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Old 15th September 2011, 08:50 PM   #11
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Nah, First thing I ever built was an AX84-P1. Works beautifully to this day.
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Old 15th September 2011, 09:29 PM   #12
sreten is offline sreten  United Kingdom
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Originally Posted by costis_n View Post
Nah, First thing I ever built was an AX84-P1. Works beautifully to this day.
Hi, pointless disagreeing when your agreeing, I did say "building a kit" as an option, rgds, sreten.

http://www.ax84.com/p1.html does have loads of documentation. Still a lot of work for a novice.
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Last edited by sreten; 15th September 2011 at 09:38 PM.
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Old 15th September 2011, 09:40 PM   #13
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Sreten, good call on the laney, i was lucky with mine, managed to pick up a used one, that had just some back from the factory for a complete repair. except the one i got wasnt the reverb version... i needing something to do to it :P

anyway back on topic.

If he was to build the amp stage by stage, channel one, then channel 2 and test it with an SS PA, should go quite well as you can test the preamp on the way. the power stage can then be done after. nothing to say a first build wont go well, its just unlikely. and im sure there isnt too much misinformation on this forum.
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Old 15th September 2011, 09:53 PM   #14
sreten is offline sreten  United Kingdom
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Originally Posted by razorrick1293 View Post

anyway back on topic.

If he was to build the amp stage by stage, channel one, then channel 2 and test it with an SS PA, should go quite well as you can test the preamp on the way. the power stage can then be done after. nothing to say a first build wont go well, its just unlikely. and im sure there isnt too much misinformation on this forum.
Hi,

Seems to me the full monty is wanted straight off the bat, it simply won't happen.

I agree a more measured approach of somekind is required.

I'm all for building stuff, within your capabilities.

rgs, sreten.

My practice bass amp is a Traynor, vintage circa 1960, valve 15w 15".
Again picked up for far less than the parts would cost, i should really
update the 15" driver but its not quite a standard 15" cutout.
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Last edited by sreten; 15th September 2011 at 10:02 PM.
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Old 16th September 2011, 12:16 AM   #15
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I agree. The amp you want to build I could probably do with a lot of time to get right. But then electronics is not new to me and I have been reading up on tube amps for the last year. Better to get a simple amp, get it going and then add or modify it to get some experience.

So far I have spent more on speakers, parts, tubes, and transformers than what I could have picked up a used Fender 15 watt tube amp.And I do not even have a working amp yet. (Mind you I have slapped together a couple prototypes as experiments.) It has been a learning experience, I do have a n oscilloscope, signal generator, and a few other toys to help me along. Starting green and thinking you will design your own amp might be a bit much to attempt for most people.
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Old 16th September 2011, 12:26 AM   #16
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wow, i didn'hope to have so quick awnser !! Thank you all for that

Thank you Sreten for your information and your care. I know that's it's not an easy job to do and that there is only few chances to sound good at firts times...
Maybe i aske too much for my first project. Would it be really easyer to build if i only keep one channel, certainly the EF86 one, and the reverb ? Something like this (Some help/advice with a guitar amp layout.) with additionnal settings for bass-treeble and a spring reverbe ? Can i keep the same parts if i add this ? (choke, output-power transf)
On the other hand i don't want it to be a 10 years long project to do !! And i don't have 50hours a week for this ! But as i said before i can have the tools needed (and somebody who is good in using them) to test the amp stage by stage as you said Razorrick, and really want to try to build my own, but if it's a suicide-mission i don't have money enough to play that way ..

If i finally change my mind and buy something in a shop it would certainly be a Vox Night Train 15W head, with the 12" speaker cab ( and change the speaker for a celestion blue alnico or a wgs black and blue if that's not too difficult....).

