Greenback 1281 102/14 Speaker/Cab

[Teddeus]

Hey dear friends.
I got an offer from a buddies friend. He’d like to sell his Marshall Cab.

It seems that these are Pulsonic Speakers.
Can you give me a suggestion if this Cab is legit and era correct?
Speakers seems in pretty good quality.

Can anybody tell me something about them?




Thanks in advance guys!

 

[BlueX]

EE speaker code May 1972, matches cone code 102/14.

Tolex with gold triming, and without corner guards could be 1972 as far as I understand.

Don't know about black grill cloth, maybe painted. Have you lifted any speaker to check cloth back side?

Price depends on location for cabs. B cabs sell fast around here at least.

 

[kuli]

Looks like the cab has 4x15" dimension?

 

[Teddeus]

Looks like the cab has 4x15" dimension?

It seems a bit suspicious to me as well

I was told that the cab is bigger than a guitar cab but it’s original Marshall. The guy says that the cab was build for bass guitar.

Can this be possible?

 

[BygoneTones]

Yeah the cab doesn't look right, but might be worth getting just for the speakers.

Not too familliar with 4x15 cabs, but those handles look too low to me? and the baffle slope maybe too shallow? Could be a replica build. Or maybe a 4x15 with a replaced baffle. Hard to say.

When the baffle comes out, the handles have to be removed and re-installed. So look for any signs of meddling there. The photos don't really reveal much. I guess the rivets would have to be drilled out and then re-rivetted. The grill material is definitely not right for 72.

 

[BlueX]

Here's a Marshall 4x12 B cab from the same era. As you can see, speakers are closer together and closer to side walls. I should have noticed this.

As already mentioned it could be an original Marshall 4x15 B cab, but "re-baffled" to fit 12" speakers instead, and given a black grill cloth in the process. With such modifications the value is probably in the speakers.

Please share more info if you get it! Always interesting to see, and know.

 

[Teddeus]

I tried out the Marshall cab. The sound was great, and the speakers look fantastic. However, I’m a bit puzzled because the speakers are labeled as 15 ohms, but when I measure at the speaker terminals, I get a reading between 6 and 7 ohms. I get the same reading at the input jack.

Is there something wrong? Can someone explain this to me?

 

[BlueX]

Are all speakers labeled 15 Ohm? Is the cab wired with one jack (mono)?

If Yes/Yes this could indicate a failed speaker. A mono cab with four 15 (or 16) Ohm speakers can be wired 4 or 15/16 Ohm. You will measure somewhat lower with the DMM (like 12-13 instead of 15).

Could also be bad contact in the jack (dirty or corroded lugs). WD-40 or contact cleaner could help.

If the cab has stereo input (two jacks) it's a different explanation.

You should sort this out before cranking an amp into that cab. Could blow the OT.

 

[Teddeus]

Yes it

Are all speakers labeled 15 Ohm? Is the cab wired with one jack (mono)?

If Yes/Yes this could indicate a failed speaker. A mono cab with four 15 (or 16) Ohm speakers can be wired 4 or 15/16 Ohm. You will measure somewhat lower with the DMM (like 12-13 instead of 15).

Could also be bad contact in the jack (dirty or corroded lugs). WD-40 or contact cleaner could help.

If the cab has stereo input (two jacks) it's a different explanation.

You should sort this out before cranking an amp into that cab. Could blow the OT.

yes, it’s wired with one jack. Mono

I measured direkt on the pins of two speakers

And on the input jack of the cab

But if I had a bad contact I should read more than 15/16 Ohms?

 

[BlueX]

Had another look at 2nd picture in post #1. Wiring at botton right speaker looks strange. I can't see properly, but maybe that speaker is shorted out of circuit due to wrong wiring? Close up pic would help.

Standard Marshall wiring is very straight forward:
- The two speakers in each vertical column are wired in series. One wire goes first to one lug on bottom speaker, and continues from the other lug to one of the lugs on top speaker. The other wire goes directly to the other lug on top speaker.
- The two columns are wired in parallel at the jack.

 

[BlueX]

But if I had a bad contact I should read more than 15/16 Ohms?

Yes, I was thinking about stereo jack.

If one speaker is shorted (failed internally or mis-wired) you would get impedance 1/(1/(15+15) + 1/15) = 10 Ohm. Corresponds to you reading of 6-7 Ohm resistance.

 

[Teddeus]

Yes, I was thinking about stereo jack.

If one speaker is shorted (failed internally or mis-wired) you would get impedance 1/(1/(15+15) + 1/15) = 10 Ohm. Corresponds to you reading of 6-7 Ohm resistance.

But I should can measure on the pins of speaker to determine what’s going on right?

 

[Teddeus]

Had another look at 2nd picture in post #1. Wiring at botton right speaker looks strange. I can't see properly, but maybe that speaker is shorted out of circuit due to wrong wiring? Close up pic would help.

