Compression Driver Compensation

[4313B]

The reason for implementing a HF bump was simply a result of a 2 week listening session to the GT network. FOR ME (only my opinion) the speaker didn't sound fullrange. I didn't want to add a tweeter cause I believe in 2 way designs. So I did start modifications.

Understandable. And both Doug and Greg would be the first to suggest that each person tailor their system to what they personally prefer.

The 2435 in this speaker sounds SO relaxed that I can't believe it.

No doubt!

I respect the listening impressions that you report and I respect that you hear "problems" of this driver above 10kHz or so. I just can't reproduce it.
Try different capacitors, try a nice amp or whatever. It will sound good....

I admire your diplomacy. And you're right, it sounds really nice.

Someone asked about the original response curve of the 435Be on the H4338 in Greg's home system and I was able to find it. The date on the file is incorrect. That's merely the date is was last opened and then saved off again. I really hesitate to post it because some people freak out when they don't see graphs with flat response to 20 kHz and beyond. But here it is and they will just have to go to therapy afterwards. When Greg says it sounds really nice he isn't joking and that's pretty much the whole point of the exercise.

( For those who aren't up on the story, Greg had a 3-way system using the 1200FE-8, 435Be with H9800 horn, and the 045Be with its horn molded into the end lip of the H4338 horn. At some point he decided to redo the system as a 2-way so he unhooked the 045Be and reworked the passive filter on the 435Be to extend its response. He said that the results better suited his personal taste. I believe that this was the version Don McRitchie heard and his comment can be read here: http://audioheritage.org/vbulletin/s...59&postcount=4 In photo number 5 one can see the disconnected 045Be.)

[4313B]

It may be a departure but don't you think Greg would be one of the first to say tune it up the way you like it??

Absolutely.

We've gone over this behavior about a thousand times now Rob.

Just becasue it departs from the curve doesn't mean it's wrong. These drivers have to work in a real livingroom and they may sound just great that way depending on the acoustics.

Yep. I think that's a real tough concept for some. Another forum member made a suggestion, perhaps some people are over obsessed with curves because they can't really hear what's going on. They figure if they can obtain a certain response curve then it must sound good.

Honestly we can stand here all day poking at each others systems looking at the graphs but what counts is what it sounds like.

Yeah, the chatter gets real aggravating at times. Greg did what he saw fit, Guido did what he saw fit, and both seem pretty damn happy with the results.

[Zilch]

Yeah, the chatter gets real aggravating at times. Greg did what he saw fit, Guido did what he saw fit, and both seem pretty damn happy with the results.

I'm standing up for LE14H-3s in detritus L55s the world over, and it would appear that I'm not the only member who rather likes that alignment:

I currently have four LE14H boxes, two ~ 2.0 cu ft @ ~ 32-34 Hz as well as two stock 240Ti boxes. I personally prefer the 2.0 cu ft boxes due to their increased portability but that's my personal preference. They're "bookshelf" size as opposed to "floor standing" size.

[4313B]

I'm standing up for LE14H-3s in detritus L55s the world over, and it would appear that I'm not the only member who rather likes that alignment:

3.5 to 4.0 cu ft tuned to 28-30 Hz for floor standing systems. The L250/250Ti box/tuning is king for floor standing systems based on the LE14H-1 or LE14H-3. The slightly smaller 240Ti isn't bad either.

The L55 box is completely unsuitable for a high performance loudspeaker system. It's an end table.

But... you know... that could be a nice project for you. Restore a pair of L55 or L65 boxes with LE14H-3's in them and the PT-F95HF / 2452H-SL combo and then start a thread on how you did it all. Half a dozen posts with photos of the finished boxes, nice blue grilles, smoked glass tops and modern JBL components inside with cc networks. Maybe a post of the voltage drive of your network and an impedance/response curve. Those boxes looked very nice when new.

I can't find my documents on the 240Ti and 250Ti right now but I think they were ~ 3.5 cu ft @ ~ 30-32 Hz and 4.0 cubic feet @ ~ 28-30 Hz respectively. The Citation 7.4 box was ~ 3.4 cu ft @ 28-30 Hz. The 1400 Array box was ~ 3.2 cu ft @ ~ 30-32 Hz.

I currently have four LE14H boxes, two ~ 2.0 cu ft @ ~ 32-34 Hz as well as two stock 240Ti boxes. I personally prefer the 2.0 cu ft boxes due to their increased portability but that's my personal preference. They're "bookshelf" size as opposed to "floor standing" size. At any rate, you should see a pattern here - 1.5 to 5.0 cu ft tuned in the 28 to 34 Hz range - nothing has really changed since the 70's in that respect. I personally feel that the 250Ti box is the largest practical volume with the lowest practical tuning - that's just my opinion.

[Ian Mackenzie]

Thanks for posting this 4313B.

When I had my 2344 horn up and going I set them up for a slight roll off at 16 kertz on axis.

When seated they were around about 30 degrees off axis and sounded just right . The difference was measurable. On axis they were on the bright side.

Same thing with the 4345.

Flat on axis in your face is not always the answer in reality.

Ian

[4313B]

Flat on axis in your face is not always the answer in reality.

I distinctly remember having issues with the 4430's in certain rooms on-axis. They didn't work in every room I had them in over the years.