Marshall cabinet Particlebaord Back- Disgusting

[Boozer58]

Ive got two 70's Marshall Checkerbaord Cabinets. Both have particlebaoard backs. Disgusting!.
I am cutting new plywood backs for both of them.
I will save the original backs for value purposes, but they will have new plywood backs for all my Marshall cabinets( 4 of them).
Particlebaoard sucks, and had NO place in tone!

 

[Zerberus]

Re: Marshall cabinet Particlebaord Back- Disgusting

While I agree that it isn´t the best material, one thing is certain: they won´t sound the same with plywood backs. The particleboard back is part of the charm of many Marshall cabs, from a tonal perspective.

Please don´t ask me what the tonal differences are, as I´m neither a Marshall cab user nor somebody who knows much about cabs in general. I have my custom 4x12 and it crushes, everything else is just trivia for me

 

[ratherdashing]

Re: Marshall cabinet Particlebaord Back- Disgusting

Did you actually bother to listen to them before deciding that the particle board was crap?

 

[butnut]

Re: Marshall cabinet Particlebaord Back- Disgusting

Hey Boozer, dig yer avatar! My Marshall cab has particle board, the cab rocks! I just had a buddy 'polish the turd' so it does'nt look so particle boardish...:approve:

 

[d1dsj]

Re: Marshall cabinet Particlebaord Back- Disgusting

I agree in as much as it's lousy to pay so much for a cab and find THAT back panel. I sold my purple Hendrix R.I cab for that reason... my beef was that on taking the back panel off to check the speakers I found it had broken in 2 places! I now wish I had kept it and replaced the panel. My mate has since had a JCM 900 cab he has replaced the back with a 12mm plywood back, we both agree the plywood back sounds livelier, better to our ears.

 

[korovamilkdud]

Re: Marshall cabinet Particlebaord Back- Disgusting

I suppose the sound wouldn't be much different from swithing from an alder body guitar to a mahogany guitar. Harder woods absorb less sound, should add a bit of spoink and punch to the tone. If that's what you want. I know that that's also not quite what Marshall cabs were really designed to do. The marshall amps are bright, so the cabinets are dark. Makes sense to me. Particle board is a nice, soft wood that will reign in some of those highs.

 

[Lake Placid Blues]

Re: Marshall cabinet Particlebaord Back- Disgusting

It's been that way since about 1970, and many think that it was done for tonal reasons rather than to cut costs.

A Hendrix cab should have plye though to be period correct.

FWIW, the early cabs up through at least 67 also had foam inside the cabs and the early grill clothes had a built in beam blocker effect, not being tonally nuetral.

Once they stopped using the foam inside the cabs they may have needed a design revision that would dampen standing waves inside the cab?

 

[Laughing Kookaburra]

Re: Marshall cabinet Particlebaord Back- Disgusting

Once they stopped using the foam inside the cabs they may have needed a design revision that would dampen standing waves inside the cab?

Interesting thought. Many of the older cabs, early 70s and back, had foam, or insulation inside. These cabs (Sunns, Kustoms, etc.) were all plywood.

However, I've read that the insulation inside a cab does something to the sound waves that simulates a larger size cab. Is that the same thing you're talking about?

 

[Lake Placid Blues]

Re: Marshall cabinet Particlebaord Back- Disgusting

Well a standing wave in simple terms are waves bouncing around inside the cab. It could be too boomy, or too much of a saw toothy top end attack, or create possible phase cancellation issues.

I have heard that foam stuff helps simulates a larger cab as well. I'm not sure what a true larger cab would sound like in comparison though?

I do know the effect it had on my Marshall 4x12 straight cab when I put foam inside it. It made it noticably warmer and smoother. I eventually settled on using it on the back mainly and leaving it off the top and sides. I thought it struck a nice balance between warmth and liveliness this way. It didn't make the bottom end flubby.

I don't think you ever want to subdue too much the effect of the wood vibrating in a guitar cab, but you may want to control it or tune it some. This may be the underlying rational with the use of the PB back plate- for now almost 40 years?

 

[glassman]

Re: Marshall cabinet Particlebaord Back- Disgusting

MDF (medium density fiberboard) has a resonance that is below the low cut-off frequency of the cabinet; this makes it so the box doesn't color the tone of the cabinet. Plywood has a higher resonant frequency and differs by species of wood used and the thickness of the panel. The effect of using a panel that is resonant in an audible frequency is that the cabinet absorbs this resonanant frquency instead of projecting it; effectively cutting that frequency range. This would work with a scooped mid tone if the resonance was in the desired range...this would take some experimentation. A foam backing would help but it would be an attempt to get the cabinet back to what MDF is already doing. MDF + foam would serve to liven/sweeten up the mids/highs like LakePlacidBlues said.