#1
Ok, today I plugged my jcm900 into a friends 1960 cab. The cab has 2 inputs, one for 4 ohms and one for 16 ohms. My head has 2 ohm settings on it... one for 8 ohms on the other reads "(4) 16".

Am I able to plug into both 4 and 16 ohm inputs with my amp on the (4) 16 setting?

OR would plugging the (4) 16 side into a 4 ohm input be overpowering the speakers with 16 ohms?
#2
Quote by andyhatescrass
Ok, today I plugged my jcm900 into a friends 1960 cab. The cab has 2 inputs, one for 4 ohms and one for 16 ohms. My head has 2 ohm settings on it... one for 8 ohms on the other reads "(4) 16".

Am I able to plug into both 4 and 16 ohm inputs with my amp on the (4) 16 setting?

OR would plugging the (4) 16 side into a 4 ohm input be overpowering the speakers with 16 ohms?

You definitely do not want to do that. I'll have to reread your second scenario.

You have a series/parallel wired cab so this might help you.




^Edit: that may not be your exact specs but probably close.
also for now, you want to focus on a mono hookup not a stereo one.
Last edited by 311ZOSOVHJH at Sep 15, 2010,
#3
Why do I get the overwhelming urge to say "RTFM"?
The manual says:
6. Impedance Selector Switch
............ Amp heads feature 8 or 16 Ohm operation. Combo versions feature 4 or 8 Ohm options.

So if you have the head select 16 ohm and go into the 16 ohm input of the cab. They have (4) 16 on the switch so they don't have to make two different switches. If you have a head it's 16, if you have a combo it's 4.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#4
Actually, which cab do you have specifically? It may not be wired for stereo either. If you want to know for sure take the back off and take some pictures. You can also use a multimeter to get a general guess (I said guess guys).


^ what Cath said
#5
Quote by 311ZOSOVHJH
Actually, which cab do you have specifically? It may not be wired for stereo either. If you want to know for sure take the back off and take some pictures. You can also use a multimeter to get a general guess (I said guess guys).


^ what Cath said



The cab is a Marshall 1960 vintage. I had on the mono setting, but there is a stereo setting as well.

So am I correct when I say the, 4 ohm setting is for running more than 1 cab parallel into the head?

It is a head not a combo, which is the part that is confusing.
Last edited by andyhatescrass at Sep 15, 2010,
#6
Quote by andyhatescrass
The cab is a Marshall 1960 vintage. I had on the mono setting, but there is a stereo setting as well.

So am I correct when I say the, 4 ohm setting is for running more than 1 cab parallel into the head?

It is a head not a combo, which is the part that is confusing.

ok. stereo would be 8 ohms per side.

no, i don't think it works that way. When daisy chaining cabs they also become a parallel load with each other. So 2 - 16 ohm cabs running in parallel would be a 8 ohm load total. For now I think you are 16 to 16 (head to cab).

fuk don't listen to me listen to Cath, he owns one and is a lot smarter than I.
#7
Quote by andyhatescrass
It is a head not a combo, which is the part that is confusing.

What part of the manual didn't you understand?
THERE IS NO 4 OHM SETTING ON THE HEAD VERSION!!
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#8
Quote by Cathbard
What part of the manual didn't you understand?
THERE IS NO 4 OHM SETTING ON THE HEAD VERSION!!


As you probably know, the setting reads "(4) 16" on the head.

I suppose I mistook the 4 in parenthesis as an ok to hook up to a 4 ohm input.
#9
Quote by andyhatescrass
As you probably know, the setting reads "(4) 16" on the head.

I suppose I mistook the 4 in parenthesis as an ok to hook up to a 4 ohm input.

I explained that already.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#10
I get it now.

Thanks for both of your patience, I'm hoping my head isn't screwed by now. I have only run the wrong impedance a few times. Just out of curiosity, what part of the amp does running the wrong impedance effect? Should I take it to a shop to get it looked at?
#11
If you did damage by running too low an impedance cab you'd know about it. It kills the output tubes and sometimes the output tranny. You can usually survive it if you didn't turn the amp up to 10. If it still sounds ok you're sweet.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band