Marshall JVM 410h and flub through different 4x12's

[mrmega]

Hi all!

I have (2) Marshall JVM 410h heads. All my 4x12 cabs are about 12 to 15 inches from the wall in my music room. Whenever I play high gain the bottom end sounds flubby (Not in hard rock gain amounts or below). Happens with both heads. Doesnt matter which cab I use (Marshall 1960 a, Marshall 1960B, Vintage Modern Straight, Vintage Modern Slant, EVH 5150III).

This also happened in my studio tracking room years ago. Cabs were about the same distance from the wall.

I dont get this behavoir from any other higher gain amp (Peavey 5150, Marshall Vintage Modern, Marshall JCM 900 Dual High Gain Reverb 100w, EVH 5150 100 w Stealth, EVH 5150 EL34s 100s).

I put a 55" TV in a box behind a cabinet that was touching the cab and the wall to get it out of the way. Sometime later I played through the JVM410h. The Flubbiness went away and it was nice and tight again. Removed the TV and the flub came back.

Last time I bought a JVM 410h I tested it through an EVH 2x12 that was in the middle of a Guitar Center guitar section, I didnt get the flub. It was nice and tight.

I havent heard any clips online that repicate this behavior.

I talked to A.I. and it basically said that my cab was too close to the wall for the JVM410h because of the way the JVM410h is voiced and the design of the tone stack and the nature of its resonance controll that something funky was happening witht the sound waves causing the flub. Was A.I. right?

Has anyone else experienced this?

For those who own this amp, how far away is your 4x12 from the wall? What do you hear?

Exactly what's happening?

What else would you like to say?

 

[Mike Oxhuge]

The room is reacting to the bass frequency depending on cab position related to the wall. Try moving the cab closer or farther and it will change. Also the effect is most pronounced in a corner hence why most home theater subs are recommended to be placed in a corner.

 

[tjnx]

^ The dimensions of the room and that particular frequency are likely creating a standing wave, meaning the reflections both forward and back are lining up so that they don't disperse and are likely creating constructive interference resulting in amplifying that particular tone.

The cabinet actually radiates in all directions with low frequencies "surviving" the radiation the most. Higher frequencies have shorter physical wave lengths so they can become out of phase easier when you listen off axis. This one reason is why 412 and 212 cabinets beam, losing highs off axis




The tv is likely creating an earlier reflector in the rear so it travels a shorter distance and doesn't add to the far wall reflections from the front of the cab. If its angled against the wall its likely shooting it up to the ceiling a little to help the reflections cancel out.

If you look up room modes you can find out more.


tldr: move stuff around or add obstacles

 

[angelspade]

The JVM410 is not a loose or flubby amp in my experience. It's as least as tight as a 5150...Something else is going on here. It's difficult to say without being in the room.