1 Topic by jayb (edited by jayb 2012-09-13 21:25:47)

  • jayb
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Topic: Speaker cab wiring

Despite playing for a few decades I'm embarrassed to say I've never been a gear head. Seeing as I've ordered the Ceriatone 2555, I've decided it's about time I payed more attention to the technical aspects of the craft. With that in mind I've come once again asking for advice. My plan is to run the 2555 and my trusty Super 60 into my quad cab. It's a stereo cab with Sammi ME300B100 speakers (I thought they were Mcauley until I opened her up today). I plan on running a head into each side and getting some tonal bliss, however I want to make sure the dream isn't shattered the moment I fire it up and discover I've overloaded something.

I've taken some pics of the cab today and would like some piece of mind that it is still wired for stereo and that the inputs on the cab are still labelled correctly. The reason I ask is that some years ago the original speakers were removed and the Sammi's installed.

Cab internal

I currently run out of the 8 ohm output on the Super 60 and into the centre input on the cab. According to the original specs of the cab, the centre input is for left side stereo at 8 ohms or all speakers in mono at 4 ohms. Maybe I've been "doing it wrong"? I have been running the setup this way for years without a problem and a lovely loud warm tone so if I'm doing it wrong, it's not killing anything. smile

back plate

Some pics of the input board if that helps.


input board bottom

Input board top

  • From: North Carolina
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Re: Speaker cab wiring

From what your saying you are runnning 8 ohms for a stereo effect on your cab.  Most likely the amp has Tremelo or some crazy cool effect built into the amp.  If your going to sue this effect I would say the stereo wiring is ideal.  If you are not using the amps effects and use pedals it won't matter and you could go 4 ohm mono.  The flip side to this is if your speakers are designed to handle 8 ohms together you need to leave it alone.  If you want to switch to 4 ohms with your speakers you need to make sure the ohms of the speakers match up to 4ohms output.  If they are 8 ohms output leave it alone.  It will depend on if it is wired in series or parrell.  I think if its working leave it alone.

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Re: Speaker cab wiring

Let's see.
If the speakers are 16 ohm, you can run two 2x12's at 8 ohms (like what Joe does) and you'd need a female plug for each respective 2x12. If your speakers are 8 ohm, however, the 2x12's would end up being 4 ohms, and you'd have to make sure your amps could handle that. Having two speaker plugs would make them two separate entities.

I'm not sure what that input board is, I'm used to see seeing wires soldered directly to a regular old speaker jack.

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4 Reply by DougH (edited by DougH 2012-09-14 10:16:54)

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Re: Speaker cab wiring

First lets look at the speakers you have in there

Sammi Sound Me300b100 12" Stamped Frame Speaker
This item has been discontinued. For possible replacements or substitutions, please check the drop-down box below for a list of related items to view more products in this category. Rugged, efficient stamped frame speaker for musical instrument and sound reinforcement systems. Cloth edge, paper dust cap, 50 oz. magnet with vented pole piece. Specifications: *Power handling: 100 watts RMS *VCdia: 2" *Le: 0.67 mH *Impedance: 8 ohms *Re: 6.5 ohms *Frequency response: 40-6,000 Hz *Fs: 48.6 Hz *SPL: 98 dB 1W/1m

I think you may need to rewire the connectors,
I see they are 8ohm so you could wire 2 speakers as 16 ohms in series or you could put 2 speakers in parallel for 4 ohms
and since you have two sets of 2 you could have 2 speakers at 16 and 2 at 4 or both sets at 16.

since they are 100w speakers, 2 of them would make a 200w speaker combo
so more than enough to handle a 60w but cutting it probably a bit close on a 100w running flat out.

check a few of these links out
http://www.jumbosunshade.com/swd01.htm

http://www.loudspeakersplus.com/pdfs/sp … agrams.pdf

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5 Reply by jayb (edited by jayb 2012-09-14 19:10:40)

  • jayb
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Re: Speaker cab wiring

Thanks guys, it's all starting to come back to me now. smile The original speakers in the cab were Celestions (dunno which model but they were too bright for my liking).

So it seems I may have been running it ok so far. Based on the jumbosunshade site it seems my speakers are wired in series/parallel with an 8 ohm load.

"These two 16-ohm circuits are connected in parallel thus: 16 (ohm load) divided by 2 (loads in the circuit) equals a 8-ohm load."

If this is the case, then I assume each pair is wired in series giving me a 16 ohm load when I run in stereo?

If I'm correct...and I'd be amazed if I am....then I have 2 choices. Rewire to run 4 ohms per side or invest in new speakers to get 8 ohms per side.

6 Reply by RickB (edited by RickB 2012-09-14 20:36:35)

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Re: Speaker cab wiring

It seems you are correct. If the amps have a 16 ohm output, you're all set. Otherwise, rewire each side in parallel and set the amps to 4 ohms. Should work fine either way.
Rick
(it won't hurt the amps if they are set to 8 and you hook up a 16 ohm load.)

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  • jayb
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Re: Speaker cab wiring

Yeehaa...I'm right. smile Thanks Rick. One last question if I may.....will I notice any difference in tone by going 4 ohms rather than 8?

  • RickB
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Re: Speaker cab wiring

jayb wrote:

Yeehaa...I'm right. smile Thanks Rick. One last question if I may.....will I notice any difference in tone by going 4 ohms rather than 8?

Gee, I'm a techie but not a player. It shouldn't but I'm not sure. hmm  Anyone know the answer?

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  • DougH
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Re: Speaker cab wiring

you don't want to run a tube amp at a lower ohm-age than selected on the amp.
you'll run the output transformer a little to hard and could burn it up.

if you run a 8ohm selected on the amp on 16ohm speaker load it will act like an attenuator and lower your overall volume.

just get a multimeter to be sure.
but just set your amps' to 16ohms and wire your two sides of the speaker cab in series so you have 2x12 running at 16ohms forget that funky switch created by Crate

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  • jayb
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Re: Speaker cab wiring

So you feel I'm better off runnning both sides in series getting 16 ohms rather than parallel and getting 4 ohms? Both amps are capable of selecting 4 ohms but the Super 60 won't do 16 ohms. What's my best option?

  • DougH
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Re: Speaker cab wiring

Your best option.
look at what the amp's can be selected to as Ohms out and wiring your cabinets accordingly

In general Tube amp theory (not solid state here), if you have an amp set for 4 ohms and a load of 4 ohm you will produce the same power and volume as setting the amps for 16ohms and providing the amp a 16 ohm load.

A tube amp will not delivery more power (unlike a solid state amp) in running an amp with a lower load. you will only tax the output transformer and unhappy results will happen
if you run a higher load you will get a reduced volume

so if both amps can do 4 then wire them for 4.
if 1 amp can do 16 and the other 4 then wire the cab accordingly.

the sum of the wattage of the combined speakers doesn't matter if they're serial or parallel.

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