great sounding clone that is not a bear to work on or that traps heat like the original.  I am sure I will change the layout numerous times during this project.  Hopefully when it is done it will be something that sounds great and can be easily built by others.  Building an AC15 or AC30 to completely original specs is very teadious and expensive.  I did an AC30 about 6 years ago and it was a bear.  I still have an extra AC30 chassis and plate if anyone wants one. :icon_biggrin:
« Last Edit: August 01, 2012, 01:10:41 pm by bnwitt »
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Offline kagliostro

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Re: Vox AC15 layouts
« Reply #19 on: August 01, 2012, 02:01:24 pm »
When I'll build it, you must see my version of an AC30 .................  :icon_biggrin:

K
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Offline bnwitt

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Re: Vox AC15 layouts
« Reply #20 on: August 01, 2012, 02:52:03 pm »
I look forward to that Kagliostro
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Offline phsyconoodler

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Re: Vox AC15 layouts
« Reply #21 on: August 01, 2012, 03:41:04 pm »
Hey Barry,
  I just don't LIKE Hoffman layouts.Too many wires off the chassis for me.The Fender layouts make sense because the wires and components are close to where they need to be.
  Not sacriledge at all,just ease of building and not trying to cram too much stuff in my old head.
If I were to build a period correct AC15 it would only correct the fact that they run too hot.The basic original layouts were fine.I too prefer amps that are slightly modernized with more accessible tubes and some improvements that make sense.
  To me Fender Hoffman layouts don't make sense.That's just me.They look 'right' in their original form.To me.
I don't have noise issues with my builds anymore after all the help I've gotten on this forum over the years.
  And it depends on customers.some pay the big money for amps that LOOK original,inside and out.
Me persoanlly,I jsut want tone.If it looks like a Fender and sounds like a Vox that may make some people do a double take but it's all about tone in the end.

b.t.w. an AC series amp chassis slides out very easily and all components are easily accessed.They just lack cooling.A fan maybe?Larger vents?All without disrupting the symetry of the Vox AC series amps.??
  I look at many Hoffman layouts in Deluxe Reverb builds and they look funny to me.They obviously work just fine.An AB763 layout as Fender did it is a work of art.Some things should not be changed IMHO.
  I bow to the work and advice you've done in your amps,Barry.I consider you a master of your art.
« Last Edit: August 01, 2012, 03:44:15 pm by phsyconoodler »
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Offline DummyLoad

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Re: Vox AC15 layouts
« Reply #22 on: August 01, 2012, 03:48:23 pm »
I really wish the Brown Note site posted schematics too and not just layouts.

err... roll yer own schema? ;-)

--DL

Offline Tyrannocaster

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Re: Vox AC15 layouts
« Reply #23 on: August 01, 2012, 04:23:53 pm »
Oh, I'm rolling on the floor at that one! ME? The guy who did his own layout on a Vibro Champ tremolo and managed to wire in two fatal errors that kept it from working? Crikey, I shudder to think what would happen if I tried to reverse engineer a whole amp. That's why I wish they had schems over there as well as their layouts, which look great. But I don't trust layouts when I don't know what the schematic is; it's too easy for somebody to slip in an "improvement" which may not be an improvement to my ears. It takes me a long time to build an amp from start to finish because I make so many mistakes and have to find them and fix them; I try to speed the process up whenever I can by working from proven ideas.

I'll be curious to see that final layout, bnwitt. Psychonoodler, as much as I think of Doug's achievements, I don't like to work from his layouts either; I find them very hard to read and work from. But obviously they work for him and a lot of other people. Yet I look at a Fender layout and it's like everything is in huge type - it's SO FRIGGIN' EASY to see what goes where and what it does while it goes there. I think those layouts and their accompanying schematics are Amp Heaven even if there are other amps that I like as much or sometimes even better. But I just figure that's because I'm not very good at this, and presumably I will get better as I continue.

Offline DummyLoad

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Re: Vox AC15 layouts
« Reply #24 on: August 01, 2012, 04:31:37 pm »
I shudder to think what would happen if I tried to reverse engineer a whole amp.

it's like learning to play guitar. if you don't practice, you'll never get anywhere.

at least try; give it a go and post up. we won't ridicule you....much. ;) srsly. give it a shot, you might just surprise yourself. remember, mistakes are usually  the best teacher - think of all the troubleshooting experience you'd have missed out on if you got right on the first go-around.

