Broke down. Got a duplex.

[Alien_Shore]

I gave in and picked up a beat up 604E. Sent it off to Bill to have him give it the GPA treatment.

Woof T/S:


Vas:


Horn T/S:

[Panomaniac]

Cool. Let us know how it is when it gets back from Oklahoma.

[voice of the theater]

Nice! Please keep us posted. I'll bet that speaker sounds amazing after you get it back from Bill/GPA. BTW, I'm inventing a triplex speaker. Altec 15" Biflex woofer with h.f. driver/horn (not to be confused with a triflex?)....

[donaldpatten]

Congrats

Welcome to the Duplex family
Are your magnets alnico or ceramic
I noticed the woofer R is about 7 Ohms. I expected to see about 12. What V.C. Are you getting on the new GPA?

Don

[Alien_Shore]

Ummmm,
I got it back from GPA yesterday - those measurements reflect the "GPA treatment"...
It's a huge mother - 604E so it's Alnico.
And yes, Don, I expected the same thing from the woofer VC - Bill told me he was putting in 16 ohm VCs for both HF and LF...

I only had time last night to very briefly hook it up through the Behringer dcx2496, as I don't have a XO for it yet. No cabinet either. It sounded...meh. The mids were very clear, and I think I got a glimpse of what everyone talks about that "point-source" sound - some extremely revealing details from the recordings, but as you'd expect I guess from an unmounted speaker it was utterly lacking any low end. I need to throw together a passive XO (plan to use Markwarts design as a starting point). But it is curious that the Woofer R is reading like an 8ohm VC is in there. Some of the other T/S params match very well with what is posted on Todd's list, while others are off by quite a bit. Does the MM number look right? I thought it was curious that DATS came back with a number that essentially equaled the amount that I applied to the cone to calculate the Vas. The math for that doesn't work out...

[Panomaniac]

Ah, those are after - sorry! I'd say Mms looks low, that's a light cone. But I'm not sure. I'll see if I can dig up files on some GPA reconed 604s (ferrite) I had here.
From the plot, it looks like an ohm woofer and horn to me.

[Earl K]

I gave in and picked up a beat up 604E. Sent it off to Bill to have him give it the GPA treatment.

From your measurements, it appears the "GPA treatment" is to turn a 16 ohm 604 into a 10 ohm 605 ( if that DAT measurement is to be believed ) .

Time will tell if your measurements hold water ( fyi, others using WT3, which was the G1 version of DATS , had many problems with it, maybe DATS is better ??? ) .

The current measurements tune up quite well ( if accurate ) using a 9.5 cu' enclosure tuned to 25hz .

[Alien_Shore]

From your measurements, it appears the "GPA treatment" is to turn a 16 ohm 604 into a 10 ohm 605 ( if that DAT measurement is to be believed )

Yep - that's what it looks like. I sent GPA an email - we'll see if they reply.
In the meantime, do you recommend another (more reliable) method for testing T/S?

[Earl K]

WT2 is more reliable than WT3/DATS ( different maker with a different way of measuring ) .

REW has a TS parameter measurement area ( you need to wire-up a small box ) that uses the same method as WT3 .

Personally, I wouldn't bother GPA with this type of thing until you've gotten similar measurements from at least one other measuring program.

[Earl K]

- Every once in a while it is worth the diy hobbyists time to check ( recalibrate ) the validity of ones measurements by using another method ( really , it's simply part of the scientific method ).

- For TS parameters ( when checking these "all-in-one" devices ) one can use the old standby method outlined here !

- I believe that verifying Re, Fs & Qts ( Qms, Qes ) is enough to know where ones device stands .