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Author Topic: Advice On Eq for TFM122M Wedges  (Read 974 times)

John Schalk

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Re: Advice On Eq for TFM122M Wedges
« Reply #10 on: May 27, 2021, 10:40:38 am »

Noticed you had applied a 58Hz HPF, the TFM122M box appears to be tuned to around 75Hz, a 70Hz BW24 will keep the cone from flapping  (making vocals gargle..) if you put kick or bass in it.
That makes sense to me, I will raise the HPF to 70Hhz for the 112M.  Can you suggest a number for the TFM152M too?  The recommendation from Turbosound is 50Hz for the 15" wedge, so that's what I'm using now.
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Almost all the peaks in the TFM122M correspond to it's narrowing pattern at those frequencies, cutting them to "flat" will improve gain before feedback stability, though those frequencies will also become relatively "dead" off axis.
A bump at 780Hz is in a range where the beamwidth is very wide, it makes sense.
Using a ground plane setup, I ended up with a +3.5dB bump at 700Hz.

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Rather than "bumping" 300 Hz, loosing about 5dB from 90 Hz to 200Hz would loose the "mud" typical on stage from mains wrap, and the LF proximity boost from vocal mics, especially if you are running them pre-eq in the monitors.
I ended up with a cut at 176Hz of 4.5dB with a Q of 1.2.  I will re-check that PEQ after raising the HP frequency and using a "real" mic position.

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The missing 16kHz "spike" in your 2M GP measurement is probably due to being off axis, beamwidth narrows to just 30 degrees above 10kHz.
I spent some time fooling around with that notch, but the resulting PEQ response plot in the amp's DSP just looked silly, and it wasn't generating much of a change when I re-measured, so I removed it.

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For coax floor wedge voicing, I'd suggest putting the measurement mic as near to a typical (for your use) vocal height above deck (open air, away from any walls or large objects), directly on axis, and shoot for flat response, with a slight rolloff below 200 Hz tapering down to Fb.

Art
Thanks for the suggestions Art.  I will raise the HP frequency and then take some new measurements using a stage mic position and see if any of my other settings need to be adjusted.
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John Schalk

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Re: Advice On Eq for TFM122M Wedges
« Reply #11 on: May 27, 2021, 10:45:50 am »

This goes to the heart of my experience retuning four different monitor rigs over the years, some with factory specs and some 'classic' designs.

- Avoid boosting frequencies in monitor tunings. Added gain makes them slightly more unstable
- High pass should be higher than the same box would be for full range / stick use - 60 to 80 hz
- turn down the high frequency driver - flat to 16k is not beneficial for a wedge monitor in fact anything above 10k is just a problem - in your last curve taking the HF driver down 2db would fix the bump just above crossover and and a shallow cut from 3k to 8k would yield a very stable wedge tuning for loud vocal monitors
I'm running the wedges passive Riley, so I can't turn the horn down.  The only high frequency boost that I have now is +2dB at 2.5kHz to go along with a -3dB cut at 4.5kHz.  Per Al's advice, I'm going to set things up again, but use a stage mic position to measure the wedge's response.  I'll post an updated plot once the rain goes away!
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Tim McCulloch

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Re: Advice On Eq for TFM122M Wedges
« Reply #12 on: June 01, 2021, 02:12:33 pm »

I'm running the wedges passive Riley, so I can't turn the horn down.  The only high frequency boost that I have now is +2dB at 2.5kHz to go along with a -3dB cut at 4.5kHz.  Per Al's advice, I'm going to set things up again, but use a stage mic position to measure the wedge's response.  I'll post an updated plot once the rain goes away!

A shelf filter from 2k(ish) , -3dB would effectively "turn down" the HF driver but it will affect phase at the acoustic crossover (measure and listen to decide if it works well or not).

Good advice from Riley and Art, and I'm going to offer a 'second' to Art's suggestion about LF eq. and how the PA and wedges can combine in unfortunate ways.  I'm still surprised by performers who want to do their entire monitor checks with the PA off.  That's not how the wedges will be used; it doesn't matter how great they sound with the PA off, it's how they sound with the band going Full Tilt Boogie and the FOH mixerperson flogging the PA.

My frustration doubles when the same performers wear ear plugs and "can't hear the wedge"... or the ones that want to "feel the wedge" while using IEMs.
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Art Welter

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Re: Advice On Eq for TFM122M Wedges
« Reply #13 on: June 03, 2021, 03:29:45 pm »

That makes sense to me, I will raise the HPF to 70Hhz for the 112M.  Can you suggest a number for the TFM152M too?  The recommendation from Turbosound is 50Hz for the 15" wedge, so that's what I'm using now.
John,

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.
 
Art
« Last Edit: June 04, 2021, 11:23:49 am by Art Welter »
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Scott Holtzman

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Re: Advice On Eq for TFM122M Wedges
« Reply #14 on: June 03, 2021, 09:55:01 pm »

John,

Take a look at the TFM152M impedance chart.
On any ported (bass reflex) cabinet there is always an impedance minima 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.
 
Art


Art, why is the arrow not on the lowest impedance point?  Am I missing something?

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Luke Geis

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Re: Advice On Eq for TFM122M Wedges
« Reply #15 on: June 03, 2021, 10:33:30 pm »

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.
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John Schalk

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Re: Advice On Eq for TFM122M Wedges
« Reply #16 on: June 04, 2021, 11:06:29 am »

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.
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Art Welter

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Re: Advice On Eq for TFM122M Wedges
« Reply #17 on: June 04, 2021, 11:31:04 am »


Art, why is the arrow not on the lowest impedance point?  Am I missing something?
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
« Last Edit: June 04, 2021, 11:39:42 am by Art Welter »
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Art Welter

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Re: Advice On Eq for TFM122M Wedges
« Reply #18 on: June 04, 2021, 11:48:50 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.
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 ;^)





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John Schalk

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Re: Advice On Eq for TFM122M Wedges
« Reply #19 on: June 04, 2021, 02:36:18 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.
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 :)
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Re: Advice On Eq for TFM122M Wedges
« Reply #19 on: June 04, 2021, 02:36:18 pm »


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