--DL

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Re: Vox AC15 layouts
« Reply #25 on: August 01, 2012, 04:48:15 pm »
I think DL is right on the $$.

You CAN do it!

But like anything else in this world that you want to learn and do well, it's gonna cost you time.

Just take it 1 step/tube at a time and then connect the dots/tubes.      :laugh:

                Brad       :icon_biggrin:

Offline kagliostro

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Re: Vox AC15 layouts
« Reply #26 on: August 01, 2012, 04:58:54 pm »
I think I'm one of the less experienced member of the forum, however, with the help of the friends of the forum I was able to reverse engineer a whole amp, and the schematic wasn't one of the simplest as it used varistor for vibrato

and if I was able to do it why you don't ?

so, take a pen and some piece of paper, look to the layout of one tube at a time, draw the schematic of what you see attached to the tube, when you finish to draw all the components attached to the tube revise and if all is correct go to the next tube and so on, till you finish all the schematic

this wasn't a stroll for me, but when I've finish the satisfaction was great

K
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Offline bnwitt

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Re: Vox AC15 layouts
« Reply #27 on: August 01, 2012, 09:31:52 pm »
Pyscho,
I do know that you don't like Hoffman layouts.  I have no problem with that as we all have things we love, like, can take a pass on and dislike.  More power to you my friend.  And you are my friend Keith.  We go pretty far back buddy.  Such is the diversity of the tube community and why when we all put our heads together we accomplish more than a single cranium can.  Never stop stepping up to the plate with your opinion.  I truly value it.  You are a confidant, not a buzzing fly or contrarian.  I know you speak from the heart.  It's too bad all of us on this forum don't all live on the same block.  Boy we could kick ass in the amp market!  My contribution would be somewhat small but I'd do the layouts and fill the gurus' beer mugs.

I happen to love Doug's layouts.  Granted his layout "drawings" are not newbie friendly (cause a guru like him doesn't need pictures like the rest of us) but the layouts themselves produce one hell of a nice amp.  This is why I re-did the Hoffman 5E3 layout so newbies could see a more photo like rendition of it and build it more easily.  And, an AB763 with a bias vary tremolo is freakin' awesome in my book.  I know you've also seen me post that Leo Fender is my idol.  I am always amazed at how wonderful his amps are when they are in full working order.  Dead quiet and great tone.   The man was amazing in my book.  Being on the left coast I get my hands in a lot of his work.  I wish Leo had been my dad instead of that drunken navy fellow mom married. :worthy1:

One thing I don't like about both Fender and Hoffman layouts (and many others) is underboard wires.  I've had so many problems with those little buggers that I now will not build an amp with anything under the board period.  Turret underboard wires are of course more problematic than eyelet underboard wires since you can't see the wire tip on a turret.  Flying wires don't bother me as long as they don't cause noise.  I mean if PTP amps with flying components can last 60 years then flying wires aren't a problem as far as I can tell.  My first Hoffman layout amps that went to customers were built back in 1998.  Not one has been returned for repair under the lifetime warranty.  That's 14 years and counting.

Adhering to any holy grail layout is not something I am a slave to though as I believe we should learn from the successes and mistakes of the past.  You'll never hear me say that an amp with a different layout but the same circuit is not an "X" amp until I play through it and can say it sounds nothing like the original.

When it is all said and done, if the tone is right I have no problem changing things since frankly I don't want to have to work really hard on an amp build, tweak or repair.  Sliding a chassis out to work on components or hop on one foot, rub my belly and pat my head while soldering is too much work.  I want to pull the back panel and have access to everything right there in front of me.  Even the Marshall head layout is a bit much for me since one has to pull the chassis from the cabinet.  Modern amp layouts.....Don't even get me started.  But if easy access ruins the tone, I'll throw away my naive ideas and go back to the original layout.  I've made changes to amps that stroked my logic bone that sounded like crap and returned to the original layout after the lesson.  So bottom line....I'm open with no restrictions whatsoever.

