Kayde

I bought a new marshall 1960a lead cab approximatly 6 months ago. I was stupidly told by the music shop to have the cab in stereo and connect both the amp outputs to the cab inputs, Connecting my solid state marshall mosfet lead 100. This ment 4 ohms from the head was going into 8ohms with one jack which is fine however it ment 16 OHMS WAS GOING INTO 8OHMS WITH THE OTHER JACK!!!!??? Using this the cab has been playing at high volumes with both tube amps and my solid state however i am unsure the ohms on the tube amps.
Should i get the cab checked, thanks

DeathByDestroyr

A stereo cab should have two completely different circuits, both 8 ohms? Normally you can (I think this is how it goes) have your cab pulling more ohms than the head, which is fine, but not optimal.

Are they wired in series or parallel? 8 ohm speakers?

If your not sure bring it in.

Kayde

parallel

Kayde

And 8ohm when in stereo

DeathByDestroyr

Oh, you where thinking that this meant the output transformer would be putting out different ohms? No, it won't. Your fine.

Kayde

I ment the out puts on the head where 8 and 16 so one would connect 8 and 8 which is fine but the other was 16 ohm from head going into 8 ohms in cab

Kayde

when in mono you get a choice on the cab of 4 ohms or 16 but i had in stereo which gave 8 and 8 ohm

DeathByDestroyr

Ok, I'm rusty on this so bear with me.

Two 8-ohm speakers wired in parallel will result in 4 ohms, while in series will result in 16 ohms. Right?

So you have 16 ohm speakers?

Also, don't run 16 ohms into 8 ohms. Just use the one jack.

Kayde

ok sorry im a begginer yes they are 16ohm so should i get it checked or is it fine.
thanks

DeathByDestroyr

It should be fine just DO NOT run 16 ohms into 8 ohms-you'll fry your output transformer.

Robbgnarly

use The 16ohm output on your amp into the 16ohm mono input on your cab.

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Kayde

Also if it has damaged the output transformer how would i know, aswell Would the damage from miss matching the ohm values effect the sound or damage the speakers, if so how would i tell
Thanks Kayde

Kayde

anyone?

gumbilicious

there is a bunch of confusion in this thread, let's try to sort it all out.

Marshall 1960a Lead Cab:
-uses 16 ohm speakers
-has a mono 16 ohm input (wired in series-parallel)
-has a mono 4 ohm input (wired in parallel)
-has stereo 8 ohm inputs (two speakers wired in parallel)

Marshall Mosfet Lead 100:

-solid state, has no output transformer, must meet minimum impedance (4 ohms)
-100W @ 4 ohms, 80W @ 8 ohms, 50W at 16 ohm (from manual)
-both outputs on the head are connected in parallel

so, we'd need to know exactly what the cabinet was set to in order to let you know how you really had it set up. the cab can only provide 4, 8 or 16 ohms, it cannot provide a mix of impedances (like it can't provide 8 ohm and 16 ohm, or 4 ohm and 16 ohm loads at the same time.

taking this into consideration: no matter how you were hooking it up, i couldn't imagine you really damaging it. providing no load to a SS amp is no big deal, providing excess impedance beyond the min impedance just decreases the output of the amp, and you didn't have a combination of speaker that could provide a load below the min required... so i'd say there was no real way for you to damage your equipment.

now, for hooking up the cabinet:
use a speaker cable (speaker cable is different from instrument cable you use for guitar) to hook one of the speaker outputs of the Mosfet 100 to the 4 ohm mono input of the cabinet. this will provide 100 watts. if you want less output, switch the cabinet over to 16 ohm mode and you'll just get 50 watts of output.

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"A perfection of means, and confusion of aims, seems to be our main problem."
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Kayde

Thank you makes sense!!
I dont no how you would say the cab was set up i just had both amp outputs running into both cab inputs with the cab set on stereo.

gumbilicious

then the cabinet would have been providing 4 ohms total. that is just a more convoluted way of setting the cab to 4 ohm mono, running into the cabinet on stereo mode requires an extra cable too. save yourself the necessity of running two cables and just use one cable with the cabinet on mono-4 ohm mode.

__________________
"A perfection of means, and confusion of aims, seems to be our main problem."
-ae

Kayde

Should of mentioned i had both the cables in when using in stereo before, so fair to say the cab will be fine?

gumbilicious

yeah, that is really no issue at all.

__________________
"A perfection of means, and confusion of aims, seems to be our main problem."
-ae