L250's and TI tweeters

[JuniorJBL]

I am in the presence of greatness on this forum. I hope that someone can excuse my ignorance about some things JBL!

Anyways I have a pair of L250’s, and so far have rebuilt the crossovers and I have started to refinish them black lacquer. I’m in Denver co so the project is on hold for now because it is cold outside. So they are all put together and I am currently listening to them. What I would like to do is replace the 044-1 with a TI of some sort and I was wondering if someone (most likely giskard) could tell me if there is a diaphragm replacement that might fit my 044-1 (maybe 044ti) does this work? I have just (as I was righting this) received my 104h-2’s!! I also was wondering it anyone has the 250Ti schematic.
In my crossover, I replaced most of the components removed the bypass caps on the HF put Holland’s in place and replaced all resistors in the circuit (not attenuation) with metal film units. The difference was AMAZING!! I am now trying to add a little more detail to the HF and I hope this is the right direction to go. I rescued these from a pawnshop in Salt Lake City, Crossovers were mostly blown one tweeter was toast foam was all but gone on the LE14H-1’s but I paid $900 for the pair!! They really are a great pair of speakers as I have a pair of Vienna Acoustic Beethoven’s (Very new speaker 3way) and much of the difference between them and my 250’s are the HF. It’s not as detailed on the 250’s Granted the 250”s are 24 years older than the Beethoven’s. And of course the low end is much tighter on my 250’s than most any speaker around!! (Except older JBL’s)! I do have a 2242H in a 10CU FT box with a crown K2 powering it as well as the 250’s. After about 100 hours of break-in the crowns have opened up nicely. Anyways just thought I would ask some people who know about JBL’s.
Thanks Shane:D

[MJC]

The bypas caps, in the hf circuit, that you took out give a more open sound. I have added polypropylene bypass caps in my L212s to make them more dynamic. I'm going to add polystyrene bypass caps to the 066 hf circuit to open up the highs.

[Don C]

You might find that just replacing the diaphrams with new standard parts makes a big improvement. It worked for me.

[JuniorJBL]

In the crossover design world this seems to be a no-no. I have read on a number of sites that this was “standard” practice at the time but has now been rethought. My Beethoven’s
Do not use them and these do sound very open they retail for $5000.00 per pair they use Seas drive units and are extremely smooth and open. So I wondered the same thing so I called a man by the name of Tom Roberts at Madisound (www.madisound.com) and he said the same thing. If someone has possibly an answer and reason why. I would really like to know why people are saying this is no longer the norm. Please do not get me wrong I am just trying to get the best possible and logical answer that I can. I would be cutting myself short if I did not do this research. Anyways it may just be it sounded sooo much better because I did use Hovland’s. So my main goal is to get more accurate HF.
The Ti’s should do this I would think.
Thanks for your reply and also any reply is most appreciated.
Shane
:)

[JuniorJBL]

I got 4 of the last 5 that Harmon had! D8R044-1
Thanks:D

[4313B]

"In the crossover design world this seems to be a no-no. I have read on a number of sites that this was “standard” practice at the time but has now been rethought."

Whatever :)

Capacitors are crap. Unfortunately it's our lot in life to have to deal with them. Hopefully our progeny will be able to shake the oppressive yokes of capacitorism. Until that time bypassing is still one viable solution. If one uses standard capacitors such as non-polarized electrolytics, metallized polyester or mylar, even metallized polypropylene, then bypassing them with high quality film and foil capacitors is a viable solution. Another solution is to bias them. JBL uses biasing and bypassing.

If one wants to "go for the gold" they can purchase larger values of the high quality "super" caps such as Hovlands, Sonicaps, Audiocaps, Relcaps, Dynamicaps, etc. These capacitors don't seem to respond very well at all to bypassing or biasing.

The only thing to rethink really is just how far one wants to take it all. Some people have a real problem with a capacitor that costs $50 a pop. Those people might have all their requirements met by adding in high quality bypass capacitors for $3 a pop. Seriously. I'm not kidding :)

The older JBL systems such as the L250 and 250Ti were using metallized mylar and NPE bypassed with metallized polypropylene and metallized polystyrene. I know some guys who wouldn't let a metallized dielectric within a hundred feet of their gear. Film and foil are the only solution for them.

Whatever floats your boat. :smthsail:

[JuniorJBL]

Originally posted by Giskard
"In the crossover design world this seems to be a no-no. I have read on a number of sites that this was “standard” practice at the time but has now been rethought."

Whatever :)

Capacitors are crap.

Yes but as you said we have to live with them!!
I hope you could answer a question for me. Can I put an 044Ti or 035Tia in an 044-1 motor?
These speakers will at some point this summer be using electronic xover (driverack) this is a project that I have wanted to do, any input would be helpful:confused: :help:

[4313B]

The 044Ti "baffle" is designed differently than the 044 "baffle". When I asked years ago about swapping in Ti diaphragms for the phenolics I was given the infamous "won't work".

Run a voltage drive on the stock network with the stock drivers and then duplicate it using the electronic network. Make sure any electronic network you use has bypass capacitors across any big nasty electolytics. They should these days but one never knows for sure unless they check :)