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DIYSG HTM-12v2 Review

ooheadsoo

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Me thinks this project would really shine as an active design.
Eleven filters seems like a lot of eq after the passive corrections for a two way.
Active would really nice, but the price of extra amplifier channels really dampens the value. I posed this very subjective question in the V1 review - is it worth it to go active? The consensus in that thread seemed to be the combo of passive+active was a better value.

One thing I saw being done with a different diy speaker was to implement the barest bones for passive crossover with the rest of the signal shaping done via dsp. This minimizes crossover parts cost and still allows for a single amp channel per speaker. Seems pretty complicated for a novice to figure out on their own, though.
 

puppet

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That would be workable, providing the drivers played nice with each other passively in and around the xo region an octave or so either way with a flat combined response. My guess though, if you had that, one could dispense with the DSP entirely.
 

Rick Sykora

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What blip at the box tuning? Unless you are looking at the EPDR plot not impedance.

Edit: Any ported speaker will have a similar blip in the EPDR due to the phase angle between the impedance peaks, those blips are not the same as ones in the impeadance graph and do not relate to resonances of the speaker drivers or cabinet. AFAIK these DIYSG speakers are the first ones Erin has calculated EPDR for, other more recent speaker reviews have been powered, so no impedance data.

My apologies as did not realize you are the designer for these. Nice work.

If did not already have CBTs in my home theater, these would be my next candidate! :cool:
 
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jtwrace

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jhaider

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One thing I saw being done with a different diy speaker was to implement the barest bones for passive crossover with the rest of the signal shaping done via dsp. This minimizes crossover parts cost and still allows for a single amp channel per speaker. Seems pretty complicated for a novice to figure out on their own, though.

That is also the approach taken by the JBL 7-series install line. It makes a lot of sense to me, so long as the drive units are reasonably similar in sensitivity.
 

mtg90

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The crossover itself is a 4th order lowpass with a bit of damping on the 1st parallel leg, the highpass is a 3rd order with a single parallel LC shaping filter in series with the driver and an L-Pad. You can't really get too much simpler with the crossover if wanting to keep adequate slopes between the drivers through the values could certainly be adjusted to minimize the efficiency losses from such a design.

Since these were designed knowing they would be kits I tried to keep the crossover optimized for as few crossover parts as I can get away with while producing a decent frequency response.

Even after designing PCBs for most of the kits and making instructions that are almost paint by number simple the crossovers are where people struggle with the most. I suspect there are numerous DIYSG speakers out there that have the crossovers assembled slightly incorrect or that have cold solder joints but technically still pass audio and sound mostly correct but a less experienced person would have no idea anything is actually wrong. Adding more parts to the equation just increases the chance of assembly mistakes.

So there is certainly more that can be squeezed out of a more complex passive crossover but most of the benefits are above 800hz as any passive corrections I've found below that are increasingly difficult to implement and require inductor values that are often larger then available. Though some of the fixes for the low midrange issues may be mechanical rather then electrical.

I found what looks to be a couple easy mods that could be made adding only two additional parts to the crossover and changing the value of three others which would fill in the sharp 4k dip, level out the HF rise and flatten the bump at 800-1000hz a little. I'll likely add this info to the HTM build thread once I actually test them.

I'll also be looking into identifying the sources and trying to find any easy fixes for the lower midrange issues whether that be additional cabinet bracing or perhaps better applications of damping.
 

richard12511

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The crossover itself is a 4th order lowpass with a bit of damping on the 1st parallel leg, the highpass is a 3rd order with a single parallel LC shaping filter in series with the driver and an L-Pad. You can't really get too much simpler with the crossover if wanting to keep adequate slopes between the drivers through the values could certainly be adjusted to minimize the efficiency losses from such a design.

Since these were designed knowing they would be kits I tried to keep the crossover optimized for as few crossover parts as I can get away with while producing a decent frequency response.

Even after designing PCBs for most of the kits and making instructions that are almost paint by number simple the crossovers are where people struggle with the most. I suspect there are numerous DIYSG speakers out there that have the crossovers assembled slightly incorrect or that have cold solder joints but technically still pass audio and sound mostly correct but a less experienced person would have no idea anything is actually wrong. Adding more parts to the equation just increases the chance of assembly mistakes.

