Bare Knuckle Pickups Forum
Forum Ringside => Guitars, Amps and Effects => Topic started by: sgmypod on August 14, 2008, 04:40:42 PM
-
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
-
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.
-
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!
-
I have a Sai 50W PA head :wink: :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.
-
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 (http://www.vintagehofner.co.uk/selmer/schematic/p1004.html)
-
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 :)
-
I have a Sai 50W PA head :wink: :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????? ;)
-
Hah! :wink: 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.
-
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!
-
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.
-
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
-
Do it....I'll lend you the bloody money ;)
-
Hah! :wink: 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!
-
Sounds cool!
-
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
-
I've got a Matamp 4x12 for sale at the moment ;)
-
I know keep looking at it, just can't afford it at mo..would need to sell my marshall 1936 one first...why you selling
-
I've got two 4x12s, don't actually NEED them both!
-
Fair enough whats it sound like is it similar to the new ones
-
Yep, the only difference between it and my Martamp is in the speakers and the cosmetics.
-
those RSC bird-cage amps are great (I have two). The OTs are pretty poor though and it's money well spent putting a beefier one in there. I've seen them with EL34 and EL84 with GZ34 and EZ81 rectifiers resptively. preamp is typically one EF86 and two ECC83s.
I gutted my EL34 one, changed the OT out, got rid of the GZ34, added a choke, put cathode biased 6V6s in and wired up an AC30 top boost preamp with the tonestack modded to have a mid control.
Its a awesome little amp that I have less than £75 in and can stand shoulder-to-should with amps in the £1000+ range.
-
yeah been chasing guy for about 8-9 months to dig it for me.....out of interest how much to clean mod one up(obviously depends on condition)
-
yeah been chasing guy for about 8-9 months to dig it for me.....out of interest how much to clean mod one up(obviously depends on condition)
depends what you want doing, but to strip an amp bare and rebuild it is very time consuming. I'd want £200 for labour and small parts, transformers and choke extra - these are really only bargains if you can mod them yourself or have a mate who could help.
-
To be honest prob a clean up make a working amp(well yet to try *L*), original spec(maybe trans & choke)
-
many of the PA heads have baxendall tonestacks which, imo, makes for a wierd sounding guitar amp. they generally have alot of negative feedback for max headroom, but thats easy to change.
so long as the amp is PTP wired, the scope to easily mod is huge.
my next project (once I'm out of hospital) is to rebuild my Epi VJ with a Marshall 2203 preamp, all PTP wired running any output valve (single ended) from a 6V6 to a KT88 - should be a little beast.
-
Yeah sorry only just read you were in hospital....
-
http://www.vintagehofner.co.uk/selmer/schematic/p1004.html
here's the schematic...although is exactly same minus valve rectifiers
1 valve per channel
-
http://www.vintagehofner.co.uk/selmer/schematic/p1004.html
here's the schematic...although is exactly same minus valve rectifiers
1 valve per channel
I cant see the picture on this hospital net connection, PM me in a couple of weeks when I should be back home. I'll have a look at it then and make suggestions on how to get more out of it for guitar.
-
yeah think is selling for 65 and has viking on front *L* it should look similar to this (http://www.vintagehofner.co.uk/gallery/gallery3/gallery6/gallery7/gallery8/amp2g.jpeg)
(http://www.vintagehofner.co.uk/gallery/gallery3/gallery6/gallery7/gallery8/amp2h.jpeg)
hopefully cleaner(el34s under metal cover at back),
can't wait to try it..that and the birdcage rsc