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 Post subject: mixing speakers in a cab
PostPosted: Mon Apr 06, 2015 7:29 pm 
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Mark III

Joined: Tue Jan 08, 2008 7:21 pm
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i have a 2x12 cab that has two eminence private jack speakers. i also have a spare warehouse guitar speaker veteran 30. i'm curious as to how it would sound if i were to put the veteran 30 in place of one of the private jack speakers. i just want to be sure first- because the private jack is 50 watts and the veteran 30 is 60 watts, is there any potential harm to my amp given the wattage mismatch? i'm guessing that they're close enough but i like to err on the side of caution. thanks to anyone who can help.

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PostPosted: Mon Apr 06, 2015 10:39 pm 
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Mark IV
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the wattage will not be the issue. you could use a 25 watter and a 200 watter, won't matter...the difference will be in the spl rating. This refers to loudness at a specific measurement (as in decibels per watt at a specific distance from the speaker). if one speaker is 95 dB spl and the other is 100 dB spl, then you will only hear the louder speaker.

you need to compare the spl ratings to make sure they are close (no more than 2-3 dB difference). Now here is the tricky part: each speaker manufacturer measures spl differently. It's easier to mix speakers from the same manufacturer than mix different makes. In your case, just try it to see if they pair well and you like the sound.

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PostPosted: Tue Apr 07, 2015 10:50 am 
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Are they the same impedance (ohms)?

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PostPosted: Tue Apr 07, 2015 4:32 pm 
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Dual Recto

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Assuming both speakers are the same impedance, and close to the same power handling, there shouldn't be a problem. If one speaker has a sensitivity of about 3 dB more than the other, that one will perceived as louder. That can be a plus in a vertical cab. Put the louder speaker in the bottom, so it will match the softer speaker that's closer to your ears.

If each speaker has a different impedance, the one with lower resistance will absorb more power and be louder.

How are the speaker jacks labeled? Typically, Mesa amps have one 8 ohm speaker out and two 4 ohm outs.

Now, here's where it gets tricky: contrary to common sense, the two 4 ohm jacks are NOT meant for one 4 ohm speaker from each jack.
They are designed to handle ONE EIGHT OHM speaker (or cab) from EACH jack.

The same holds true for a Mesa amp with two 16 ohm jacks. They want to see an 8 ohm load at each jack.

You don't have to believe me, just look in any Mesa owner's manual. All of them are available at the Mesa website.

Two 8 ohm speakers in parallel will have a total impedance of 4 ohms.
In series, you get 16 ohms. Them's your choices. You can't get 8 ohms from two 8 ohm speakers.

However, you are allowed to experiment to a certain degree. The manuals even encourage it. Try plugging the 4 ohm cab into the 4 ohm jack, then compare it to the 8 ohm jack, etc. You may prefer the sound and feel. It's safest to put the amp on standby before unplugging speakers. Tube amps don't like being run without a speaker plugged in.

Mesa amps can handle a 100% mis-match, up or down. Mesa (and Fender), not Marshall.

As far as two speakers with different power ratings:

The rule of thumb is to take the lowest rated speaker's power rating and multiply that by the number of speakers. In the case of a 25 watt speaker paired with a 200 watt speaker, 25 x 2 = 50 watts is a maximum safe power handling for the pair.

In your case of a 50 watt paired with a 60 watt, the safe power level would be 100 watts. Not 110, but, yeah, it's only 10 watts.


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PostPosted: Tue Apr 28, 2015 10:21 pm 
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Mark II

Joined: Wed Sep 28, 2011 11:52 pm
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Back in the days of the Mesa metal-grill 4x12s, you could order cabinets with mixed speakers directly from Mesa. I've got two:
-one came with Celestion 90 watters on top and Eminence Vintage 50s on the bottom.
-the other came with Celestion 90 watters on top and Electro-Voice EVM12Ls on the bottom.

The EVM 12Ls can handle 300 watts each.

They definitely sound different. Experiment!


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