Speaker Ohms

[Pappy]

I'm new here. Just picked up a used 5:25 1x10" combo this weekend at a killer $$$. Kind of a hassle to get the deal done, but she mine and I allready love her!
Anyway........ 3 speak inputs on the back panel. 1 ea 8 Ohm that the 10" speak is plugged into and 2 ea 4 Ohm inputs. Can I plug the 10" onboard speak into one of the 4 Ohm inputs and a 16 Ohm 12" cab to the other 4 ohm input?
I unplugged the on board 10" and plugged in my Epi 12" 16ohm Lady Luck to the 8 ohm input as instructed in the amp manual and it sounded great, but can I run both 10" and 12" of different ohm at the same time in the 4 ohm inputs
with out messing up the spearker, or the amp ? Or, if I can run it that way, will it sound unbalanced and crappy?
Please give me guidence. :mrgreen:
Thanks
Pappy

 

[thunda1216]

if you plug the 16 ohm speaker into the 4 ohm output, the power to the speaker will be reduced to 1/4 of the rated output. To work right, you would need to have two 8 ohm loads connected to one of the 4 ohm outputs, or two 16 ohm loads connected to the 8 ohm output...

ty

 

[THE TUBENATOR]

Pappy,

You don't want to induce an unbalanced load to the output section of the amp. Before you get too carried way and possibly into some trouble check with the owner's manual. I realize you purchased your amp used but if you didn't get the owner's manual you can download one from the Mesa website. Worth looking into.

 

[Pappy]

The reason I asked this question is that I have a Epiphone Valve cab loaded w/ a 16 ohm 12" Eminence Lady Luck speaker .
The 5:25 has 8 ohm input and 2 ea. 4 ohm inputs.
I wanted to use both the internal 10" 8 ohm B.S. and the external Epi 16 ohm at the same time.
I know now that I shouldn't and I won't!
The manual says I can disconnect the 8 ohm internal 10" and pul my 16 ohm 12" into the 8 ohm input.
So... I'll just use one at a time until I can get my hands on a good 12" 8 ohm speaker and switch it out with the Lady Luck 16 ohm in the Epi cab.

Any recommendations on a good reasonably $$$ 8ohm 12" speaker? :mrgreen:

 

[MrMarkIII]

It's safe to use both the internal 8 ohm and 16 ohm external. The tone changes a bit, and only you will know if it's a change you will like. The 8 ohm speaker will be a bit louder than the 16. Some will argue that your output tubes will wear faster, but the output transformer should easily handle this safe mismatch. This is covered, by the way, in the back of the owner's manual, downloadable at Mesa's website.

 

[soundchaser59]

It's safe to use both the internal 8 ohm and 16 ohm external. The tone changes a bit, and only you will know if it's a change you will like. The 8 ohm speaker will be a bit louder than the 16. Some will argue that your output tubes will wear faster, but the output transformer should easily handle this safe mismatch. This is covered, by the way, in the back of the owner's manual, downloadable at Mesa's website.

I cant find where the manual specifically addresses the OP's mismatch example of a 16 ohm + a 8 ohm, but..... after reading the manual I would tend to agree that it should be ok. One 8 ohm plus one 16 ohm will give an impedance of about 5 ohms. The only thing they specifically recommend against is going lower than the jacks rating, like a 4 ohm into the 8 ohm jack, or a 2 ohm into the 4 ohm jack. But they say the power tubes will wear out faster, not anything about damage to the amp. Seems they would have stronger warnings if it would actually damage the amp?

My question would be which jacks to use??

The 16 ohm in the 8 ohm jack + the 8 ohm in the 4 ohm jack?

Or both 16 ohm and 8 ohm plugged into the two 4 ohm jacks?

Or should the 16 ohm and the 8 ohm be daisy chained to each other, then one cord plugged into one 4 ohm jack?

I need to find out, because I may be trying this soon, if I can get this used Weber speaker as cheap as I would like.

 

[thunda1216]

If you plug a 16 ohm speaker into an 8 ohm output jack, you will cut the power the speaker delivers in half. (You are doubling the resistance, only 1/2 the power will get through...)

ty

 

[MrMarkIII]

"My question would be which jacks to use??
The 16 ohm in the 8 ohm jack + the 8 ohm in the 4 ohm jack?"

Yes.
The basic idea is: whatever the impedance of the speaker,
use the jack which is half that value, i.e., as you have stated above.
So, 16 ohm speaker into 8 ohm jack, 8 into 4, etc.
You will not blow anything up, unless you try two 4 ohm speakers. That takes it down to 2 ohms, too low.

 

[soundchaser59]

Thanks MrMark.

Makes sense.

IF I get this Weber cheap, and IF it sounds smoother than the EV (doubtful, but I would like to know) then I will probably end up putting the 16 ohm Weber in the amp. I know it changes the tone a slight bit, but I know from previous trials that it is a change in favor of the tone I'm after. It almost has the same effect as using a less efficient speaker.....

And, of course, there would be times when I would want to play the amp with an external cab, 16 ohm Weber in the amp + 8 ohm Weber in the cab.

 

[Pappy]

Okay. Thanks to all for clarifying this.
I'll try it out this weekend. 8 ohm speaker in the 4 ohm jack and 16 ohm speaker in the 8 ohm jack. I'll let you know how it sounds Monday.
I want to get a good reasonably priced replacement 8 ohm 12" for the Epi Valve cabinet. Please give me your recommendations.
Celestion?
Weber?
Jensen?
Eminence?
Others?

 

[soundchaser59]

Weber - any, Blue Dog and Michigan are my favs

Eminence - Cannabis Rex

Celestion - Greenback, or I bet a Hot 100 would sound good with that amp

Jensen - C12K

Tone Tubby if money is not a problem

 

[Trea]

I have a similar question. If I have a 2x12 extension cabinet rated at 4 ohms is it safe to run the internal speaker out of the 8 ohm jack and the extension cabinet out of one of the 4 ohm jacks at the same time?

Thanks in advance

 

[J.J]

I have a similar question. If I have a 2x12 extension cabinet rated at 4 ohms is it safe to run the internal speaker out of the 8 ohm jack and the extension cabinet out of one of the 4 ohm jacks at the same time?

Thanks in advance

Yes, that is fine. These amps can except wide speaker impedance mismatches. The main thing to avoid is running a speaker with a much lower impedance than the amps output as others have said. That case is hard on the output tubes.

 

[Trea]

Thanks for the advice. It seemed like that would be ok, but I just wanted to make sure. It does sound nice with both the internal speaker and the 2x12 cab running at the same time.

 

[Trea]

One more quick question. The cabinet can be run at 4 ohm mono or 8 ohm stereo. Would it be better to connect it to the 5:50 with two cables from the 4 ohm outs to the 8 ohm stereo inputs? Or one 4 ohm out into the 4 ohm mono input. This is while running the internal speaker at 8 ohms.

Thanks in advance for all the help guys.

Trea

 

[Trea]

I actually figured out my own question. Once I did the math, having the internal speaker and the 4 ohm cab running at the same time gives a 2.37 ohm load. Not good. I would have to rewire the speakers to show a 16 ohm load in order to be safe, but I think I'm just going to take the cab back and get something different.