setting Low Res. Freq. w/ mesa 2x12 recto cab . . . (also - major score for a brand new recto cab)

Alabama man

Alabama man

Inspired
Sooooooooo. . . I just got a brand new Mesa Boogie horizontal 2x12 Recto cabinet for $240! This thing has literally been untouched - even came with the slip cover! Guy just wanted to get rid of it quick (don't worry - he was super wealthy and had no use for the cab - wasn't stolen).

*Main question* - will the low res. frequency control in the speaker tab in the amp block be the same for whatever amp I'm using when running my axe with a Matrix GT1000? I'm just using the axe + power amp into this 2x12 cab - no frfr.

And does anyone know what the number would be that I need to set it to?


Thanks

God - I am so friggin' happy

(also, apologies if this post is in the wrong section. wasn't sure where to post)
 
Last edited:
Seems like a good place to ask...

I've heard it said around here that when using a traditional cab matching the resonant frequency brings out a lot of clarity, and I've experienced this somewhat by just sweeping the dial, but how do you go about finding the exact, mathematical high & low resonant frequency, level, and Q?
 
psycle_1 said:
My measured settings on my Mesa 2x12 are as follows:
114.26 Hz
Low Res 5.79
Q=3.173

Nice deal on that 2x12!
Click to expand...

That Q seems awfully high. How did you arrive at that figure. FWIW the Qts, Qms, etc., reported by loudspeaker testers is not the same as the effective Q used in the Axe-Fx.

The way to measure Q is first find the resonant frequency which is the frequency of maximum impedance, in this case 114.26 sounds right. This is f0. Find the impedance at that frequency. Take that impedance and divide by the DC resistance Rdc. Take the square root and multiply by Rdc. Call this value Zbw. Now find the bandwidth defined by the points at which the impedance equals Zbw. The Q is then f0/bw.

For example:
f0 = 114
Zmax = 100
Rdc = 7
Zbw = sqrt(100/7) * 7 = 26.5
Measure the bandwidth at Z = 26.5 ohms. Let's say it's 50 Hz.
Q = 114 / 50 = 2.28

The observant reader will notice that Zbw = sqrt(100/7) * 7 = sqrt(100 * 7).
 
I got Q exactly how you described. Unfortunately I don't remember what my bw frequencies were since I measured my cab a couple of years ago. Ever since Quantum came out I haven't felt the need to fool with the Speaker tab at all, especially with Quantum 2.
 
psycle_1 said:
I got Q exactly how you described. Unfortunately I don't remember what my bw frequencies were since I measured my cab a couple of years ago. Ever since Quantum came out I haven't felt the need to fool with the Speaker tab at all, especially with Quantum 2.
Click to expand...

Cool. I should add this to our database.

You can find the bw frequencies by noting that f0 = sqrt(flow * fhigh). So if f0 = 114 and Q = 3 then bw = f0 / Q = 38 Hz. With a little math you can then get the lower and upper freqs.
 
Yeah, I though of that. Not doing any math today though... Too busy fixing amps (including an Engl Powerball that has nothing wrong with it). LOL.

BTW, the Mesa spec V30's in my cab are quite a bit older and slightly darker sounding compared to the newer ones. If desired, I can measure my other guitarist's Mesa 2x12, which is only a couple of years old.
 
psycle_1 said:
My measured settings on my Mesa 2x12 are as follows:
114.26 Hz
Low Res 5.79
Q=3.173

Nice deal on that 2x12!
Click to expand...

Thanks so much!

Does anyone know if there's an IR for my cab out there? It's the rectifier 2x12 rated for 120 watts, so the newer model I guess.
 
Also, for the
psycle_1 said:
My measured settings on my Mesa 2x12 are as follows:
114.26 Hz
Low Res 5.79
Q=3.173

Nice deal on that 2x12!
Click to expand...


Forgot to ask - are these settings going to be the same for every amp I use in the axe? These controls are all in the amp block, right?

Thanks again
 
Ideally, if you want to want to exactly match the low end response, yes. Just play around with my values vs the amp defaults and see what you like. Like I told Cliff, I really don't worry about it anymore with Quantum 2.
 
Alabama man said:
Sooooooooo. . . I just got a brand new Mesa Boogie 2x12 Recto cabinet for $240! This thing has literally been untouched - even came with the slip cover! Guy just wanted to get rid of it quick (don't worry - he was super wealthy and had no use for the cab - wasn't stolen).

*Main question* - will the low res. frequency control in the speaker tab in the amp block be the same for whatever amp I'm using when running my axe with a Matrix GT1000? I'm just using the axe + power amp into this 2x12 cab - no frfr.

And does anyone know what the number would be that I need to set it to?


Thanks

God - I am so friggin' happy

(also, apologies if this post is in the wrong section. wasn't sure where to post)
Click to expand...

Are you referring to the 2x12 slant vertical recto cab or the 2x12 straight horizontal recto cab?
 
psycle_1 said:
Ideally, if you want to want to exactly match the low end response, yes. Just play around with my values vs the amp defaults and see what you like. Like I told Cliff, I really don't worry about it anymore with Quantum 2.
Click to expand...

That's good to know. I finally got a chance to update to 2.0 today and will give a whirl in a few.
 
I was just asking about this today and more Google netted me a link to this thread. I have a new Mesa 2x12 Recto cab (horizontal) and was looking for exactly this info. Doing it by ear wasn't working for me.

@psycle_1 I don't suppose you actually measured that other, newer Mesa cab?

Also, I'm not completely math challenged, but I'm trying to wrap my brain around this enough to work out the high and low frequencies from the data posted so far in this thread.

Thanks!
 
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