Two basically identical Marshall 1960A cabs - totally different sound :/

[Setneck]

Hi!

Imagine two 1960A cabs from the same year (1996), so same speakers, same internal cables, same wood, aprox. same playing time, everything is totally the same. But both sound totally different.

One is very bright and in-front sounding, and the other is dark and dull, very muffled and muddy. The tone is like there's a blanket on the cab. I changed two upper speakers in that second cab for known good 75's - no change for better. The amp is Splawn Quickrod but similar impression was while using Bogner XTC.

What's wrong? Any solution for that second cab? Note that I want to keep the 75's there as their tone suits to what we play.

Thanks in advance, Andy

[pdf64]

The grille material; any differences on close examination? Is there a second layer underneath the outer grille on the muffled cab? Has the grille got laquered or painted?

[Setneck]

The cloth is identical, there is no second layer and the second cab isn't painted or lacquered. The cabs are technically totally the same.

Regards, Andy

[jrfrond]

The amount of use/wear on the speaker in each cab may be different, as the surrounds, spider and cones tend to get soft with age (there's a Viagra joke in there somewhere!), and also the cabinet resonance. Remove the backs of both cabs and bang on the sides with a tympani mallet or closed fist. No all plywood is created equally, just like any other wood product.

Even with guitars produced right next to each other on a production line, variables can and do happen. This is why some gear is just OK, and other seemingly identical gear is excellent.

[imaradiostar]

Are they wired the same? Series/parallel versus parallel series?

[big_teee]

I'm retired with lots of time.
I bought an old 4x12 Cab and it rattled when You played it.
I thought I had a bad speaker.
I unhooked the Wiring harness and played the speakers one at a time.
Nothing sounded too bad.
I took the speakers out one at a time.
Cleaned out all the dust and Caked on Dirt.
Blew out All the floating around Debris between the speakers and the grill.
I put it all back together and it played like a new Cabinet.
Not as dead sounding.
It must have been stored in a warehouse UnCovered!
Like John says must be the plywood.
Good Luck,
Terry

[Gtr_tech]

I'd check for a speaker wired out of phase. That'll make a pretty big difference in sound.....

[imaradiostar]

I'd check for a speaker wired out of phase. That'll make a pretty big difference in sound.....

Ooh, good point.

To clarify my post- I've read but never experimented with the whole branch inductance thing- supposedly a cabinet can be voiced darker or brighter by wiring pairs in series or parallel then wiring those pairs in parallel or series. Maybe it's bunk- I don't know!

jamie

[in a vacuum]

What gtr_tech is referring to is that if the speakers are wired incorrectly, they will cancel each other out. This is not a parallel/series issue. Speakers have a polarity. All positive leads need to go to positive terminals. Connect a 9-volt battery to the cabinet by touching one battery terminal to the tip of a speaker plug and the other to the shaft of the speaker plug on a cable plugged into the speaker jack of the cabinet. All the cones of the speakers should shoot forward, or backwards. If one of them goes the opposite direction, reverse the leads to that speaker. When speakers are out of phase they cancel each other out.

[Chuck H]

Imagine two 1960A cabs from the same year (1996), so same speakers, same internal cables, same wood, aprox. same playing time, everything is totally the same.

OK, but do you KNOW the speakers are the same? Have you actually checked? This whole thread is moot if you haven't. Otherwise...

Do check that the two cabinets are wired the same (series parallel OR parallel series) or for that matter check that both cabs are actually wired correctly so all speakers have the same load and the cabinet is presenting the correct impedance. And of course be sure you have correct polarity on all speakers.

IMHO the wood (as in 'the cabinet itself) isn't the problem. Both cabs use the same plywood, construction and dimensions. Any difference in the plywood density would be VERY subtle and even more subtle as an audible difference.

[Enzo]

Add my vote for checking speaker phasing. Just looking at the wires, they may look the same, but all it takes is one of the four speakers having its wires reversed, and the whole system will sound crappy.

Plug a cord into the cab, and touch a 9v battery to the free end plug to make the speakers pop. Watch the cones. Do all four move the same direction when the battery is touched?

[gbono]

Swap the speakers and see how each cab sounds - I assume that the cabinets are in the same location when you compare them?

[Setneck]

I checked almost everything in both cabs and it seems that I have found the reason. Which is WOOD .

Yesterday I opened both cabs and checked the wiring and speakers. They were totally the same. The speakers have had even quite close serial numbers. After that , followed by the tip given by jrfrond, I knocked a few times both cab's sides with the fist. And bingo - while one cab's box was responsing brightly the other's response was dull and muffled.

The difference in wood response is equal to the difference in overall sound. The speakers and everything else is working fine. So now either I have to find other box or buy complete cab. Fortunately I have a good sounding specimen to compare with .

Thanks for everyone for help and tips

Regards, Andy

[jrfrond]

Good wood is SO important.

All is not lost on that cabinet. You can stiffen the cabinet and raise the resonant pitch (via the addition of mass) by adding bracing across the short dimension of the side and top panels. Use 2 x 2 lumber, and divide each into four smaller ones via three braces per side. Glue and screw it to the sides so that it becomes part of the wood.

[Enzo]

My wife also tells me that good wood is important...