#1
Noob stack question here.

I ordered myself a cab- Mesa Road King 2x12. Got a great deal on a mint cond. used one. I like the open back on one side design plus the V30 speaker.

As far as the amp (fingers crossed)- picking it up tomorrow- JCM900 50 watt MKIII

Now for the noob question- How do I hook up the head to this cab? I will be running 8ohms on the head, which the cab can handle. Pic attached of cab. Do I use 2 cables to run from the back of the JCM and connect to the A and B inputs on the cab?


http://www.mesaboogie.com/Product_Info/Guitar%20Cabinets/2x12+4x12RoadKing-JackplateLG.htm
#2
You only need one speaker cable. And as far as the 8 ohms goes make sure you check the cabs impedance first. I believe most Mesa 2x12s are either 4 or 16 ohms. DO NOT mismatch the head/cab impedance. Or you may cook something in the amp
If you start a reply with: I have never played one but I have heard good things about it! Your opinion is invalid.
#3
Quote by boxcarmonument
You only need one speaker cable. And as far as the 8 ohms goes make sure you check the cabs impedance first. I believe most Mesa 2x12s are either 4 or 16 ohms. DO NOT mismatch the head/cab impedance. Or you may cook something in the amp



The Marshall can do 8/16. The back of the Mesa, as pictured in the link has:

-Input A- closed back speaker, labeled 8ohms
-Input B- open back speaker, labeled 8 ohms

and also 4ohms-A/B combined- too low to use


Does this mean each speaker-A and B- is 8 ohms? Mesa's site describes the cab as "4 Ohm Mono / 8 Ohm Stereo"
#4
are you buying it from a small shop or something? because your best bet would be to ask the guys there for help
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#5
What the site is saying equates to 8 ohms stereo which means that particular input jack powers 1 speaker. Which in turn 4 ohms mono means you are using both speakers.

If you are getting a JCM there should be a dial or switch on the back to change the amp to 4 ohms. Change the amp to 4 ohms and plug your speaker cable into the amp and mono input on the cab.

The stereo jacks are for if you are going to run 2 heads into 1 cab. To put it simply.
If you start a reply with: I have never played one but I have heard good things about it! Your opinion is invalid.
#6
Quote by boxcarmonument
What the site is saying equates to 8 ohms stereo which means that particular input jack powers 1 speaker. Which in turn 4 ohms mono means you are using both speakers.

If you are getting a JCM there should be a dial or switch on the back to change the amp to 4 ohms. Change the amp to 4 ohms and plug your speaker cable into the amp and mono input on the cab.

The stereo jacks are for if you are going to run 2 heads into 1 cab. To put it simply.



The Marshall only does 8 and 16, no 4 unfortunately. So does this mean I can only use 1 of the speakers on the Mesa?

edit- pic of Marshall back below. Does the "4" in parentheses on back of the amp mean it can do 4?

http://www.auctiva.com/hostedimages/showimage.aspx?gid=745744&image=223723428&images=223722370,223722444,223722505,223722561,223722615,223722670,223722726,223722787,223722838,223722887,223722936,223723428,223723509&formats=0,0,0,0,0,0,0,0,0,0,0,0,0&format=0
Last edited by bigfoamfinger at Mar 1, 2009,
#8
Quote by Darkice
No all your speakers will work.



So if i have the head set to 8ohm, and run a cable to input A OR B, the sound will come through both speakers? If so its confusing the way they have it because it makes it seem like you need a cable going into each input for BOTH speakers to work
#9
The 900 will run on 4, 8 or 16 ohms.

Switch the cab to mono and plug it into the (4)16 input.
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#10
Are you trying to run in stereo?
as I know it if you plug in your cab to other of the speaker jacks all your speakers will work as long at your running the proper ohms
The A and B is for having more then one Cab hooked up.
#11
Almost all heads with the exception of some SS are switchable between 4,8 and 16 ohms. Or they have separate inputs in the back. So just change the head to 4 ohms and plug into the mono input on the cab.
If you start a reply with: I have never played one but I have heard good things about it! Your opinion is invalid.
#12
Quote by MatrixClaw
The 900 will run on 4, 8 or 16 ohms.

Switch the cab to mono and plug it into the (4)16 input.



