The perfect IB driver...

[cycole]

Have you been here alot of great info.

"Cult of the Infinitely Baffled"thinking outside the box - Login

[JimP]

Sonnie,

Have your drivers arrived? installed? hosting a GTG?

[Chrisbee]

cycole wrote:

Have you been here alot of great info.

"Cult of the Infinitely Baffled"thinking outside the box - Login

I wouldn't want to belong to any forum that would have me as a member!

[Jack Gilvey]

The now discontinued Ascendant Audio Avalanche 18 was about perfect for IB use.

Yeah, that one was cool. I thought the old Atlas drivers were almost "perfect", too, as they were designed from the outset with a second, smaller voice coil with which to vary the Qts. I use a pair on my IB, the 15's.

[Sonnie]

cycole wrote:

Have you been here alot of great info.

"Cult of the Infinitely Baffled"thinking outside the box - Login

Yes... I have a thread over there now. Great place!

Btw... welcome to the Shack!

JimP wrote:

Sonnie,

Have your drivers arrived? installed? hosting a GTG?

Got the amp, but no drivers yet. I told Mike at SoundSplinter to take his time as I mailed him a personal check for the subs. Saved me a little on fees and him too. I need to start getting the manifold ready, but I've had so much to do around here lately... soon... really soon!

[CIBELTRAN]

Guys,

I agree with alot of what is written. If I may be so bold, I think many of you get caught up in parameters...and maybe push other important factors down the list. I have worked on and designed drivers for many companies in the last 16 years (KEF, Bose, Velodyne, Boston Acoustics, Peavey, Harley Davidson, Audio Technica, Fender MI, etc.). Parameters are one of several STARTING points in designing a subwoofer driver. Once you start integrating the system, LOTS of other issues come up.

Ultimately, when it comes to very low frequency transducers (real SUBwoofer drivers), it is ALL about linearity, moving far, moving cleanly, and moving reliably. Specifically:

1) Having a very linear and long throw motor system. This requires a lot of voice coil overhang or underhang and a linear magnetic field.
2) Having a very linear and long throw suspension.
3) NO NOISES!!!!!! WOW, this is one of the primary reasons people switch to Acoupower and Bully drivers. I can't tell you how may emails and phone calls we have recieved from people in the last month alone who just bought a nice Adire or Dayton driver, and the leads are slapping, or the cone is ticking, or the coil is rubbing....all at just a handful of volts .
4) Having a reliable moving systems and lots of power handling.
5) Having low power compression

I don't have the time right now to discuss all of the above here in this relpy...the Acoupower site gets into much of this. However, let me stay with #3 above. No Bully drivers ships unless they are noise free (ticks and buzzes) through 90% of their mechanical limit. Acoupower drivers do not ship until they pass a free air sweep of 50V RMS for the 15" driver and 70V RMS for the 18" driver:holycow: . Go ahead and try that with any other driver. Just don't complain to me that the driver broke.

Also, and I am sure that many of you will agree, published specs are almost always exaggerated. You don't always get what you think you are getting.

In short, and simply, you have to try a driver and push it hard before you can pass any judgement on it.



Carlos

[Chrisbee]

Carlos

The deafening silence following your post leaves me wanting more.

I have seen your website videos several times and marvel at your beautiful products, their construction and claimed perfomance.

But I have to ask what specific advantages would there be to buying your drivers for IB use?

Until recently it was quite possible to buy 8 quite modest 15" drivers for the price of one of yours. (AE IB15, PE IB15)

While nobody is suggesting for a moment that these modestly priced drivers are any better than their specs allow at their price point, they do manage the job of IB drivers well enough when used in suitable quantities.

For the benefit of those who do not share your expertise please explain why we should use your "Aston Martin" of drivers rather than our base models in our IBs?

Would one 15" of yours best 8 of "ours" in a typical IB installation?

If not, then how many of your 15" drivers would we need to match 4 or 8 of ours?

It is not even a matter of space requirements since most IB builders hide their drivers away in a manifold as if they were ashamed of them.

So 8 hidden drivers behind a neat screen covering a hole in the ceiling or floor is neither here nor there.

How would distortion levels and noise for your drivers in an IB compare to 4 or 8 of "ours"?

Please don't think I'm attacking you or your products. If I can use one of yours to 8 of mine to achieve the same SPLs at even lower distortion levels then that would be truly excellent value. Being an ignorant cynic I doubt this is really the case.

Regards
Chris

[jagman]

bump

[CIBELTRAN]

Chris,

All of your points are very good. The bottom line is 4 or 8 15" drivers is overkill, and I think that is the fundemental attraction of IB....the wall of 15" or 12" drivers is TOTALLY COOL MAN!! High SPL's can be obtained at low frequencies and you are still not pushing the drivers. IF I were the typical DIY guy on a budget AND I had in mind to install 4 or 8 15" drivers on a wall in my room, I would probably pass on the Acoupower drivers as well.

