[JohninCR]

Here's another option if you use a 12" or a 15" on top (a small driver may look silly paired with it).  With a 1927 sq cm Sd, this 21" will move some air.
http://www.shredmuzic.com/ProductDetails.asp?ProductCode=813%2D008

[mcgsxr]

Agree with JoshK that the 15's I mention are for music use, and that observation about the FS is correct.

JohninCR - yikes, that might even make me happy!  Pricey to ship to Canada I bet, and with the FS and QTS, I would expect a TON of bass around 30Hz...

[bassboy]

John, I have one of the mach5 15's.  The backside is so pretty I was going to mount it magnet facing out in my tl.  I tested it first boxless to determine how 'quietly' it operates.  I fed it a 10 hz tone at decent excursion and it certainly does chuff, although I'm not sure how bad it would be a few feet away, especially on the backside of a baffle.

I will be building a heavily stuffed U for it.  The baltic birch is cut already.  I just have to get up and do it.

[Bob in St. Louis]

Welcome BB

[mcgsxr]

Welcome indeed bassboy!

I am not sure that it makes sense to measure it so low, does it?  Very little musical content below 25Hz, let alone 20Hz, even if you are into the Bass Mechanik, or DJ Magic Mike scene.

Do you recall if it was making nasty noises at or above 30Hz or so?

I might be convinced to sell off my 12's, and 10's, and other 12 (gawd, what a collection of subs over the years!) and move to a pair of the 15's, if for musical reproduction, they are sound.

All the best,

[JohninCR]

Mark,

I like to do the same type of thing to check a driver for operating noise, 10-15 hz with near full excursion and no baffle.  At 30hz near full excursion any noise can only be worse, because the driver is moving faster.  The reason I like to do a very low test is because the sound output is inaudible, so noises from the mechanical operation are easily identified.  It's part of my woofer break-in process anyway.  In addition, it's a good way to get a feel for a driver's mechanical limits, so you don't accidentally do so with sound playing and not notice until it's too late.

[mcgsxr]

Thanks for the information, I will have to find a way to try that!

[bassboy]

First off, I'd like to be clear that I'm not talking trash about the driver.  I'm not sure any driver could be completely silent in this kind of test, although I've never done it before, so I really don't know how much noise is considered acceptable.  The driver was going into a large HT sub where fairly large excursion is normal, and driver facing into the room at ear height a few feet away from the listening position, so I was especially worried about noise.

Again, I only tried it because the backside is so exceptionally attractive.  It's got a beautiful cast frame and it's a really solid, heavy unit.  Based on looks alone (since the specs are so wildly different) my Dayton Quatro is not even close to being in the same league.  AFAIK the mach5 site has no large high res pics, but they really should. 

In the end, looks don't really count, but I fear that mach5 is considering printing a logo on the dustcaps sometime in the future which I think is a HUGE mistake.  I'm going to have to get another matching 15 before they start that nonsense.

[JohninCR]

Bassboy,

I thought you would have graduated to BassMan by now.

Here's a dustcap to wear proudly.  Unfortunately I was only able to score one of these for the price of an Augie before shipping, duties and taxes.  Some day I'll track down a 2nd, so I can use them OB.  Look at that vent...no chuffing here.  With the extreme LF test the only noise comes from flexing the stiff rubber surround, which I probably never have fully broken in.  I really like the futuristic retro look.  If the Jetson's had a sub, I think it would look like my 1500GTI.  It's the kind of sub that Augies, Mach 5's, and the rest dream of becoming when they grow up.  Nearly an inch of Xmax and the linear dual VC makes it all useable, because once it reaches Xmax the 2nd VC acts as an electromagnetic brake, preventing over-excursion, similar to RDO but without wasting a VC.

This driver was JBL's all out engineering effort to enter the SPL competition arena.  While its thick heavy cone make it useless above the pistonic operation range, it makes a great sub, even for OB use.  Like I said, I'll land a 2nd one eventually, and display the unique cast frames as OB bass augmenters.  I'll also need to acquire a big amp to drive them properly (800W rms & 5kw peak).  http://manuals.harman.com/JBL/CAR/Boxes%20and%20Parameters/W15GTi_rev_f.pdf

[bassboy]

John, the inside diameter of that blowhole before it takes on the large flare looks about the same as the mach5.  It's still in the tl right now getting daily use and I have fever and flu right now, but when I'm better I'll take it out and get some pics.  I guess that big flare on yours helps to reduce noise, but unless you had told me, I would have thought there would be some noise, since the vent is fairly restricted at it's narrowest point.  But it is good to know that there are drivers capable of producting no chuffing noise.  I just won't be able to afford them anytime soon.  Not that model, anyway.

Granted, that jbl is a logo to wear proudly, and a driver to show off.  So let me try to qualify my thoughts on the mach5 one more time.  It's not as special as a Christmas miracle, but at a pricetag considerably less than a dayton quatro (especially since I am in Canada) they are really not in the same league.  Of course the difference in specs leads to a possiblility for wildly different applications and results between the two, so it's hard to make direct head to head comparisons.  And since I've not tried either in OB I have no idea how they would sound.  IIRC, the dayton and the mach5 made about the same chuffing noise, although the mach5 vent is considerably larger.  I'm going to have to get some side by side pics and redo the testing (and pay attention) soon.

The bassboy will not grow into MR BASSMAN anytime soon.  Since getting a real taste of imaging, I've started a small fostex collection, a pair of Decware modded FE206EM, a pair of 126's modded by planet_10 and I'm working on acquiring a pair of 108 sigs because someone told me the key to unreal holographic imaging is usually narrow boxes so I'm going to make a variety.  This summer is going to be boxed fun, then back to OB in the winter or next year.  And the U should be done in a week, I just have to get out and slap it together.

[mcgsxr]

bassboy, where in Canada are you?

John - ahhh, the old standby, the GT1500 - love them!  I recall hoisting one of those around 10 years ago, when I was car sub shopping, and being very impressed.  A solid piece, and no one questions JBL's design abilities, and commitment with that piece.

But, if we are going to have a manly "look at the size of my pole piece vent" competition, I MUST bring up my Fosgate Punch HX2 12.  This is the first sub I tried on OB, with 1 VC open, and if I could find a pair of 15's of these, for low enough $$, my search would be over.  I have absolutely pounded this 12 in a sealed box with 500w in my old BMW, and subsequently played around with it in OB.

Nice BART rubber surround, cast basket, 500w rms, 1000w peak rating, nice piece.  Oh, and a vent like a pop can!







The 12's still go for more than $100 on eBay (were $500 new, around 7-9 years ago), and the 15's are even more.  I saw the Mach5 gear, and was impressed with the build quality, and truth be told am very pleased with the pair of 12's, but I just HAVE to know what 2 or more 15's would be like....

[bassboy]

Yeah, that's a big hole.  I'm just outside London, Ontario.