Gpa 416-8c

[Alien_Shore]

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.

[GM]

Normally, the specs change in complementary ways, so short of Vas being off a lot, the cab size/tuning should stay the same.

GM

[Altec Best]

They look nice Mike ! Let us know how they sound/perform...

[VolvoHeretic]

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

[cradeldorf]

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.

[Alien_Shore]

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!

[Old Guy]

Altec published Xmax is very conservative. They have probably 20% higher if you used typical ratings.

[gortnipper]

It's indicating an 8.6 CF vented box tuned to 24 Hz.

GM - how do you think these would play in that big GPA 604 box that you simmed for Jay that I built?

• L = 42.5"
• CSA = 422.04"^2
• vent = 6" diameter x 2"
• Driver center point down 19.625" from top interior.

[VolvoHeretic]

It is illegal to put a 604 in a 1.5 cu ft box!

[GM]

GM - how do you think these would play in that big GPA 604 box.....

Using the measured plus derived specs [attached], it will need to be tuned lower [Fs] to get a 'close enough' similar response, so will probably need at least a 6? long vent.

GM