Halfback metal grill slant 4x12 questions?

[SnS77]

Hey guys,

Been running a Mark IV widebody w/EVM-12L and a thiele (EV) for a few years now and absolutely love it. It is THE sound to my ears. Though, I have noticed at gigs lately that the sound doesn't disburse like a 4x12 so I have been keeping my eyes peeled for one around my area.

Lo and behold I found a cab. THE cab. Its a Mesa 4x12 halfback metal grill slant with four EV's, casters, cover, the whole deal. Only thing was when I demo'd it only the bottom two speakers were working, not the top two? Anyone ever have a similar experience? If so, what would cause that? Took the back off and seemed to be wired correctly to the rear jack, but I am more of a player than a gearhead so im not very handy or knowledgeable of electronics.

Also the speakers seemed to be very dusty around the edge -- almost like they were deteriorating very slightly around the edges of the cone, but not ripped, cracked, or punctured in any way. Is this something I should be concerned about or typical of an older speaker? (sorry no pics, no smartphone or digital camera)

Was the 4 EVM's a stock option, special order, or did they swap out the top two to put those in? I'v only ever heard of them being on the bottoms.

Last question. Who has one of these paired with a Mark series and how awesome is it?

 

[Audiokill]

Not very likely that the top speakers are both completely fried. They're probably ok, especially if they're EVs. It sounds like you may have a bad electrical connection somewhere. Unscrew the back panel and look for any loose wires around the jack or speakers. If you don't see anything obvious, you'll need a voltmeter to test for electrical continuity, or find a friend who knows how.

It's normal for old speakers to have collected a good amount of dust around the bottom edge of the cone. If you're careful, you can clean it out yourself. Hopefully there's no actual damage. Either way though, that shouldn't be affecting the sound, or rather lack thereof.

The EV quad combo was one of 3 stock speaker options you could select from, so they're most likely the original speakers. I used to own the exact same cab. I played it extensively with a Mark IV and a C+. I really liked it at the time. Cleans in particular were pretty darn amazical. 75 and 85 watt amps don't pull much crunch out of 800 watt cabs though, and eventually I started wanting a little more color/character out of my speakers...wanted them to interact with the amps more by adding to the tone rather than just faithfully reproducing the amp's tone only. I ended up trading it in for a 4x12 with V30s. Still, I kinda wish I hadn't sold it.

 

[gts]

Audiokill is right on target, the four EV's are most likely original as these 4x12's came this way as well as with a few other speaker configs
EV12L's, C90's, MS-12's, VS-12's, mixed and matched in various combinations.
He's also correct about the dust etc. With the open metal grille they can/ do get dusty over time.

Imho they sound great with Mark series amps. Bit of a beast to lift as each EV weighs ~20lbs hopefully it has casters.
As for the top two not working, yeah pull off the bottom panel.
The top two as well as the bottom two speakers are usually wired directly to the input jack. They might be disconnected.

You can see it in these pics.
Yes, different speakers in this 4x12 but the wiring would be the same.

 

[SnS77]

Thank you guys for the replies, I really appreciate you guys and this board in general. The seller emailed me back and said the voice coil was frozen on the one speaker and he was sending it out to Parts Express to be replaced. I will update the thread as this unfolds. Not giving up YET, I really want this speaker cabinet.

 

[morgan138]

Since the top two and bottom two speakers are in series with each other, I think that if one blows it'll break the circuit and cause the working speaker to stop getting any signal. So it makes sense that both would be silent even though only one is actually dead!

 

[SnS77]

Update: Heading to grab the cab tonight around 615. Speaker is fixed, cab is wired up and ready to go. This one has a small single countersunk input jack, looks old school. Anyway, and I am showing my ignorance here.. I know a single EVM cab is 8 ohm, and when running 2 single extension cabs you run two separate 4 ohm leads out of the back of the Mark iv, but what impedance do I plug into for the 4xEVM-12L cab? I will be disconnecting the combo's speaker, essentially using it as a head. I cant find anything online, and the way this is wired (series i believe) is screwing up how how I figured out Ohms settings in the past? So ya, which output should I use on the Mark Iv to run the EVM 4x12 cab? Same old boring questions I know.. My current setup is a Mark Iv combo w/EVM (3/4 back) on top of an EVM thiele, so I'm guessing/hoping it will sound similar but with better sound disbursement. Doing a show with Agent Orange on Thursday, excited to bust out my new toy! Will post review after I get a few hours alone with her

