Musicians Roadhouse

Hi, i want to run my 215c with my cab, i have heard that if i plug the 16 ohm speaker of the 215c into the 8 ohm and the 8 ohm speaker of the 1936 cab into the 4 ohm on the back of the combo i will be ok.

this has come from the JVM forum and i have no reason to doubt them but i may have misunderstood this so could you please advise.

I think you have probably misunderstood the original post. The rear panel outputs on the JVM are identified by their (total) impedance ratings. Only one impedance option should be used at any time otherwise damage may be incurred.

The '1 x 16ohm' output is for use with a single 16ohm cabinet like our 4 x 12s.

The '2 x 8ohm' outputs are for use with either a single 8ohm cabinet OR two 16ohm cabinets which give a total impedance of 8ohms too, because they will be in parallel configuration.

The '2 x 4ohm' outputs are for use with either a single 4ohm cabinet OR two 8ohm cabinets which give a total impedance of 4ohms too, because they will be in parallel configuration.

I suspect the original post suggested plugging your amps internal 16ohm speaker AND your 1936's MONO connection to the 2 x 4ohm outputs on the JVM. The resulting parallel impedance of the speakers will be 5.3ohms which is not too far away from the rated 4ohms.

Alternatively, using the other input on the 1936 would use only one of its 16ohm speakers but the total impedance would be 8ohms giving a better match. Try both ways to see which you prefer.

quote - there won't be a mismatch if you plug the 8ohm cabinet into the 1x4ohm output and the 16ohm cabinet into the 1x8ohm output. Everything will be perfectly matched and the power splitted equally into both cabinets
Hi Steve thanks for reply, Above is the quote i found on the JVM forum so you can see why im a bit confused.

If you read the JVM manual it states that only one impedance option should be used at any one time. That quote advises using a 4ohm output and an 8ohm output simultaneously. It's wrong as far as I'm concerned.

Thanks Steve, My dealings with you in the past tell me you know your eggs, the last thing i want to do is blow a tranni.
Big thanks again
spike

Eggs?? Is this Britsh for "shit"? Never heard that one before, I think ya all are using code words us Yanks don't know.

spikei wrote: the last thing i want to do is blow a tranni.

Sorry, sometimes I revert back to adolescent humor to get me through the day.

Wish i hadnt said it like that, cant stop laughing now, Just the thought of blowing a tranni LOL.

-- Tue Jul 26, 2011 3:27 pm --

I thought id better add that after further investigation into the amp i discovered its an 8 ohm speaker just that it had come plugged into the 16 ohms socket from new, naughty naughty. So plugging into a 1936 cab was straightforward.
I also decided i didn't like the stock speaker of the combo and changed it for a Vintage 30, wow what a difference, love it. If you have a JVM 215c and it ain't doing it for you i strongly recommend trying a V 30.

First, hello to everyone, another forum with a wealth of of information. 
I'd like to continue this thread as I am wanting to do the same, i.e. connect my JVM215C to a 1936 cab.
However, the speaker in the combo is 8ohms, not the 16 stated in the original thread. I've used a multi-meter to confirm this. Also, the cab is loaded with vintage v30's, at 8ohms each.
The cab hasn't arrived yet so I cannot confirm this with a meter, but guy who sold it said 8 ohm, stereo or 4 ohm mono, which leads me to believe they are two 8 ohm speakers.

So my question is, would I be better off re-wiring the cab, so that the speakers are in series to achieve a total impedance of 8 ohms, which would make it easy to connect to the JVM212 combo?

Or, leave them wired as they are (assuming total total impedance is 4 ohms) and use some combination of the JVM's tapped outputs?

Ideally, I'd like an even spread, volume wise across the 3 speakers.
I'm also assuming the 36's speakers are wired in parallel and that the circuit is broken if used in stereo, by the 2nd jack, as there is no mono/stereo switch, like on a 1960?

In addition, I may consider switching one of the V30's with a heritage of same impedance. 

Many thanks for any help with this.

Tony

Oops, wiring speakers in series would make 16 ohms, not 8.........

Use the 8ohms on the JVM with that cabinet. If you find its not enough the best bet will be to just get a 4x12. You can make the 1936 a 16ohm cab but would need to change the speakers.