On a philosophical note, I once had a friend who was always telling how great his VW beetle was.  He told me he could pull the whole engine himself with out any help and completely rebuild it on his patio.  In fact, he'd done it three times.  My response to him was "Well, I prefer my Buick Centurion 455.  It has over 130k miles on it and I've never had to pull the engine.  You tinker on your patio, I'm going to the bars where the chicks are.

Love ya man.
« Last Edit: August 01, 2012, 09:36:19 pm by bnwitt »
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Offline Ed_Chambley

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Re: Vox AC15 layouts
« Reply #28 on: August 02, 2012, 05:38:14 pm »
Barry,
I don't give a crap about what layout and schem is used.  I just wanna see it.  I can tell you I really appreciate the work you and the others did on the Princeton Reverb. Man what an asset to me that was, just like I am sure this one will be as well.  Always wanted a real AC15 and I am extremely interested in this progress.  I have played a few clones and the new handwired one and they all missed that wonderful ringing bell like tone of a 63 I stupidly sold years ago because of the inherent problems I had with it.  You could say I am Voxless, but I've got a feeling I won't be for long.

Thanks for the work you do and share freely.

Offline tubeswell

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Re: Vox AC15 layouts
« Reply #29 on: August 03, 2012, 03:09:31 am »
TW,
I did a little googling and he is/was someone who was building a hybrid AC15/AC30 looking for feedback on his layout on Ampgarage and a couple other websites.  There is no evidence that layout is correct or that it was ever built but thanks for sharing it.  It does look nice. :smiley:

TFT, To be honest I never took a close look at it, but on closer inspection the PI layout looks wrong, and maybe other stuff is too, (so the image has now been consigned to the garbage heap).

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Offline tubenit

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Re: Vox AC15 layouts
« Reply #30 on: August 03, 2012, 05:28:52 am »
Here is some stuff that might help as you guys put all of this together?   This is stuff from our schematic files

With respect, Tubenit
« Last Edit: January 13, 2013, 01:39:14 pm by tubenit »

Offline tubenit

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Re: Vox AC15 layouts
« Reply #31 on: August 03, 2012, 06:02:14 am »
You can try Trinityamps for some ideas also to draw from:

http://www.trinityamps.com/phpbb/index.php

They have a layout that might be a useful guide?  It's an image that comes up when googling Vox AC15 layout

With respect, Tubenit

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Re: Vox AC15 layouts
« Reply #32 on: August 03, 2012, 12:25:22 pm »
Thanks Tubenit,  I'll peruse those layouts.  Ed, I appreciate the support.  This will take a while since I am working on a really large Photovoltaic farm but I will share things as I make progress.  I know sharing things as I progress will allow the real braniacs in here to catch my mistakes.
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Re: Vox AC15 layouts
« Reply #33 on: August 04, 2012, 07:31:17 pm »
Ok, I'm making a little progress.  I'm working on the first layout with the "C" channel standard Marshall 18" watt chassis which is 20" x 6" x 2.5"  This chassis is available from a couple of vendors.  I've decided to keep the layout close to the original with the preamp tubes in the same order and in the middle of the chassis back with the two circuit cards above and below just like the original.  This will keep things close to the original layout.  I'm even using the same component labels as the schematic.  This is the 1960 version.  Everything is on turret boards.  I am finding some discrepancies in the schematic/layout from my older version of the AC30 service guide but I have a new one on the way and hopefully that will help.  Nothing major, just incorrect socket pin numbering so far.  Hopefully by late tomorrow I'll have the basic layout done.
« Last Edit: August 04, 2012, 07:35:33 pm by bnwitt »
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Re: Vox AC15 layouts
« Reply #34 on: August 04, 2012, 08:07:17 pm »
Impressive!  Thanks so much for sharing your hard work.  Looks like it's coming together great.

With respect, Tubenit

Offline bnwitt

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Re: Vox AC15 layouts
« Reply #35 on: August 05, 2012, 02:07:24 pm »
Ok, I'm a little farther along with this layout
« Last Edit: August 05, 2012, 05:17:16 pm by bnwitt »
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Offline tubenit

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Re: Vox AC15 layouts
« Reply #36 on: August 05, 2012, 04:24:33 pm »

That is coming along excellent!  Looks fantastic!   THANK you so much for sharing it!

