Peerless 830657 for <$6a piece!

[WernerM]

Don looks to me like #9 & #10 are your closest matching pair followed by #7 & #8, #3 & #11 or #12

[Chris Roemer]

If you're building "Stent-a-likes" (6 drivers / enclosure), I'd suggest these 2 groups (I eye-balled your numbers off your graphs):
Group A: 1, 4, 6, 7, 9, & 10. Averages: Fs=49, Qts=0.51, Vas=0.19cf
Group B: 2, 3, 5, 8, 11 & 12. Averages: Fs=51, Qts=0.53, Vas=0.18
These 2 groups will box-model about the same as each other.

[donradick]

Thanks for the input guys!

Stay tuned - T/S retests with Blu-Tak are coming out much different. I have new hope that this project will go forward with these drivers.

[WernerM]

The four I received are reasonably close (no break-in):

#1 and #4 look close to being a matched pr, but would have to see T/S params to know for sure. Both those look to have an Fs near 49Hz and they both track very close at 10ohm just past 100Hz and again back to 10ohm at 800Hz, both bottom and measure same between 200-300Hz as well

[thekorvers]

The four I received are reasonably close (no break-in):

Could see the pictures (attachments) yesterday, but not today! Noticed you edited your post this morning.

[donradick]

So I'm almost finished with retesting - looks like the major problem was how I attached the 10G weights (2 US nickels) to the cone/dustcap.
(BLU-TAK is the best, with the intersection of the dustcap and cone as best position)
If I look at the units with large variations from the norm, the MMS is way off. Resting 2 and 3 times shows a more normal MMS, and then
the rest of the parameters fall in line. Final results soon.

[ecj]

The four I received are reasonably close (no break-in):

Could see the pictures (attachments) yesterday, but not today! Noticed you edited your post this morning.

I think I broke something while trying to resize the images.

[donradick]

Lots and Lots of LIMP yesterday. Got real good at applying nickels to cones.
Much more consistency, but a few drivers in the bunch that are definitely out of spec.

I tested some of the drivers 3 - 4 times, so I feel that results are good.
The project will move forward - sims will use the average vaiues, with out of spec drivers
matched left to right.

FS:


QTS:



VAS

MMS:

[Chris Roemer]

Even though #2 & #6 don't match the others, if you box-model them (ave of 2&6), you'll see that they almost perfectly match the others (ave of the other 10) as far as final Vb & F3 values go. IF Qts goes up, but Fs ALSO goes up, AND Vas goes down - they end up essentially modelling the same (exactly the way your data shows).

[donradick]

Even though #2 & #6 don't match the others, if you box-model them (ave of 2&6), you'll see that they almost perfectly match the others (ave of the other 10) as far as final Vb & F3 values go. IF Qts goes up, but Fs ALSO goes up, AND Vas goes down - they end up essentially modelling the same (exactly the way your data shows).

Yeah, I thought that was pretty instructive - text book parameter shifts.

[Pallas]

Lots and Lots of LIMP yesterday. Got real good at applying nickels to cones.

Why use the nickels at all? I usually just weigh out poster putty and mash it flat.

[donradick]

Why use the nickels at all? I usually just weigh out poster putty and mash it flat.

good point - I try to simplify every aspect of measurements - now I just need to buy a sub .1 gram accuracy scale.

[Pallas]

The one I use cost under $10 on a site where PE also sells, and is very consistent though I haven't really calibrated it.

[donradick]

thanks. Very good tip! I found that the little pieces of putty that I used to attach the nickels was .6g

Time to repeat the LIMP tests.

[donradick]

Finished another round of the "out of spec" drivers, results a bit more consistent, but I've still got several drivers as outliers,
so I'll match those left to right and top to bottom.

Now it's time to look for a nice high efficiency tweeter. I got excited about the H25 / H26 tweeters, then saw the rather high Fs.
I figure that I'll need to crossover the tweeter about 2500, since the woofer response is a bit unknown at this time.
Looking to spend about $30-35 and have 93db efificiency.

Actually, this Vifa ring radiator looks about perfect.
One thing that isn't clear from the specs is how loud a tweeter could play without damage or distortion.
Do I need to worry about that?

Any other suggestions?

http://www.parts-express.com/peerles...eter--264-1016