sony buyout

[XtremeRevolution]

Re: sony buyout

So I was decided to play around with one of these drivers some more. Ran a few test tones for a while with my receiver, and played around with the cones by hand to loosen up the suspension. Well, sure enough, I loosened up teh susp

Went back and tested it with the WT3 15 minutes later, and I got something quite different from a fresh one out of the box.

Here's how I tested a driver fresh out of the box:


And here's the driver I played around with some:


Seems I may have loosened up the suspension a bit. Lowered the Fs by 8hz, and lowered Qes and Qms. Models better than the fresh driver. F3 of 71hz in 6 liters tuned to 70hz and within 3mm of xmax the whole way there.

[Leroy R]

Re: sony buyout

I need to confirm, but I tested over 20 of mine when I recieved them and I think I had some that returned an fs in the mid 60s. I saved 20 of them to memory so I'll check when I get home from work this morning.

[r-carpenter]

Re: sony buyout

I'm currently using two 10" subs sealed. I am planning to bring in a 15" ported sub. I just thought it would be a better idea to cross lower than 100hz.

I guess I'm building two line arrays then. That should use up all of the drivers I have and give me a nice bit of sound. How would placing two of these line arrays sound next to each other? How about two tweeters and 24 drivers per baffle?

It is a better idea to cross lower then a 100. Let's see what happens then measured.
2 line arrays next to each other, not sure how that would sound. 24 drivers per array= different summed up response, different crossover, we would be back to square one with measurements.
Get a Mic, Arta, Holmi and measure, it's very helpful. :D

[nottaway]

Re: sony buyout

My suggestion is not to get involved in to TM, TMM or MTM with this driver. Sensitivity is low, distortions are highish, motor is weakish.

How about a MMTMM? Should help with the low sensitivity and weakish motor.....

[r-carpenter]

Re: sony buyout

that's a better idea.

[Leroy R]

Re: sony buyout

I was wrong, all of mine that I tested were mid 70s to mid 80s. Haven't had time to mess around with breaking any in.

[Sydney]

Re: sony buyout

r-carpenter:
In light of this:

Seems I may have loosened up the suspension a bit. Lowered the Fs by 8hz, and lowered Qes and Qms. Models better than the fresh driver.

Have you gathered enough "statistics" to determine typical specs after sufficient burn-in?
How much variance there is within the batch(es)?

[johnnyrichards]

Re: sony buyout

Well, I flogged the single unit I have with both music, and pushing the cone in and out to the maximum throw and it gave me numbers very similar to XR's post just above. ~70 Hz Fs and ~0.7 Qt

[r-carpenter]

Re: sony buyout

r-carpenter:
In light of this:
Have you gathered enough "statistics" to determine typical specs after sufficient burn-in?
How much variance there is within the batch(es)?

There isn't any variances with the batches or at list the variances are well within the accepted limits.
I assume that we may run in to occasional fluke of nature but after checking about 20 of these I am confident on the specs. Variations are very small. Burn-in lowers FS slightly and changes Qs a bit but for the over all performance of the driver it is not a significant change.
The variations in measured results among members here are caused by measurement conditions and methods such as applied voltage, frequency at which Le measured and so on and not by the drastic differences in driver batches.
HTH.

[Leroy R]

Re: sony buyout

I have 3 cases and have sampled at least 10 drivers from each case and all measure very close.

When I was thinking of fs in the 60s I was confusing them with the Bravox drivers I measured. The Bravox drivers all measured approx. 61 Hz fs.

[Sydney]

Re: sony buyout

Thanks all:
I was wondering if 7 - 8Hz drop was typical for these Sony's and how close post burn was to published spec.
( It's been a while since I fired up my WT2 and had a new driver to do a pre/post eval.
Last one I had was an 8 bass driver with a published F much lower.
It dropped approx 3db after 24Hr burn-in )

[johnnyrichards]

Re: sony buyout

Roman, I have measured a lot of woofers the same way I did the Sony and have gotten results almost always within acceptable margin of error to published specs as well as other peoples measurements. The few times my measurements were way off of published - other people have experienced the same thing.

[XtremeRevolution]

Re: sony buyout

How about a MMTMM? Should help with the low sensitivity and weakish motor.....

that's a better idea.

I'll start designing a crossover for these, but I don't feel too confident with a MMTMM. The midrange just looks much too rocky. I simply don't like crossing this driver very high for some reason, but I can put together a crossover for you if you'd like. It would likely be a 2.5 way.

I was thinking more on the lines of a WWMTMWW based on the 3-way I designed in the other thread.

Opinions?

[r-carpenter]

Re: sony buyout

Roman, I have measured a lot of woofers the same way I did the Sony and have gotten results almost always within acceptable margin of error to published specs as well as other peoples measurements. The few times my measurements were way off of published - other people have experienced the same thing.

Well, let's find a culprit.
Your measurement shows Re of 7ohm. All mine show 8ohm. Xtreme has 8.5-8.7ohm roughly. I suggested before, check DC resistance with DMM. If you get 8ohms and WT2 shows 7ohm or 8.7ohm, it's a problem.
Now, let's look at Le that we all got all over the place. WT2 as well as S&L WT measures on small signal. On a driver like this, small voltage signal may simply not be enough to excite the motor. S&L WT measures at 1khz. What frequency WT2 measures at? I am asking because Le is frequency dependent.
Oh, and Extreme's Le goes up after "burn in"?
Don't take PE measurements as a reference, because guess what they are using? WT of cause. :D
Johnny, I know you use ARTA for acoustic measurements. Use LIMP for your TS. It's much better then WT and measures at large signal. WT tester is ok for consistency quick checks.

I'll start designing a crossover for these, but I don't feel too confident with a MMTMM. The midrange just looks much too rocky. I simply don't like crossing this driver very high for some reason, but I can put together a crossover for you if you'd like. It would likely be a 2.5 way.

you mean, something like this?

http://techtalk.parts-express.com/showthread.php?t=218707

[XtremeRevolution]

Re: sony buyout

Well, let's find a culprit.
Your measurement shows Re of 7ohm. All mine show 8ohm. Xtreme has 8.5-8.7ohm roughly. I suggested before, check DC resistance with DMM. If you get 8ohms and WT2 shows 7ohm or 8.7ohm, it's a problem.
Now, let's look at Le that we all got all over the place. WT2 as well as S&L WT measures on small signal. On a driver like this, small voltage signal may simply not be enough to excite the motor. S&L WT measures at 1khz. What frequency WT2 measures at? I am asking because Le is frequency dependent.
Oh, and Extreme's Le goes up after "burn in"?
Don't take PE measurements as a reference, because guess what they are using? WT of cause. :D
Johnny, I know you use ARTA for acoustic measurements. Use LIMP for your TS. It's much better then WT and measures at large signal. WT tester is ok for consistency quick checks.




you mean, something like this?
http://techtalk.parts-express.com/sh...d.php?t=218707

Something like that yes, only a whole lot cheaper.