# Getting that last 10% out of the cabinet - Speaker baffle interface and cabinet resonance questions



## johnp98 (Jun 29, 2020)

Hello,
I am about to built a pair of DIYSG HTM-12 speakers was wondering if there were potential ways I could maximize the quality of the speaker build. Reading around it does appear there are some potential things that could help but I am just wanting to make sure they are correct and ask for feedback.

1) I was wondering about the speaker driver / baffle interface. I have read that having some dampening material (such as weather stripping or neoprene etc) can help reduce the transmission of vibrations to the speaker cabinet. I could not get it to be a fully floating driver but I was wondering if instead of the driver being simply screwed into the MDF if this design would be beneficial:
Speaker driver -->
Dampening material -->
MDF baffle (drilled through, so no direct contact with the bolts)-->
Dampening material -->
1” plywood with T nuts for bolting the speaker to (the plywood could either be cut around the whole speaker cut out, or could be in smaller pieces for each individual bolt hole)

Do you think that would help isolate the driver from the baffle and be worth doing? Any room for improvement?

2) I was looking to minimize cabinet resonances and so I have read that the main way to do this is through adding more mass to the walls, adding more bracing to the walls, adding dampening material, absorption.

Mass: I have looked into constrained layer dampening and using green glue, and so I could potentially put another layer of MDF on the back wall. Would this be beneficial? Any other options / thoughts?

Bracing: I certainly can add more MDF bracing to the cabinet. Are window braces most effective? Any places that I should avoid putting bracing (i.e. right behind the main driver)?

Dampening: This is where I haven seen lots of opinions yet have not figured out what truly would be best. I have heard of people using dynamat, roofing felt, industrial floor tiling, rubber gym mats, memory foam, bubble wrap, etc. Would all of these be options? Any personal preferences people have? Also how does this affect the effective volume of the cabinet, like can one go too overboard with this stuff?

Absorption: The speaker design is a ported design and calls for ~3inches of absorption on the back wall and 1.5inches on the side and to keep the ports clear. I have read that the maximum velocity of standing waves is in the middle of the cabinet, so then hanging the absorption material ½ way through the cabinet would be most effective would it not? But are their down sides to this? Also if it was in the way of the direct path from the speaker to the ports would that change the port tuning, or is that all about the internal volume and should not be a problem? Also, more absorption would change the effective volume and thus change the port tuning so maybe not changing the absorption would be ideal? I have also heard that there are significant downsides with over stuffing a speaker yet I have not personally made any speakers so what should I be looking for if that occurs?

Ok, I think those were the main things that I was looking into to try and squeeze that final 10% of performance out of this DIY build. I would appreciate any feedback on the proposed alterations and also let me know if there are any glaring ways I could further improve on the cabinet making.

Thanks!


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## dreadknot (Jun 9, 2017)

you really dont need any Dampening the wall thickness of that cabinet take care of any cabinet resonances

iv got to ask whats your receiver an amp setup like you know amount of channels , power output , ohms ,

how big is your listening room , an how loud do you like to get and what your budget per speaker an/or for your ht sysyem total

because for me every last dime counts i wouldn't have bought a pair DIYSG HTM-12 for the total i would have suggested to you to do what iv done an doing is complete from scratch custom builds
with driver tailered custom crossovers an cabinets

depending on preferance it can save you money

you should model that woofer an ported cabinet spec in winisd to see if it will perform as you'd like ie' fq responce an spl at desired listening distance an to make sure that power input does not wear the drivers cone excursion

see if you can find that 12in woofer by Eminence model number in the www.loudspeakerdatabase.com an if you can find it download the .wdr file for winisd ,, those Eminence woofers get good a loud but have major fq drop off past 100hz
that box doesnt appear to be more then maybe 1.5ft3 tuned at 50 somthing hz an in winisd that still gets bad cone excursion with 50watts now even in a 11.5ft3 ported with 50watt tuned to 35hz gets a very nice flat fq responce down to 33hz before any fq dropoff but without any eq'ing you still get some drivers cone excursion at 100hz past its limit between that an port noise that were you get the noticeable distortion those two factors are some of the most important

either build get in winisd at 50watts at a 15ft listening distance 100db of spl but you need some good eq to clean up cone excursion past 100hz

you should consider from scracth custom builds

you pay a lot to have pre cut wood cabinets like in diy kits

if you got a router an some clamps you can make some nice cabinets for less

what is your speaker pref ie' size, weight, driver size , fq responce , an room placement

if you'd want i could do so cad mockups for you based on those detail an even create some stencil templates for use as router guides that can be made of metal from sendcutsend.com they've been a godsend for me in my cabinet building

as an exsample heres mine fyi im still buying my drives before i get the wood an metal stencils for my current builds
but this is the to be build

























































the grey pix is concept of 4 metal stencils as router guides for my build which will be a 2 way at 500hz 300 watt 10in woofer twin 10in passive rad build with a sealed 5in mid/high fq driver

these will help produce flawless cuts for both the inner an outer frame of the cabinets including the sealed chamber
an rotating the baffles will do the rad cut outs

im doing both the cabs from layers of mdf wood an grand total of 140$ for the pair an the scrap will make the mount

