Funny to see the woofer suspension resonance which was discussed before now shows up in a similar way in the JBL M2 measurements. The same goes for other large mid bass woofers (such as the Faital 12PR320), seems to be a common problem and because of EBR in this frequency region, manufacturers probably just decided they'd leave it as is. So when JBL decided not to EQ for the resonance in the M2's woofer, which they could have done easily, what do you think was their rationale?
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DIYSG HTM-12v2 Review
- Thread starter hardisj
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Correct me if I am wrong, but weren't you able to measure with relatively simple tools and a distance of 3 meters of mic and transducer to the nearest boundary the suspenion resonance in the Faital woofer? Woofer was even a little closer to the ground, right?
This is the test rig shown in one of JBL's brochures. Could be that the bottom of the cabinet is only around 2 meters above the flour, hard to judge. Woofer and waveguide both are about 30 cm in diameter, cabinet could be 65 cm. But then, we do not know if this measuring rig is not further extandable, at least there is some rail left. So maybe they should have seen it too. With all their possibilities, why would they allow them a window of uncertainty between near field and far field bass response? I would not construct a measurement room and rig for a whole lot of money that is leaves a shadow of doubt.
This is the test rig shown in one of JBL's brochures. Could be that the bottom of the cabinet is only around 2 meters above the flour, hard to judge. Woofer and waveguide both are about 30 cm in diameter, cabinet could be 65 cm. But then, we do not know if this measuring rig is not further extandable, at least there is some rail left. So maybe they should have seen it too. With all their possibilities, why would they allow them a window of uncertainty between near field and far field bass response? I would not construct a measurement room and rig for a whole lot of money that is leaves a shadow of doubt.
I did measure it. I'm not saying that JBL doesn't know about the resonance, i'm sure they do. My guess is that trained listeners weren't able to discern suspension resonance as negative in one of harman's blind listening tests so they decided that it isn't important and isn't worth the hassle.
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Yup, look at those graphs. The HTM-12 has it's faults for sure, but the directivity and dynamics are excellent, and eq will fix a lot. Like some of these other speakers, they are typically used in environments where EQ is standard practice. Amazing what this kit gets you. A wider directivity is the main way these speakers are not in the same mold as the others. If Matt releases a revised woofer for a V3, I'd probably be interested.
I need to build a pair of woofers to cross at 2-300hz. My wife is getting displeased with the wood sitting in the living room.
I need to build a pair of woofers to cross at 2-300hz. My wife is getting displeased with the wood sitting in the living room.
hollis
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Looks like there is an updated xover for the HT12 if folks want it:
www.hificircuit.com
HTM Speaker Kits
HT-6 Measurements... HT-6? Is this a new speaker due out? A bit smaller than the HT-8s I assume?
www.hificircuit.com
You can't get I-core inductors anywhere in the US right now which nearly all of the kits use, this is why they are all out of stock. From what I understand some of the backordered parts were expected to be back in stock within a couple weeks at the time the order was placed but that was over 6 months ago! Currently some say another 2-3 months but who knows if that's even true since the date just keeps getting pushed back further and further as the quoted time approaches.
hollis
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Guess its time to buy a second pair and try a 100% active build! Wonder how loud these can get with 8th order xovers.....
The crossover fix/mod I posted for the HTM-12 v2 in the official thread (link here) fixes a separate issue which was the narrow dip ~4kHz. Newer boards have that change implemented but none have sold yet because there are no inductors for the kits.
The upgrade crossover posted above is for the HT-12 not HTM-12 v2 so different speaker. That was an experiment I did to see what it would take to flatten out the response better then the normal crossover on that speaker which is designed to be geared more towards value and ease of assembly. The upgraded crossover basically takes the response from +-3dB to +-1.5dB (100-10khz).
You can see the difference here:
HT-12 Measurements
HT-12+ Measurements
The only solution I have found so far for the surround on the HTM-12 was wedging either foam cord or paracord into the center channel of the surround. I tested coating the surround in a rubber material similar to Plasti Dip on my one extra sample driver but all it did was shift the resonant frequency lower. Link to the surround info/testing I did if you missed the link posted on the previous page.
The upgrade crossover posted above is for the HT-12 not HTM-12 v2 so different speaker. That was an experiment I did to see what it would take to flatten out the response better then the normal crossover on that speaker which is designed to be geared more towards value and ease of assembly. The upgraded crossover basically takes the response from +-3dB to +-1.5dB (100-10khz).
You can see the difference here:
HT-12 Measurements
HT-12+ Measurements
The only solution I have found so far for the surround on the HTM-12 was wedging either foam cord or paracord into the center channel of the surround. I tested coating the surround in a rubber material similar to Plasti Dip on my one extra sample driver but all it did was shift the resonant frequency lower. Link to the surround info/testing I did if you missed the link posted on the previous page.
I finally got around to buying some paracord and trying the surround mod last month. I guess I don't listen loud enough, because I really don't have any issues with the paracord falling out. From a visual aspect, the main deal is that the nylon innards of the paracord show up bright against the dark surroundings. Some black sharpie helps a little, but it could be better.
I don't have any measurements to show you guys, but it's a super easy, cheap, and quick mod. All hail the accordion surround, you can't really do this mod on a more typical rubber surround
I don't have any measurements to show you guys, but it's a super easy, cheap, and quick mod. All hail the accordion surround, you can't really do this mod on a more typical rubber surround
beagleman
Major Contributor
Are these even available now?
I went to the site, but beyond being painfully slow to load, can not find this new version etc...??
I went to the site, but beyond being painfully slow to load, can not find this new version etc...??
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