So there is certainly more that can be squeezed out of a more complex passive crossover but most of the benefits are above 800hz as any passive corrections I've found below that are increasingly difficult to implement and require inductor values that are often larger then available. Though some of the fixes for the low midrange issues may be mechanical rather then electrical.

I found what looks to be a couple easy mods that could be made adding only two additional parts to the crossover and changing the value of three others which would fill in the sharp 4k dip, level out the HF rise and flatten the bump at 800-1000hz a little. I'll likely add this info to the HTM build thread once I actually test them.

I'll also be looking into identifying the sources and trying to find any easy fixes for the lower midrange issues whether that be additional cabinet bracing or perhaps better applications of damping.
Your point about keeping it simple is a really good one IMO. A more complex crossover probably would result in better potential, but very well may result in poorer average performance.

Still, the horizontal directivity of this speaker is arguably the best we’ve seen. Been looking back through other reviews, and the only two I've found that are about as good are the Genelec 8341a and the Neuman KH80DSP.
 

johnp98

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Ok, so I had a fun little project today and wanted to add a layer of active EQ to my HTM-12 v2!
Based on the Klippel measurements I made an EQ filter in REW and then did moving mic method (MMM) measurements around my listening position (MLP) and got these results (results are separated to make them easier to see, and unfortunately I was running them with my subs, which are a little hot compared to the speakers.... so just ignore the low end to focus on what the EQ is going after)

1624677737152.png


Purple = Klippel Measurements
Orange = No EQ on my HTM-12v2 doing MMM at my MLP
Blue = Klippel based EQ on my HTM-12v2 doing MMM at my MLP.

Ok fair enough, but since I have slightly different box dimensions, did constrained layer dampening on the whole inside of the box and on the waveguide itself, and had various layers of different dampening material inside the speaker and because there were concerns with the consistency of drivers in the prior HTM-12v1 I thought I would do some nearfield gated measurements of my own HTM-12v2s to see how the high end compared to the klippel measurements and here is what I got:
1624678384185.png

Purple = Klippel Measurements
Green = Nearfield measurements at 3ft gated to ~4ms I believe.

So it looks like the high end does line up rather nicely! (Although not perfect, presumably due to some of the above mentioned factors, or just my UMIK-1 and its calibration file not being perfect).

But then I got a random idea that I could use my own nearfield gated measurements to EQ the high end.
I thought that it looked to have reasonable resolution from 1,000hz upward so I made an EQ file for 1,000 - 20,00hz and here are the results:
1624679257435.png

Purple = Klippel Measurements
Green = Nearfield measurements at 3ft gated to ~4ms I believe.
Blue = Post EQ nearfield measurements at 3ft gated to ~4ms I believe.

Then use the Klippel measurements to make an EQ from ~250hz-1,000hz (trying to bridge down to the schroder frequency of my room) and got this:
1624679545022.png

Purple = Klippel Measurements
Blue = No EQ - MMM at MLP
Orange = Combo of Klippel and Gated EQs - MMM at MLP

Then I used my raw MMM to make an EQ file from 60-400hz based on the in room response for the left speaker and then again for the right.
Then I spliced all the EQ filters together. Since I had good faith in the resolution of each step / segment I was ok with the sheer amount of filters (24 filters for the right and 28 for the left). This is what I got:
1624680587155.png

Purple = Klippel Measurements
Blue = No EQ - MMM at MLP
Green = Combo EQ (MMM + Klippel + Gated) - MMM at MLP

Pretty dang happy with these results!

And now to comparing all the EQ possibilities and adding some measurements I had with Dirac and also EQ based completely on MMM at MLP you get this:

1624680811094.png


Blue = No EQ - MMM at MLP
Purple = Klippel based EQ on my HTM-12v2 doing MMM at my MLP
Red = Global EQ based on MMM at MLP (EQ generated off the above Blue graph)
Blue = Dirac EQ / results - MMM at MLP
Green = Combo of EQs (MMM + Klippel + Gated) - MMM at MLP

Wow, ok that's a lot of measuring for one day!
But as you can see you get better results using this method!

