Marshall 1965 4x10 cab, 8ohm with Matrix gt1000fx and fm9

D

Davester1234

Member
Hi all, I got my hands on a vintage Marshall cab. Its model 1965B, 4x10, marked at 8ohms and 140W R.M.S. It has a single 1/4 input.

I just obtained a matrix Gt1000fx 2u, and the brains are my fm9.

I don't want to blow anything up, I'm a newbie and don't know the best way to connect the fm9 to the matrix, and the matrix to the cab. What connections should I use?

Beyond that, I don't know how to run the matrix in such a way as not to blow out the speakers. Ohms and rms confuse me.

What settings should I apply on the matrix and fm9? Can anyone help me with what to do?
 
If you run that amp mono to a single 8Ω cab it delivers 1000 watts. That cab has 35W speakers. That power could smoke them quickly.

If it were mine I would re-wire that cab with a pair of speakers in series as 16Ω on one jack
And the other pair also in series on another jack.
That would give you 150W per channel. And it would be in stereo. It's a simple wiring job that can easily be returned to stock.

You could also replace the single stock TS jack with a TRS and make a short pigtail with a male TRS plug to 2 female TS jacks.
Edit: that trs jack won't work for speaker level! ignore that part.
 
Last edited:
WKSmith said:
If you run that amp mono to a single 8Ω cab it delivers 1000 watts. That cab has 35W speakers. That power could smoke them quickly.

If it were mine I would re-wire that cab with a pair of speakers in series as 16Ω on one jack
And the other pair also in series on another jack.
That would give you 150W per channel. And it would be in stereo. It's a simple wiring job that can easily be returned to stock.

You could also replace the single stock TS jack with a TRS and make a short pigtail with a male TRS plug to 2 female TS jacks.
Click to expand...
Interesting. So I wouldn't need to actually change the speakers just change the wiring? that sounds like a great idea. I don't know how to wire for crap but I can get someone to help me...
 
WKSmith said:
If you run that amp mono to a single 8Ω cab it delivers 1000 watts. That cab has 35W speakers. That power could smoke them quickly.

If it were mine I would re-wire that cab with a pair of speakers in series as 16Ω on one jack
And the other pair also in series on another jack.
That would give you 150W per channel. And it would be in stereo. It's a simple wiring job that can easily be returned to stock.

You could also replace the single stock TS jack with a TRS and make a short pigtail with a male TRS plug to 2 female TS jacks.
Edit: that trs jack won't work for speaker level! ignore that part.
Click to expand...
 
I see your update. Two questions though. How does this rewiring turn it into 150w per channel?

This might be the greenest question ever posted, but do the upper and lower lefts get grouped together or do the top right and left speakers get paired together?
 
Davester1234 said:
I see your update. Two questions though. How does this rewiring turn it into 150w per channel?

This might be the greenest question ever posted, but do the upper and lower lefts get grouped together or do the top right and left speakers get paired together?
Click to expand...
A couple of things.. the power rating of the matrix amp is dependent of the speaker impedance load. And if it is used in stereo or mono. From their site:
IMG_0591.jpeg
Second:
To make that cab into 2x16Ω stereo, un-solder the speaker wires. You need a red + and black - from a 1/4 jack to the top and bottom speakers on one side. The red + goes to the top speakers + terminal. The black - goes to the bottom speakers- terminal. A single piece of wire connects the top speakers - to the bottom speakers +

Repeat this for the other pair on the opposite side.

For the best stereo separation add a piece of plywood inside as a baffle separating the left side from the right.

You can make a new jack plate for two jacks easily that will fit that stock circular jack plate.

Easy peasy 🙂👍
 
I run Matrix into speakers that are impedance matching, but rated lower and am just careful not to have the Matrix turned up so hi that it exceeds the speakers' capability - Afaik thiis is fine, except for some risk of accidentally setting volume too loud (but I've never done that yet).
 
sprint said:
I run Matrix into speakers that are impedance matching, but rated lower and am just careful not to have the Matrix turned up so hi that it exceeds the speakers' capability - Afaik thiis is fine, except for some risk of accidentally setting volume too loud (but I've never done that yet).
Click to expand...

Ditto… I’ve always had amplifiers that would outrun the voicecoils/transducers; manage accordingly 👍

Matrix gt1000fx 2u into 2 (stereo) 2x12s w v30s
 
there is zero need to rewire the cabinet or anything..
set your output level on FM9 to -10db; and volume knob to zero
connect via xlr to the matrix, and set the volume knobs to 9am

use the volume knob on the fm9 for volume adjustments, and if you cannot get enough volume then turn the matrix up..

is it possible to blow your speakers up?.. yes, but there is no reason you have to... setting the matrix volumes as a "limiter" is all you have to do.
 
Mystic38 said:
there is zero need to rewire the cabinet or anything..
set your output level on FM9 to -10db; and volume knob to zero
connect via xlr to the matrix, and set the volume knobs to 9am

use the volume knob on the fm9 for volume adjustments, and if you cannot get enough volume then turn the matrix up..

is it possible to blow your speakers up?.. yes, but there is no reason you have to... setting the matrix volumes as a "limiter" is all you have to do.
Click to expand...
what happens if you set the volume knobs to 9pm?
 
i have that same cab except the top cab model 1965A. It’s my favorite cab. I like them so much I bought a second one. It’s like a lighter weight 4X12 with the punch and clarity in a smaller format.

I modded both of mine to stereo and it is awesome with my Fryette LXII power amp. The stereo mod is an easy mod and you can install this jackplate. It does require cutting the back he cab to get it to fit.

https://reverb.com/item/66386802-mo...are&utm_campaign=listing&utm_content=66386802

i can dig up my hand drawn wiring diagram if you need it.
 
79_limited said:
i have that same cab except the top cab model 1965A. It’s my favorite cab. I like them so much I bought a second one. It’s like a lighter weight 4X12 with the punch and clarity in a smaller format.

I modded both of mine to stereo and it is awesome with my Fryette LXII power amp. The stereo mod is an easy mod and you can install this jackplate. It does require cutting the back he cab to get it to fit.

https://reverb.com/item/66386802-mo...are&utm_campaign=listing&utm_content=66386802

i can dig up my hand drawn wiring diagram if you need it.
Click to expand...
I'd love to see the diagram this something I really want to do!
Thanks!
 
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