JCM 900 4x12 Build Quality? 13ply Birch or MDF?

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JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by harddriver » Fri Apr 24, 2009 12:03 am

I had a JCM900 2x12 1936 cabinet, it was all MDF! It was the most lifeless tonesucking cabinets I ever had. Had is the operative word! :lol:

What was Marshall using for their JCM900 4x12's during this time period for materials? 1990's until?

MDF? or 13ply Baltic Birch?

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Re: JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by RACKSYSTEMS » Fri Apr 24, 2009 2:26 am

birch till this day. They have a particle board back though just like 70's cabs
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Re: JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by paulster » Fri Apr 24, 2009 3:48 am

The 1912 and 1936 have been MDF for some years (were they ever ply?), so they're not representative of the corresponding 4x12s.

I'll concur with tonesucking comment. Absolutely lifeless.

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Re: JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by 62sg » Fri Apr 24, 2009 4:31 am

paulster wrote:The 1912 and 1936 have been MDF for some years (were they ever ply?), so they're not representative of the corresponding 4x12s.

I'll concur with tonesucking comment. Absolutely lifeless.



I believe the 36 was birch ply when they were 1st introduced...not sure about the 1912....also, isn't the 1922 [compact 2x12] also MDF?
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Re: JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by paulster » Fri Apr 24, 2009 4:45 am

John

I think you're right about the early 1936 cabs being ply; that jogged my memory. I wonder when they changed then, as a ply one of these could make for a nice compact cab.

I've never seen a 1922 up close and personal but I'd say for sure that they'll be MDF now unless they're a complete exception to the rule.

I've just dug out Doyle to have a browse and, according to him, the 1936 was introduced in 1986 whereas the 1912 and 1922 were introduced alongside the JCM900 series in 1989, so the lineage is slightly different.

It would be interesting to know when the change occurred and indeed whether the 1912/22 were ever available in ply construction as they'd be useful cabs to have the odd occasion, whereas the current MDF ones aren't!

Paul

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Re: JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by 54strat » Fri Apr 24, 2009 9:04 am

The 1936 started out as ply with MDF back. I have one purchased new in 1976 that I am still using.
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Re: JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by harddriver » Fri Apr 24, 2009 12:00 pm

Thanks for the info on these guys! I do remember reading somewhere that the early 1936 and 1922 were Birch plywood at some time and not 100%MDF.

I tried every speaker in that cab thinking it was my speakers, NOPE, the cabinet just plain sucked! Muddy with absolutley no bounce! :roll:

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Re: JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by paulster » Fri Apr 24, 2009 12:39 pm

harddriver wrote:I tried every speaker in that cab thinking it was my speakers, NOPE, the cabinet just plain sucked! Muddy with absolutley no bounce! :roll:
That's why there's a 1912 with a Scumback M75 sat in my storage unit, because even the Scumback couldn't rescue it! It's awful.

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Re: JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by novosibir » Fri Apr 24, 2009 3:32 pm

I have an early 90's 1912 cab with a '81 15ohms G12-65 in it. It's completely MDF and the sound is ~ok~, though not convincingly. But I don't care too much about it, because it's only my quick test cab and I know, that everything what sounds acceptable through this cab then sounds great through my mid 70's 4x12" :D

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Re: JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by jester » Tue May 19, 2009 8:55 pm

MDF sucks, birch is good if you have a birch baffle, Alot of the marshalls and other manufactures have swapped to MDF baffles.
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Re: JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by Scumback Speakers » Tue May 19, 2009 9:13 pm

1912, MDF.
1922, MDF.
Early 1936 (JCM 800 era at least), plywood.
Later 1936, MDF.
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Re: JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by bdc » Sat May 30, 2009 5:04 pm

