Normally, the specs change in complementary ways, so short of Vas being off a lot, the cab size/tuning should stay the same.
GM
The Fed Ex truck brought a pair of nice boxes yesterday.
Inside are my factory-new 416-8Cs from Great Plains:
Here is the impedance plot: (not broken in whatsoever)
If you can't make them out, here are the (non-broken-in) 416-8C T/S parameters:
Re = 7.46
Fs = 24.22
Qts = 0.305
Qes = 0.321
Qms = 6.904
Le = 1.478
Mms = 68.56
Vas = 21.19
Zmax = 149.3
Got them in my 816 enclosures right now breaking in, then I'll re-run the TS sweeps and do some FR measurements.
The cones are incredibly light; I'm not sure about the Mms and Vas numbers (I used the delta mass method), so I am going to build a test box to test them out that way. What size box would work?
Here's the default WinISD box sim for the (non-broken-in) driver:
It's indicating an 8.6 CF vented box tuned to 24 Hz. This will get re-measured as well after a healthy break-in period.
Last edited by Alien_Shore; September 5th, 2013 at 08:13 PM.
- Mike
Normally, the specs change in complementary ways, so short of Vas being off a lot, the cab size/tuning should stay the same.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
However did they survive in that flimsy box when the FedEx driver threw them over your fence?
http://www.youtube.com/watch?v=D7Sb_r7BKTc
Last edited by VolvoHeretic; September 6th, 2013 at 01:00 AM.
"James, a little knowledge is a dangerous thing!" World's scariest Volvo: [url]http://www.youtube.com/watch?v=AKn-LTNa4rc[/url]
Isn't the zmax saying 5 inches? 149.3? Isn't that MM? or is it thousands of an inch?
Edit: never mind I was thinking xmax... I'm getting too old for this stuff.
The 24 Fs is pretty impressive though. They ought to dig pretty deep with that.
Last edited by cradeldorf; September 6th, 2013 at 12:33 PM.
Yeah, the published Xmax is 3.8mm.
The Fs I measured right out of the box is pretty close to what GPA publishes (within 5%), which is good to see. The Qts and Qes are pretty far off though, enough to change the EBP considerably (the published specs yield a box size of 4.7 CF tuned at 23 Hz). Does anyone know if Qes will change much as the speaker breaks-in? I would expect Qms to move some as the suspension loosens a bit.
The beefy Le is probably due to the beefy voice coil and no shorting rings, so a zobel will likely be in the new XO...
I can tell you that the speakers sound amazing even on the current crossover (designed for my old 416As). It's going to be fun designing a 2-way using these drivers!
Last edited by Alien_Shore; September 6th, 2013 at 04:30 PM.
- Mike
Altec published Xmax is very conservative. They have probably 20% higher if you used typical ratings.
Your neighbors called. They like your music.
Here's an FR plot from a measure I did. This is taken with the driver mounted in an Altec 816 bass horn, 1' from the horn front, on axis.
As good as this plot looks, the driver sounds even better. It has quite an extended range; and the mid-bass sounds absolutely gorgeous.
Next up is to put one into a 1.5CF test box to zero in on the Vas number, then build a ported cabinet for it. I'll probably start with a 2-way waveguide design.
- Mike
That's interesting. There's a 10dB slide starting at 900Hz and ending around 2300Hz. That's understandable. I wonder what accounts for the 9dB bump from 2300 to 2700?
Was this measured inside?
GM - how do you think these would play in that big GPA 604 box that you simmed for Jay that I built?Originally Posted by Alien_Shore
• L = 42.5"
• CSA = 422.04"^2
• vent = 6" diameter x 2"
• Driver center point down 19.625" from top interior.
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