Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Archives of favorite topics => Topic started by: bnwitt on July 30, 2012, 06:04:35 pm
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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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I mailed you the original vox layout,
Unbuilt by me but vox made a few.
Hth
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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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Here's a(nother?) version (courtesy of Fabio Mayo):
(Image removed)
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TW,
Who is Fabio Mayo?
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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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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.
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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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The Brown Note Foxy 18 has all the essential EF-86 VOX AC15 DNA plus a few nice extras.
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The ceriatone 'creme brullee' is an AC15 with an EF86 preamp.Very nice tone.I'm building one now.
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Hi Bnwitt
here a very well documented build with all you can desire to know
http://members.ziggo.nl/jheijer/AC15.htm (http://members.ziggo.nl/jheijer/AC15.htm)
(http://members.ziggo.nl/jheijer/images/AMP-Klaar-4.gif)
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 (http://www.el34world.com/charts/Schematics/files/Vox/Vox_AC15HTVH1_handwired.pdf)
Ciao
K
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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:
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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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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
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WoW Barry
Really an impressive plant :thumbsup: :thumbsup:
Many thanks for sharing
K
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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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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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Barry if you want to redraw the layout I think you have your reasons
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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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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:
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When I'll build it, you must see my version of an AC30 ................. :icon_biggrin:
K
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I look forward to that Kagliostro
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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.
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I really wish the Brown Note site posted schematics too and not just layouts.
err... roll yer own schema? ;-)
--DL
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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.
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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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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:
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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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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.
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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.
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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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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
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You can try Trinityamps for some ideas also to draw from:
http://www.trinityamps.com/phpbb/index.php (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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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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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.
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Impressive! Thanks so much for sharing your hard work. Looks like it's coming together great.
With respect, Tubenit
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Ok, I'm a little farther along with this layout
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That is coming along excellent! Looks fantastic! THANK you so much for sharing it!
With respect, Tubenit
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here a very well documented build with all you can desire to know
http://members.ziggo.nl/jheijer/AC15.htm (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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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 (http://www.youtube.com/watch?v=vCj6Vvjk7fM#)
I would estimate most of the clean sounds on the AC15 will come from the Vib/Trem channel.
Barry
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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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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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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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... 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.
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Barry, can we see the schematic you're working from?
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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 (http://www.el34world.com/charts/Schematics/files/Vox/ac151960.pdf)
Barry
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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.
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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.
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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 (http://www.youtube.com/watch?v=ZLKFy9MzGb0#ws)
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Oh yeah and a clip with the trem effect:
'63 VOX AC15's vib/trem channel - with KAY K161 reissue (http://www.youtube.com/watch?v=igZFOcbNtmU#)
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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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HBP,
I'm reaching the limit of what I can squeeze into this chassis. It is 20" W x 6.5" H x 2.5"D. As far as the Top Boost is concerned, there may be a way to add it as originally it was an external add on kit before it was integrated into the AC30/6. It basically needs an additional set of input jacks bass and treble controls and an extra ECC83 tube. I do have room for those components. What is tight is adding the additional support components. I could probably add the inputs and controls and put everthing else in a box on the interior cabinet wall or do it just like it was done to the AC30/6. See link below:
http://www.marshallforum.com/419422-post355.html (http://www.marshallforum.com/419422-post355.html)
Barry
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Thanks for the heads up. Evidently my virus protection is protecting me well. I replaced the link in my post with the one from Doug's library. On the virus front, I was searching for a website called guitaramplifierpcbs.com the other day and the actual website wasn't coming up in Google. So I typed it in the url bar and bam! Instant malware download which bypassed my virus protection and put my machine into a restart. It took me 3 hours to get rid of it. I've never seen anything that powerful before.
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On the virus front, I was searching for a website called guitaramplifierpcbs.com the other day and the actual website wasn't coming up in Google. So I typed it in the url bar and bam! Instant malware download which bypassed my virus protection and put my machine into a restart. It took me 3 hours to get rid of it. I've never seen anything that powerful before.
:w2:
Glad you where able to fix it. I'm not sure I'd be able to figure out how to get ride of it.
