AmpTalk.com

[davii]

Hi all

Am new to all this amp building lark, but not totally naive (if that's anywhere close to a correct spelling!) with putting things together, but...

I've been rumaging around the net for amplifier schematics, only to find that many assume that you already know which units are being used for capacitors especially.

Is making it a right pain to effectively cost out building a Vox AC100 clone

Q. Anyone know where to find concise componant lists for amplifiers???

Thanks for any help

[tw001_tw]

davii -
I can't help you with a parts list.. but...
http://www.voxamps.co.uk/downloads/circuits/ac100.jpg

And I'm not sure exactly what you mean by "many assume that you already
know which units are being used for capacitors especially" you mean the
values & ratings? Let me know!
-tw

[davii]

Hi TW,

I've found several schematics, but there are only numbers attached to the capacitors, like "25" and no mention of whether it's uF, pF etc.

I'm ok with reading the numbers, from an explination on a website, but that was in direct reference to old polystyrene capacitors that were always rated in pF. But... If that's the case, then the schematic I'm working from specifically states one capacitor as pF, so I'm nowhere near confident that this is also the case for those without ratings, as my assumption is that either all or none would have a rating attached.

Think I'm making sense here, rushing a lil bit - rehearsal in 15mins

[tw001_tw]

Chances are the "25"s would be 25uF 25 or 50V electrolitics. You are
refering to the caps coming from pins 3 &/or 8 on the 12ax7's? then thats it.
(that is a semi-common value for cathode bypass caps. You can use
anywhere from 1uf to 25uf. and even lower then 1uf. Personally I prefer
either 10uf or 25uf.)

There are a lot of common denominations (I guess thats the term) in our
beloved tube amps. This might help you, but as a general rule, all caps
in (tube amp) schematics are uf unless otherwise specified. Thats not to
say everyone follows that line of thinking, but most do. And you can always
compare your schematic with other amp schematics with the same tube
compliment to get an idea what the range of 'normal' values are.

For example, find C7 in the tone stack on the schematic I posted, its
specified pF. But I know the others (unspecified) are uF.

[davii]

That's fantastic help there TW and goes to show how far adrift I am from knowing enough about what I could be undertaking! Good news is, I've as much time as I need for now, as we just sacked the Bass player and ol' muggins here will be covering that duty. Oh joy.

Back to building the AC100; I'd like to add in the option of creating channel selection, with tone control over each. Can I literally just employ a switch system + controls prior to the 12au7's??? (I've a schematic of the AC100-2 power amp, which appears to include these) Would be nice to have clean/crunch/lead on the go

[tw001_tw]

[davii]

Uhuh, it them it be

3 channels min (clean, crunch, lead), either that or start building 2 identicle heads and A/B 'em, though cost is a bit of a mission on the latter. I'd only be doing half a job if I didn't involve channel switching.

The other guitarist has built a Marshall clone and a Fender Bassman clone, so do have somebody to hand if need be. Only trouble is, getting yes/no answers out of him can be a nightmare at times - y'know, the answers that come complete with a history, the wife's dog's second assistant's flea groomer was unwell that day...