Bill Daniels at dstechlabs [email protected] did my custom crossovers they were 410$ that includes tax an shipping
































they were each a 2way 2nd order butterworth with a 4ohm input at 300watt with a 2ohms for the woofer at 220watt an 4 to the mid/high at 80watts

with this custom build in winisd i get no bad cone excursion an a flat responce down to 30hz with 95db spl at 15ft an no eq'g at all

an yes they'll be red

my total for all drivers an wood an xovers an ete
1300$ which i know is far more then a pair of those of DIYSG HTM-12

but mine are to match my crown xli 800 amps an get a specific fq response and power load

the driver an xovers were 1136$ alone if my amp only put out 100watts at 4ohms my cost would have been for some

Dayton Audio PS220-8 8" Point Source Full-Range Neo Driver

or Dayton Audio RS270P-4A 10" Reference Paper Woofer 4 Ohm

an matching tweeters an a pair of dayton xovers for 70$

mabye around 370$

so it depends of your amp an your budget


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## johnp98 (Jun 29, 2020)

Thanks for the info and the offer! I am part way through upgrading my system and actually the HTM-12s are the last piece of the puzzle for now and I already purchased them.

The room is ~25ft wide and 12ft deep, speaker 3feet from the front wall and listening position 3ft from the back wall (so 6ft away from the speaker)
I use it 50% for HT and 50% for music.
I do not play the music that loud, usually under -18
I got a Marantz sr7002 receiver and it says it does 110 wpc @ 8-ohms I think 
I built two 18" subwoofers and have them hooked up to a behringer nx6000d so I can EQ the subs and they are more than capable and thus it does not matter if the HTM-12s cannot go below 80hz.
I have a large ~8ft screen for a projector and so I go with a phantom center and so I wanted to get the L and R speaker upgraded and hence the HTM-12

So given my situation, I am looking to optimize the HTM-12s themselves.
They come with a pre-cutout and routered front baffle, so I am going to make the rest of the cabinet (so I guess it is not a full flat pack combo).
Using winisd what would be the ideal internal volume for the driver? As the DIYSG website recommends ~1.8ft3, I don't know what it is tuned to though.

Thanks again for the info!


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## RLouis (Jan 20, 2010)

Another good/cheap cabinet dampening material is common wall-to-wall carpet padding. It has random mixed density (good to breakup sound) and can range from 1/4 to 5/8 inch thick, but ½ inch is most common.


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## AEIOU (May 3, 2011)

johnp98 said:


> Hello,
> I am about to built a pair of DIYSG HTM-12 speakers was wondering if there were potential ways I could maximize the quality of the speaker build. Reading around it does appear there are some potential things that could help but I am just wanting to make sure they are correct and ask for feedback.
> 
> 1) I was wondering about the speaker driver / baffle interface. I have read that having some dampening material (such as weather stripping or neoprene etc) can help reduce the transmission of vibrations to the speaker cabinet. I could not get it to be a fully floating driver but I was wondering if instead of the driver being simply screwed into the MDF if this design would be beneficial:
> ...


Please quit saying "Dampening" unless you really like it wet. The correct terminology to use is DAMPING. Damping factor - Wikipedia


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## AEIOU (May 3, 2011)

There is mechanical damping and acoustical damping, they are different. You can mechanically damp the enclosure walls by adding a compliant mass. You can damp the interior volume with some sort of acoustical batting, poly stuffing.


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## dreadknot (Jun 9, 2017)

johnp98 said:


> Hello,
> I am about to built a pair of DIYSG HTM-12 speakers was wondering if there were potential ways I could maximize the quality of the speaker build. Reading around it does appear there are some potential things that could help but I am just wanting to make sure they are correct and ask for feedback.
> 
> 1) I was wondering about the speaker driver / baffle interface. I have read that having some dampening material (such as weather stripping or neoprene etc) can help reduce the transmission of vibrations to the speaker cabinet. I could not get it to be a fully floating driver but I was wondering if instead of the driver being simply screwed into the MDF if this design would be beneficial:
> ...


hey whats your plan for your speaker appearances stain or a duratex coat of some sort or even some epoxy resin


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## dreadknot (Jun 9, 2017)

how do you like these colors or should i go all black


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## AEIOU (May 3, 2011)

Looking at the crossover there, the inductors are placed too close together and should be oriented orthogonally to each other.


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