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DIYSG HTM-12v2 Review

13029 Views 81 Replies 24 Participants Last post by Teeeejay, 10 mo ago

ErinH

Discussion Starter · Jun 14, 2021

Too much to copy/paste here, so please go to the link below for the written review and graphics.

DIYSG HTM-12v2 Speaker Review

DIYSG HTM-12v2 Speaker Review

www.erinsaudiocorner.com

Alternatively, you can watch the video review here:

Cliffs: Tons of potential. A few problematic areas that would make me either not use the speaker or modify it (the latter makes the most sense, if you're already DIY'ing the speaker). As is, however, great directivity, great neutrality above about 800Hz, and great ability to be EQ'd to be more neutral. But the resonance(s) in the lower midrange need work.

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jcmccorm

· #2 · Jun 14, 2021

Another great review Erin! Thanks!

a.lio

· #3 · Jun 14, 2021

Thanks for the review, Erin. I wonder if someone without a NFS can figure out a solution to the resonances. I remember clearly the box howling from the thrashing my sander was giving it, and I wonder if just stuffing polyfill in the cabinet will really do the trick. That would be a very nice and easy fix. Adding bracing seems tricky if you've already assembled the speakers.

brettus

· #4 · Jun 14, 2021

I find 1" dowel is easy to use for bracing when the cab is already assembled. Slightly scallop one end and on the other end scallop the opposite so when you stand it up to brace X walls you don't bend the mdf to much. Screw and glue.

Reactions: 1

jcmccorm

· #5 · Jun 14, 2021

Is it possible for a DIY'er, armed with REW, to regenerate that CSD waterfall? What's an easy way to evaluate any changes?

Zarkoff500

· #6 · Jun 14, 2021

Possibly some No-rez or alternative?

Charles Collins

· #7 · Jun 14, 2021

Thanks Erin, some very valuable information, after some very good work. And it is appreciated immensely.

Reactions: 1

jcr159

· #8 · Jun 14, 2021

I love seeing these reviews of the DIY stuff!

Thanks Erin!

Samps

· #9 · Jun 14, 2021 (Edited)

jcmccorm said:
What's an easy way to evaluate any changes?

Easiest would probably be to DIY an impendance jig and use REW to make impedance sweeps. Those will show all the little nasty things going on in your cabinet. Making the jig is a little tougher than it looks because you're working with super tiny wires. But once it's made, the REW sweeps are really easy. Even easier than regualr sweeps becuase you don't need to hook up a mic or use the AVR, just the jig connected to the speaker terminal.

Or even easier would be to buy the woofer tester from parts express, forget what it's called. And use that for your impedance testing.

This is the one I made. Took a while to figure out this diagram.

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spitfire91104

· #10 · Jun 14, 2021

Samps said:
Easiest would probably be to DIY an impendance jig and use REW to make impedance sweeps. Those will show all the little nasty things going on in your cabinet. Making the jig is a little tougher than it looks because you're working with super tiny wires. But once it's made, the REW sweeps are really easy. Even easier than regualr sweeps becuase you don't need to hook up a mic or use the AVR, just the jig connected to the speaker terminal.

Or even easier would be to buy the woofer tester from parts express, forget what it's called. And use that for your impedance testing.

This is the one I made. Took a while to figure out this diagram.

View attachment 3144210

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You referring to the Dayton Dats tester?

I just picked one up and only have dampening material left to add to my 3 HTM12v2. May have to experiment with how much denim I use and maybe poly fill. Need to assemble one and start testing.

jcmccorm

· #11 · Jun 14, 2021

Thanks @Samps !

Are you referring to DATs from PE? I have one. What would resonance show up as? A positive-going ripple in the impedance curve? Erin included an impedance plot in all of his data and I don't see anything there that correlates to the resonance shown in the Spectral Decay plot he provided.

spitfire91104

· #12 · Jun 14, 2021

jcmccorm said:
Thanks @Samps !

Are you referring to DATs from PE? I have one. What would resonance show up as? A positive-going ripple in the impedance curve? Erin included an impedance plot in all of his data and I don't see anything there that correlates to the resonance shown in the Spectral Decay plot he provided.

