My quad should be here today. I may play around with them and see if they can be improved on. I'm thinking of masking the gap and trying to drill the pole piece and add a rear chamber. We'll see.
I'd figure the chips would be a real bear to deal with due to the magnet. I would probably experiment packing the gap with something that hardens but is reasonably easy to wash out like drywall mud. That way you can forcefully wipe the chips away without pushing them into the gap.
I've drilled out the pole piece on tweeters before. It's no big deal at all. Just firmly apply a piece of blue painter's tape across the face of the tweeter motor and drill straight through the pole. The metal filings and chips are easily brushed off and the hole blown out with compressed air. Then you can safely remove the painter's tape and Bob's your uncle
My 4 buyout tweeters were on my front porch when I got home yesterday. Haven't had a chance to take any measurements but they were packaged very well and look kinda cool.
@PWRRYD said:
My 4 buyout tweeters were on my front porch when I got home yesterday. Haven't had a chance to take any measurements but they were packaged very well and look kinda cool.
Cool I'd love to hear if your measurements resemble mine. Would help me know if I'm doing my measuring correctly.
Did a quick DATs sweep on all 4 tweeters. Two of them measured nearly identical. One had a higher impedance peak (20 ohms vs the other two's ~10 ohms) but it sounded ok during the sweep. The forth was way different and sounded about 10 dB quieter during the sweep. It had an impedance peak of about 5 ohms. Strangely all 4 had pretty much the same Fs ranging from 752 to 803 Hz. I'll be calling PE tomorrow morning.
I forgot to mention that the two "good" ones didn't have that impedance glitch at around 2kHz, the one with the higher peak did have it, and the 4th is just a hot mess.
@PWRRYD said:
Luckily I'm pretty sure PE will take them back and refund my $10. I've spent that much for a lunch meal at McDonalds and regretted it probably more!!!
Yeah, I've never really regretted cheap driver purchases. A pair of Aurum Cantus drivers I regretted buying. First the pair had wildly different TS parameters. Second while I was running one in at Xmax (thinking maybe a breakin would help) the glue holding the spider to the basket let go. Sadly I bought them used so in the garbage they went. Junk brand. Can't believe people still buy their stuff.
@jr@mac said:
So a guy needs to order 4 or 5 to get a useful pair?
I got 6 and had 1 bad one. I returned 2 so I'd have 2 "good" pair. Both pair match each other reasonably on the impedance plots. I picked one from each pair and compared response. There was little difference so I'd bet any of the 4 I have now would work together fine.
So I made a router template to flush mount these buyout tweeters. I was originally going to only make a test baffle to take some on and off axis FR measurement. Fast forward a couple days...
I have a pair of left over enclosures that will work pretty good for this project and enough left over MDF to make two real baffles. So I made two new baffles for these.
Pics to follow.
I modified the one tweeter that was sort of different that the two "Good" measuring ones. I took it apart and drilled a 7/16" diameter pole piece vent and chamfered the back side of the hole. I stuffed some cotton in the vent cavity and glued on a back cup filled with recycled demin. The back cup was only 99 cents at Menards:
In my opinion the modifications aren't worth it. I'm going to just roll with the other two tweeters unmodified. Neither of them have the slight impedance bump at 2K.
I'll likely be crossing them over 4th LR around 2500 Hz, where the 2nd order distortion is down about 50 dB and the 3rd is down about 55 dB.
I'm pretty sure that dip at 3K is due to the small waveguide like faceplate. It fills in pretty well off axis, 30 and 60 deg:
Comments
No ferrofluid.
Good luck drilling it out, I imagine keeping the chips out of the gap may be a challenge.
Good to see no ferrofuid, that stuff can get pretty nasty after many years and I have no idea how old these tweeters are.
My quad should be here today. I may play around with them and see if they can be improved on. I'm thinking of masking the gap and trying to drill the pole piece and add a rear chamber. We'll see.