With respect, Tubenit

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Re: Vox AC15 layouts
« Reply #37 on: August 05, 2012, 06:10:37 pm »
here a very well documented build with all you can desire to know

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

I have a dumb question for you all. I have always admired the ACxx tone but have never actually played one. The tone I like is the wonderful clean tone as represented beautifully in the MP3 files on the site linked above. My question is ... "which channel of the AC15 produces this clean sound?". Is it the channel with the EF84 or the all-12AX7? Is the Hoffman version able to produce this tone (with verb added of course)? Thanks much (back to lurking).

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Re: Vox AC15 layouts
« Reply #38 on: August 05, 2012, 06:45:30 pm »
Moonbird,
Check out this demo on the AC15 Heritage Hand wired.  It will give you and idea of the sounds of the two channels:

Vox AC15 Heritage Handwired

I would estimate most of the clean sounds on the AC15 will come from the Vib/Trem channel.

Barry
« Last Edit: August 05, 2012, 09:03:11 pm by bnwitt »
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Re: Vox AC15 layouts
« Reply #39 on: August 05, 2012, 07:07:16 pm »
So at this point I'm looking for some feedback.  Should I install the triode/pentode switch on the EF86 and the EL34s like in the Heritage model?
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Re: Vox AC15 layouts
« Reply #40 on: August 05, 2012, 07:36:51 pm »
Barry -

Thanks much - very interesting demo. Trouble is I guess I DO "need" both channels afterall :laugh:. FWIW think BOTH triode/pentode switches are way cool!!

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Re: Vox AC15 layouts
« Reply #41 on: August 05, 2012, 07:48:53 pm »
Notice the Treble and Bass controls of the Vox Top Boost circuit were added in place of the original AC15's Vib/Trem circuitry in that Heritage edition.

I think I might find having the EF86 and Top Boost channels and no Trem as the most useful combination.

As for the triode/pentode on the EF86, I'm not sure it would be that useful in a recording situation, where you could simply turn down. The mu g1-g2 of the EF86 is ~38, which makes this tube similar to having a single-12AY7 when switched to triode mode. But if you have an arsenal of other amps, is this really different enough to be needed? The pentode-mode EF86 is certainly "different enough" but I don't know if triode-mode would be the same.

The bass-shift seems useful, as does multiple settings for the Brilliance control, which is the EF86's only tone-shaping tool aside from the master Top Cut control.

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Re: Vox AC15 layouts
« Reply #42 on: August 05, 2012, 07:55:36 pm »
... The tone I like is the wonderful clean tone as represented beautifully in the MP3 files on the site linked above. My question is ... "which channel of the AC15 produces this clean sound?". ...

I can't really tell. Maybe the 12AX7 vibrato channel, or maybe the EF86 on a low volume setting.

The songs are swimming in echo and reverb making it hard to know exactly what the amp sounded like. Also, he's playing very clean (presumably Hank Marvin & the Shadows style), where the magic of an AC15 or AC30, in my opinion, is when it starts to get a little fuzzy.

I say this because I've owned a lot of vintage amps; when you play very clean on all of them, much of the tone difference seems to be the speakers and tone control flexibility. I mean a blackface Princeton Reverb, tweed Deluxe (with non-used channel volume adjusted to provide mid-scooped tone), early 70's 50w Marshall and a Hiwatt DR504 all sound very much alike when you only turn up to 2 or 3. It's the upper volume ranges where they're not clean that the personality comes out.
« Last Edit: August 05, 2012, 09:08:15 pm by HotBluePlates »

Offline sluckey

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Re: Vox AC15 layouts
« Reply #43 on: August 05, 2012, 08:26:33 pm »
Barry, can we see the schematic you're working from?
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline bnwitt