Standard Marshall wiring is very straight forward:
- The two speakers in each vertical column are wired in series. One wire goes first to one lug on bottom speaker, and continues from the other lug to one of the lugs on top speaker. The other wire goes directly to the other lug on top speaker.
- The two columns are wired in parallel at the jack.

This should be the connection you’re referring to.

It seems a bit weird

 

[BlueX]

This should be the connection you’re referring to.

It seems a bit weird

That might be the problem. I think the black wire from top right speaker should go directly to jack.

The left column looks like standard wiring:
- Black wire from sleeve lug on jack to - lug on bottom left speaker.
- Black short wire from + lug on botton left to - lug on top left.
- Red from + lug on top left to tip lug on jack.

Right column should be:
- Red wire from tip lug on jack to + lug on bottom right speaker.
- Black/white from - lug on bottom right to + lug on top right.
- Black from - lug on top right to sleeve lug on jack.

If you got AWG 18 wire with red insulation you could replace the black/white (to make it look correct).

 

[BlueX]

But I should can measure on the pins of speaker to determine what’s going on right?

Speakers are wired in parallel so you will measure the combined resistance.

Easiest is to de-solder the wires at the jack, all four wires separated from each other. Then you can measure each vertical column and compare.

 

[Gene Ballzz]

But I should can measure on the pins of speaker to determine what’s going on right?

You may or may not get any kind of acccurate/meaningful reading, with the speakers connected to each other. This, of course, depends entirely on "HOW" they are connected to each other. The most accurate/bestest way would be to disconnect all wires from the speaker lugs and measure each speaker separately!

Simply Speakerin'
Gene

 

[Teddeus]

So my friends, finally brought it home.

To the Problem above. It was a wiring issue.
I resolderd all wiring and measured the speakers each after another’s. Resistance was from 12.7 to 14.2 Ohms.

All have the following numbers

T1281 102/14 EE a nice quad from May 1972

I think that’s the normal range?!

I will have to buy new wires and solder it again and will also ad a new checker board grill cloth.

Now I took some pictures.
Every panel says „Chris“ just the one on the Baffle says „Les“ I have no idea if this is from factory stock or there is a new baffle board to match these 12“ Speaker.
The size of the cab is like the 4x15“ Cabs.
Interesting is that the color and grain of the wood matches exactly the other panels inside.
Also a picture attached.


What do u guys think I hope you like it - I do and I hope to got a good deal for 1400 bucks on this beauty!

Speakers are wired in parallel so you will measure the combined resistance.

Easiest is to de-solder the wires at the jack, all four wires separated from each other. Then you can measure each vertical column and compare.

 

[Teddeus]

Here I tried to took a picture of all speakers through the grill cloth
Normal color?

Greetings Ted!

 

[BlueX]

So my friends, finally brought it home.

To the Problem above. It was a wiring issue.
I resolderd all wiring and measured the speakers each after another’s. Resistance was from 12.7 to 14.2 Ohms.

All have the following numbers

T1281 102/14 EE a nice quad from May 1972

I think that’s the normal range?!

I will have to buy new wires and solder it again and will also ad a new checker board grill cloth.

Now I took some pictures.
Every panel says „Chris“ just the one on the Baffle says „Les“ I have no idea if this is from factory stock or there is a new baffle board to match these 12“ Speaker.
The size of the cab is like the 4x15“ Cabs.
Interesting is that the color and grain of the wood matches exactly the other panels inside.
Also a picture attached.


What do u guys think I hope you like it - I do and I hope to got a good deal for 1400 bucks on this beauty!

Congrats on solving the problem! Now you've got a quad of very nice speakers. I would've paid that price for that cab, with those speakers. Regardless if the 4x12 baffle is a custom order from Marshall or later mod it's still a nice looking cab. Once you get the correct type of grill cloth on it will look great. Please share pic's!

Have you tested the speakers for spider lift or coil rub? I recommend to do that when you're doing some other work on the cab, before you put everything back together.

Good instructions on Bygonetones web site:

How To Test A Vintage Celestion Greenback Speaker - Bygone Tones

How to test a speaker for: voice coil rub, blown speaker, torn cone, and other common problems. Using an audio generator for 'sweep testing'.

www.bygonetones.com

 

[Teddeus]

Congrats on solving the problem! Now you've got a quad of very nice speakers. I would've paid that price for that cab, with those speakers. Regardless if the 4x12 baffle is a custom order from Marshall or later mod it's still a nice looking cab. Once you get the correct type of grill cloth on it will look great. Please share pic's!

Have you tested the speakers for spider lift or coil rub? I recommend to do that when you're doing some other work on the cab, before you put everything back together.

Good instructions on Bygonetones web site:

How To Test A Vintage Celestion Greenback Speaker - Bygone Tones

How to test a speaker for: voice coil rub, blown speaker, torn cone, and other common problems. Using an audio generator for 'sweep testing'.

www.bygonetones.com

No sadly I couldn’t test all the stuff but I read the blog.
It’s pretty usefull and I will do it if I remove the speakers.

But at first I have to find a checker board cloth.
And damn I couldn’t find a lager one than 32“ wide.
Do u have any idea?