DIY "4345" Project

[Ian Mackenzie]

I think it depends on the important details.

I have no doubt in a purely diy system you can optimise the result with the 2202.

More than a few have resorted to adding a different horn ect on to of the 4355 to satisfy the expectation.

I also think it looks really cool!

Only a few have done such with the 4343-4345 but they have tried other compression drivers upgrades like the Tad 2002 and dusting the titanium diaphragm with acquaplas.

For a example the actual mid, hf and uhf driver layout on the baffle of the 4355 is not going to work as well as a vertical arrangement. I am betting l get flamed for saying that. But people are using the more advanced compression drivers than in the stock 4355 such SL version of the titanium diaphragm in the 2446 in purely diy systems. (Some still like the diamond surround aluminium diaphragms.)

But that is not a stock 4355.

That is diy audio doing what is a smart thing to do.

I personally found after rigorous investigation with another forum member upgrading to a Pass Lab discrete class A active crossover the biggest single improvement toward an audiophile experience with these vintage systems. Those who are lucky enough to own the JBL DX1 are aware of this.

They demand the finesse of enhanced passive crossovers and electronics like many older vintage systems.

If you need an efficiency hike on the top three drivers there's an option now.

Not everyone needs that and some purists win with an enhanced fully passive systems like the 4344 using their own hi end amps. I completely get that.

Of course each to their own desires, needs and resources and do what makes you happy.

Pm me if you have a specific question or need support.

[speakerdave]

In my SOTP fiddling around with the factory 4345 I found the large format JBL CD with a dusted diaphragm was a clear improvement over the stock treble arrangement (with an old diaphragm, however). The 2450 body, because of its shape, just fits around the midrange dog box when mounted on the 2311. I think the 4" diaphragms just sound better, even when crossed over at 1200Hz. That arrangement lost out, however, to TAD 2001 on the stock horn. No question. Used the stock crossover for all three set ups, making no measurements, and adjusting levels using my lucky dime, so this comment should be taken as miscellaneous anecdotal data, i.e. something maybe worth trying. Note that we who tried this wondered if successfully using the nominally 8 ohm TAD where the stock driver is 16 ohm may actually depend on the presence of the tapped inductor in the stock crossover, although just4kinks now indicates success with the redrawn 4345 crossover.

[Ian Mackenzie]

It's an interesting point.

Taking nothing away from main theme of this thread I actually heard Bo's 4345 with the Tad 2002 BE drivers and they are very nice.

As l recall they were almost a drop in modification.

I think that was before Bo upgraded to the Bryston active crossover.

Somethings just seem to work.

If you can still get them they are very expensive and wrong brand.

I was wondering if the 2450 neo 2 inch driver would fit?

Being pragmatic it fetches a big asking price (new US$1542 or US$599 each on eBay plus $150 for the SL diaphragm. That's a US1500 investment that might be out of reach.

We need to consider what those new to the game want to know before they take the plung on these systems

Putting it in perspective the 4345 with stock drivers is absolutely fine.

GT in the designer post has personally reviewed the important upgrades for the 4345.

Sometimes the journey is more than the end result.

Appreciate what you have so you can appreciate an upgrade.

Assuming you might be thinking about what's next having ticked GTs improvement list then enhanced drivers are a logical step.

But it won't be a 4345 no more. Something to consider.

So looking around at driver options Wrong Brand again but has anyone considered the 475BE PB 1.75 inch Radian Be drivers?

They are US$599 each from Usspeaker.com plus shipping.

I have not done the Maths on shipping but if they are close to the Tads in performance, fit the bolt circle and work with the equivalent crossovers it's something to investigate. I might pull the trigger on that and find out.

Then make some Jbl foil labels for the rear caps to make you feel better!

Another upgrade is lightly dusted stock titanium diaphragms. They have a less live character and you loose 1 db sensitivity so just adjust your Lpad

This is a relatively low cost non invasive upgrade and won't impact on the crossover network.
Okay as Dave points out it's not a 2 inch driver but it's a sensible improvement.

This is what l personally use in the 4345 and l own TAD 4003's.
Keep your original diaphragms for comparison.

I actually heard the acquaplas dusted JBL 275nd driver in Japan and it was very nice.

The 275nd had a "lighter" titanium diaphragm and was acquaplas coated and was used in the JBL 3100mk11 and the 4344mk11. Reference to the Library may find that driver in other models.

Unfortunately the 275nd is NLA. I have seen them on JP auctions but consider it a risk based acquisition.

[ivica]

Hi Ian,

I have to say that , for ME, 2202 & 2441 (2450) &2311 &2308 combos are "light years ahead" then 2122 & 2420& 2307 & 2308

but I like 2245 (earlier models) more then dual 2235, as I prefer 2231A more then 2235.

regards
ivica

Hi,

from time to time JBL 2450 (2-inch) can be seen on www.eaby.com that have reasonable price, about 300$
per piece, so adding about 100$ more for the NEW diaphragm ( Ti or Ti-SL) per driver, it can be , I think, very good
4345 upgrade. Finding 2311 horns can be much more tedious work in that situation.

ivica

[bldozier]

great job.

