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quindecima
09-20-2006, 11:16 AM
I am thinking about adding one of the slot tweeters from jbl to my 416-8b and 802-8g speaker system I just built, BUT only if it is going to improve my sound, which is pretty darn nice as it is. Does anybody have any experience in this???????? Also, which slot would be good to use and how do I cross it with my model 19 xo's??????????? The first question is the key here, I'm not doing anything unless I am going to hear a NOTICEABLE improvement.

Wardsweb
09-20-2006, 11:41 AM
Well better and improvement are subjective terms. What I can say is I had been running a pair of A7 (825 cabs) with 416-8C, 802-8G and 511B for several years. I personally like high end crispness. The 511B has phenominal mids but rolls off before i prefer. So I now have custom cabinets using the same drivers, but also incorporates a JBL 077 super tweeter. I like it. The 077 adds the sizzle to the upper end that I like. Will you hear it as much on Van Halen Hot for Teacher? No. Will it open up Dave Brubeck Time Out? You bet.

http://wardsweb.org/misc/051806.jpg

edgewound
09-20-2006, 11:47 AM
The 077 adds the sizzle to the upper end that I like. Will you hear it as much on Van Halen Hot for Teacher? No. Will it open up Dave Brubeck Time Out? You bet.



Ward....that's a great, concise description of where a VHF tweeter is useful.

Nice post.

Thom
09-20-2006, 12:13 PM
My experience is mostly with 075 but this tweeter is supposed to be the same except , unusable below 6khz and has reasonable dispersion. Since in any JBL 3 way ( augmented 2 way ) that I knew of, the top came in at 7 khz and the major complaint of the 075 was that it was way directional these are good things. It makes so much difference that in the days of reel to reel, before dolby I dumped my B77 because anything less than 15ips was unbearable (hiss). We used to have a pair that we could move cabinet to cabinet (again 075) and turn on and off and the difference was unbelievable. If someone offers them to you on trial, don't do it if you can't afford it because you won't take them back. Cautionary, I have heard, actually read, of the lens comming unglued on the 077 but have no personal experience with that.

edgewound
09-20-2006, 12:50 PM
Cautionary, I have heard, actually read, of the lens comming unglued on the 077 but have no personal experience with that.

That's not possible with an 077 unless it was damaged and glued together....which would be a dumb repair.

The phase plug is held in place by a machine screw throught the back of the motor. That phase plug also serves to clamp the center of the ring radiator diaphragm in place.

Same with the pro version 2405's aluminum phase plug.

Zilch
09-20-2006, 01:11 PM
My experience is mostly with 075 but this tweeter is supposed to be the same except , unusable below 6khz and has reasonable dispersion.Well, you're up against a gaggle of 077/2405 afficionados on this site.

075/2402 is beamy and doesn't have the HF extension that 077/2405 does.

077/2405 is also beamy, but mainly in the vertical, less of a problem.

It does, however, seem to make its own artificial "sizzle" when crossed at 7 or 8 kHz, rendering it unlistenable for me.

The current consesus seems to be that it's fine if crossed over at 10 kHz or above. I haven't compared that yet.

2404, I like, and the mylar-diaphragm 2407, on a suitable pattern (I use 90 x 50) horn....

Thom
09-20-2006, 01:40 PM
I can't say anything bad about crossing at 10k+ because I haven't done it but jbl used n7000 with it and it was common to just us it high pass as an add on. All I know about the lens coming apart was a sight where they had ( I wish I had the address) all sorts of parts for them cheap and it appeared that it was a common problem, as I stated I personaly have never encountered it, so perhaps I misinterpited something from the sight. Any way JBL claimed that no instrument made any fundemental above 7000, that all you were reproducing was harmonics (that is different than the new super tweeters which would be reproducing information that the dac isn't being fed or isn't programed to translate if it were, but that's someone else's ricebowl) and that made crossing less than critical. I'd try crossing as low as 7k and see what I liked. The used to cross the 075 as low as 3.5 but the horn on the 077 isn't good down there and at high level that could lead to buying new diaphrams. At my age I play those things hot so I can hear them, and if someone younger who can hear better finds them to bright they're more subdoed in the kitchen. (the tweeters)

quindecima
09-20-2006, 04:52 PM
Well better and improvement are subjective terms. What I can say is I had been running a pair of A7 (825 cabs) with 416-8C, 802-8G and 511B for several years. I personally like high end crispness. The 511B has phenominal mids but rolls off before i prefer. So I now have custom cabinets using the same drivers, but also incorporates a JBL 077 super tweeter. I like it. The 077 adds the sizzle to the upper end that I like. Will you hear it as much on Van Halen Hot for Teacher? No. Will it open up Dave Brubeck Time Out? You bet.

http://wardsweb.org/misc/051806.jpg

Cool, pretty much what I have, so 077 but how did you cross them?

Wardsweb
09-20-2006, 05:08 PM
combination of the N501 and 3106 crossovers



http://wardsweb.org/misc/a7_3106modcrossover.jpg

quindecima
09-20-2006, 05:35 PM
O.K. I have model 19 crossovers for mine but I can interpolate. My next question, I have another spkr project that I am doing. This time utilizing the 511b horn, 902-8b drivers and the 515b woofs with an N8500-8a xo. I assume the slots are going to give these the same amount of ooomph on the high end and that I can use this xo schematic to hook them up?

Thom
09-20-2006, 05:52 PM
Without doing any headache work do you have the 800 or 1200 values for that xover I've got the 800 horns it's not a big deal but I see you played with it a while and picked quite a few brains so if you could help without going to a lot of trouble I'd appreciate it. Thanx in advance for even considering it.

Thom

quindecima
09-20-2006, 05:58 PM
Which values do you want? I just picked these up and took them apart to check the components. I have the values written down do you want them all? I can't help you with the inductors though. I assume you are addressing me and asking about the N8500-8a's

Thom
09-20-2006, 06:17 PM
Quindecima, I had in mind wards web because I could see from a couple other sights that he'd kinda gotten into it and I didn't realize that you weren't crossing at 500hz but if you have values and locations I'd be happy to get the information since I've repaired the leads on the diaphrams on these I especially dont want to give them too low material. Thank you for responding.

Thom

quindecima
09-20-2006, 06:38 PM
I am going to cross the 515b's and the 902's at 500.

The caps are 16uf@100v
6uf@ 50v
28uf@125v
8uf@ 75v

The resistors are 6.5 and 15 at 10 watts ea

I haven't replaced any components because the xo has never been used as far as I can tell but more than likely I will but use 200v and 400v caps. I don't have a schematic but if you need more info I could take one apart and trace it out.

Thom
09-20-2006, 07:00 PM
What model cross is it

quindecima
09-20-2006, 08:04 PM
N8500-8A, It just dawned on me that you were looking for 800/1200 values, these are 500/800. sorry 'bout that.

Thom
09-20-2006, 09:42 PM
information may still be useful just needed to know whay it was thanks