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- DrewsBrews 5:13PM
- Inertiaman 5:13PM
- jholtz 5:13PM
- rjj45 5:13PM
- Tom_S 5:13PM
New project - The Dymaxions
These will be large monkey coffin 3 ways. Woofers are Peerless 830668 10" in 2 cubic feet sealed, with a variovent and stuffing. The mids are those HiVi DMB-A 2" domes. And the tweeter will be Wavecor TW022WA-05's.
The enclosure panels are made of pre-laminated particle board. A neighbor gave me a bunch of the stuff. It is the most dense particle board I have ever seen. The 3/4" thick PB is laminated on one side with 1/16" thick poplar (that's what it looks like). The pretty side is about 1/8" thick fake burl something. So it's almost 1" thick and very heavy. It was some sort of counter top in a conference room. Unfortunately it is pretty scratched up. I'll probably just sand it smooth and paint it. Anyway, I finished machining the baffles this weekend and got them glued on to the boxes last night. A pic of one baffle:
I really love the quality of midrange in my Gormachos (Morel CAM558 domes) and I hope these HiVi's domes have a similar sound.
Comments
Nice baffle material! Finalizing a 3 way now with Cam558 mids.
What are you pairing them with?
Airborne 5002 AMT tweeter, the Morel Cam558 dome mid, and a RS270 sealed with a linkwitz transfom.
You'll like that combo, Don!
Craig- the 'burl something' looks like either Formica or Wilsonart 'Golden Nugget' design:
https://www.google.com/search?q=formica+golden+nugget+surface&client=avg&source=lnms&tbm=isch&sa=X&ved=2ahUKEwiH3Oqd-LbrAhUHcq0KHaD0BrQQ_AUoAnoECA0QBA&biw=1366&bih=625
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Don, I am assuming you are going active for the linkwitz transform and not the big cap for low end extension.
Nope- he's using the caps, as he's talked it up for a bit now...
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Craig, the 3ways with the ushers were really good in a bookshelf package. What is the tuning looking like with the vent?
I liked Craig's Gormachos as well! Integration was really good.
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https://www.madisoundspeakerstore.com/flares/ports/vents/scanspeak-290001-aperiodic-vent-ssv/
Aperiodic vents so no tuning. I can't believe how expensive they are now. I paid like $12 for the pair back 30 years ago lol
I believe you are correct.
Let me know if yours buzz too while woofers are moving. Since then (I paid very little as well for mine too) a good ol' drain fixture and some open-cell 2" thick foam works pretty good.
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That price is insane. I could 3d print a frame to stuff with ultra-touch denim for under 5$
So, model for sealed, and just drop in the vent? how does it affect the low end or there is no estimation. I have not modeled for aperiodic vent, nor do i know how to or what tool would work best.
Set leakage to 3, and use heavy fill or a low alpha absorptive number, and set Qtc for 1.0
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I use Unibox sim and enter the actual net box volume, set Ql = 3, and set Qa = 10. A Qa of 20 is a typical "walls lined" value and Qa of 5 is "you stuffed that box really tight". With an aperiodic vent you want to fill the box with stuffing but not cram it in there too tight, so 10 seems about right based on my experience. Then I let Unibox calculate what the final Qtc will be. In this case right about 0.7. F3 is about 48 Hz but the roll off is quite shallow so I don't freak out that a ported alignment might lower that F3 number a bunch. Paul C used this same driver in about the same sized box but with a low tuned port for his Tarkus design. I wasn't overly impressed with the bass quality even though it boasted a low F3.
I can't believe you didn't just fab up an aperiodic vent. That's DIY 101!
You totally got me there but I had these babies just sitting on my shelf doing nothing
They have been in 3 different projects so far so this project will make number 4 for them (anyone see my MO with drivers and parts? 
). I bought these from Madisound back in about 1990 for a car audio sub box that sported 2 Oz Audio 10's. Man those were some of my best sounding car audio subs second only to a pair of SoundStream SS10R reference subs. The next project was the bass bins in my Trials project that I demo'd at DIY Chicago. Those bass bins had some old school ACI DV12 subs from Madisounf around 1993. Again awesome and deep bass. The last project was one I think I demo'd at Indy, maybe it was Iowa. It was the Dynaudio 17W75 woofers I bought from CraigK and the Dynaudio D28A tweeters. Anyway I hope they perform as well as they have in the past with these 10" Peerless woofers.
Gotta love a good monkey coffin!
Ok, so after modelling in unibox with those parameters, just add the vent to the box? That would lower the f3 a bit? Does the leakage =3 account for the vent?
What would a days reading look like... Two peaks with a valley like for vented or just one peak like sealed?
I like monkey coffins, except when the time comes to load, unload them....
Ok, I'll let it slide. I was assuming you were buying new ones for this project.
+1 on the the Oz and SS subs, both awesome! ...and yes the SS Reference units were (hell, still are) the fucking bomb track!!!
Thanks Craig. Once you build the box, could you post an inbox impedance sweep with the vent?
Sure.
The variovent lowers the Qtc at the expense of a slightly higher F3.
The blue line is same 10" woofer in a 60 Liter box that has no vent (Ql = 30) and no fill (Qa = 120). It has a Qtc of 0.8 and an F3 of 38 Hz.
The pink line is same 10" woofer in the same 60 Liter box with an aperiodic vent (Ql = 5) and filled (Qa = 10). It has a Qtc of 0.68 and an F3 of 42 Hz.
I was able to get them put together today so now I can start taking measurements!
looking forward to your thoughts, and measurements, on aperiodic venting
How tall is it? Short stand required?
Those look schweet!
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They are 29" tall. The tweeters are 24.5" up from the bottom. I like to place my tweeters between 36" and 38" above the floor so I will build some 12" tall stands for these.