Single Rectifier impedence/speaker outs

[Pasc22]

Hi, im looking at buying a single rectifier in the near future, and i currently have an extension cab that is great, but its 16 ohm. i noticed the speaker outs on the solo 50 are 4, 4 and 8 ohm. My cab is a 2x12 with 2 8 ohms speakers in series, so what would be best; to connect each of the speakers to a 4 ohm output individually, (cos the cab has a second spot to connect the speakers to), or to leave them in series and put them into the 8 ohm output? Will the first option give me a stereo setup??
Also what is the difference between speaker cable and guitar cable, Ive been using a normal guitar cable for a while now and didn't notice anything weird??

Thanks

 

[mrd]

You can plug your 16ohm cab into the 8ohm jack just fine. The sound will be a bit darker than it should be, because you're presenting a bigger load to the amp than it is expecting (16ohms vs. 8ohms), but nothing will be damaged. The only thing to look out for is UNDER-loading your amp. Like if you were to plug in a 4ohm cab into an 8ohm speaker tap... the amp is expecting 8ohms of resistance but only getting half of that. You can actually do this if you want, but it will run your power tubes ragged in no time, and it's pretty hard on the amp itself. But, nothing is going to go "boom", if you do this.

The first option will not give you a stereo output because you only have one amp in the first place, there isn't anything to make the signal stereo. Stereo is defined as two signals that are displaced in time or amplitude. Running the same thing through 2 speakers isn't stereo, it's just mono through 2 speakers. If you want stereo, get a stereo chorus/delay/reverb effect, or run 2 amps through one cabinet.

Without beating around the bush, using guitar cable to connect your amp to the cab is bad. Bad, bad, bad. Speaker cable is a thicker gauge because it is meant to carry a very high-voltage. I think that power-amp outputs are in the range of 400-600 volts, which is several hundreds of times higher than the output of your guitar's pickup. In fact, your guitar's pickup probably has a peak output voltage of something like 0.5v, so guitar cable is likely only rated to 1v or something like that. To run 500volts through a cable rated for 1volts is asking for it. You could start a fire, wreck your amp, or both. Go buy speaker cable now, sir, and don't use guitar cable for that anymore. You'll likely notice a difference in your tone after you switch over to proper speaker cable, as well.

 

[Pasc22]

so it would be cool to take the first option? running an 8 ohm speaker into each of the 4 ohm outputs, i think the manual said something about this saying it would add up to the right impedance? and then if i had a stereo effect it would work? ill get myself some speaker cable asap
also how do u think the solo 50 would go with a 2x12 cab? its similar to an orange cab, vintage 30's.

 

[mrd]

Yeah, the first option should work fine. The equation for figuring out total load presented to an amp is as follows:

Total ohmage multiplied together DIVIDED BY total ohmage added together.

So for instance, two 8 ohm speakers present a load of 4 ohms because:

8x8 = 64
8+8 = 16

64 / 16 = 4, which is the 4 ohm load that the amp will be presented with.

Same thing works for two 16 ohm cabs and 8 ohm taps:

16x16 = 256
16+16 = 32

256 / 32 = 8, which is why two 16 ohm cabs will need to go into two 8 ohm taps.

I don't think running a stereo effect will work in this case, with one amp. I'm pretty sure the power amps in mesa amps are mono, meaning that once the signal is passed from the pre-amp, that's it, there's no way to split it. And you can't run a stereo chorus in between your amp and your speaker (for the same reason you can't use guitar cable to connect your cab up to the amp). So... either buy a stereo power amp and run your pre-amp through THAT, or buy another amp. Or just live with mono, lol.

EDIT: Solo 50 should go fine with a 2x12 cab. I have a recto 2x12 as well and I love it. It's super punchy, very loud for it's size. It's a great little unit, very well built.

 

[mrd]

Actually, I just read my Road King manual, and it says that running two 8 ohm speakers in series is additive, meaning the that total load is then 16 ohms. So... you'll have to plug them both into the 8 ohm tap. You could plug one into the 8 ohm tap and one into the 4 ohm tap and it would LIKELY be OK but I'm not 100% sure.. maybe wait for someone else to chime in, or just call Mesa and ask them how to best wire it up.

But, if you get that Recto 2x12, it's meant for Mesa amps obviously, so it just goes straight into the 8 ohm jack no problems.

 

[FJA Mods]

Running a speaker load that is higher than the amp is looking for (16 ohm cab, 8 ohm jack on amp) can cause flyback voltages which take out power tubes, rectifier tubes, tube sockets, and output transformers. This is especially bad at high volume levels when pushing a distorted signal. I have seen this type damage in Mesa amps. My opinion as a guy that fixes amps is only run the amp with the correct load or be prepared to pay for repairs.
Amps do not put out 400-660 volts, a speaker cable will see about 26 volts AC for a 100 watt amp. It's not the voltage that's the problem with using an instrument cable to connect the amp to the speaker, it's the current. Speaker cables handle more current.
Simple way to figure impedance of multiple cabs is to remember two equal resistances in parallel is equal to half of each. Two 16 ohms cabs = an 8 ohm load, two 8 ohms cabs = 4 ohm load, etc.
Jerry

 

[Pasc22]

Ok, so let me get this straight

I have a 16 ohm cabinet
it is a 2x12, with 2 8 ohm vintage 30's in series, hence 16 ohms.
but if i were to take them out of series, and wire each speaker to its own tap(correct wording? i have 2 inputs on the back of the cab that can be used, but obviously im only using 1 as they are in series to it.) thus having two 8 ohm taps that i would then plug each into one of the two 4 ohm outputs on the mesa.
this would be correct impedance? is this the best sounding and easiest way?

