Valve Pa as guitar head?

[sgmypod]

Would a 100w valve pa work as a guitar head without too much messing, have seen one that is turret based on the selmer 100/4 pa

[TwilightOdyssey]

Try it, might work great. I think that the EQ wouldn't be tuned for a guitar's signal (if it has any) and it might not have enough gain on its own, but might sound tremendous.

[Oli]

Generally, they're pretty easy to mod to a 'full' guitar amp spec - especially as they tend to be turret and point to point construction :) As is the usual warning, take great care if you do decide to open one up!

[martinw]

I have a Sai 50W PA head    :D which Iused the other night after minimal mods (removed NFB, added bypass cap to V1) and it was ok, but lacked some tope end bite and gain.
I'm going to mod the preamp to be like the simple Watkins Dominator/Marshall 18W type, which should make me a nice guitar amp.

[sgmypod]

Glad to hear thats working well, this is a invader(basically a selmer 100/4channel pa) has el34, not sure how many pre amp valves. bass, treble, mast for each channel and mast overall and fx loop etc. same as this but without valve rectifier, can't find a good copy of other schematic
http://www.vintagehofner.co.uk/selmer/schematic/p1004.html

[Brow]

A guy I was in a band with a while ago used an home made 4x10 PA cab with a 100w valve, 6 channel Simms Watts PA head for guitar.

It never worked long enough to know wether it sounded anygood or not (that and he used a Metal Zone  :shock:) but I'd more than likely put that down to him treating his gear like cr@p than any failings within the amp.

Old valve Carlsbro PA heads go for fairly cheaply on Ebay, and some of them still have the original Mullards in some cases :)

[Twinfan]

I have a Sai 50W PA head    :D which Iused the other night after minimal mods (removed NFB, added bypass cap to V1) and it was ok, but lacked some tope end bite and gain.
I'm going to mod the preamp to be like the simple Watkins Dominator/Marshall 18W type, which should make me a nice guitar amp.

Where did you get that idea mate?????   ;)

[martinw]

Hah!  Afraid I'd considered that not long after getting the amp, but initially had rejected it in favour of a full-on Plexi type pre-amp rebuild. After trying the amp without mods, though, I thought it might fly as was, but you have rekindled the thoughts of a simpler mod job. The EL34  "18W" has been done before, so it's not new ground, although a fixed bias version might be.

[Twinfan]

Full on rebuilds to PA amps just seems wrong to me for some reason!

I think any valve PA amp with a few simple tweaks would be great for guitar.  The simpler the better too!

[martinw]

Yes agreed.
The easiest to mod has to be the Marshall PA. With 4 channels, it's also easy to use one of them as an extra gain stage, and one of the volumes as an MV. Change a couple of coupling caps, and you've got a 100W Superlead. They even look mostly like guitar amps. The great news is that you can find PA amps in much better nick at lower prices.
The 20W PA is also a great sleeper amp, although it's even less different to the respective guitar amp and therefore a bit more sought after.

[sgmypod]

Well thats the idea he has a rsc linear amp(Birdcage) which am going to tinker with and a 100pa the one I mentioned that he want £50 for

[horsehead]

Do it....I'll lend you the bloody money ;)

[PhilKing]

Hah!  Afraid I'd considered that not long after getting the amp, but initially had rejected it in favour of a full-on Plexi type pre-amp rebuild. After trying the amp without mods, though, I thought it might fly as was, but you have rekindled the thoughts of a simpler mod job. The EL34  "18W" has been done before, so it's not new ground, although a fixed bias version might be.

My Ceriatone JTM45/18 is similar, it has the TMB and the EF86 mods though, but it gives a great sound and with an A/B switch you have both Marshall and Vox(y) sounds!

[martinw]

Sounds cool!

[sgmypod]

Yeah will be next week go to try, just need a 4x12 to run it through *L*.....aaah gas

P.S. got to be good has a maurauding viking on front..he has another one he's trying to get me to take for about £20 that needs biasing sorting out