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Question for valve amp people
Posted: Wed Sep 02, 2009 9:22 pm
by Fran
So, last night i skanked a 1970s Laney 60watt valve head.
On the back there is a dial to change the ohm setting. It works set at 16 ohms but not at 8 ohms. No sound at all.
I think (will check) my cab at rehearsal is 16 ohms but the one at home loaded with Celestions is 8 ohms.
1/ Will it damage the head using the 8 ohm cab?
2/ What could possibly be wrong with it to not work on the 8 ohm setting?
Thanks.
Re: Question for valve amp people
Posted: Wed Sep 02, 2009 10:05 pm
by Markn951
disconnected leads on the switch in 8 ohm setting?
Posted: Wed Sep 02, 2009 10:16 pm
by Fran
Hmm. Makes you wonder if it has been modified to just be on one setting.
Im going to get it serviced but need it for 3 gigs starting next weekend and would'nt get it back in time. Looks like i'll have to risk it, or use the Crate Powerblock.
Posted: Wed Sep 02, 2009 10:30 pm
by benecol
Sounds like a nice score, Fran - post pics?
Re: Question for valve amp people
Posted: Wed Sep 02, 2009 10:45 pm
by Doog
Defo don't use the 16ohm setting into an 8ohm cab- not sure on why it doesn't work. Sounds like an odd mod to have done, so I guess something's just come loose or broken?
You could rewire your cab at home to run at 16 maybe, presuming it's more than one speaker?
Posted: Thu Sep 03, 2009 2:02 am
by Sloan
i did this on my BELOVED AMPEG when the impedance selector broke and i couldn't find a replacement, so def check that out.
Posted: Thu Sep 03, 2009 5:37 am
by dub
I have an 80s laney with a similar mystery. When I bought it the guy told me that it's output transformer had blown up and been replaced and that it would only work on 16 ohms. But since it's really a matter of just connecting a few more wires.. seemed wierd to me. I've never tried the other settings and always gone into 16 ohm cabs just in case.
I really should get it checked out, since everything else the guy told me about the amp has slowly been proven wrong, he had the wrong fuses in it (how the fuck do you do that when they're written next to the bloody slot?) and he'd shoved in mismatched output tubes... I had a look inside and if the transformer blew it was ages ago because it doesn't look like a replacement. Also I know the last guy was running both outputs on the 16 ohm setting, which according the manual you're not supposed to do and I think means it was actually putting out 32? I think he was creating his own problems through shear ignorance.
anyway.
What kind of Laney is it? a Klipp?
Pics?

Posted: Thu Sep 03, 2009 8:45 am
by Mike
The switch should be simple, just wires from the various taps on the Output Transformer to the switch then to the output jacks.
I wouldn't fuck with it though, so get it serviced/fixed up. The wires could be missing/broken or the OT could be slightly fucked.
Posted: Thu Sep 03, 2009 4:50 pm
by Fran
Thanks for all the advice.
Its a mid 70s 'L60' PA head, but they were used more by guitarists apparently. I'll make sure my other cab is wired at 16 ohms until i can get it serviced.
The singer in Master Charger offered it me for £50 but said it was broken, i fiddled with it and got it working in 10 minutes, much to his annoyance
He'd had it set on 8 ohms and had given up on it.

Posted: Fri Sep 04, 2009 2:25 am
by Sloan
looks trill!
Posted: Fri Sep 04, 2009 2:37 am
by hotrodperlmutter
what a beaut.
Posted: Fri Sep 04, 2009 2:45 am
by laterallateral
VERY, VERY nice looking amp.
Posted: Fri Sep 04, 2009 9:14 am
by NickS
Nice score! The suggestion that the original transformer has been replaced by a cheaper* transformer that only does 16 ohms sounds a distinct possibility. Good thing he didn't blow it up with no load (on the 8 ohm setting).
*If you're winding a transformer for 8 and 16 ohms, you'd use heavier gauge copper (more expensive) for the first (8 ohm) half of the output winding. You also have the additional labour time/cost of switching gauge and soldering to the 8 ohm tap.
Posted: Fri Sep 04, 2009 9:41 am
by Mike
ROLF @ Union Jack cloth.
Posted: Fri Sep 04, 2009 3:17 pm
by Fran
Mike wrote:ROLF @ Union Jack cloth.
From teh pistolz days. I think Dogg named it the
BNP Cab lol.
Posted: Fri Sep 04, 2009 3:20 pm
by Mike
haha BNP was on the tip of my.. err.. keyboard fingers actually
Posted: Fri Sep 04, 2009 3:20 pm
by Doog
Fran wrote:Mike wrote:ROLF @ Union Jack cloth.
From teh pistolz days. I think Dogg named it the
BNP Cab lol.
"Fo' rizzle?"