i doubt that thing is pratical in application for subs :-). i was talking to jt, about dont read too much into anything. i guess that wasnt clear, so i edited my previous post.

I'm not missing any output, I just know I'm close to the limit of the amp because the clipping light has a tendency to come on

edit: After recalibrating the sub now the only time it goes into soft clipping is durring huge explosions, the rock wall in the 2nd LOTR, platform explosion in one of those Star Wars movies...

I've purchased TrueRTA and I'm going to get a Behringer measurement mic and see how it does but I'm sure it goes very deep



[This message has been edited by Unferth (edited May 27, 2004).]

curegeorg, ok. Fixed mine too. What does "practical" have to do with anything?

I was speaking about driver efficiency, not amplifier efficiency. Class "D" amplifiers are extremely efficient. The driver it is powering is undoubtedly quite inefficient. It's not really an issue in a finished system since they can make the amplifier as powerful as needed. The efficiency issue only comes into play if you are designing a speaker from scratch and must spec an amplifier to drive it.

Unferth:
Finally, I get to hear from a Tumult owner. Congratulations on your choice of Adire Audio. I happen to be a fan of their drivers. I have a Shiva subwoofer built from ground up. It weighs about 150 lbs and I put 2 casters towards the rear which saves my back when relocating it (just lift the front and push or pull).

I’m surprised that yours clipped with 500 watt amp. How loud were you running it? My Shiva never clipped even when turned up to door shaking volume and its efficiency is at 87 db. I use 150 watt amp from Parts Express and the enclosure is 5 cu ft with 15 inch passive radiator.

Those of you with expertise on speaker design, does Vas number matter a lot for subwoofer drivers? Adire’s Tempest which is also a 15 inch driver, has half as much of Xmax distance but almost twice as much of Vas as Tumult does. What does this mean in terms of the potential of each driver?

Maybe someone else can add, but Vas is driver/suspension stiffness. Bigger Vas means bigger box. I think Vas has mostly to do with getting the proper size box and efficiency.

Clipping a 500 watt amp surprises me too. Is it hooked up right? That should be a LOT of bass for a HT.

Xmax is how far the driver can move before distortion becomes audible. That is because some part of the sub reaches a limit of control. It should be self explanatory as to why that is important. The BL (motor strength) vs x (position) curves look different too. Let's make sure the above stuff is understood and correct first though.

[This message has been edited by JT Clark (edited May 27, 2004).]

[This message has been edited by JT Clark (edited May 27, 2004).]

jt pointed this out to me already. i didnt realize you guys were talking about drivers only.

i think you guys are delving into too technical terms as to what makes a subwoofer a good one. the understanding of everything is nice, but how important it is matters most.

for diy, i think you can get a better sub than what unferth has for $900. not that his isnt nice or good or whatever, but 500wts rms is not enough for my tastes. components for subs are WAY overpriced though. i guess a lot of technology is proprietary though, and that is why it costs so much for someone to buy and why a lot of companies design parts in house.

i hope this market changes in the future, because i would like to have in wall subs when i get space for a nice theater room. its gonna be hard to part with the ones i have now, but i really like the idea of having it buried in the wall. id do four, one in each corner...

Sorry I was stuck on a plane and couldn't respond earlier

I'm running the voice coils in series so together it's 4 ohms (really 3.6)..

Anyway.. I'm home now and tomorrow I'll reverify the clipping with LOTR or something.. maybe I can get my wife to leave the house for a little bit

the highest I've had the gain of the amp has been about "4" of "10".. right now it's at about 2.5.. and at that time the sub trim on the 950 was set to 0 and the highest the volume would've been was around -13db

The amp also has an eq feature on it and I may have had it set a too low.. I had it at 18hz and adding a couple of db in a pretty wide band (the manual and the adjustment nob is a little vague on exactly what the settings do) so that probably had some to do with it

I'll post my findings tomorrow...

[This message has been edited by Unferth (edited May 28, 2004).]

Well I started the topic with no real direction to it. If someone wants to talk technical then we'll talk technical. Some of these things are precisely how you can tell a sub is good or not without even hearing it.

Good, big, small, better? All relative to your expectations. Not everyone has the same goals.

Unferth, did you mean wired in series? The Tumult is a dual 2 ohm sub. Or did you have some special version made? If you have it in parallel then you're running it at 1 ohm. The amp may be going into a protect mode which may be confused with clipping, even with the indicator light.