Ok I got thrown off when I saw the 16(4) on back of the amp. I thought it was ONLY 16ohms on that setting. What exacltly does "16(4)" mean? How does the cab know Im running 4 and not 16?
#13
I talked to the guy at the guitar store thats getting it for me and he said for me to run the Marshall on 8ohms, and plug the cable from the head into spot "B" on back of the Mesa where it says "Bi-Amp" see below

http://www.mesaboogie.com/Product_Info/Guitar%20Cabinets/2x12+4x12RoadKing-JackplateLG.htm

I was glad to get an answer and hopefully this can help out anyone else who may run into this situation
#14
I'm telling you. If you plug it in there only the 1 speaker will work. Look at the jackplate. It says B 8 ohms. And off to the right it says openback. That means that particular input is the stereo input for the openback side of the cab. You want the 4 ohm mono input to power both speakers. They are both aren't going to work if you plug into the A or B stereo inputs.
If you start a reply with: I have never played one but I have heard good things about it! Your opinion is invalid.
#15
Quote by boxcarmonument
I'm telling you. If you plug it in there only the 1 speaker will work. Look at the jackplate. It says B 8 ohms. And off to the right it says openback. That means that particular input is the stereo input for the openback side of the cab. You want the 4 ohm mono input to power both speakers. They are both aren't going to work if you plug into the A or B stereo inputs.



Thats what I originally thought and kind of have been re-thinking what the guy at GC told me... Since the Mono input is only 4ohms, then I cant use that with this head then since its only 8 or 16ohms right? (Marshalls instruction book and website list this amp as being 8 and 16. Nothing is mentioned about it being 4ohms, as you suggested above)


Also, Can I run a cable from EACH output jack on the Marshall (set at 8ohms), and plug one into both slots A and B?
Last edited by bigfoamfinger at Mar 1, 2009,
#16
Quote by bigfoamfinger
Thats what I originally thought and kind of have been re-thinking what the guy at GC told me... Since the Mono input is only 4ohms, then I cant use that with this head then since its only 8 or 16ohms right? (Marshalls instruction book and website list this amp as being 8 and 16. Nothing is mentioned about it being 4ohms, as you suggested above)


Also, Can I run a cable from EACH output jack on the Marshall (set at 8ohms), and plug one into both slots A and B?


running each jack on the head is only necessary for running a full stack
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#17
Quote by the boogieman
running each jack on the head is only necessary for running a full stack


Ok. What does the Bi-Amp input mean then? I have to be able to run this cab at 8ohms and have both speakers work. So, that would mean I plug into A, or B, as the other one is too low-4.
#18
Quote by bigfoamfinger
Also, Can I run a cable from EACH output jack on the Marshall (set at 8ohms), and plug one into both slots A and B?

Actually, I think this would work. I'm not 100% sure, but I think so.
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#19
I figured it out... The pic on Mesa's site where it shows the front view and back view of the cab (where the cab specs are,before you zoom in to see the back panel) is different than when you actually zoom in. Its an error. Here is a pic of an actual cab

http://dane.lauda-audio.pl/prod/6375/2x12Alone-Rear.jpg


zoom in and I think it says 8ohms Input on the right side of the panel
#20
It wouldn't work because the load on the amp would only be 4 ohms. It would be the same as running 2 cabs you would have to halve the impedance. So again your at 4 ohms. The only way to get around this would be to have the cab rewired to 16 Ohms.

Edit: If you are ordering the cab new you could specify that you want 16 ohm speakers. Instead of the standard 8 ohm speakers.
If you start a reply with: I have never played one but I have heard good things about it! Your opinion is invalid.
Last edited by boxcarmonument at Mar 1, 2009,
#21
Quote by boxcarmonument
It wouldn't work because the load on the amp would only be 4 ohms. It would be the same as running 2 cabs you would have to halve the impedance. So again your at 4 ohms. The only way to get around this would be to have the cab rewired to 16 Ohms.

Edit: If you are ordering the cab new you could specify that you want 16 ohm speakers. Instead of the standard 8 ohm speakers.


Im getting it used. An out of state GC is shipping it to me tomorrow

I assumed since the amp can do 8, and the cab can do 8 it would work.
Last edited by bigfoamfinger at Mar 1, 2009,
#22
Quote by bigfoamfinger
Im getting it used. An out of state GC is shipping it to me tomorrow

I assumed since the amp can do 8, and the cab can do 8 it would work.

Unless the cab runs both speakers on 8 ohms, this won't work. Running them in stereo at 8 ohms will only allow you to run one speaker out of the cab. Even if it had two 8 ohm inputs, you'd be running each input at 4 ohms since they would be wired in parallel.

A quick search on the internet will tell you that the (4)16 ohm input is used for both 4 and 16 ohm cabs. Why Marshall doesn't state this on their website is beyond me.
Quote by Dave_Mc
I've had tube amps for a while now, but never actually had any go down on me
Quote by jj1565
maybe you're not saying the right things? an amp likes to know you care.





www.SanctityStudios.com
Last edited by MatrixClaw at Mar 1, 2009,
#23
Quote by MatrixClaw
A quick search on the internet will tell you that the (4)16 ohm input is used for both 4 and 16 ohm cabs. Why Marshall doesn't state this on their website is beyond me.



I found that too. I also found things like this link below. The guy is right about their hand books- They do only mention 8 and 16ohms. I dont know what to think. If I try it like that when I get the cab, will I know immediately whether or not it will work without ruining the amp or cab?

http://www.blamepro.com/marfaq.htm