Super 8

[woody]

Apexjr. at http://www.apexjr.com has cute little 8" driver.

FS 47.75 Qts .514 Vas.376 cu. ft. Re 2.653

Sensitivity ? I see two figures SPL=85.22 @ 1w /1m
and SPL =90.01 with 2.83 v/ 1 m.

Could this driver be used in a tline of ~50" legnth with
a tapered line from 3 x sd to sd at the mouth.

Thanks,

Woody

[Ouroboros]

An Fs of 48Hz in a 8" unit? That's very high. I know that's what the site says, but is it really 8"? (The oversized dust cap on the picture on the website makes it difficult to check, but it looks more like a 5" unit at a glance.)

[Hybrid fourdoor]

This driver has been used in several projects on the net, so I'm sure one of those poeple would have said something if it wasn't ~8".

Not being rude , just saying that thats probably not the case.

[Robert_J]

For a little more money you can get a Tang Band 8 or a Resonant Engineering 8. Both have a lower fs and higher xmax. The RE is a single 2 ohm voice coil.

-Robert

[BillFitzmaurice]

Assuming that you're going for about a 70 Hz line that driver should work just fine. However, using Sd to calculate the line size is obsolete. A better method is with Vas; for your Vas of .376 cu ft a total line volume between .25 and .3 cu ft would be appropriate. With so little volume that could give a fairly tight vent, so I'd go 2.5 to 1 on the taper ratio.

The differing SPLs are due to the fact that the driver is not 8 ohms; by the Re value it may be only 3 ohms, and that could be a problem. A 4 ohm driver with 85dB/1 watt (2.0 volt) sensitivity would have 2.83 volt (2 watts into 2 ohms) SPL of 88 dB, while a 2 ohm driver would not have an Re that is higher than the impedance, so something is remiss with those figures.

[sreten]

Originally posted by woody
Apexjr. at http://www.apexjr.com has cute little 8" driver.

FS 47.75 Qts .514 Vas.376 cu. ft. Re 2.653

Sensitivity ? I see two figures SPL=85.22 @ 1w /1m
and SPL =90.01 with 2.83 v/ 1 m.

Could this driver be used in a tline of ~50" legnth with
a tapered line from 3 x sd to sd at the mouth.

Thanks,

Woody

Not a TL guru but apparently modern practise bases line size
on Vas not Sd. So in this case perhaps suited to a compact TL.

The high Fs is entirely consistent with the very low Vas for an 8".

Suggest you repost this with TQWT or MLTWQT or TL in the title.

IMO the Qts of ~ 0.5 at ~ 50Hz is promising for TL's or (ML)TQWT's.

Though by the looks of that dustcap you are talking 3 Way.

sreten.

[woody]

Thanks for all the feedback no pun intended. I make no clames
about what it SOUNDS like but the frequency responce seems to
extend past 10k !

[Apex Jr]

Woody...
They are 8" and heavy (18 lbs) I've sold for Car Speakers
and Computer Game Speakers I've not found the right
market for these and there not moving as fast as I thought.
There are a high end speaker used by a major company
but where I bought them won't tell me.. I got these spec's
from a customer and posted them in hopes of selling more.
I'm hopeing for more feedback but haven't received much.
As High end speakers I figured they would sell more and
would have received more feedback and maybe some plans.
Maybe down the road. Have about 150 of these still in stock.
Steve @ Apex Jr.

[BillFitzmaurice]

Woody. I wouldn't put much faith in going to 10kHz with these. A top end of 1kHz is probably the best you'll be able to hope for. That's in line with what other similar drivers measure out at.

Steve, I'd guess that the reason they haven't checked out is that the kids buying sub drivers for their cars are into watts and size, because they don't know any better, and they are far more likely to buy a bigger driver rated (probably falsely) with more power, while those in the home DIY market who know about drivers realize that the Fs is at least 10 Hz too high for hi-fi/HT sub use.