Treble drivers in 4345

[speakerdave]

On another thread I mentioned that I was listening to my 2450's with SL diaphragms, and Z-man asked:

May we know the details, David, when you have a chance? Two or three-way? Horn? Other drivers?

So here goes:

I have them on 2311's in my 4345's. Ya, they fit. They are almost an inch smaller than the 2441 (which I believe was tried by Bo), and the fattest part is just aft of the dog box for the 2122.

Both the diaphragms were new, and I believe there was a break-in period, though a rather steep one. They don't seem to be changing much now after about twenty or thirty hours of listening.

I plan to go back to the original 2421's when my new diaphragms get here. I've been experimenting while waiting. The old diaphragms in the original drivers were exhibiting some of the characteristics of fatigued aluminum.

I like the aquaplas coated titanium 4" driver. Of course there are a couple of aspects of what I'm doing that make any conclusions difficult, to say the least. 1) I'm plugging and playing with the stock networks. With the current substitution that probably means that the frequency balance of this portion of the frequency range has been shifted downward a bit. 2) the 2311 horn may be acoustically different from the 2307. Taking those unknowns into consideration, I'll say that I like the sound of this combination. It's not as warm as I like, but it is listenable at high volume, which I cannot say for all compression drivers and horns I've heard.

I've also experimented with a pair of refurbed TAD 2001's on 2307's. Those I like very much, although they do not seem to respond well to high levels. (Widget says the diaphragms may not be seated correctly). At lower volume they are quite marvelous. That aside, I'll say that beryllium seems to be the bee's knees. It is the only driver I've listened to that did not make it difficult to balance the imaging and harshness. That is to say, with other CD/horn setups I've always had to work with the levels to find a compromise between tizz and hash on the one hand and letting the imaging recede into the speakers on the other. I'm guessing that with these drivers on the stock network the frequency balance would be shifted upward slightly. The detail and lifelikeness with beryllium comes through nonetheless.

I never heard anything objectionable with the 2420's in my 4333A's, and I'm hoping the same will be true with the new diaphragms in my 2421's. I am aware that some people prefer the 2420 to the 2421, though. Anyway, we'll see.

I believe some of the Australian members with 43XX monitors are using 2425's with titanium diaphragms and find them to be good. I may have a go at that before I revert to standard form.

David

[Ian Mackenzie]

David,

Your post sums up my findings.

Its a careful balancing act with these 4 ways. You can expect to spend weeks not days setting them up properly. The better controlled diaphragms are easier to balance. I heard some Tad 2001 when in the States and they are impressive but $$. The titanium is warmer than the aluminium, aquaplas make them sound more mellow and refined and lowers the sensitivity by about -1 db so you can compensate by adjusting the L pads.

If you intend to use better diaphagrams the stock networks warrant improvement with more current day soa parts. Pm me for details on how to go about that.

[speakerdave]

It could be interesting to see someone come up with a 1.5" version of the old fog horn to retrofit into the 4344/4345 and maybe even 4355. I think subwoof had a pair but I'm not sure how that turned out.

Ya. He called it the 2313. He never reported on a listening test as far as I know. My personal hunch is that with a throatless driver like the 2435/435Be that horn would be too short. I think it should have been made from a 2312 instead of a 2307. I'd try it myself, but I don't have the shop facilities. On the other hand, that $210 Japanese 1.5" to 2" adapter on the 2311 would probably work as well.

David

[Ian Mackenzie]

This is taking a wider berth on the topic but if you do a re hash it would be fun to see a Be driver mated to a better horn like one of Jack's horns or something. The depth of the 2307 and the resulting offset causes some power response issues around 1300 crossover point in the vertical plane. The sweet spot is usually a one seat affair making it a pretty selfish experience. I am sure it would image better too with something else, a bat slayer on top would also be really cool if one were to really tart it up.

That means a whole rethink but if someone has the resources to trial some waveguides and other stuff the outcome may prove productive.

[Ian Mackenzie]

Thanks Rob

Could be interesting, I will try and find Zilchmeisters data.

Again this is drifting OT but with all the current information Jack as presented recently if we are talking Hifi I think we are talking about a different bird of prey. I think one of the guys has a diy version of this in train at the moment

Otherwise someone may as well DEQX the stock setup and be done with it but frankly the money would be better mortgaged on a Array System .

[boputnam]

They are almost an inch smaller than the 2441 (which I believe was tried by Bo), and the fattest part is just aft of the dog box for the 2122.

