Why does my 4x12 Marshall sound like ass?

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Killcrop

Active member
I have a JCM800 4x12 slant cab. I loaded it with a quad of G12K85s. Killer speakers. But the cab sounded like shit. No punch to it at all. I thought maybe my memory of those speakers ins't that good. So I loaded a pair of Vintage 30s along with Greenbacks in an X pattern. All UK speakers. Good stuff right? Re-wired with premium wire.
Well the cab still sounds shitty. What gives? Do I just not like 4x12s? Is it a phasing issue?
 
Hard to tell without being in the room - Do you know for sure the amp sounds good on another cab, and you haven't moved rooms/changed anything in the room?

Clip would help
 
Remove the back of the cab and plug in a speaker cable - on the exposed end of the cable, touch the tip to the + Terminal of a 9V battery and the sleeve to the - Terminal. That will show you in an instant if any of the 4 speakers are out of phase. All 4 cones should push forward when contact is made. Out of phase speakers will pull inward when contact is made. I learned this the hard way having 2 sets of speakers that sounded like ‘ass’ in my 4x12. Sure enough, the top 2 were out of phase. I reversed the wiring on the top 2 to get them in phase and the cab sounded glorious. (No telling how good the first set of speakers would have sounded wired in phase.) Oh well. Live and learn. And pass on whatever knowledge you can along the way!
 
I have the Marshall BV with made for Marshall v30s, they are based off late 80s early 90s v30s . Anyhow. It’s huge sounding and great . But sometimes some heads just react odd . My Hermanson Recto sounds amazing in my Diezel and Bogner and Randall cabs . But it just reacts weird and shitty with my Marshall cab . It’s just odd
 
Killcrop said:
I have a JCM800 4x12 slant cab. I loaded it with a quad of G12K85s. Killer speakers. But the cab sounded like shit. No punch to it at all. I thought maybe my memory of those speakers ins't that good. So I loaded a pair of Vintage 30s along with Greenbacks in an X pattern. All UK speakers. Good stuff right? Re-wired with premium wire.
Well the cab still sounds shitty. What gives? Do I just not like 4x12s? Is it a phasing issue?
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Did you just buy the cab? If not, did it sound much better before? Check the ohms of the cab by plugging in a speaker cable and measuring with a multimeter. Sometimes the speakers are mislabeled and aren't what you think they are ohm-wise. Pretty rare but it has happened.
I've bought 3 blackback cabs from the 70s and all 3 sounded like ass. Sometimes, the speakers are shot or the cab has been stored in a place where it absorbed a lot of moisture; putting it outside on a hot dry day can help.
 
Could be a few things. Then again, Marshall cabs are built with pretty loose tolerances, so it could also be leaking air.
 
I had a Marshall 2x12 that started sounded pretty rough. Turns out that every single screw and bolt in it was loose and the thing was about to come apart. I only ever play it at full band volume, so it gets a workout. Once I cinched everything back down, it sounded great.
 
Does it have the plate/board in the back with the stereo/mono switch?
Ive seen 2 of those go tits up over the years, got thin and ratty sounding.
I always take those out and hardwire everything to 1 of the jacks
 
Killcrop said:
I have a JCM800 4x12 slant cab. I loaded it with a quad of G12K85s. Killer speakers. But the cab sounded like shit. No punch to it at all. I thought maybe my memory of those speakers ins't that good. So I loaded a pair of Vintage 30s along with Greenbacks in an X pattern. All UK speakers. Good stuff right? Re-wired with premium wire.
Well the cab still sounds shitty. What gives? Do I just not like 4x12s? Is it a phasing issue?
Click to expand...

Have you inspected and thoroughly tested each speaker (the V30's and the 85's) individually before wiring them all together? You may possibly have one that's bad, affecting the overall sound of the cabinet.

I agree with JTyson. If you have the switching plate, that's most likely the culprit. Another way to check if it is the actual cabinet, is, (if possible) without undoing any of the wiring, including the plate, swap all four speakers (both V30's and the 85's) into a different 4x12. If it sounds much better, then the JCM800 4x12 slant is the culprit. If it is the cab, there are many things to consider as to what is going on

I hope you get it figured out, hit me up with any questions.
 
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Techdeth said:
I have the Marshall BV with made for Marshall v30s, they are based off late 80s early 90s v30s . Anyhow. It’s huge sounding and great . But sometimes some heads just react odd . My Hermanson Recto sounds amazing in my Diezel and Bogner and Randall cabs . But it just reacts weird and shitty with my Marshall cab . It’s just odd
Click to expand...


Just fyi, they ARE the original V30, not the other way around.
 
Killcrop said:
Amp sounds killer through my 2x12 closed back with a V30 and Cream 65
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This all but confirms a phase issue with at least one - and likely a pair - of the speakers in your 4x12.

BTW - the 65 Watt M Creamback / V-30 pairing is one of the absolute best speaker mixes going.
 
PDC said:
This all but confirms a phase issue with at least one - and likely a pair - of the speakers in your 4x12.

BTW - the 65 Watt M Creamback / V-30 pairing is one of the absolute best speaker mixes going.
Click to expand...
I will test with the 9v today. But the G12k85s that also sounded like ass came from a 4x12 cabinet. Seems like a quad of speakers would be tested for phase issues. They were in a peavy cab that I garbage picked. The cab was a loss due to cat piss but the speakers were great.
 
Just to confirm, a phasing issue is not a flaw or a problem with the speaker itself - phasing just has to do with the direction of current through the speaker. If you find that any of the speaker cones pull in toward the magnet when the 9v is feeding current through the speaker cable (tip +, sleeve -) then just reverse the wires (+/-) on that speaker.
 
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