Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums > Audio Measurement and Testing

Advice On Eq for TFM122M Wedges

<< < (4/4)

Luke Geis:
He is pointing to the box tunings minima. Not always the lowest impedance point of the graph. The other position where it is actually minimum would make what I feel is the ideal HP point. The lowest point at around 180hz. While 180hz is probably a bit high to roll it off, 140-160hz is a good starting point.

John Schalk:
Here are some screenshots detailing the HPF and PEQ values I ended up with after remeasuring using a stage mic position for each wedge.  One thing that I noticed right away is that the 15" wedge has a more even unprocessed frequency response.  The 15" wedge seems big when it's sitting next to it's little brother, but it's still pretty compact and very light.  The only value that I'm kind of nervous about is the one adding +3dB @ 2.5kHz for the 12" wedge.  It does go against my better nature to increase any frequency in that area.

I am waiting to hear back from the band leader for the July 4th gig to see if the show is going to happen or not.  That will be my first opportunity to put my work here to use and get some real world feedback on how these wedges sound and perform.  Thanks to all of you for your help.

Art Welter:

--- Quote from: Scott Holtzman on June 03, 2021, 09:55:01 PM ---
Art, why is the arrow not on the lowest impedance point?  Am I missing something?

--- End quote ---
I missed part of the explanation:
On any ported (bass reflex) cabinet there is always an impedance minima between the two lower frequency peaks at Fb, (Box tuning Frequency).
Excursion is also at it's low frequency minimum at Fb, it increases above and below Fb ( around 70Hz).
Put a white dot on the cone, do a sine wave frequency sweep between those two peaks and the dot will appear near stationary at Fb.
The impedance peak above Fb (in this example, near 110Hz) will be around the maximum excursion above a BW24 HPF of around 65Hz.

Art

Art Welter:

--- Quote from: John Schalk on June 04, 2021, 11:06:29 AM --- The only value that I'm kind of nervous about is the one adding +3dB @ 2.5kHz for the 12" wedge.  It does go against my better nature to increase any frequency in that area.

--- End quote ---
The 2.5kHz dip corresponds to it's widening pattern at that frequency, so it needs more gain on or off axis, without the +3dB boost, the monitor will fail to bring hearing to the deaf ;^)





John Schalk:

--- Quote from: Art Welter on June 03, 2021, 03:29:45 PM ---Take a look at the TFM152M impedance chart.
On any ported (bass reflex) cabinet there is always an impedance minima between the two lower frequency peaks at Fb, (Box tuning Frequency). Below Fb, excursion climbs rapidly, cones flap (and/or add lots of second order distortion, adding the "missing fundamental") - so as a general rule, the HPF frequency should be no more than about 10% lower than Fb, which looks to be about 70Hz.

--- End quote ---
Art,

I went back to the original Turbosound documentation and compared the impedance charts for the TFM12 & TFM15 and they are nearly identical. I was expecting the bigger 15" box to go a little lower, so that's why I took a guess at a 60Hz HPF for it.  I will go back in and raise it to 70Hz.  I'm still processing your first set of comments about how the frequency response that I am seeing is a reflection of the on & off axis response charts in the Turbosound docs!

Luke,

Since these settings are getting stored in the amp's DSP module, and I don't typically bring a laptop with Armonia to gigs, I want to use the HPF for the "protect the speaker" use case rather than optimizing it for say a vocal wedge.  I see a lot of bands with tracks these days, often synth and keyboard parts because they don't have that musician on stage, so I'd like the wedges to be able to reproduce those sounds if needed.  If the artist only wants vocals in their wedge, then the effective HPF will be in the range you recommend because that's what I use on all of my vocal channels anyway.

All,

I've re-read this thread and I am processing everyone's comments and suggestions again, so I may still go back and incorporate the idea of a slow HF shelf, but first I'm going to set the wedges up indoors and ring them out with my e935 & e945 mics and see if I like the results.  I'm also working on my golf wedge game, which needs A LOT more work than these speakers :)

Navigation

[0] Message Index

[*] Previous page

Go to full version