 

[gts]

Update: Heading to grab the cab tonight around 615. Speaker is fixed, cab is wired up and ready to go. This one has a small single countersunk input jack, looks old school. Anyway, and I am showing my ignorance here.. I know a single EVM cab is 8 ohm, and when running 2 single extension cabs you run two separate 4 ohm leads out of the back of the Mark iv, but what impedance do I plug into for the 4xEVM-12L cab? I will be disconnecting the combo's speaker, essentially using it as a head. I cant find anything online, and the way this is wired (series i believe) is screwing up how how I figured out Ohms settings in the past? So ya, which output should I use on the Mark Iv to run the EVM 4x12 cab? Same old boring questions I know.. My current setup is a Mark Iv combo w/EVM (3/4 back) on top of an EVM thiele, so I'm guessing/hoping it will sound similar but with better sound disbursement. Doing a show with Agent Orange on Thursday, excited to bust out my new toy! Will post review after I get a few hours alone with her

A 4x12 cab is typically 8 ohms.
With all four speakers being 8 ohms and wired in a combination of "series/ parallel" the end result is an 8ohm load.
Plug it into the 8ohm speaker jack on your Mk-IV
(I am assuming no other speaker cabs are being used just the 4x12.)

 

[SnS77]

Cheers guys. I wanna do a review and compare it to my previous setup (Thiele w/EVM + Mark IV widebody w/EVM) but I don't have enough time with the cab yet for my review to be worth wile. I am thinking I'm gonna try to close the top of this thing up. Closed back just seems to work out better with my band's sound, and this thing is only used live for obvious reasons! So I asked around and I guess 14 ply Baltic birch is what mesa uses? Can anyone validate that? I'd like to use as close to the same wood as the rest of the cab if possible. Is this the type of wood you can get at a hardware store or is this something I am going to have to find/order? Also, when I close up the back should I put a "gasket" in between my new top piece and the rest of cab? Appreciate it as always

 

[gts]

I am thinking I'm gonna try to close the top of this thing up. Closed back just seems to work out better with my band's sound, and this thing is only used live for obvious reasons! So I asked around and I guess 14 ply Baltic birch is what mesa uses? Can anyone validate that? I'd like to use as close to the same wood as the rest of the cab if possible. Is this the type of wood you can get at a hardware store or is this something I am going to have to find/order? Also, when I close up the back should I put a "gasket" in between my new top piece and the rest of cab?

Baltic Birch probably wasn't used on any of the old Metal Grille 4x12's.
Just look at the pics of the 4x12 I posted and you'll see it wasn't.
I've re-tolexed a few of them and none that I re-tolexed were made with Baltic Birch.
This said it's highly unlikely yours was made with it.

Fwiw I doubt there would be significant sonic/ tonal differences if you used Baltic or some other 3/4" plywood for a top back panel.
(even if your 4x12 had been made with Baltic Birch).

As for where to buy it: A specialty hardwood lumber yard. These typically sell various hardwoods and high quality finish grade veneered plywoods.
Maybe, just maybe you might find Baltic Birch a regular lumber yard.
But bottom line you don't need Baltic Birch to make a top panel for your 4x12.
Any decent grade (perhaps an A/C grade) 3/4" plywood would work.

Imho you don't need a gasket either.
Take the bottom panel off your 4x12 and see if there is one there. Probably not!

Fwiw the "three quarter" Baltic Birch Mesa uses is 13 ply and measures around 0.70"-0.71" thick. So it's not really 3/4" thick

 

[Nathan2k]

What happened, PLEASE!! I am running into the same midrange tones running the Dual Rectifier. Will be taking it apart to see what speakers are on the bottom.
Just from the little i know about speakers and having both closed and open back, closed sounds "tighter". Did closing the Halfback work with your tone?