I've always been dumbfounded at how people with the brains/gifting to do so much with a computer would use it just to hurt someone else, really as many as they can. :BangHead: :cussing:
Brad :w2:
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After doing some research on the different Vox AC series amplifiers I found the following:
1. The AC 15 was used by numerous British players with great satisfaction. It was a great sounding amp but as venues got bigger more power was needed. Two more power tubes were added hence the AC30/4
2. The EF86 versions of the AC15 and AC30/4 were altered to an ECC83 after "Bass" players complained about microphonics due to their bass frequencies. This was not a guitarist complaint.
3. Along with this preamp tube change a third channel (Brilliance channel) was added since the dual triode allowed it hence the AC30/6.
4. After the preamp tube change, players noticed a change in tone. There wasn't as much gain and clear tone in the new AC30/6
5. To satisfy the complaints on the AC30/6, the treble models were introduced (which had a treble boosting RC at each volume controll)
6. Shortly after that the Top Boost add on kit came out. Eventually the Top boost circuit was made stock in AC30s.
6. Most players of the AC30 amps consider the original circuit with the EF86 to be the best of the series in tone.
After reading all of this, I have decided not to add the top boost components or the 3rd channel to this amp layout It seems to me that the original AC15 and AC30/4 with EF86 were the British gutarists' favorite of all models issued. Of course it was common for guitarists and bass players to share an amp in those days and if the bass players had just had their own amp I wonder if good enough might have been left alone. And of course if Public Address systems had existed back then I doubt there would have been a call for the AC30 at all. So bottom line, I will be building the 1960 EF86 AC15 amp as it was originally issued and the layouts will be in both a combo and head style chassis.
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Why not design the layout so that you can easily incorporate a top boost later if you change your mind? (I'm always fiddling with my builds down the line). Besides, in a gig/jam situation you'll probably be thankful for some mid-high freq boost - either that or some kind of rangemaster cloney thing in front. JM2CW
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Tubeswell,
Putting in a Top Boost circuit later would be no problem, just like the original. But, I'm after the orginal EF86 AC15-AC30/4 tone which is reported to have had excellent highs, great overall tone and great gain. The Top Boost circuit came along after Denny changed the original circuit (which was considered awesome by guitarists) to try and bring the AC30/6 back toward the original tone. Unfortunately not many of the original AC15-AC30/4 amps are still around since fewer were made than subsequent models. There is a fellow out there who converts AC30/6 amps to the original AC30/4 circuit:
http://members.optusnet.com.au/~glen325/AC30convert.html (http://members.optusnet.com.au/~glen325/AC30convert.html)
Evidently there is a market for that which is surprising. To think that someone would do that to a valuable amplifier worth lots of moolah to achieve the tone of the very first original circuit tells me that the tone is worth it. The oldest AC30 I have every played was a 90s reissue and I wasn't impressed. I really want to hear for myself what the original circuit sounds like. The way this is going I am going to be pretty darn close to the original layout and exactly on the circuit so I think it will be very close. I've even got a UK made "Blue" speaker to put in the cabinet.
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Very interesting info -- sounds GREAT to me!!
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There is a fellow out there who converts AC30/6 amps to the original AC30/4 circuit:
http://members.optusnet.com.au/~glen325/AC30convert.html (http://members.optusnet.com.au/~glen325/AC30convert.html)
Evidently there is a market for that which is surprising.
Yikes!
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Yikes!
Yeah! That's what I thought.
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http://livinginthepast-audioweb.co.uk/index.php?p=xfrmrclassic (http://livinginthepast-audioweb.co.uk/index.php?p=xfrmrclassic)
UK made Vintage style Vox transformers various models available.
Not sure if this link has been posted before but might be useful for European builders
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a bit pricey. $45 for a $19 choke is a pretty heavy mark up but if it's all that's available in one's area. I guess the OT and PT are fairly reasonable if one is after the vintage look. Thanks Carausius
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As always shop around, I doubt if a choke makes a large difference compared to an output or power transformer :icon_biggrin: Even if it's authentic :laugh: Non EU buyers would save 20% VAT on those prices.
