More amp questions.

ekwatts · Post by **ekwatts** » Mon Oct 08, 2012 7:37 pm

So it says 16 ohm, and that's it. There's a switching jack up top, a normal jack below. So my question is, basically, can I plug an 8 ohm cab into this amp?

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NickS · Post by **NickS** » Mon Oct 08, 2012 10:51 pm

Better pics, but I can't make out all the numbers on the switched socket; I think I can see 2, 3 and 8. If it's a standard MJ-188 socket, pin 2 connects to the tip contact (so does pin 9, opposite pin

and that's also wired to the tip contact on the internal speaker socket. With no plug in the extension socket, pin 2 will be connected to pin 3 (white wire) and with the plug in both sockets will be connected to pin 1 (black and orange wires).

My interpretation: plug an 8 ohm cab into the extension (switched) socket, or 16 ohm cab into the non-switched, or 16 ohms into both.

Johno · Post by **Johno** » Tue Oct 09, 2012 10:43 am

No, cab should always be greater or equal to the amp. If you had x2 8ohm speakers wired in series that would give it a load of 16ohm's which would be fine.
Your cab is just a single 8ohm speaker?

ekwatts · Post by **ekwatts** » Tue Oct 09, 2012 11:15 am

It's nothing yet, but I wanted to get two different speakers and wire them in parallel, which would mean two 16ohm speakers making a total load of 8ohms for the cab overall (right?). Apparently wiring in parallel brings out the characteristics of the two different speakers. Otherwise I suppose I could just wire two 8ohm speakers in series for a total 16ohm load.

NickS · Post by **NickS** » Tue Oct 09, 2012 12:39 pm

Johno wrote:Your cab is just a single 8ohm speaker?

That was my assumption from the original thread that Eric couldn't be assed to resurrect.

Johno wrote:No, cab should always be greater or equal to the amp. If you had x2 8ohm speakers wired in series that would give it a load of 16ohm's which would be fine.

I'll take issue with Johno's "no" there. This amp has two sockets wired in parallel. One of them is intended for a 16 ohm primary speaker (internal speaker in the combo format). The other is intended for a 16 ohm extension cab. When you plug a jack into the extension cab socket, it operates a changeover switch* that selects a different tap on the transformer. That tap is intended to drive two 16 ohm speakers in parallel = 8 ohms. Therefore, you can plug a 16 ohm cab into the primary socket, a 16 ohm cab into each socket or an 8 ohm cab into the extension socket only.

Eric, if you have the cash option, two 16-ohm 1x12 cabs in a mini-stack would be fine. 2x 8-ohms in series in a 2x12 cab as Johno says would also be fine (in the non-switched socket).

* Actually, it operates two as it's really a stereo socket, but we'll ignore that. Typo in my original post - that should be pin 4, not pin 9, on the MJ-188 switched jack socket.

NickS · Post by **NickS** » Tue Oct 09, 2012 12:50 pm

ekwatts wrote:It's nothing yet, but I wanted to get two different speakers and wire them in parallel, which would mean two 16ohm speakers making a total load of 8ohms for the cab overall (right?). Apparently wiring in parallel brings out the characteristics of the two different speakers. Otherwise I suppose I could just wire two 8ohm speakers in series for a total 16ohm load.

There's nothing to stop you having two jack sockets on the cab, one for each speaker. You could make one a switched socket and wire them in parallel so that if each speaker is 16 ohms, plugging into the unswitched socket leaves them in parallel (8 ohms) and plugging into both gives you separate (stereo!) 16 ohm speakers.

ekwatts · Post by **ekwatts** » Tue Oct 09, 2012 1:10 pm

NickS wrote:
ekwatts wrote:It's nothing yet, but I wanted to get two different speakers and wire them in parallel, which would mean two 16ohm speakers making a total load of 8ohms for the cab overall (right?). Apparently wiring in parallel brings out the characteristics of the two different speakers. Otherwise I suppose I could just wire two 8ohm speakers in series for a total 16ohm load.
There's nothing to stop you having two jack sockets on the cab, one for each speaker. You could make one a switched socket and wire them in parallel so that if each speaker is 16 ohms, plugging into the unswitched socket leaves them in parallel (8 ohms) and plugging into both gives you separate (stereo!) 16 ohm speakers.

Ah, hadn't thought of that.

The cab is built and on its way, it just doesn't have any speakers. I assume the guy at Zilla installed a single-jack plate, but I'm sure I could replace that with a 2-jack plate and wire it up the way you say.

ekwatts · Post by **ekwatts** » Thu Oct 25, 2012 9:22 am

So I think I'll be going with a 16ohm Wizard and a 16ohm Swamp Thang and wiring each up to an individual socket on the jack plate sos I can plug each individual speaker into both of the output sockets on the head.

The cab came with a single socket installed and it's one of those plastic-y ones with tags sticking out. Where can I get a matching jack socket like the one already installed? I take it I can't just use a garden-variety jack socket?

NickS · Post by **NickS** » Thu Oct 25, 2012 11:27 am

Something like this?
Or do you mean it's fitted with a combined Speakon/jack?

ekwatts · Post by **ekwatts** » Thu Oct 25, 2012 11:31 am

The top one, I found one on Hot Rox anyway. How do I know which tag is for the tip and which for the sleeve, though?

wwrrss · Post by **wwrrss** » Thu Oct 25, 2012 11:32 am

ekwatts wrote:The top one, I found one on Hot Rox anyway. How do I know which tag is for the tip and which for the sleeve, though?

tip is furthest from the hole.

ekwatts · Post by **ekwatts** » Thu Oct 25, 2012 11:34 am

Oo-er.

Thanks guys.

ekwatts · Post by **ekwatts** » Tue Nov 06, 2012 9:40 am

So the speakers arrived.

After a minor flap over the screws they're in, wired up and I had a quick blast through the amp last night on reaaaaaally low volume. Nothing exploded or died. Sounded good. Going to try and crank it at some point over the next week.

ekwatts · Post by **ekwatts** » Tue Nov 20, 2012 2:14 pm

Feels good brah.

Pushed it hard the other night and it performed brilliantly. Sounds fucking amazing, to be honest. I suspect it isn't fifty watts... probably closer to 40. Not sure. I think it may have had KT88s rather than EL34s when it was originally made, or so some poster on a forum claimed, but I don't know if that would make a difference.

Anyway, the setup I currently have is both 16ohm speakers wired up independently to their own sockets, running in stereo. However, I was wondering if it would be possible to also have a second option with both wired in parallel (8ohm) to a third socket. It would make the cab more versatile and play nice with other amps. So my question is...

Is this possible without having some big switch or something for the routing? For instance, the speakers have four lugs each, so could I just use the two I didn't use in wiring them up to their own individual sockets on each speaker to wire them in parallel to another socket, or would this cause the universe to explode forever?

Edit: And would the different speaker wattage ratings make any difference? One is 75watts max and the other 150.

ekwatts · Post by **ekwatts** » Wed Nov 21, 2012 8:39 am

Bump for above question.