#1
I have a JCM 2000 DSL50 that works fine hooked up to a 4x12 on 16 ohms, but the 8ohm output on the amp doesn't work for anything.

Please help!
Mesa Single Rectifier
Marshall 1960A vintage
Rg3exfm1 w/ EMG 85/81
Big Baby Taylor Acoustic
Ibanez TS808
#3
Why do you need to use the 8 ohm jack if the 16 is working?
MARSHALL JVM 210H
PEAVEY JSX
KRANK 412
MESA 412
FENDER STRATS
DIMARZIO
CELESTION
#4
Quote by Van Noord
Why do you need to use the 8 ohm jack if the 16 is working?


2x16ohms cabs = 8ohms.

TS, take it to an amp tech! if it's a more complicated issue with the jack and the speaker load isn't being placed on the amp, you could have burnt up yer toobes. :O
#5
Either the OT is f'ed, or there is a bad connection on the 8 ohm tap in which case you need to get it fixed before using it. A bad connection there is dangerous and using it would be the same as not having a load connected.
#6
Quote by Elvendar
2x16ohms cabs = 8ohms.
I know that, but there was no mention of a secondary 16 ohm cab.
I do aggree that you have a tech look at the jack. If you have some contact cleaner I would try spraying some in the 8 ohm jack too. If you rarely use a jack it's open to all kinds of dirt, dust and grime. This can cause connection problems.
MARSHALL JVM 210H
PEAVEY JSX
KRANK 412
MESA 412
FENDER STRATS
DIMARZIO
CELESTION
#7
Could be a bad jack, bad connection, or bad OT. Jacks can go bad from lots of use and from lack of use.
#8
OT = ?

The actual situation is:

the DSL50 is my friend's amp, and we are trying to fix this problem.

I own a marshal 1960VA cab so I can run it on 16ohms fine. My friend though, only owns an 8ohm load 2x12, so we can't use it at band practice with his cab.

I'm not mixing loads, I set my cab to stereo (meaning 2 2x12s in the same box... 2 8 ohm loads) and I use one of them to test, no sound.
Mesa Single Rectifier
Marshall 1960A vintage
Rg3exfm1 w/ EMG 85/81
Big Baby Taylor Acoustic
Ibanez TS808
#10
Marshall 1960 4x12 cabs can be ran in 4/16ohm mono (all 4 speakers) or 8ohm stereo (2 speakers)

The latter allows for dual head input into the cab, it's not required to use both cab inputs when running stereo. Some people use it just because they want their amp to run on 8ohms and not 16 or 4
Mesa Single Rectifier
Marshall 1960A vintage
Rg3exfm1 w/ EMG 85/81
Big Baby Taylor Acoustic
Ibanez TS808
#11
311, you have the OT mixed up with the PT, which you are correct, it works in the power supply. The OT bridges the low current, high impedance output stage of your amplifier to the high current, low impedance speaker.
#13
I just hooked the DSL up to the 2x12, just out of curiosity.

It worked fine for about 5 minutes, but after that it just went out. Like the signal was lost..

It's done that before in the middle of practice. The amp is on but the signal from the head to the 2x12 just stops.

any ideas?
Mesa Single Rectifier
Marshall 1960A vintage
Rg3exfm1 w/ EMG 85/81
Big Baby Taylor Acoustic
Ibanez TS808
#15
The DSL series heads have 3 output jacks: 1 16ohm jack, 2 8/4 ohm jacks.

I had it set to 8 ohms and tried both of them
Mesa Single Rectifier
Marshall 1960A vintage
Rg3exfm1 w/ EMG 85/81
Big Baby Taylor Acoustic
Ibanez TS808
#16
The schematic shows a 4/8 ohm switch. The switch could be bad, doubtful both jacks would go out. If its not the switch then its probably gonna be the OT.
#17
You really shou;dn't be experimenting with this if you suspect that it's broken. Everytime it doesn't work could mean that the load is less, or significantly more than the amp is expecting to "see" and everytime you are damaging the OT or the power valves.
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