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post #1 of 661 Old 01-17-2009, 12:41 PM - Thread Starter
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I haven't done build threads before because I suck at it. I've also known that subwoofer manufacturers have read most of what we discuss in these forums over the years (several have told me, and it's only common sense) so I chose to keep some things less obvious.

With this thread, I've decided to have some fun, but it will be as time permits and I apologize in advance for being lame at this sort of thing.

1) Over the years I've had numerous requests to explain ThruVent Cooling. I will explain it in detail in this thread and answer any questions.

2) I thought it might be interesting to compare the Tumult MKI against the Tumult MKII when both are in the same environment with the same signal and in the same enclosure. This is a week or so out, but I'll post some results for discussion.

3) I recently finished 3 subs and I'm waiting for the glass tops, so I'll hold off talking about Driver-Vu until they're installed, at which time I'll post pics and details.

In the meanwhile...meet The Raven...


Tumult MKI vs Tumult MKII


ThruVent Cooling System (diagrams and full details coming)


Driver-Vu (design, materials and details of the advantages coming)


Bosso
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post #2 of 661 Old 01-17-2009, 12:50 PM
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awesome! looks quite interesing. can't wait to learn more.

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post #3 of 661 Old 01-17-2009, 01:04 PM
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Ahhhh..... more sealed subwoofers..... They look great !!!!!!!!!!

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post #4 of 661 Old 01-17-2009, 01:15 PM
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That looks awesome! I can't wait to read the details.. and that vent and how it works.How long do we have to wait?

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post #5 of 661 Old 01-17-2009, 01:30 PM
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Is that an Aperiodic vent ?

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post #6 of 661 Old 01-17-2009, 01:45 PM
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Ok. I'll bite. Looks interesting.

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post #7 of 661 Old 01-17-2009, 01:53 PM
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Come on Dave give them the whole 'dog-n-pony' show...

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post #8 of 661 Old 01-17-2009, 02:27 PM
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sweet....
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post #9 of 661 Old 01-17-2009, 02:32 PM
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Bosso...I don't venture into this section often.....only did so now looking for Warpdrv's new subs.

Glad I came across your thread and looking forward to reading more!

-curtis

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post #10 of 661 Old 01-17-2009, 03:31 PM
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Yeah, i'm pretty interested in your motor venting too.

YID DIY
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post #11 of 661 Old 01-17-2009, 03:45 PM
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post #12 of 661 Old 01-17-2009, 04:21 PM
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They look great as always, are you going to be selling them any time soon?

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post #13 of 661 Old 01-17-2009, 04:34 PM
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Hmmmm . . . . . ? I thought for sure any new project of yours would involve one of the latest and greatest 18" drivers.
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post #14 of 661 Old 01-17-2009, 06:15 PM
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That's the highest level of DIY subwoofer I can think of. I'm very interested in hearing how you went about it?.. Just as much as the workings of the unit itself.

Klipsch RB-75
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post #15 of 661 Old 01-17-2009, 06:34 PM
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Fascinating idea, excellent presentation, what are its's flaws?

Great website.
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post #16 of 661 Old 01-17-2009, 06:42 PM - Thread Starter
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As always, I appreciate the positive feedback.

Bosso
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post #17 of 661 Old 01-17-2009, 06:56 PM
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bosso,

Those are really gorgeous - kind of future-retro-modernistic or something; they keep you guessing, which adds to the allure.

Am I correct that a small part of the output is canceled because the pole vents are connected to the volume behind the dust caps?

Noah
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post #18 of 661 Old 01-17-2009, 06:56 PM
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Look at PC cooling. What provides the best results?

Also, look at the functionality of woofers at differing temperatures. Woofers are like car engines, they have a temperature range where they are most efficient.
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post #19 of 661 Old 01-17-2009, 07:07 PM - Thread Starter
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Quote:
Originally Posted by LINEARX View Post

Hmmmm . . . . . ? I thought for sure any new project of yours would involve one of the latest and greatest 18" drivers.

I've been commissioned to do the low end of a HT in Pittsburgh later this year and I'll use dual 18" versions there, but generally I find that the look of the increased box size (and the associated labor of a bigger enclosure) just isn't worth the output increase for most applications.

The M-X is a good driver. I didn't have to hear one to know that, I just can't design a sub for a driver that isn't readily available.

I've used some great overhungs in the subs I've built and sold (keeping the Tumults for myself) and have no problems getting them when I need them, but the Tumult/Brahma is a prime example of being burned after purchasing a dozen of them and engineering signal chain/enclosure/amplifier to them.

Other than the M-X, box is too big or increase in performance is not significant enough to justify the cost, IMO.

Bosso
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post #20 of 661 Old 01-17-2009, 07:13 PM - Thread Starter
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Quote:
Originally Posted by noah katz View Post

bosso,

Those are really gorgeous - kind of future-retro-modernistic or something; they keep you guessing, which adds to the allure.

Am I correct that a small part of the output is canceled because the pole vents are connected to the volume behind the dust caps?