However, being an electro-acoustic engineer, I would stop and say "who am I trying to kill anyway"? Many high end theater installs are using just two Acoupower 15" drivers in a vented box. These drivers are almost always along two boundaries....let's do the math:
89dB + 6dB (back wall in addition to the floor) + 6dB (two drivers) + 33dB (2kW per driver...conservative) = 134dB at 1m. This will energize most rooms beyond 120dB. Who needs more than that? The typical rock concert at the typical listening position in about 110dB.

Honestly, when I started Acoupower in 2003 I did not even think about IB. IB, after all, is a tiny market. I just wanted to design and manufacture the very best, truly low frequency 15" and 18" drivers possible. Parameters were not pre-determined like almost every other woofer I had designed. The drivers are simply designed for MAXIMUM linearity in every area. As it turned out, the parameters came out useable for all box types, from small sealed boxes to vented boxes to bandpass boxes.

To answer your questions more specifically, in an IB scenario, an Acoupower 15" driver will do 2-3dB more output than other 15" drivers in the very low end excursion limited domain, and some 6-10dB more above that, depending on what you are comparing it to. If you use an Acoupower 15" driver in a properly vented box, you can get that 6-10dB more output accross the whole band.....which is very significant.

One big difference between the DIY audio world and the rest of the audio world I have noticed is extension. Check this out:

Application , -3dB low freq. Limit
I-Pod Stations , 200Hz
Boom Boxes , 80-100Hz
Bose Speakers , 52.5683Hz, exactly
Pro Audio Speakers , 45-50Hz
European Hi-Fi , 40Hz-50Hz
American Hi-Fi , 30Hz-50Hz
Bad Subwoofers , 50Hz
Typical Subwoofers , 30Hz
Good Subwoofers , 25Hz
Recording Studios , 18-20Hz
DIY Fanatics who spend too much time on forums like this one 10-15Hz

Was that as much fun for you guys as it was for me?

Anyhow, the real point is there is rarely real information below 40Hz in music. SOME movies go lower than 20, but that is NOT the norm. You need to pay lots of bucks and invest in lots of volume displacement to go really low......back to IB....how did that happen?

Just for grins, each of you should make a Genesis Jr. box (plans available) and use it for your subwoofer. This box uses just one Acoupower 15" driver. It has a -3dB point of 28Hz, but it is 97dB at 1W in half space and takes 3kW, can you say 144dB in a corner .

O.K., that is enough fun for one night.

Carlos

[Chrisbee]

CIBELTRAN wrote:

Chris,

DIY Fanatics who spend too much time on forums like this one 10-15Hz

Just for grins each of you should make a Genesis Jr. box (plans available) and use it for your subwoofer. This box uses just one Acoupower 15" driver. It has a -3dB point of 28Hz, but it is 97dB at 1W in half space and takes 3kW, can you say 144dB in a corner .

Carlos

Carlos

I can't speak for others but I'm afraid you have rather misjudged the IB builder. It is hardly supercool to hide your drivers in a discreet manifold. Which seems to be the norm since very few build visible arrays. Visible arrays are supposed to have the acoustic edge over manifolds. So you might even consider IB builders almost perverse in building manifolds rather than showing off their visible arrays. (Let's ignore mechanical cancellation for the moment)

I am a classical organ music enthusiast. 32ft = 16Hz. I have electronic music CDs which have strong bass at 12Hz.(checked with Spectrum Lab)
Many films on DVD have even lower frequencies as a matter of course these days.

My very modestly priced SVS 16-46PCI cylinder sub is -3dB at 14Hz at the listening position. This is relative to +30dB at 15Hz 3 metres from the nearest corner and completely unequalised. It is however limited to ~110dB @ 3 metres at the listening position. (uncorrected SPL meter)

My IB was built for similar extension but far more importantly very low distortion. It was not built for high SPLs though it can be lots of fun in that direction too. Though I find anything above 115dB very uncomfortable and sometimes find nausea not far away on quite ordinary music at much lower levels. Self-flagellation with bass is not the name of the game with IBs. Very high sound quality is.

Your 28Hz -3dB Genesis Jnr sounds no better than many quite modest European floorstanding speakers on extension. I would dismiss it as a real subwoofer on that parameter alone. However loud it might go at higher frequencies on several extra kilowatts of unnecessary global warming.

It is said that anybody can build a Ferrrari but it takes a genius to build a Mini.

Give us a 15" "Bully Jr." with 25mm Xmax and 15Hz Fs for £100 dollars and we'll all sit up and take notice. Just don't give it an aluminium cone!

Regards
Chrisbee

[CIBELTRAN]

Chris,

Don't worry, no AL cones from Acoupower.

If distortion is important, than the Acoupower driver deserves some serious thought. The distortion of an Acoupower 15" or 18" driver is so low that it is inaudible with music till over 1kW RMS. I have had a few seasoned loudspeaker professionals tell me they thought something was broken with their equipment when they measured the distortion on the Acoupower drivers. There are many reasons for this low distortion...I really can't take time and talk about it here- this is not the place. Most of the reasons for this super low distortion are covered on our website. If you can't afford the $800 each for the Acoupower driver, than by all means give the Bully a shot. The bully has very low distortion as well. See these independent distortion measurements. Keep in mind the Bully is now available at a much lower price.

