Dual Rectifier not agreeing with JCM800 cab

[act1021]

My dual rectifier makes my cab (Marshall JCM800 1960B straight) bottom out like crazy. I tried messing with all the controls, bass mid treble etc. but no matter what when i palm mute the whole thing makes this terrible bassy buzz noise. I thought i read something about this specific combination being known to do this, but ive been searching this board and all over the web for like a week and i cant find anything about it. I hope this isnt a redundant post but I swear ive read something in the past on this. Maybe someone knows what im referring to, thanks.

 

[Guitarzan]

That shouldn't happen... Have you checked to see if a speaker is coming loose inside the cab?

 

[act1021]

Yeah, it sounds great with my marshall 8100 valvestate head, and i plugged the DR into my buddies berhinger cab and its still a little bassy but not to the point where it feels like damage is being done to the speakers.

 

[Guitarzan]

look inside.

 

[act1021]

Well, it was recently fixed, like probly a week ago, one of the EL34 tubes cracked and me not knowing this turned it on and the power just blew half the thing out, but i had it serviced and even before that happend it was overly bassy, im new at these tubed amps and ive heard about people removing tubes to lower the wattage??? maybe that has something to do with it

 

[Guitarzan]

You're going about it the wrong way.
1.Check the cab first.
2. What kind of tubes were put back in?
3. Yes you can run with two tubes on a DR remove the two inner tubes. 4.Was only one tube replaced?

 

[ibanez4life SZ!]

You said you had EL-34s in there....were 6L6s put back in afterwards? If so, they are going to be much bassier than the EL-34s...

Check the cab....sounds like something is wrong with the speakers.

 

[Charlie]

I had a problem with my 73 Marshall cab years ago maybe it's the same problem.

Here's what was happening - There is a wooden post, inside the cab in the middle, that goes from the front to the back and rests up against the back panel of the amp. When I would play low notes on the E string (palm muting a low G was when it happened the worst) the panel would vibrate up against the post and make a really nasty, low thumping/ vibration. I ended up drilling a hole through the back of the cabinet and secured the panel to the post with a really long wood screw and it's been fine ever since.

It's hard to know what is going on from your description but I figured I'd post this just in case it's the same thing.

 

[dumeril7]

I had a problem with my 73 Marshall cab years ago maybe it's the same problem.

Here's what was happening - There is a wooden post, inside the cab in the middle, that goes from the front to the back and rests up against the back panel of the amp. When I would play low notes on the E string (palm muting a low G was when it happened the worst) the panel would vibrate up against the post and make a really nasty, low thumping/ vibration. I ended up drilling a hole through the back of the amp and secured the panel to the post with a really long wood screw and it's been fine ever since.

It's hard to know what is going on from your description but I figured I'd post this just in case it's the same thing.

+1. That's a real common problems with Marshall 4x12s (and that's exactly how most folks fix it). I'd speculate that it only happens with the DR because those amps have a lot more low-end grunt than the Valvestate.

D7

 

[siggy14]

also make sure every screw is holding the back panel on, i had the same problem because i was missing half the screws off the back of a marshall cab and it was not sealing right. You can get the screws and the eyelets at home depot for cheap.

 

[lailer75]

i would also tighten all screws, speaker, handles, and the back. if its an "800" i`m sure it needs it.

 

[Kung-Fool]

Yep, listen to these guys. Either your speakers are loose or your back panel is vibrating against the cross brace. Easy fix.

 

[Russ]

Yep, listen to these guys. Either your speakers are loose or your back panel is vibrating against the cross brace. Easy fix.

So true...

I have 4 Marshall cabs currently and always check the fasteners if I hear a little rattle or strange woof.

 

[SneakyPete]

I had a problem with my 73 Marshall cab years ago maybe it's the same problem.

Here's what was happening - There is a wooden post, inside the cab in the middle, that goes from the front to the back and rests up against the back panel of the amp. When I would play low notes on the E string (palm muting a low G was when it happened the worst) the panel would vibrate up against the post and make a really nasty, low thumping/ vibration. I ended up drilling a hole through the back of the cabinet and secured the panel to the post with a really long wood screw and it's been fine ever since.

It's hard to know what is going on from your description but I figured I'd post this just in case it's the same thing.

I had the same problem with my Mesa traditional 4x12 cab. Instead of the wood screw, I had some foam rubber that I packed in there between the post and the back of the cover- deadened the vibration nicely

 

[Russ]

I had a problem with my 73 Marshall cab years ago maybe it's the same problem.

Here's what was happening - There is a wooden post, inside the cab in the middle, that goes from the front to the back and rests up against the back panel of the amp. When I would play low notes on the E string (palm muting a low G was when it happened the worst) the panel would vibrate up against the post and make a really nasty, low thumping/ vibration. I ended up drilling a hole through the back of the cabinet and secured the panel to the post with a really long wood screw and it's been fine ever since.

It's hard to know what is going on from your description but I figured I'd post this just in case it's the same thing.

That is another fix. Some have used rags attached to the end of the brace just to put a little pressure on the back panel in past years.

I had the same problem with my Mesa traditional 4x12 cab. Instead of the wood screw, I had some foam rubber that I packed in there between the post and the back of the cover- deadened the vibration nicely