Building a guitar

^ you can always take less of a valve, but never more, there is no minumum wattage  - but an EL34 would have been an (expensive) overkill - well spotted.

Trademark wrote: Hughes   & Kettner used to make a little tube preamp (used a 12Ax7 I think) that had an output of around 5w when hooked directly to a speaker cab.  I practiced through mine a lot.  Don't know if you could get this onto battery current though.  I suspect not unless you raid the folks' car.

It would have had to have had a built in power amp somewhere down the line.
5 watts suggest it would have used a single EL84 or 6V6 power tube somewhere in there.
As for the preamp tube, the only 3 that spring to mind immediately are 12AT7s, 12AU7s and of course, the 12AX7, the AX7 being the highest gain preamp tube of the bunch.
You don't recall the exact name of the H&K preamp you used do you?

Edit: nevermind, didn't see the extra posts when I posted mine


Edited by HughesJB4 - March 02 2009 at 19:48

Cant recall the model number, but I believe it was called the "Bluesmaster" or Crunchmaster".  It was a 1/2 rack unit with the H&K Red Cab circuitry for cabinet simulation (mid eighties style).  Can't help you on the tubes.  It may have another tube for power output (EL34 maybe?), I don't remember.  I haven't seen one in close to 15 years since I got rid of mine.

Trademark wrote: Hughes   & Kettner used to make a little tube preamp (used a 12Ax7 I think) that had an output of around 5w when hooked directly to a speaker cab.  I practiced through mine a lot.  Don't know if you could get this onto battery current though.  I suspect not unless you raid the folks' car.

opps, yeah I did mean 384 (I'm was a little preoccupied with sourcing heatsinks at the time)

Yeah I just noticed that myself PP3 batteries really aren't suitable for this project unless I limit myself to a really low power chip like the LM386, which is going to be very disappointing.

thanks mate.

Dean wrote: ^ good luck with that, it sounds like a good project.   (I think your going to struggle to get 5Wrms from 9V batteries but let us know how you get on)

Well I've just stumbled upon the LM385, a power amp chip that produces 5w at 22v, since I'll be running at 18v it'll be slightly less but still fairly close.

that would be the peak power, I reckon that the average will be closer to 2.

It's a warm up for my final year electronics project, we've been given free reign to design and build something. anything goes as long as we can finish it in 12 weeks (+3 weeks over easter). I'm currently coming to the end of the design process.

As it stands the amp will require 9 or 18 volts from batteries this will be determined by the type of operational amplifiers I use. the power amp section will be fairly standard and should kick out just under 5 watts RMS or just over 5 watts peak to peak to an 8 ohm speaker.

It's the pre amp that's taken most of my time to develop, it starts with a unity gain amplifier which simply acts as a small current booster which will make working with the signal a little easier. Then there is the EQ section which has taken ages to develop, the EQ uses the standard Baxandall style tone stack as used by the likes of Fender and Marshall, however it is in fact 2 EQs in one as I will be building both Fender and Marshall style EQs (modified slighty to suit my intended control layout) and the design will allow blending between the 2 EQs giving access to all sorts of mid atlantic tones.

After the EQ I've got a small fixed gain amp that will take the voltage up to the level required by the power amp. 

Doesn't sound like much but for a 15 week period it's a lot of work particularly since I've got to build a prototype.

Just spotted this post, this will be my first post for ages.

The wilkinson is a great trem, it's say it's really just an alternative to the standard Fender 2 point trem that needs a different rout ,so no floyd rose style whammies to be had. If you really a wilkinson trem a new one has been released that will fit any guitar with a fender 2 point trem. Although it is really expensive, but that's inevitable for a brand new design that fixes all the little niggles with the original. link

tbh the best trem of this type that I've used is the one fitted to recent Burns reissues, pity that their guitar aren't right for my playing style though.

Amazingly I've still not had time to set the guitar up properly, a mix of exams and a rather demanding project have got in the way (designing a battery powered guitar amp).

My brother is learning to build guitars at a college nearby. He's working on his second and third guitar at the moment, but his first one was made all with hand tools! It's acoustic guitars by the way. He said he'd get around to making me a bass if I got him money for the cost of the materials.