No, I balked. After taking and re-taking careful measurements, it was clear I'd need to mod the dog house - the motor was just too dang fat. Subwoof was anxious for me to give it a go, but I decided it wasn't the type of corrective surgery I felt was needed.

What I did do was put new diaphragms into the 2421B's and have been real happy with that.

[Ian Mackenzie]

Yep,

I think your looking a plain better diaphragm or a better driver like the Tad 2001. There ain't much room in there.

Does anyone know what became of Guido's after market be stuff?

On a different note I am going to try an experiement next week with soft cell foam around the mouth of the 2307 and if I can a soft cell plug like the Geddes plug to see if it does anything better.

Ian

[Earl K]

It could be interesting to see someone come up with a 1.5" version of the old fog horn to retrofit into the 4344/4345 and maybe even 4355. I think subwoof had a pair but I'm not sure how that turned out.

- 6 Months ago I acquired a bunch of 2431H drivers ( as part of a refurb project for my SR business )
- As a laff, I created a 2313 out of a 2311 and a Selenium 1.4" to 2" adapter .
- I achieved my ( bench project ) goal of creating flat response from 1K to 10K ( this was July I think ). I could actually entertain an 800 hz crossover point.
- If I remember correctly, I did construct ( and use ) either a two pole ( or maybe 3 pole ) bump filter . I coupled the DI index of the horn / with say the 2.5 db per octave "lift", available from creating a frequency dependant LPad ( buried coil ) . The overall lift was moderated ( and flattened ) by a lowpass coil ( cutting in at a lowish value ) . Anyone who has studied the N9800 will understand what I was up to and why.
- It was a bench study only (so no records were kept ).
- I'll also assume a series LCR notch filter was necessary to make it all really smooth / since I can't remember building much in the last couple of years that couldn't benefit from even a tiny one .

- If I had a 434x type box , I'd be going this route in a heartbeat ( the better the compression driver / the more I want to hear it / somewhat like the expanded duties in the 4348 ).
- The 435Al prices ( if and when available, represent great value ) . I'll assume the 435Be prices that you can get also represent great value.
- I haven't heard any Be products from JBL , so I don't know what I'm missing .

[Earl K]

The Al is bearable once you aquaplas it as JBL did with the 435Al-1.

Oh,,, for some reason I thought ( assumed ) all 435AL variants were aquaplased . I guess not .

[Earl K]

I should say that "bearable" is a subjective term. I personally have a low tolerance for any kind of compression driver / horn anomalies. The usual suspects really wear on me after awhile, more so for CD music than DVD movie playback.

-hmmm,,, well my tolerance of all these sort of anomalies did lead me to give up on the use of JBL drivers for the home environment ( 2.5 years ago now ) / while at the same time finding that what I was after, came from big Altecs' ( I wouldn't have thought that a few years back ).
- Obviously given the testamonials for the new 475Be . I would be keen to accept a pair for my 55th birthday .

[speakerdave]

It's been posited that the driver is operating as a direct radiator on 2311, in some part. Seems the length would also partially mitigate time alignment issues. . . . .

. . . . at 500 Hz, yes. A deep throated driver like the 2450 should still be loaded at 1.3K, using the half-wavelength standard.

David

[Ian Mackenzie]

While we are talking about the horns and system in general I would like to mention that I have successfully modified a stock factory 3145 network with minimal invasive surgery. We identified a number of issues that have been addressed.

Playing the modified stock networks for the first time this afternoon they literally blow the stock networks out of the "water".The system is biamped with the JBL DX1.

Better diaphragms would (are) be nice and the icing on the cake but the system delivers an otherwise stellar performance with the modifications.

I will post some details later in the week.

Ian

[4313B]

I was under the impression that speakerdave was talking about his 4345's. I thought he had purchased a stock pair. My mistake. I have removed all my posts.

[Ian Mackenzie]

Rob,

I agree, there are a number of diyers who are interested in advanced technical solutions and there are an equal number of members with stock systems who may like them refreshed. We've all been over this numerous times but it would be interesting to see a V3 equivalent network. Its horses for courses with all this stuff.

I decided to look inside the stock 3145 network because I was asked to by a member and I was interested in doing some measurements, a subject evaluation, identifying areas for improvement and exploring the potential for upgrading it. I am not aware if any previous thorough "physical" examination of a stock 3145 network pulled from a vintage system. More on this another time.

[Ian Mackenzie]

I am also finding it also hard to remember who has what, there are so many things a happening on the forums these days.