I completely disagree with the premise of this thread.......Though I agree birch ply is a better quality material and is more durable than pressboard......I contend that the dimensions of a closed back cab and it's dampening have far more to do with it's tone..than the quality of the wood...The number one rule in a closed back cabinet is that you don't want it to resinate.....Thats why they are braced. Some players prefer Peavey cabinets to Marshall because the pressboard offers more dampening. Theres some sreious snake oil sales going on here IMO. The demensions of the cabinet as well as the speaker choice have everything to do with it's sound. The demensions determine the airflow and speaker movement which is paramount to tone. Those who didn't like the 1936 cab didn't like it for it's dimensions..The dimensions do indeed offer certain limitations....
The resonance of these cabinets can be dampened and improved opon by insulating behind the plastic handles. Try adding a couple braces, or insulating!
Another huge factor is the speaker choice, those cabinets came out with G 12 75s. A speaker that sound best in a 4/12 and also at 75 watts it's hard to push
-a speaker that emphasizes highs and lows and scoops mids....A lot of guys don't like that speaker...I own a 1922, pulled the original speakers and installed a Hellatone 30 and an eminence GB legend series....Now it's ridiculous to expect a cabinet of these dimensions to sound like a 4-12 cab......It does however have it's own sound which works pretty damn good to my taste and a lot of other peoples who have heard me at gigs. I own a couple 1960s as well and love them but can't see lugging em' around....Tom Mitchell said in his book that the best cabinet would be made of cement because it wouldn't resonate at all. It is of course impratical but pressboard remains an excellent choice IMO......Now I personally might choose the higher quality birch cab, but not because i think that birch offers any tonal magic.......cause it don't....The reason they use void free in part is that it is less resonant! To each they're won I guess.....Lets not forget the number one thing really in the tone chain, and thats a guys ability to actually play a guitar......

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Re: JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by jbzoso2002 » Sun May 31, 2009 8:48 pm

:shock:
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Re: JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by beaulieu » Mon Jun 01, 2009 7:15 pm

I never really sat and compared a MDF cab to a Birch cab. I think the MDF might sound OK. I think when you are talkin guitar cabs alot of people do stuff thats a waste of time.I got a 1970 Marshall cabinet that some goofball used wood putty and RTV inside all the corners and the handles.Were talkin guitar cabinets...not bass cabinets. I would think haveing a 100% sealed cabinet would be more practical on a Bass cab and not a guitar cab.The most important parts about guitar cabs are the speakers and what its made out of. I just don't see how people think they are going to "improve" on something thats dosent need improving. Well speaker changes are fine but to take a Vintage cab and Hog it up with RTV and wood putty :? What was he thinkin??This thing was a mess inside. I really don't think a 4x12 cabinet with 25 watt speakers is going to benefit buy sealing up the handles and edges??
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Re: JCM 900 4x12 Build Quality? 13ply Birch or MDF?

Post by bdc » Wed Jun 03, 2009 6:39 pm

beaulieu wrote:I never really sat and compared a MDF cab to a Birch cab. I think the MDF might sound OK. I think when you are talkin guitar cabs alot of people do stuff thats a waste of time.I got a 1970 Marshall cabinet that some goofball used wood putty and RTV inside all the corners and the handles.Were talkin guitar cabinets...not bass cabinets. I would think haveing a 100% sealed cabinet would be more practical on a Bass cab and not a guitar cab.The most important parts about guitar cabs are the speakers and what its made out of. I just don't see how people think they are going to "improve" on something thats dosent need improving. Well speaker changes are fine but to take a Vintage cab and Hog it up with RTV and wood putty :? What was he thinkin??This thing was a mess inside. I really don't think a 4x12 cabinet with 25 watt speakers is going to benefit buy sealing up the handles and edges??
I have used silicone to stop handles from rattling.....
You don't want to record a cabinet with rattles
Or have your audience listen to your cabinet rattle.
The dimensions are more important than the materials......
You don't want air leaks in your Marshall cab, other than
maybe from an unused speaker jack. This stuff matters....
There are ways to do this stuff nicely......I've noticed rattles in lots of speaker cabinets.....Silicone and bracing can do wonders.......and dimensions have a ton to do with speaker movement and tone....It's that control of airflow.

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