Meet The Raven...

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

As always, I appreciate the positive feedback.

Bosso

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

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

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

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

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

Bosso