Is my amp kaput?

CeeBee

I bought an Orange TH30 combo s/h off here a few months back, I've used in my studio only and I've been dead chuffed with it.

Today though plugged in and I get sound from it but very quiet.

The EL84's all have a feint glow, but switching from standby to half or full they don't give off any more glow. Is my power stage knackered or just the valves? The clean channel sounds louder, the gain channel seems to have lost all power. Is this going to be expensive?

Incidentally last week I bought an EHX A/B switch, but surely this can't have anything to do with it? I had it set up with my Marshall head, both going into an Orange 2x12 cab, all 16 ohm so all fine presumably. I did get some low hum and higher pitched squeals sometimes?

Thanks in advance for any advice.

ICBM

Exactly how did you hook up the A/B and the two heads going into one cab?

That is potentially very harmful to one or both amps.

CeeBee

Its an EHX switchblade plus. I connected output A to the input jack on the Marshall, and output B to the input jack on the Orange, connected tuner to the tuner jack and plugged in guitar to the input jack.

What have I done wrong? the Marshall is OK. What's the damage likely to be? I didnt smell burning or anything like that.

CeeBee

The Orange cab has two inputs. Connected 16 ohm out from each head into the cab inputs.

ICBM

Oh dear… that's what I thought you would say. The jacks on the cab are in parallel, so both amps were connected to each other. The two jacks are not both inputs - one is meant to be used as an output for daisy-chaining to a second cab.

You should never connect the outputs of two amps together like that. When one amp is not producing a signal, the other amp is driving it as a load and you can generate higher than designed for voltages in the output transformer and other related parts. Was the Marshall 50W or 100?

Chances are you have blown the output transformer in the Orange, although if you're lucky it may be something less serious - but making a quiet sound is a worrying sign, if it had blown a fuse it would be silent.

DartmoorHedgehog

CeeBee said:

The Orange cab has two inputs. Connected 16 ohm out from each head into the cab inputs.

Unless it's a stereo cab (which I don't think the Oranges are), those inputs on the cab are connected together, meant for daisy-chaining two cabs, not connecting two amps.  Sounds like you connected the two amps outputs together, which is not a good thing.  Quite likely to shaft the output transformer on one or both amps I'd say.

CeeBee

Oops. Thanks guys, my bad then, put it down to experience. The Marshall is a 50 watt and seems fine, so I may have been lucky with that one. If the output transformer has gone on the Orange, what are we looking at cost wise roughly?

ICBM

£100+ depending on how hard it is to get at, up to maybe double that if it's done any other damage as well.

Worth getting it checked before assuming the worst though, it is just possible it could be something less serious.

CeeBee

Ok thanks your all brilliant on here. Anyone know of good amp repairers in Warwickshire?

not_the_dj

CeeBee said:

Ok thanks your all brilliant on here. Anyone know of good amp repairers in Warwickshire?

MDM Music in Kenilworth offer repairs. Never used them myself despite the fact that I live in the town.

It's a bit further afield but I had great service at Phoenix Soundworks (near Northampton) when I had amp issues earlier this year (blown output transformer on an Egnater). That place was recommended to me on here.

not_the_dj

Here's the links:

http://www.phoenixsoundworks.com/repairs.htm

http://www.mdm-music.info/repairs.php

CeeBee

Thank you all. I am a dick. Won't do it again though......

ICBM

You didn't know. You aren't the first and won't be the last…

With nothing on the cab to warn about that, it maybe does look as if you can use both jacks as inputs. For example the old Trace Elliot bass cabs with multiple jacks have a warning printed on the jack panel, which is the right thing to do.

If jacks *can* be connected, sooner or later someone *will* try it!