If you go to 12:47 in the YouTube video Erin posted he has a impedance plot where he points out the two small blips. I believe we can replicate that graph with the dats if I’m not mistaken? Enclosure is about 1.8cuft without bracing or driver volume accounted for.

Edit: I pointed out the wrong blips I believe.

ErinH

Discussion Starter · #13 · Jun 14, 2021

Yea, that's the tough one... normally resonances show up as impedance blips but the 250Hz resonance didn't show up there (though, other ones do).

In this case, I think the easiest thing to do would be a simple ground plane test using REW and a USB mic (assuming REW lets you create a CSD without a loopback). Since the frequency in question is low enough in frequency, you don't really have to worry about aiming the speaker perfectly for the HF response. Also, it's not so low that you have to worry about reflections, either. If you can find a spot that is about 40+ feet away (radius) from the nearest building/fence/house then you are good. Plop the speaker on the ground, use REW and a USB mic and measure the response. Set the gate appropriately - about 40ms or so - and plot the CSD. Make sure to mark the location you used. Then go and make some changes to the enclosure. Come back to the same spot and repeat the test.

@jcmccorm if you want, maybe one day on a weekend you can come over and bring your tools (or we can use mine; I have plenty to build cabs with). We can test the setup after making some changes together and see if we can find something that works.

Edit: Honestly, it might even be easier to just to use some test tones and listen. The resonance is easily audible. I heard it well before I measured them. In fact, I had to plot the CSD just to sanity check myself because the impedance data didn't clearly show what I knew I was hearing.

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ErinH

Discussion Starter · #14 · Jun 14, 2021

The question I have is: what will be the fix. If I have some time this week, I may throw my accelerometer on the enclosure to see if I can measure any wall vibration around this frequency. If that's it, then bracing is the way to go. If not, then stuffing of some sort will be the way to go.

Reactions: 1

Samps

· #15 · Jun 14, 2021

Yes, the DATs from PE. I'm a little surprised the resonance we're trying to fix doesn't show up in the impedance test. Unless this is one of those cases where the low voltage impedance test isn't loud enough to get that resonance excited. @Ricci has talked about this in the past. We really need an amplifier in the mix to get the speaker loud enough, but that complicates things enough that I never tried it.

Samps

· #16 · Jun 14, 2021

The area of the box right behind the woofer looks like the weakest part with the largest unsupported areas. Maybe an additional window brace like the one between the waveguide and woofer would help in the lower third of the box.

jcmccorm

· #17 · Jun 14, 2021

Samps said:
The area of the box right behind the woofer looks like the weakest part with the largest unsupported areas. Maybe an additional window brace like the one between the waveguide and woofer would help in the lower third of the box.

That's what I was thinking. That's the largest unbraced surface.

383-s-10

· #18 · Jun 14, 2021

Might try something on the ports and waveguide too... like dynamat or similar; lots of options on amazon.

ErinH

Discussion Starter · #19 · Jun 14, 2021

Samps said:
Yes, the DATs from PE. I'm a little surprised the resonance we're trying to fix doesn't show up in the impedance test. Unless this is one of those cases where the low voltage impedance test isn't loud enough to get that resonance excited. @Ricci has talked about this in the past. We really need an amplifier in the mix to get the speaker loud enough, but that complicates things enough that I never tried it.

Sometimes I do a comparison. The standard is 0.10v and that is done so you do not get in to the non-linear range of a speaker. But I also do/have done measurements at 2.83v. I recently did this for the 1099 and there was no difference. However, that was the first time I have tested a speaker that has no difference at all.

Reactions: 1

jcmccorm

· #20 · Jun 14, 2021

bikinpunk said:
@jcmccorm if you want, maybe one day on a weekend you can come over and bring your tools (or we can use mine; I have plenty to build cabs with). We can test the setup after making some changes together and see if we can find something that works.

Sounds like a plan. I've got a big bag of polyfill, MDF scraps, and a saw

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