Marshall Jcm 900 impedance
SAmuel Pacheco Higuera
I have a jcm-900 head, & it has this switch on the back to select mono or
stereo.Then i need to know if i select mono , which one of the txo output
jacks gives me 4 & which one gives me 16?
& if i put it in on stereo , then both outputs give 8 ohms then i should
plug both jacks to the amp speaker (marshall 1960A) ?
It is more clear on the cabinput.
One last question , i´m making a 2x12" cab , which kind of speaker ( 8-16
ohms) should i buy to play it with my 4x12" & my jcm-900?
Thanx
Mr Scary
It has two speaker jacks - which are wired in parallel (sp? :-))
If you use one 4x12 cab - you should use the 16Ohm setting
If you use 2 4x12s you should use the 8 ohm setting.
On the cab - leave the switch set to mono (unless you are using either two
heads, or a stereo power amp) - and plug the head into the 16ohm socket.
If you already have a 4x12 and are making a 2x12 to use with it - then you
should buy 8Ohm speakers, and wire them in series with each other - this
will give you a 16ohm cab. Then you can plug both cabs into the head - and
set the impedance switch to 8ohms.
Have a look at:
http://www.marshallamps.com/images/handbooks/pdf/jcm900.pdf
M.
--
------------------------------------------
Stircrazy!
Making the world a louder place.
http://www.stircrazy.fsnet.co.uk
------------------------------------------
"SAmuel Pacheco Higuera" <samu...@navegalia.com> wrote in message
news:a30ncm$sog$1...@news.wanadoo.es...
SAmuel Pacheco Higuera
16 ohms in the head , cause is not quite clear.
If i select the stereo on the head & plug it into a 8 ohms input in the cab
, will the 4 speakers of the cab be working?? Or just 2 of them?
Can i also run 2 cabs in mono selecting one with 4 & the other with the 16
ohms output?
"Mr Scary" <NOmr...@stircrazy.SPAMfsnet.co.ukPLEASE> escribió en el
mensaje news:z3S48.70660$ru2.798560@NewsReader...
Mr Scary
> But what i don´t know is which one of the two output jacks gives me 4 or
16
> 16 ohms in the head , cause is not quite clear.
The are wired together - they give exactly the same output.
There is no stereo switch on the head - there will be a 16/8 ohm switch, but
no stereo switch.
You need to select 16Ohms on your head, and select MONO on the cab, and plug
the head, via either of the output jacks, into the 16Ohm socket on the cab.
This way, all 4 speakers will be working.
>
> If i select the stereo on the head & plug it into a 8 ohms input in the
cab
> , will the 4 speakers of the cab be working?? Or just 2 of them?
There is no stereo on the head. Really there isn't.
>
> Can i also run 2 cabs in mono selecting one with 4 & the other with the 16
> ohms output?
You can, but something will blow up. If you run two cabs through one head -
then plug the head into the 16ohm socket on each cab, set each cab to be
mono. Set the head to be 8Ohms.
Please read
before you blow something up...
M.
SAmuel Pacheco Higuera
if both outputs give the same impedance , 16 mono - 8 stereo , everything
is clear.
One last thing , what is the 4 ohms in brakets for? It is on the mono
selector of the head , by the 16 ohms.
thanx for the help
"Mr Scary" <NOmr...@stircrazy.SPAMfsnet.co.ukPLEASE> escribió en el
mensaje news:iLV48.2385$oK1.17013@NewsReader...
Mr Scary
Glad to be of help.
The 4 ohms in brackets?
Ok - on the early Marshalls - JCM 800 and pre-that, the output selector
could give 16,8 or 4. This was to cater for the Canadian market - where cabs
had to be 4 ohms. Not sure why though. Also - you could power 4 16Ohm cabs
with that setting!
Now, the Canadian models switch between 8 and 4, rather than 16 and 8. Few
people use the 4 ohm setting. You amp can be modified to give 4 ohms (for
example you might have 2 of 8 ohm cabs - 2x12s for instance) it is just a
matter of opening her up, and moving some wires around.
The 2 way switch is cheaper than the 3 way one of old...
--
------------------------------------------
Stircrazy!
Making the world a louder place.
http://www.stircrazy.fsnet.co.uk
------------------------------------------
"SAmuel Pacheco Higuera" <samu...@navegalia.com> wrote in message
news:a31d8v$g18$1...@news.wanadoo.es...