Orange AD200 and Matamp 2x12 - no sound

UnDoNe · #1 08-20-2010, 05:02 AM

So there I am, rocking away at practice with an AD200B and the Matmp 2x12. The head is moving around the top of the cab a few inches and I pull it back everytime it gets too close to the edge.

Mid-song and it stops making any noise...not a whistle. Everything still turned on, lights on, valves glowing as they should. No flashes, no smoke, no funny smells.

Changed leads, bass is passive and worked through different amps.

Any thoughts? I'm thinking the vibrations maybe loosened something? Good job it was the last song of the practice!

Thanks for any help you guys can offer

Bassmec · #2 08-20-2010, 05:48 AM

Did the loudspeaker LS output cable come loose at any point with all this unusual cab walking.
I would check the HT fuse and then find out if you have pre amp output by plugging a cable into the fx loop send and then into the input of another amp.
If you have an ht fuse intact and an operating pre amp then
check the speaker cab and the output transformer in the amplifier.
If you look at the tubes do you see a blueish glow augment the orange glow in the output tubes when you take the amp out of standby?.
You may have just had an op tube short and blown the ht fuse
if so that tube should be replaced with a tube matching the good ones for quiescent current for a given grid bias voltage.
Running the amplifier into no load IE when the cabinet fails or
when the loudspeaker cable comes out when being driven at high power will destroy the output tubes and the output transformer.

PS If your hearing has recovered, see if there is any noise coming from the cabinet at all hum hiss crackle etc?

UnDoNe · #3 08-20-2010, 06:43 AM

Hi Bassmec,

Wasn't running the amp incredibly loud...gain about noon and master about 10 oclock. The head was moving on the cab, the cab didn't move at all during this. The cab has a speakon connector and it didn't come out at all during the whole practice.

I'll have to check when I get home about the fuse, but there was definitely no blue glow on the valves. I knew to look out for that, and they were glowing fine.

Thanks for your help so far

Bassmec · #4 08-20-2010, 06:53 AM

A small amount of blue glow in output tubes is plasma from having HT present, nothing wrong with that, for the amp to work its a necessity.

UnDoNe · #5 08-20-2010, 07:04 AM

Whoops! Haha, can't say I've seen any blue glow on the valves. I used to own a Bassman 135 and that did have the blue glow. The Orange has been faultless apart from this one time.

TaySte_2000 · #6 08-20-2010, 07:40 AM

Seems like it would be the head not the cab

I have no information to give other than when you get it up and running again use a Isopad between the head and cab, it will also extend tube life.

My 8x10 doesn't vibrate externally as much as my 2x12 but then my GT200 must be heavier than the AD200 as it's never moved ever.

heath_r_91 · #7 08-20-2010, 07:53 AM

Plug the head back in (to both the wall and the cab) and turn it on and take it out of standby. Then, go around to the back and look at the tubes and make sure all of them still glow and also look for the red dots on the back for the tube fuses.

If neither of those turn anything up, I don't know what to tell you. You may just have to push the tubes back into the sockets.

UnDoNe · #8 08-20-2010, 07:56 AM

Cheers Ste, I'm leaning more towards the head aswell.

I'll look into a pad between the head and cab. Not sure on weights between the two heads, but the AD200 is a fairly easy lift...even for my weak arms.

Nightlyraider · #9 08-20-2010, 09:39 AM

What does an AD200 weigh? The image of just the head walking around atop anything it could jump off is scary.

I don't think I could make my 400+ move without picking it up and carrying it.

UnDoNe · #10 08-20-2010, 10:08 AM

According to Orange - 25kg.

Back with the amp now...valves still glow nicely, no lights on to show any blown fuses.

When I take it out of standby there is a tiny hum, similar to how it sounds when it's working. A stab in the dark here....but maybe a pre-amp valve has gone? Not sure if that would not let any signal through.

KramerBassFan · #11 08-20-2010, 10:09 AM

Swap Pre amp tubes.

UnDoNe · #12 09-20-2010, 10:55 AM

I thought I'd bump this as I've just picked the amp up. It was the Orange at fault...dodgy resistor apparently. All is well now though...God, I've missed it!

Cheers for all the suggestions.

BassmanPaul · #13 09-20-2010, 11:45 AM

Remember you can check your speaker cabinets with a 9V battery. Touching the battery terminals to the tip and sleeve of your speaker cable should produce a healthy thunk from the cabinet.

Paul