So it looks like splicing together gated nearfield measurements, with Klippel measurements, with in room MMM you can get pretty killer results for your own specific speaker!

And now to leave you with my left and right and L+R measurements with psychoacoustic smoothing to remind myself that the remaining wiggles seen at 1/12 smoothing is actually water under the bridge:
1624681251943.png


Thanks for slugging through the long post!
And yes it does sound quite wonderful!
 

richard12511

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Ok, so I had a fun little project today and wanted to add a layer of active EQ to my HTM-12 v2!
Based on the Klippel measurements I made an EQ filter in REW and then did moving mic method (MMM) measurements around my listening position (MLP) and got these results (results are separated to make them easier to see, and unfortunately I was running them with my subs, which are a little hot compared to the speakers.... so just ignore the low end to focus on what the EQ is going after)

View attachment 137453

Purple = Klippel Measurements
Orange = No EQ on my HTM-12v2 doing MMM at my MLP
Blue = Klippel based EQ on my HTM-12v2 doing MMM at my MLP.

Ok fair enough, but since I have slightly different box dimensions, did constrained layer dampening on the whole inside of the box and on the waveguide itself, and had various layers of different dampening material inside the speaker and because there were concerns with the consistency of drivers in the prior HTM-12v1 I thought I would do some nearfield gated measurements of my own HTM-12v2s to see how the high end compared to the klippel measurements and here is what I got:
View attachment 137455
Purple = Klippel Measurements
Green = Nearfield measurements at 3ft gated to ~4ms I believe.

So it looks like the high end does line up rather nicely! (Although not perfect, presumably due to some of the above mentioned factors, or just my UMIK-1 and its calibration file not being perfect).

But then I got a random idea that I could use my own nearfield gated measurements to EQ the high end.
I thought that it looked to have reasonable resolution from 1,000hz upward so I made an EQ file for 1,000 - 20,00hz and here are the results:
View attachment 137456
Purple = Klippel Measurements
Green = Nearfield measurements at 3ft gated to ~4ms I believe.
Blue = Post EQ nearfield measurements at 3ft gated to ~4ms I believe.

Then use the Klippel measurements to make an EQ from ~250hz-1,000hz (trying to bridge down to the schroder frequency of my room) and got this:
View attachment 137457
Purple = Klippel Measurements
Blue = No EQ - MMM at MLP
Orange = Combo of Klippel and Gated EQs - MMM at MLP

Then I used my raw MMM to make an EQ file from 60-400hz based on the in room response for the left speaker and then again for the right.
Then I spliced all the EQ filters together. Since I had good faith in the resolution of each step / segment I was ok with the sheer amount of filters (24 filters for the right and 28 for the left). This is what I got:
View attachment 137462
Purple = Klippel Measurements
Blue = No EQ - MMM at MLP
Green = Combo EQ (MMM + Klippel + Gated) - MMM at MLP

Pretty dang happy with these results!

And now to comparing all the EQ possibilities and adding some measurements I had with Dirac and also EQ based completely on MMM at MLP you get this:

View attachment 137463

Blue = No EQ - MMM at MLP
Purple = Klippel based EQ on my HTM-12v2 doing MMM at my MLP
Red = Global EQ based on MMM at MLP (EQ generated off the above Blue graph)
Blue = Dirac EQ / results - MMM at MLP
Green = Combo of EQs (MMM + Klippel + Gated) - MMM at MLP

Wow, ok that's a lot of measuring for one day!
But as you can see you get better results using this method!

So it looks like splicing together gated nearfield measurements, with Klippel measurements, with in room MMM you can get pretty killer results for your own specific speaker!

And now to leave you with my left and right and L+R measurements with psychoacoustic smoothing to remind myself that the remaining wiggles seen at 1/12 smoothing is actually water under the bridge:
View attachment 137464

Thanks for slugging through the long post!
And yes it does sound quite wonderful!
Unless your speaker was the speaker measured by Erin/Amir, I think gated 1m measurements like this are your best bet for EQing above the transition zone. I think you’ve got the right approach.
 

johnp98

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Unless your speaker was the speaker measured by Erin/Amir, I think gated 1m measurements like this are your best bet for EQing above the transition zone. I think you’ve got the right approach.