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Re: Vox AC15 layouts
« Reply #44 on: August 05, 2012, 08:37:08 pm »
Steve,
I'm actually working from the 1960 AC15 Schematic in Stephen Grosvenor's book "A Service Engineer's Guide to the Vox AC30 Valve Amplifier".   I'm also using the layout from that book.  I have an old version of it but I have his new one on the way for error checking.  The official schematic for that amp is here:

http://www.el34world.com/charts/Schematics/files/Vox/ac151960.pdf

Barry
« Last Edit: August 08, 2012, 10:40:57 am by bnwitt »
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Re: Vox AC15 layouts
« Reply #45 on: August 05, 2012, 08:43:42 pm »
HPB,
Thanks for the feedback.  You're right on the triode/pentode switch usefullness in my situation but I'm thinking about others who might want to build this amp too.  I'll probably never use those switches in my studio. I do want the Vox Tremolo though.  I will probably replace the speed switch with a Pot to get better control of the speed.  I am already showing an accessible "Depth" control for this amp instead of the one on the circuit card.  I may make it switcheable so you can have the Vox set speeds and a variable control.

My amp line is going to be an AC15, Tweed Deluxe, BFDR, Marsahall 18 Watt, Marshall 2204, November amp and a Tweed Champ.  I might just add Tubenit's D'Mars amp for the OD tone but I really think I need to get it down to an 18 or 15 watt version.  50 watt amps are just too danged loud.
Guides on your quest for tone.
 Oh yeah, and I'm usually just kidding so don't take me too seriously.

Offline bnwitt

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Re: Vox AC15 layouts
« Reply #46 on: August 05, 2012, 09:02:28 pm »
Just a little more info on what I am trying to do here.  I'm trying to get and orginal AC15 with the EF86 and Vib/Trem channel built into an inexpensive "C" channel aluminum chassis and installed into a standard Marshall 1x12" cabinet which are available everywhere.  The replica Vox cabs are rediculously expensieve ($449) and I don't really care if it is period correct.  I figure I'll order the cabinet finished with black basket weave, change the grill cloth to Vox style and make the valance a little wider.

I figure with the original circuit (with maybe a couple of tone and trem speed/depth versatility mods) in the Marshall cabinet containing a Celestion Blue speaker I'm going to get pretty darn close to the signature tone.  Also I hope to leave a design PDF file for anyone else who wants to build the "tone" and who doesn't care about the look so much.
« Last Edit: August 05, 2012, 09:06:01 pm by bnwitt »
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Re: Vox AC15 layouts
« Reply #47 on: August 05, 2012, 09:13:22 pm »
Here is a clip of a JMI AC15 amp on clean tone which is close to what I am building:

JMI AC15 VOX AC 15 -- sample clip

Guides on your quest for tone.
 Oh yeah, and I'm usually just kidding so don't take me too seriously.

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Re: Vox AC15 layouts
« Reply #48 on: August 05, 2012, 09:16:23 pm »
Oh yeah and a clip with the trem effect:

'63 VOX AC15's vib/trem channel - with KAY K161 reissue

Guides on your quest for tone.
 Oh yeah, and I'm usually just kidding so don't take me too seriously.

Offline HotBluePlates

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Re: Vox AC15 layouts
« Reply #49 on: August 05, 2012, 09:22:16 pm »
Opinion time:

The EF86 and Top Boost channels are iconic tones. You really want to have the Vox trem channel too. Is there room enough in the chassis for all three?

I'm not familiar with the 18w chassis, so I don't know what the dimensions are like. But if you think you might be able to cram everything in it, I might have a suggestion.

Ever seen the inside of a McIntosh MC-30? The circuit card has caps on one side, resistors on the other. The card uses L-shaped brackets to mount it with one edge closest to the chassis. Wires make the connection to the sockets.

Now that card is wider (for a deeper/taller chassis than what I think you're proposing) that you'll likely go, but it might be a helpful way to fit more circuitry inside the chassis. If you run out of control space, you could use the upper and lower faces of the chassis and mount the tubes horizontally. I did exactly that on my last build.

I don't think you want to do this, but I also use turret strips akin to terminal strips (but with turret lugs) running along both sides of the row of tube sockets, ran wires to the sockets and mounted components spanning the two rows (over top of the sockets).

Not trying to muddy the waters, but I'd hate you to think, "man I wish I added that Top Boost" later.

 


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