EDIT More interesting stuff http://charliehall.proboards.com/index.cgi?board=project&action=display&thread=593 (http://charliehall.proboards.com/index.cgi?board=project&action=display&thread=593)
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I've been working on a single board layout for the AC-15. It will fit in a 20 x 6.5 x 2.5 chassis with a 'Marshall' style layout...
http://home.comcast.net/~seluckey/VAC15.pdf (http://home.comcast.net/~seluckey/VAC15.pdf)
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I think these SCH schematic and layout could be easily converted into what you guys are looking for.
With respect, Tubenit
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Well I hope to have this preliminary layout done in the next week. I have been slammed with PV design work and have had it back burnered. Sluckey has been purusing the Steven Grosvenor layout and already found two mistakes so thank you thank you to him for his contributions. I would appreciate it if after the preliminary layout is done all of you brainiacs would look at the 1960 AC15 schematic and the layout side by side to look for any other errors. More heads are better for sure.
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Hi.
Awesome topic and exactly the thing I'm looking at for my next personal amp project... Have you finished it? How does it compare to the real one you had before? Where did you source the various parts (mainly speaking about the chassis and faceplate!)?
Thanks!
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Hi Bnwitt
I was thinking to your layout this days
Have you finish to plan it ?
Can you show us something ?
Thanks
K
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Well I hope to have this preliminary layout done in the next week. I have been slammed with PV design work and have had it back burnered. Sluckey has been purusing the Steven Grosvenor layout and already found two mistakes so thank you thank you to him for his contributions. I would appreciate it if after the preliminary layout is done all of you brainiacs would look at the 1960 AC15 schematic and the layout side by side to look for any other errors. More heads are better for sure.
Hi bnwitt!
Have you finished this build? How has it turned out?
Thanks!
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I have been watching this as well. Sluckey's layout says corrupted when I attempt to open it. I am interested in building this in a Marshall chassis and make a head out of it. Let us know how it is going.
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Sluckey's layout says corrupted when I attempt to open it.
Actually, it says...
"Sorry, the page you were looking for could not be found."
I can put the file back online if there is any interest.
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Sluckey's layout says corrupted when I attempt to open it.
Actually, it says...
"Sorry, the page you were looking for could not be found."
I can put the file back online if there is any interest.
Well, I was more looking for a double chassis layout, just like on the original, but a single chassis layout would be a good start I guess... Thanks Sluckey!
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Well, I was more looking for a double chassis layout, just like on the original
Why? Their a pain. It was a big mistake on their part.
Brad :laugh:
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My single board/chassis version of the 1960 Vox AC-15 is back online. No guarantees on how long it will remain online.
http://home.comcast.net/~seluckey/VAC15.pdf (http://home.comcast.net/~seluckey/VAC15.pdf)
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My single board/chassis version of the 1960 Vox AC-15 is back online. No guarantees on how long it will remain online.
http://home.comcast.net/~seluckey/VAC15.pdf (http://home.comcast.net/~seluckey/VAC15.pdf)
Oh my... This is totally terrific Sluckey, thanks! So all I need now is to find the guy who can make the right faceplate to make it look like the original... :think1:
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Well, I was more looking for a double chassis layout, just like on the original
Why? Their a pain. It was a big mistake on their part.
Brad :laugh:
Yeah, you're probably right, although Vox and the Vox fans assert that the double chassis actually helped reduce hum because of the two different metals used for the chassis (power section in the steel chassis, preamp section in the aluminum chassis)...
The other fact is that I have finally found someone who can build the double chassis... But nevermind, I trust Sluckey more than anyone else in this world when it comes to amps...
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The layout has a 12Ax7 in the normal preamp section, but the schematic has a EF86. Excuse my ignorance, but why?
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Yeah, you're probably right, although Vox and the Vox fans assert that the double chassis actually helped reduce hum because of the two different metals used for the chassis (power section in the steel chassis, preamp section in the aluminum chassis)...
V hav other vays to kill hum you know. :undecided:
Brad :laugh:
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The layout has a 12Ax7 in the normal preamp section, but the schematic has a EF86. Excuse my ignorance, but why?