Not that I can detect (if I understand the question correctly). As long as the area of the combined holes in the pipe is greater than the pole vent hole area, there seems to be no added noise or loss of air flow from the motor into the box.

I've done more traditional versions. I'm working on one now and I'll post pics when it's finished so you can see what a difference some slight modifications to the trim parts can make.

Bosso
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post #21 of 661 Old 01-17-2009, 07:19 PM - Thread Starter
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Quote:
Originally Posted by matt5112 View Post

Look at PC cooling. What provides the best results?

Also, look at the functionality of woofers at differing temperatures. Woofers are like car engines, they have a temperature range where they are most efficient.

Correct.

I got the idea to use thermal grease from the computer parts industry, and Zalman makes great (and quiet) fans for same.

Note: The main reasons I didn't try the LMS drivers (though I think they were great drivers and wanted to use them) is that the motor is so huge (mounting depth) I couldn't get an enclosure to size properly when allowing for the diameter and depth of dual opposing drivers, and...

That motor is so massive, you'd have to pound techno tunes at full output all night long to need a cooling system.

The XBL^2 motors, OTOH, definitely can benefit from a lower motor heat ceiling.

Bosso
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post #22 of 661 Old 01-17-2009, 07:24 PM
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Real rice work, and good to see some original ideas hit the public space.

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post #23 of 661 Old 01-17-2009, 07:47 PM
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+1 for active cooling!

Did you do any air temperature measurements of the vent's exit?

Looks good.
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post #24 of 661 Old 01-17-2009, 09:38 PM
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Stunning!....Well thought out implementation as always Bosso. One question.....how many DB's are you gaining from the lack of thermal compression from heavy use? Do u notice a big difference or is it mostly to protect the drivers? I don't think I've ever seen this on any commercial setup I 've seen.
Now excuse me while I go kick my unfinished Avalanche boxes.
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post #25 of 661 Old 01-17-2009, 09:47 PM - Thread Starter
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Quote:
Originally Posted by Vinculum View Post

+1 for active cooling!

Did you do any air temperature measurements of the vent's exit?

Looks good.
Dr V

Yes, I did, years back when I built the first protos. I have the numbers in my measurements computer somewhere, but, of course, they would vary depending on the drivers/amplifiers used.

I built a sub using very nice split gap 15s from Zomax (Taiwan) years back. I remember playing the SW II fly over/landing/explosion scene at reference level.

I shut the system down after the quick eval and went to do something else. When I came back and fired the system up to play a SACD, I heard a terrible rattling noise.

After removing the driver and becoming stumped as to the cause of the rattling, I removed the surround/cone/VC assembly and inspected the motor, whereupon I found loose chunks of hardened glue laying at the bottom of the gap.

The SW II scene had melted the glue that attached the VC former to the cone. You could see the streaks of melted glue running down the former. It dripped into the gap and after shutdown it cooled and hardened and was rattling around inside the gap after it was fired up again.

The problem was solved by better adhesives, but the point was made how high the temperature can get in a relatively short time (although that landing scene is fairly sustained compared to most LFE) when high power is applied.

Even more so when certain types of music is played loudly for sustained periods.

I like small, high powered sealed subs, as everyone knows, and it can get quite warm inside the box in many in-use scenarios. Driver self venting designs are useless when the ambient (interior) temperature climbs.

Still waiting for the ACP thread...

Bosso
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post #26 of 661 Old 01-17-2009, 09:53 PM
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Beautiful enclosures! Very nice work.

Regarding the cooling. Is there really any benefit to active cooling on a driver that is designed to be adequately cooled passively?

I've run the Tumult's brother, the Brahma in my car's trunk in sub-freezing conditions and never saw any performance benefit.

Just kinda curious to see if you've done any a/b testing to conclude active cooling provides a positive benefit.
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post #27 of 661 Old 01-17-2009, 09:55 PM - Thread Starter
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Quote:
Originally Posted by robseyes View Post

Stunning!....Well thought out implementation as always Bosso. One question.....how many DB's are you gaining from the lack of thermal compression from heavy use? Do u notice a big difference or is it mostly to protect the drivers? I don't think I've ever seen this on any commercial setup I 've seen.
Now excuse me while I go kick my unfinished Avalanche boxes.

Hah! I think there's a law against kicking subwoofers.

Bosso
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post #28 of 661 Old 01-17-2009, 10:13 PM
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Maybe you need to try liquid cooling like computers or dry ice cooling for that extra cool factor.
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post #29 of 661 Old 01-17-2009, 11:04 PM
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Quote:
Originally Posted by bossobass View Post

Still waiting for the ACP thread...

Yes, yes I know.. It'll be here, with pictures, measurements and all the goodies. I've since decided I'm going to go with an AT screen, so that opened up some new subwoofer options I never had to explore before. I think I've almost figured out my enclosure design. Some kind of large double sided heatsink on the back has been in my head for some time. Always wondered how you implmented yours. Now we know!

Dr V
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post #30 of 661 Old 01-17-2009, 11:42 PM
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Very NICE, I wish you the best of luck with it!

Lot's of low rent stuff stacked up into a medium rent pile.
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