Also if i decided to grab another 2x12 down the track to combine with this one, what impedance should i look at?

thanks for the help, and yes i did buy a speaker cable !

 

[tennisplayer]

I have the same situation. I just called Mesa tech support and Mike out there told me it's a fine mismatch and will not hurt the amp. Asked him about any tone difference, said he doubt's I would be able to detect it. So you are good to go.

 

[Chuck Bravo]

Ok, so let me get this straight

I have a 16 ohm cabinet
it is a 2x12, with 2 8 ohm vintage 30's in series, hence 16 ohms.
but if i were to take them out of series, and wire each speaker to its own tap(correct wording? i have 2 inputs on the back of the cab that can be used, but obviously im only using 1 as they are in series to it.) thus having two 8 ohm taps that i would then plug each into one of the two 4 ohm outputs on the mesa.
this would be correct impedance? is this the best sounding and easiest way?

Also if i decided to grab another 2x12 down the track to combine with this one, what impedance should i look at?

thanks for the help, and yes i did buy a speaker cable !

Here's what I would do.
Rewire your cab with the two 8s in parallel giving you a 4 ohm load. Jack into the 4 ohm speaker out. I would say it's going to be your best option right now.

If you go and get another 2x12 down the road, look for 8 ohm speakers. Reverse the wiring in your original cab and wire the new cab with the two 8s in series so you have two 16 ohm cabs. Run the two cabs in parallel into the 8 ohm speaker out.
Enjoy your Solo 50. Don't be afraid crank the snot out of it. They're so sweet.

 

[Pasc22]

OK thanks for the advice chuck, that is very helpful information, exactly what i needed.
Cheers
may as well ask now, to run the 2 x 16 ohm cabs in parallel, how is this done? considering i ever get one

 

[Chuck Bravo]

Make sure your new cab has at least two jacks. They'll be marked in/out or parallel or something like that depending on manufacturer. Stereo capable cabs can have two or four.

You're going to need another speaker cable. One cable out of the amp, into the first cab, second cable out of first cab into second cab. Dead simple.

 

[b0nkersx]

Make sure your new cab has at least two jacks. They'll be marked in/out or parallel or something like that depending on manufacturer. Stereo capable cabs can have two or four.

You're going to need another speaker cable. One cable out of the amp, into the first cab, second cable out of first cab into second cab. Dead simple.

Correct me if I'm wrong, but I'm pretty sure that's series, man. Parallel would mean having to connect one jack on the amp to one cabinet, and another jack on the amp to a different cabinet. If you're daisy chaining them together like that, then they're in series (right after each other) which means resistance is purely additive (32 ohms with two 16 ohm cabs). In parallel, the inverse of the total resistance is equal to the sum of the inverse of the individual resistances (8 ohms with two 16 ohm cabs).

 

[Chuck Bravo]

It does appear to be series but it's not. If it was in series, you wouldn't have sound in the first cab if you unplugged the last cab. It would be a nightmare to wire cabs in series.

You could run directly to the amp from each cab, but then you would have two 16 ohm loads to plug into an amp that has three speaker jacks. One 8 Ohm and two 4 Ohm.

The Solo 50 manual states "when using two 8 Ohm speakers, connect each of them to the 4 Ohm speaker jacks that are provided, this will equal a 4 Ohm load which is the proper impedance required when using this particular speaker configuration."

So, the amp wants to see 8 Ohm loads. I think there's only one way to do that with four 8 Ohm speakers. That would be series/parallel.

 

[Pasc22]

now im a bit confused :S

 

[thunda1216]

Ok, so let me get this straight

I have a 16 ohm cabinet
it is a 2x12, with 2 8 ohm vintage 30's in series, hence 16 ohms.
but if i were to take them out of series, and wire each speaker to its own tap(correct wording? i have 2 inputs on the back of the cab that can be used, but obviously im only using 1 as they are in series to it.) thus having two 8 ohm taps that i would then plug each into one of the two 4 ohm outputs on the mesa.
this would be correct impedance? is this the best sounding and easiest way?

Also if i decided to grab another 2x12 down the track to combine with this one, what impedance should i look at?

thanks for the help, and yes i did buy a speaker cable !

if you take them out of series, you are correct, you will have two 8 ohm speakers. Does your Mesa not have two 8 ohm outputs? Connect one 8 ohm output to each speaker. If you connect an 8 ohm speaker to a 4 ohm output, your output power will be reduced by 1/2. If you re-wire them in parallel (+ to +, - to -), then you will have 2 8 ohm loads that will equal one 4 ohm load. The ohms will not really affect the sound as much as the power. You should wire the speakers in parallel for a 4 ohm load and use one 4 ohm output from your amp.

ty