I'd figure the chips would be a real bear to deal with due to the magnet. I would probably experiment packing the gap with something that hardens but is reasonably easy to wash out like drywall mud. That way you can forcefully wipe the chips away without pushing them into the gap.
I've drilled out the pole piece on tweeters before. It's no big deal at all. Just firmly apply a piece of blue painter's tape across the face of the tweeter motor and drill straight through the pole. The metal filings and chips are easily brushed off and the hole blown out with compressed air. Then you can safely remove the painter's tape and Bob's your uncle
He's always out hangin with "some dude" and "florida man".
Was Uncle Bob too "touchy" with you?
Bob is not your uncle anymore.
I actually had an uncle Bob. Anyone else?
Yes, me too.
Yep. Me too.
InDIYana Event Website
My 4 buyout tweeters were on my front porch when I got home yesterday. Haven't had a chance to take any measurements but they were packaged very well and look kinda cool.
Cool I'd love to hear if your measurements resemble mine. Would help me know if I'm doing my measuring correctly.
Did a quick DATs sweep on all 4 tweeters. Two of them measured nearly identical. One had a higher impedance peak (20 ohms vs the other two's ~10 ohms) but it sounded ok during the sweep. The forth was way different and sounded about 10 dB quieter during the sweep. It had an impedance peak of about 5 ohms. Strangely all 4 had pretty much the same Fs ranging from 752 to 803 Hz. I'll be calling PE tomorrow morning.
I forgot to mention that the two "good" ones didn't have that impedance glitch at around 2kHz, the one with the higher peak did have it, and the 4th is just a hot mess.
So a guy needs to order 4 or 5 to get a useful pair?
Seems so
Luckily I'm pretty sure PE will take them back and refund my $10. I've spent that much for a lunch meal at McDonalds and regretted it probably more!!!
Yeah, I've never really regretted cheap driver purchases. A pair of Aurum Cantus drivers I regretted buying. First the pair had wildly different TS parameters. Second while I was running one in at Xmax (thinking maybe a breakin would help) the glue holding the spider to the basket let go. Sadly I bought them used so in the garbage they went. Junk brand. Can't believe people still buy their stuff.
I got 6 and had 1 bad one. I returned 2 so I'd have 2 "good" pair. Both pair match each other reasonably on the impedance plots. I picked one from each pair and compared response. There was little difference so I'd bet any of the 4 I have now would work together fine.
So I made a router template to flush mount these buyout tweeters. I was originally going to only make a test baffle to take some on and off axis FR measurement. Fast forward a couple days...
I have a pair of left over enclosures that will work pretty good for this project and enough left over MDF to make two real baffles. So I made two new baffles for these.
Pics to follow.
Here is the simple router template. It's just some scrap MDF pieces cut to length and glued together. Only took me about 15 minutes to make it.
I modified the one tweeter that was sort of different that the two "Good" measuring ones. I took it apart and drilled a 7/16" diameter pole piece vent and chamfered the back side of the hole. I stuffed some cotton in the vent cavity and glued on a back cup filled with recycled demin. The back cup was only 99 cents at Menards:
https://www.menards.com/main/plumbing/pipe-fittings/pvc-pipe-fittings/sioux-chief-reg-hardhat-trade-pvc-test-cap-dwv/880-02ppk/p-1484292077305-c-8571.htm?tid=ce62714b-e460-4d44-b035-d4414e794a2f&ipos=3&exp=false
Blue is unmodified, Red is modified
Green unmodified, Blue modified
Unmodified distortion:
Modified distortion:
Looks like an improvement to the response, flattening it a bit. but worth it?
Your measurements look so much better than mine. Guess the cardboard baffle wasn't up to the task.
In my opinion the modifications aren't worth it. I'm going to just roll with the other two tweeters unmodified. Neither of them have the slight impedance bump at 2K.
I'll likely be crossing them over 4th LR around 2500 Hz, where the 2nd order distortion is down about 50 dB and the 3rd is down about 55 dB.
I'm pretty sure that dip at 3K is due to the small waveguide like faceplate. It fills in pretty well off axis, 30 and 60 deg: