JCM 2000 blown by Hot Plate

jkm · 06-29-2009, 12:50 PM

Hey,

I am inexperienced at dealing with Marshall's, but I recently purchased a used JCM 2000 DSL 100, and a used THD Hot Plate to keep my neighbors from calling the cops. The Hot Plate seems to have broken my amp twice! I plug it in and the amp just stops making sound thirty seconds later. What did I do wrong? I have the right settings on the amp and the attenuator. Thanks for any help.

PaoloJM · 06-29-2009, 04:15 PM

What settings are you using?
What ohmage is the attenuator, amp and speakers?

HotPlates wont cause amp failure, but they will show up problems that mightn't otherwise come up, as you're running the amp a lot harder than you normally would.

American Viking · 06-29-2009, 05:18 PM

still don't understand why people put attenuators on master volume amps...

jkm · 06-29-2009, 06:05 PM

Just plain old ignorance on my part, American Viking. Are you not supposed to use one on this type of amp?

PaoloJM,

I was on the Classic Gain Channel with the volume (I think) at 3 and the gain probably the same. It's a 16 ohms attenuator, plugged into the 16 ohm jack on the amp. Obviously I'm pretty new at all this, I'm sure I did something wrong. Thanks for your help.

stargazer76 · 06-29-2009, 06:06 PM

With an attenuator, you can drive your power amp full out with the overall volume "low". Otherwise to get the same power section drive, the master volume would have to be on 8, and the cops would be at your door..... With master set low and pre-amp cranked, your not getting any of that power section sweetness.

rockinr0ll · 06-29-2009, 06:19 PM

I wouldn't have used the Hot Plate, now people should understand why!

Check your tubes or the wires.. chances are the the hot plate burnt the wires in the input!

jcmjmp · 06-29-2009, 08:12 PM

The hot plate is probably not the problem when running the amp at "3" on the master volume unless it is faulty, which is very rare.

Have you tried the amp without the hotplate with the same settings?

American Viking · 06-29-2009, 10:42 PM

Quote:

Originally Posted by stargazer76

With an attenuator, you can drive your power amp full out with the overall volume "low". Otherwise to get the same power section drive, the master volume would have to be on 8, and the cops would be at your door..... With master set low and pre-amp cranked, your not getting any of that power section sweetness.

yeah yeah, i know i know but at the same time you're never going to be pushing any serious air through some speakers. if you have to play leveled down to a whisper what does it matter anyway? a little power tube distortion isn't going to matter to me if I have to be that low. power section sweetness, just turn the master to 10 and your pre-amp gain down to 1. booyah!
it's all or nothing IMO. don't start the car if you can't drive it home

sorry your amp is busted, dude. check your speakers with a multimeter or ohm meter and make sure one of them isn't faulty. mismatched impedance can cause this. if all the speakers are ok then we would be moving on to checking on the tube life, bias of the tubes, etc...

stargazer76 · 07-07-2009, 01:11 AM

I'm cool, American Viking! I agree 100%, My 800 MV is usually around 7 or 8 with pre on 8 for the stuff I play (not metal). I don't own an attenuator, just describing what they do.....

pleximajor · 07-10-2009, 02:09 PM

so what if you are playing live and the sound guy says your to loud with master on 3...
thats where hot plate comes in ...you dont have to use attenuator just on none mv heads....and you dont have to crank your amp on ten when you use one....
if tubes are old and bias is not set or if you dont hook up right you will blow tube and crap in you amp...you have to keep an eye on your tube wear and not just throw a hot plate on a amp that has year old tubes and wonder why it blew

big dooley · 07-11-2009, 08:51 AM

Quote:

so what if you are playing live and the sound guy says your to loud with master on 3...

fire him...?

MattWrath · 07-27-2009, 09:24 AM

Quote:

Originally Posted by big dooley

fire him...?

hehe.
Sound guys can be a pain in the ass

06-29-2009, 12:50 PM	#1 (permalink)
jkm Junior Member Join Date: Jun 2009 Posts: 2	JCM 2000 blown by Hot Plate Hey, I am inexperienced at dealing with Marshall's, but I recently purchased a used JCM 2000 DSL 100, and a used THD Hot Plate to keep my neighbors from calling the cops. The Hot Plate seems to have broken my amp twice! I plug it in and the amp just stops making sound thirty seconds later. What did I do wrong? I have the right settings on the amp and the attenuator. Thanks for any help.

06-29-2009, 04:15 PM	#2 (permalink)
PaoloJM Senior Member Join Date: Jun 2008 Location: Cork, Ireland Posts: 534	Re: JCM 2000 blown by Hot Plate What settings are you using? What ohmage is the attenuator, amp and speakers? HotPlates wont cause amp failure, but they will show up problems that mightn't otherwise come up, as you're running the amp a lot harder than you normally would. __________________ www.youtube.com/paolojm

06-29-2009, 05:18 PM	#3 (permalink)
American Viking Senior Member Join Date: Jan 2009 Location: RICHMOND, VIRGINIA Posts: 1,510	Re: JCM 2000 blown by Hot Plate still don't understand why people put attenuators on master volume amps... __________________ -I'd rather be a good liver than have one...

06-29-2009, 06:05 PM	#4 (permalink)
jkm Junior Member Join Date: Jun 2009 Posts: 2	Re: JCM 2000 blown by Hot Plate Just plain old ignorance on my part, American Viking. Are you not supposed to use one on this type of amp? PaoloJM, I was on the Classic Gain Channel with the volume (I think) at 3 and the gain probably the same. It's a 16 ohms attenuator, plugged into the 16 ohm jack on the amp. Obviously I'm pretty new at all this, I'm sure I did something wrong. Thanks for your help.

06-29-2009, 06:06 PM	#5 (permalink)
stargazer76 Member Join Date: Mar 2008 Location: Dallas, Texas Posts: 42	Re: JCM 2000 blown by Hot Plate With an attenuator, you can drive your power amp full out with the overall volume "low". Otherwise to get the same power section drive, the master volume would have to be on 8, and the cops would be at your door..... With master set low and pre-amp cranked, your not getting any of that power section sweetness. __________________ JCM 900-4100 JCM 800-2204 1960A/G12T75 1962RI Stratocaster

06-29-2009, 06:19 PM	#6 (permalink)
rockinr0ll Senior Member Join Date: Feb 2009 Posts: 1,340	Re: JCM 2000 blown by Hot Plate I wouldn't have used the Hot Plate, now people should understand why! Check your tubes or the wires.. chances are the the hot plate burnt the wires in the input!

06-29-2009, 08:12 PM	#7 (permalink)
jcmjmp Senior Member Join Date: Nov 2008 Posts: 1,341	Re: JCM 2000 blown by Hot Plate The hot plate is probably not the problem when running the amp at "3" on the master volume unless it is faulty, which is very rare. Have you tried the amp without the hotplate with the same settings?

07-07-2009, 01:11 AM	#9 (permalink)
stargazer76 Member Join Date: Mar 2008 Location: Dallas, Texas Posts: 42	Re: JCM 2000 blown by Hot Plate I'm cool, American Viking! I agree 100%, My 800 MV is usually around 7 or 8 with pre on 8 for the stuff I play (not metal). I don't own an attenuator, just describing what they do..... __________________ JCM 900-4100 JCM 800-2204 1960A/G12T75 1962RI Stratocaster

07-10-2009, 02:09 PM	#10 (permalink)
pleximajor Member Join Date: May 2009 Posts: 41	Re: JCM 2000 blown by Hot Plate so what if you are playing live and the sound guy says your to loud with master on 3... thats where hot plate comes in ...you dont have to use attenuator just on none mv heads....and you dont have to crank your amp on ten when you use one.... if tubes are old and bias is not set or if you dont hook up right you will blow tube and crap in you amp...you have to keep an eye on your tube wear and not just throw a hot plate on a amp that has year old tubes and wonder why it blew

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