My general thoughts are:

1) You need Klippel measurements to see if a speaker is any good and has good directivity (and is worth EQing and would not be harmed by it).

2) If you have Klippel measurements and then EQ based on that above the Schroder frequency (assuming there is reasonable speaker consistency or you did not tamper with your speaker at all) and then EQ the speaker/room with MMM at the MLP.

3) If you do not have Klippel measurements then you could try and get by with nearfield gated measurements getting you down into the Schroder frequency (so you would have to do it outside with a longer window/gating - to get reasonable mid frequency resolution) and then combine this with MMM at MLP. But I have never done this and I assume you still would always be questioning point #1.
 

Zvu

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You can do it without Klippel. NFS has no magic properties. It's not like measurements were off before NFS. What NFS does, it makes things easier. Dwelling on measurements accuracy always exist, with or without NFS.
 

sully45

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Over on AVSforum, the designer seems to have isolated the issues ~200 hz and 400 hz to a resonance in the surround. Dampening the surround with something like paracord seems to be something that helps. He seems to be working on a permanent fix but the results show most major issues here can be resolved.

https://www.avsforum.com/threads/diysg-htm-12v2-review.3204391/page-3

Taken from Matt Grant's post (Raw midwoofer response).
1628003604682.png
 
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tomtoo

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If i would be some years younger, this would be my speakers. Great design. Fu** this toy speakers. ;)
 

Zvu

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What's wrong with those being your speakers now ?

Fu** this toy speakers still aplies. Who cares about age.
 
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johnp98

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Well, Erin just measured the JBL M2 (one of the highest regarded speakers on the market) and it made me realize how special the HTM-12s directivity and sound power are.


HTM-12
1629962598096.png

vs the JBL M2
1629962618769.png



My understanding is that the JBL M2 has an active EQ ontop of the passive crossover and thus if one adds an active layer of EQ onto the HTM-12 then they also can become pretty legendary in my opinion.

This is especially obvious looking at the normalized horizontal contour plot.
HTM-12
1629962704663.png


vs JBL M2
1629962724456.png



Obviously the JBL M2 has far superior low frequency extension, yet if someone is using multiple subs, then this is less of an issue.

I am not saying that the HTM-12s can go toe to toe with the JBL M2s, I am just reminded how impressive the directivity of the HTM-12s truly is and if one can add a layer of EQ and some subs, then likely in the same ballpark.
 

tomtoo

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What's wrong with those being your speakers now ?

Fu** this toy speakers still aplies. Who cares about age.

My live circumstanses after a stroke. But iam on your side, if you can, fu** this toyspeakers.
 

Zvu

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Sorry to hear that. I thought that age is the problem.

Avoid carbs, eat unprocessed meat/fat and lots of fiber rich vegetables and fruit low in sugar content. Drink lots of water and occasional Schnaps is ok too ;)

I wish you good health my friend :)
 

tomtoo

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Well, Erin just measured the JBL M2 (one of the highest regarded speakers on the market) and it made me realize how special the HTM-12s directivity and sound power are.


HTM-12
View attachment 149626
vs the JBL M2
View attachment 149627


My understanding is that the JBL M2 has an active EQ ontop of the passive crossover and thus if one adds an active layer of EQ onto the HTM-12 then they also can become pretty legendary in my opinion.

This is especially obvious looking at the normalized horizontal contour plot.
HTM-12
View attachment 149628

vs JBL M2
View attachment 149629


Obviously the JBL M2 has far superior low frequency extension, yet if someone is using multiple subs, then this is less of an issue.

I am not saying that the HTM-12s can go toe to toe with the JBL M2s, I am just reminded how impressive the directivity of the HTM-12s truly is and if one can add a layer of EQ and some subs, then likely in the same ballpark.

Its a great speaker, some EQ and two subs and it will rock the house with good sound.

For the oldies:
For the not so-o old
For not the youngest.

:)
 
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