BillFitzmaurice.info

Strange Kevin wrote: ↑Wed Apr 29, 2020 1:47 am

How wide did you build yours

Crazy enough. 8-1/2" total "width"

It's been so long I had to double check, all I could remember was it was built to just fit in my old mk3 vw golf without sticking up above where hatch opens.

Crazy coincidence. Too funny. Mine's going in a Golf too. Mk6 though.

Seth
What's the overall weight going to end up at build end please?
Cheers G.O.

David, other than any touch up's and final details, it's all ready for final assembly in the morning. I'll put it on a scale afterward and let ya know.
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The terminal dish I have has the nuts proud of the dish surface
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The dish is going on the down side/bottom of the cabinet and to avoid potential issues with them breaking or cracking the plastic dish, I decided to inlay it below the cab surface.

I have a flush cut bit, but didn't have a pattern bit with the bearing on top. The only one I could find in town had a 1" deep cutting surface. I would have preferred half inch, but anyway... I had to laminate 3 layers of scrap for the "pattern" circle in order to accommodate the length of the bit and not cut too deep. I kept track of cut depth with the depth finder pokey out dealeo on my digital caliper. Depth of cut was just under a quarter inch, at 0.225". The location of the dish is essentially triangulated and very near panels 2,6, and the mounting flange of the old driver location. I'm not concerned about the remaining flange thickness. Although I may add some anchor blocks for the screws.

Made the bottom layer bigger so I could tack and hold it in place with 23 gauge pin brads
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This is the side that had the driver hole in it. Can't tell at all.

Grey Owl wrote: ↑Wed Apr 29, 2020 7:40 pm Seth
What's the overall weight going to end up at build end please?
Cheers G.O.

Decided to go ahead and put it together tonight. According to my $10 bathroom scale its 54lbs./24.5kg fully loaded.
. . Drivers haven't been broken in yet. I'll put them on the bench tomorrow. Gonna need to put an amp in the car too.

Thanks. Looks great.

Rather than tie up old mate's best driver thread let's talk up some of the TS parameters, efficiency, Vd, Maximum output, so we can get it straight, and advise people asking the same way???

I'm happy to kick it off in another thread if that would be preferred..

Grant Bunter wrote: ↑Fri May 01, 2020 1:18 am Rather than tie up old mate's best driver thread let's talk up some of the TS parameters, efficiency, Vd, Maximum output, so we can get it straight, and advise people asking the same way???

I'm happy to kick it off in another thread if that would be preferred..

This is the perfect place to discuss that sort of stuff... unless you want to be able to find it in a thread search at a later date.

So, what's up for ironing out?

I guess one question/curiosity is; is a driver with less Vd but a higher displacement limited voltage limit capable of more peak volume when compared to a driver with more Vd, yet lower displacement limited voltage limit?

Specific example is these two drivers for use in a T30:
18 Sound 12NLW9300 Which has a Vd of 425cm­³ and a displacement limited voltage limit of 60 volts (450 watts)
vs.
Eminence 3012LF Which has a Vd of 496cm³ and a displacement limited voltage limit of 50 volts (313 watts)

Which has more output potential in a T30?

The 18Sound Vd is higher than the 3012LF, because 18Sound measures xmax differently. For the lack of Klippel specs I estimate it at 10mm. Xlim is longer too, 18.5mm versus 14.5mm.

Bill Fitzmaurice wrote: ↑Fri May 01, 2020 4:11 pm The 18Sound Vd is higher than the 3012LF, because 18Sound measures xmax differently. For the lack of Klippel specs I estimate it at 10mm. Xlim is longer too, 18.5mm versus 14.5mm.

Thanks Bill. Ironed that out quick!

Good one!

Okies Seth, tell me about your efficiency thoughts in that other thread as well.

Grant Bunter wrote: ↑Fri May 01, 2020 5:13 pm Good one!

Okies Seth, tell me about your efficiency thoughts in that other thread as well.

Well... with the xMax ratings being apples and oranges, I'm not sure that whole efficiency thought still makes sense anymore. I'll have to give it some thought. Although, 135 watts to make 0.9mm more xMax does seem a little much. However, comparing it against the typical hypothetical 4x power it would take to double the xMax to 20 (another +6dB), maybe it's right there in the land of all good?

... and the Lab 12 is also 450watts (50 v, but 6 ohms), yet achieves 13mm xmax /659cc Vd, vs. 450 watts getting 10mm/531cc Vd for the 18 Sound using Bill's estimated figures. So, it seems it would be the king of output potential and efficiency. maybe?

Dunno, just thinking out loud.

SethRocksYou wrote: ↑Fri May 01, 2020 7:43 pm ... and the Lab 12 is also 450watts (50 v, but 6 ohms)

Correction... 417 (not 450) watts for the lab12 to achieve 13mm xmax, 450 for the 18sound to reach 10mm (estimated).

Is the Lab more efficient? Are they both, in fact, reaching their xMax at the stated voltage?

Is the Lab louder with less power?

Good questions.
I'll stick my neck out and say they are all reaching Xmax at the respective voltage displacement limits.
I might suggest the 18 sound is the least efficient, and note it probably has the longest VC ( I read somewhere that VC length can have a correlation to efficiency).
But I'm not sure efficiency is really relevant, because we do know efficiency when used in horns is increased anyway...

These comments sound like a great start to a physics lesson.
Watching with interest.
Cheers