How to improve a 1960a Marshall cab

[billyz]

Today I am picking up a jcm900 cab. The last 4x12 cab I had was a late 60's with g12h speakers, it was good and I wish I still had it. I'm getting this new /used one cause it's cheap and I need a bigger shop cab for the bigger amps I am getting in. Seems Washington has a lot of heavy loud musicians.
Anyway, any suggestions? I think I'll change a couple of the speakers at least and improve the input jack and wiring. Maybe add some dampening and either replace or stiffen the back. It is loaded with some crappy gt75 celestions.
I don't want to turn it into a super custom modded cab loaded with the finest. But want a good all around sounding 4x12. I will probably replace the impedance switch with a heavy duty system, but do want to be able to switch impedances. My inclination is to pickup some used celestions . Any preferences? Like anniversaries ? Vintage 30's well broken in? G12m? Avatar is close by and I see a few of his hellatone celestions for a good price.

[rp]

The G12H30Anni, at least the '90s UK ones I'm familiar w/ are a hell of an all arounder, seem to work well with everything. Not sure if that's a plus or a negative with amp testing. Not sure you'd want 4 of them either, but mixed speakers for evaluating might be confusing too. Just can't go wrong w/ a 4x12 of broken-in 90s greenbacks which can be found used for $70. Little dark and early break up might be a problem for shop cab but it's a sound people know and love. What I like about the GBs is that they're ~97db not 101-103 like all the Eminance, WGS, etc these days.

Best maybe a quad of older G12-65s? A quad of the new but expensive UK made ones if they are still good as old ones? Again it's a sound everyone knows and loves.

Edit: on a budget used well broken in V30s are good all arounders too and like $50 as people think they're generic and shredder speakers.

[billyz]

I had a few Jubilee series , actually 3 full stacks at one time. I was renting them out. Anyway everyone was in love one of the cabs, it had some special celestions in it, but I do not remember what they were. Anniversary or vintage 30 maybe. the others had 75's i am pretty sure. Anyway, that one cab was the one, I had stuffed it with insulation too and wired it. one of my competitors who was doing the PA at a 3 day festival asked me what was so special about that cab, because all the guitarist were fighting to use it. When I told him he scoffed and said you cannot do that to a marshall cab, ( stuff it). Wish I could remember what those speakers were. I bought them all from Steve at angela instruments, they were part of some big tour and he sold them to me pretty cheap.

[billyz]

I really don't like these g12t75 speakers. They have got to go. I rewired with heavier wire and it just brought out the worst in these speakers. Very scooped , kind of hollow sounding. I want Cream . The cab seems ok apart from the plastic. I beefed up the input panel by soldering over all the traces. The center post fell of when I barely bumped it. Took it out and glued and nailed it, pretty sturdy now.

[Gibsonman63]

Beyond speakers, I believe that Miles had a trick for tuning the sound post that involved removing a handle and putting a wedge between the post and the back to get the tension just right to produce the right thump. I don't remember if the post was here or at Metro.

[Scumback Speakers]

I really don't like these g12t75 speakers. They have got to go. I rewired with heavier wire and it just brought out the worst in these speakers. Very scooped , kind of hollow sounding. I want Cream . The cab seems ok apart from the plastic. I beefed up the input panel by soldering over all the traces. The center post fell of when I barely bumped it. Took it out and glued and nailed it, pretty sturdy now.

BillyZ: What you experienced is typical of my experience with these cabs. You can put tolex, rubber or some other type of material over the end of the sound post to tighten and tune it to taste. Or you can cut a whole new one that's 1/8-3/16" longer so it bulges the back panel out slightly for the same effect.

As for the speakers, up to you, whatever you prefer tonewise. I'd imagine those plastic handles are ready to start being an issue in the near future from cracking corners, etc.

Shoot me an email if you like, I'm about to clear out the shop of old G12M's that have been rebuilt to Scumback M75 or BM75 specs, and I also make replacement metal handles for your plastic ones so you don't get that "rattling" sensation. I'll cut you a deal on all of it if you're interested.

[billyz]

Jim,
Emailed you just now. Thanks. Always liked your speakers.
They have the tone.
Z

[Scumback Speakers]

Jim,
Emailed you just now. Thanks. Always liked your speakers.
They have the tone.
Z

Didn't receive your email, maybe it got mis-typed.

sales@scumbackspeakers.com is what you should be sending to.

[billyz]

Sent another one. The first one I used the email button at the bottom of your post. This one I copied from your link.

[Scumback Speakers]

Sent another one. The first one I used the email button at the bottom of your post. This one I copied from your link.

Thought I'd fixed that previously. I just did now...sorry.

[billyz]

Jim,
Good talking to you. Looking forward to getting this 1960a jcm 900 sounding decent. I know the pcb is trouble , hence the reason I soldered over
All the traces . I am hoping to use it though for the impedance changes. I'll put the m75 on one side and the m55 on the other so I can switch them on or off. The metal handles are well metal and not cracked up cheap plastic.
Z

[billyz]

Got the speakers today. I only looked at one and compared it to the g12t75. The frame on your celestion is thicker . I tapped on each and the 75 has a tinny tinky tone, yours has a thicker darker tone and does not ring.
I thumped the cones and the scumback cone sounds deeper with a clarity of sound, the 75 sound raspy , slightly higher pitch and almost rattles.
I'll report after I get em in. I decided to regrill it with Marshall check .

[billyz]

Loaded with scumback recones . 2 greenback m75's 2 blackback m55's .
Regrilled with large check. Added Scumback metal handles and rewired with 16ga. Added a few more features. reglued all the edges and battens etc.

[IMG768]http://i1039.photobucket.com/albums/a471/kingsnake54/Marshall/IMG_2521.jpg[/img]

[IMG:768:1024]http://i1039.photobucket.com/albums/a471/kingsnake54/Marshall/IMG_2519.jpg[/img]

[IMG768]http://i1039.photobucket.com/albums/a471/kingsnake54/Marshall/IMG_2433.jpg[/img]

[IMG768]http://i1039.photobucket.com/albums/a471/kingsnake54/Marshall/IMG_2522.jpg[/img]

Test to come.

[billyz]

I have had time to Put this cab to work testing various amps. Even tested two amps at once . It sounds really great . I do prefer the m75 greenbacks but the mix is sweet n fat. Most everybody that comes Over to pick up their amp oogles it. The regrill does look like that 70's show.
Just tested a rebuilt 66' bassman through it at 4 ohms , the owner said his speakers (stock 2x12 fender small cab) sounds like a turd compared to it.
Tested a 61' 6bq5 tremolux with it to diagnose a jbl in the tone ring cab.
Wow, did not know two 6bq5's could be that bold.
Decided the jbl d110f suffered from the usual jbl chrome dome cry. The jbl was good at low volume but turn the amp up and it did the thing I don't like about jbl's.
Anyway, the cab and speakers are my new best shop test speakers. I hope
The jack plate holds up cuz its impedance Options are just what I needed.

[ampmike]

Hey B,I want to find a marshall 4/12 this year and wanted to know if the newer ones are made of birch ply or partical board.I have a 2/12 thats mayby 10 years old and its flake board inside,but it sounds great.I just didnt know if marshall stuck with plywood as a standard or not.There is something in the sound of a 4/12 that makes my wrecks sound the best.I have a borrowed one here.Also the slant like yours is what Im after as well.Your cab is exactly what I would like to get,love the grill cloth.Mikey