Good point. And the rectifier (V8) in the schematic is present, but it's gone in the layout...
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The layout has a 12Ax7 in the normal preamp section, but the schematic has a EF86. Excuse my ignorance, but why?
Because it's a labeling error on the board layout. Pins connections are correct for an EF86.
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Good point. And the rectifier (V8) in the schematic is present, but it's gone in the layout...
And same for transformers, filter caps, switches, fuse, etc. My layout is not a total layout. It's meant to show board construction and interconnections. You will have to refer to the schematic for any components or connections that do not interface directly with the board.
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The layout has a 12Ax7 in the normal preamp section, but the schematic has a EF86. Excuse my ignorance, but why?
Because it's a labeling error on the board layout. Pins connections are correct for an EF86.
Thanks Sluckey. I have always wanted one of these. Do you know anyone who has built it? I cannot see any reason why it would sound different. This is my next project for me.
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Hi Steve
I completely missed to see this layout
as always a fantastic one :thumbsup: :thumbsup:
Franco
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I've built a VAC-15 Lite. It only has the EF86 preamp. I've never built the Vibrato channel but was sure close to pulling the trigger back in early September. Then I discovered that old RCA radio. Lost focus on the Vox. But it's not completely out of mind. If I do build it, I will use this board design rather than a dual chassis design.
BTW, the labeling error has been corrected on the board layout. If you spot any more errors, let me know. Thanks...
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If one of you guys start a full VOX AC15 one-chassis build I want to see it... I'm too scared to be the first one to try it and report...
Where do you guys get the proper chassis for the one-chassis AC15 btw?
There's a model from 1960 up for sale on TGP right now, just shy of $4000 (and that's probably a good deal!)... We need clones out there, that's too darn expensive!
Thanks!
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I start with a blank chassis. There are some members here that can make them. Or you can buy blanks from several websites.
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Sluckey, what was the outcome of your single board AC15? I'm interested in building this and would like to know if there has been any revisions since. I already printed out the file and will order the turret board material and turrets. I can cut and drill press holes and press them in myself
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eBay uk has vox chassis for sale FYI
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Sluckey, what was the outcome of your single board AC15? I'm interested in building this and would like to know if there has been any revisions since. I already printed out the file and will order the turret board material and turrets. I can cut and drill press holes and press them in myself
That was over a year ago. Lost my website and then rebuilt it. Somehow I overlooked that file. Anyhow, I've reposted the most current file and I 'think' there are some minor revisions but I can't say for sure. I still have not built this. If you get started on it, please share with us. Here's the updated file...
http://home.comcast.net/~seluckey/VAC15.pdf (http://home.comcast.net/~seluckey/VAC15.pdf)
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:icon_biggrin: I absolutely will. I was just about to build Hoffmans Blackface Princeton Reverb and wound up buying a Gretsch T6118. Could you recommend a chassis? I seen the size you posted and was wondering if that is a Marshall style? I have no problem using a Marshall style and making it look like a Vox. I'll Gladly post pics and what not on my build in progress. That file is what I printed out today and will use to transfer onto board. One question tho about layout, on page 4 and page 6, you show a buss ground( going from left to right) from ground 1 section all the way to ground two but on the other page you dont. I know its all grounded but should those two sections be seperated as seen in page 6 with the template above it.
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There were a couple inconsistencies between the pages. I've made corrections and updated the file on my website. Your concerns about the on-board ground busses were addressed. Please download the latest pdf. You may have to refresh the page to see the changes. Let me know if you spot any more discrepencies or if you have other questions. Good luck with the build. Here's the link to the updated file...
http://home.comcast.net/~seluckey/VAC15.pdf (http://home.comcast.net/~seluckey/VAC15.pdf)
BTW, the unconventional front panel, board, and tube layout work well together to provide short, neat, and logical interconnections. If you change the front panel to look more like the original layout, wiring may no longer be neat and logical.
I've included a source for a nice blank chassis for this project on the chassis layout page.
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What to say Steve .......... this thing is GREAT :thumbsup:
Thanks for sharing
Franco