I don't disagree that there are some music and movie audio tracks with sub 20Hz information. But it is rare. When I was at BA, one of the engineers spent a few dozen hours over several weeks looking at the frequency content of Music and Movies. Most music had no content below 40Hz! If you are a bass fanatic like me, this is just a sad and dissapointing fact. Saying that most movies have content which goes below 12Hz is simply not true. In fact, the majority of movie soundtracks, even with lots of explosions and other effects, filter the very low frequency content out, so as to maximize the actual sonic impact that most systems can deliver. Seriously, professional audio theater systems from JBL and EV (that covers most of the theaters here in the U.S.), often don't go below 30Hz. Check out this link from JBL. Very interesting. Their 15" systems are -10dB at 30 Hz, and they have THX ceritified subs that are -10dB at 25Hz. Their lowest sub is -10dB at 22Hz . These are vented systems with sharp roll-offs below tuning. Again, the published specs say -10dB as it is!!! The Genesis Jr. compares favorably to these systems, and it is small enough to put in your home. Now before I get yelled at here...let me state something important. You will find SOME content at 10-15Hz in anything because filters are not infinitely sharp! But finding information at a high level as such low frequencies really is uncommon.


Anyhow....must get back to work.


Carlos

[Darren]

I don't disagree that there are some music and movie audio tracks with sub 20Hz information. But it is rare.

That statement is where you veer off track Many many action/adventure/sci-fi movies have sub 20Hz information. Most systems just can't reproduce it which is why I went with IB. There are lists on this and other forums where people have measured 5Hz information in many popular movies. Most of the movies for bass demo have lots of sub 20Hz info. If you are into home theater then you realize the subwoofer is a beloved aspect of that. We strive to perfect the lowest frequencies and reproduce every last bit available.

My subwoofer is flat at 10Hz.... I can't measure below that personally so I'm not sure where my -3 piont is at. I do know that while most movies won't be in that area, when there is information in that region I will feel it. IE: Matrix, U571, Blackhawk Down....

Whats the aversion to aluminum cones? They peform well in subwoofers. Just curious really.

Chrisbee has pointed out a good misconception of the IB guy. We, as most, are all about cool factor but an IB's cool factor is it's stealth. We HIDE our subwoofers, nobody can see them unless you build an exposed array. Most build manifolds like myself. They are tucked away in the attic or the crawl space or other adjoining space. The benefits are great WAF as well.

[Chrisbee]

I'm afraid I see the Acoupower drivers and present enclosure suggestions as PA/club designs. Which have very little to do with Home Theatre or domestic audio subwoofers. The knee of their response curve is so high in frequency they would need considerable equalisation just to achieve a flat response to 20Hz, let alone any sort of house curve. In domestic use I can't see the point of such high SPLs if you have to watch films wearing industrial ear defenders.

[jagman]

It seems to me the accupower is a wonderful driver... Carlos just seems to be barking up the wrong tree if he wants IBers to use his stuff. IB's in general provide very clean music. Sure, the Accupower may be a little cleaner, but I would suggest the decrease in distortion is most likely much less evident to most people than the massive low end that most current IB drivers easily hit. The fact that the drivers are cost prohibitive to multiple purchases only makes them more unrealistic to IBers.

[Sonnie]

I think you hit the nail on the head jagman!

Bottom line, you can make it as big and bad as you want, but if the price is out of reach, most IB'ers are gonna pass. If there's not an extreme differential in performance, people won't spend that extra 50 buck per driver.

As stated before, if the Bully was to get down around the $179-199 mark, Carlos might have himself a big seller in the IB arena, provided there was some testing done on it... and ThomasW hasn't spoken yet, that I know of.

[Sonnie]

Darren, would you be willing to test four of the Bully's for comparison to the SoundSplinters?

[jagman]

That would be worthwhile!

[Darren]

Sonnie wrote:

Darren, would you be willing to test four of the Bully's for comparison to the SoundSplinters?

I'm not sure I'm up for the work Been pretty busy and changing out those drivers is a bit of a chore... It is a tempting idea though.

I don't think there is a question that these drivers would perform well in an IB... I think the question is whether the extra $$ per driver would make a difference. Judging it solely as a subwoofer for HT application I'd say they would perform similarly to the RL-P15 although possibly not as high SPL around and below 20hz.

I'd be perfectly willing to spend more $$ on a driver that gave me higher performance but I'm not sure it would be necessary... currently I don't have a need for SPL above 120db.

Darren

[jagman]

Yeah... but wouldn't it be fun? It would be interesting to read if you noticed a decrease in distortion and whether there in fact is a decline in output below 20Hz. At this point all we have is speculation.

[Darren]

he he, yeah... it would be fun. I'm not sure I could physically tell if there was a decrease in distortion since I hear none presently. The output below 20Hz would be interesting. I should be able to measure down to 10hz but of course my mic isn't professional level.