But do you think it's difficult to add the line out and/or phone outputs on the night train? And what about the reverb ? I know that i have to add a 12AX7 tube configuration , can i keep the same power set or do i need to change it ? I imagine that it would be too difficult to change for EF86 on it ?!

mmmmmm, or, maybe, ?? What about buying the night train, and building another element (kind of box ?) ,that i will plug between the head and the cab, with reverb and headphone output inside ?? is it stupid ? Will it be easier than building the amp itself ? How is this kind of elements powered ?
I already test this amp in a shop and i must admit that's it's really a nice one, easier to move than a AC15... but miss a few things

Thanks for your awnser, i didn't hope to have so much so quick !
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Old 16th September 2011, 06:30 AM   #17
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building something like EF86->12AX7->12AX7 ->EL84 (keep it single ended for now?) should pretty simple as long as you keep space for whatever else you may want to add. its going to be a long project if you dont know what your doing. but theres nothing wrong with learning.

as for buying the amp, the speaker change is simple. and i doubt youd be able to add anything to the night train, the idea of it is its compact, not alot of room for anything especially a reverb tank or more tubes.

as for putting a box between amp and speaker, the only thing that should be here is a load. even if you use an input transformer to match the load and bring the voltage back up, you will need another power amp. you might be able to mod in an effect loop to the night train, with maybe some highvoltage MOSFETs, a source follower and a clean amplifying stage. inbetween the tone stack and phase splitter.
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Old 16th September 2011, 11:14 AM   #18
sreten is offline sreten  United Kingdom
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Originally Posted by dabitsusan View Post
Something like this (Some help/advice with a guitar amp layout.) with additionnal settings for bass-treeble and a spring reverbe ? Can i keep the same parts if i add this ? (choke, output-power transf)
Hi,

I'n no valve layout expert, but neither is the guy that did that layout, I
could do a lot better, which is not saying much. That is not a good place
to start, a first attempt by someone who has never built anything electrical.
Already a lost cause IMO, all of the problems with that layout will never
be addressed, such is the price of relatively clueless originality.

People like that in the planning stage think it will be easy, they are so
wrong. Ignore such posts and check out well documented kits / designs
by experienced designers and the service manuals and / or descriptions
of classic designs, very hard to do better than the best out there.

rgds, sreten.
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Last edited by sreten; 16th September 2011 at 11:17 AM.
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Old 16th September 2011, 03:12 PM   #19
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why not try the fender champ project, if i remember, it has a pentode in the preamp, and in time im sure you could add another preamp stage/ more advanced power stage eventually. out of curiosity, why do you want 15 watts? just becasue the AC15 is 15 watts?
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Old 18th September 2011, 03:40 PM   #20
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Quote:
Originally Posted by dabitsusan View Post
what do you mean by phase splitter ? if i need i'll add one tube more, ok ? but why ?
Have you the schematics for the amp you want to simulate? I've got a mass of AC30 circuit diagrams, but no two are identical; we always used to say Vox built round the components they had on hand. Depending on the reverb unit available, you might be able to get by with one double triode without a transformer - more likely one and a half.

It's basically a Mullard 5-10 circuit, with a pair of output valves (tubes) in push/pull, and the phase splitter inverts the polarity of the drive to these.
If you're building on tag board rather than printed circuit (convenient for modifications) it's a good idea to punch holes for one or two more valve holders, and leave some empty tags, for future improvements.


Est que vous avez les schemas de l'ampli vous voudrez simuler? J'ai un tas des diagrammes pour les AC30, mais il n'y en as pas deux sur le même circuit. On disait à l'époche que Vox les fabriquaient suivant les composants qu'ils avaent dans le tiroir. Suivant quelle resort on peut acheter pout le reverb, peut-être on peut s'en sortir avec un seul double triode sans transformateur, mais c'est plus probable qu'il en faut un et demi.

C'est essentiellement un Mullard 5-10 (une lampe redresseur (à eliminer), deux EL84 puissance un pour préampli et l'inverteur de phase, pour que les lampes de sorti sont poussé equilibré), et si vous le fabriquez sur 'tag board' ou equivalent, pour pouvoir faire les modifications plus tard, ça vaut le pein de fair les trous pour encore une ou deus petites lampes, el laisser des contacts non-utilisés pour les ameileurations à l'avenir.
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