[Ian Mackenzie]

Yes those 2311 are rare these days.

I plan to look at it but l don't think it's appropriate to cast this modification as a "mandatory must have change" to the 4345 diy clone or an upgrade to the 43xx 4 ways. It could make the diy 4344-4345 look like some kind of elitist project.

When you look at cost realities people loose interest all together.

If you are going to spend that kind of money the justification is around a soa two way which some of us have done in other threads. Jbl are walking away from supporting parts and it's about maintaining what you have.

[ivica]

Yes those 2311 are rare these days.

I plan to look at it but l don't think it's appropriate to cast this modification as a "mandatory must have change" to the 4345 diy clone or an upgrade to the 43xx 4 ways. It could make the diy 4344-4345 look like some kind of elitist project.

When you look at cost realities people loose interest all together.

If you are going to spend that kind of money the justification is around a soa two way which some of us have done in other threads. Jbl are walking away from supporting parts and it's about maintaining what you have.

Hi Ian,

You are right that some the 2311 & 2308 , are rare to be found , but these days a pair of them can be get for 550U$D

http://www.ebay.com/itm/Two-JBL-2311...EAAOSwytlZsKu8

usually lenses 2308 (pair) cost round 150 U$D, and may be some DIY work can convert SELENIUM HL14-50 (2inch short horn, 25 U$D per piece),
https://www.parts-express.com/seleni...-bolt--264-316
to be used instead of JBL 2311. especially if are masked with 2308 lenses.
Mentioned horn is very similar to the JBL2311 (from the specification point of view), and applied a kind of lenses such as 2308 would spread horizontal dispersion of the driver&horn combo, making almost flat driver&horn&lenses FR response from about 1kHz to 10kHz.

Generally speaking JBL 244x/50 driver combined with 2311 horn and 2308 lenses would produce almost flat FR response from about 1kHz to 10kHz, so as 242x combined with JBL horn 2307 and 2308 lenses. I think larger drivers (244x/50) have several ( about 2dB) larger efficiency, then 242x drivers, but can be compensated with L-pads.

regards
ivica

[christo]

Hi Ian,

You are right that some the 2311 & 2308 , are rare to be found , but these day a pair of them can be get fro 550U$D

http://www.ebay.com/itm/Two-JBL-2311...EAAOSwytlZsKu8

usually lenses 2308 (pair) cost round 150 U$D, and may be some DIY work can convert SELENIUM HL14-50 (2inch short horn, 25 U$D per piece),
https://www.parts-express.com/seleni...-bolt--264-316
to be used instead of JBL 2311. especially if are masked with 2308 lenses.
Mentioned horn is very similar to the JBL2311 (from the specification point of view), and applied a kind of lenses such as 2308 would spread horizontal dispersion of the driver&horn combo, making almost flat driver&horn&lenses FR response from about 1kHz to 10kHz.

Generally speaking JBL 244x/50 driver combined with 2311 horn and 2308 lenses would produce almost flat FR response from about 1kHz to 10kHz, so as 242x combined with JBL horn 2307 and 2308 lenses. I think larger drivers (244x/50) have several ( about 2dB) larger efficiency, then 242x drivers, but can be compensated with L-pads.

regards
ivica

You might want to consider the information in this thread when considering the SELENIUM HL14-50 as a substitute for the 2311 with a 2308 lens.
http://www.audioheritage.org/vbullet...H93-2311-again

[Ian Mackenzie]

Hi Ian,

You are right that some the 2311 & 2308 , are rare to be found , but these days a pair of them can be get for 550U$D

http://www.ebay.com/itm/Two-JBL-2311...EAAOSwytlZsKu8

usually lenses 2308 (pair) cost round 150 U$D, and may be some DIY work can convert SELENIUM HL14-50 (2inch short horn, 25 U$D per piece),
https://www.parts-express.com/seleni...-bolt--264-316
to be used instead of JBL 2311. especially if are masked with 2308 lenses.
Mentioned horn is very similar to the JBL2311 (from the specification point of view), and applied a kind of lenses such as 2308 would spread horizontal dispersion of the driver&horn combo, making almost flat driver&horn&lenses FR response from about 1kHz to 10kHz.

Generally speaking JBL 244x/50 driver combined with 2311 horn and 2308 lenses would produce almost flat FR response from about 1kHz to 10kHz, so as 242x combined with JBL horn 2307 and 2308 lenses. I think larger drivers (244x/50) have several ( about 2dB) larger efficiency, then 242x drivers, but can be compensated with L-pads.

regards
ivica

As a general statement these old horn lens combinations may appear flat.

On close inspection with a precise measurement (LMS) the response is not flat as such but tilts.

Jbl put some effort into compensating for the tilt in the network voltage drives

The efforts to improve the smoothness of these systems progressed from the early 43xx to the later JBK4344mk11.

The measurements show subtle and no doubt audible variations.

At some stage l will post a series of measurements.

[ivica]

As a general statement these old horn lens combinations may appear flat.
On close inspection with a precise measurement (LMS) the response is not flat as such but tilts.
Jbl put some effort into compensating for the tilt in the network voltage drives
The efforts to improve the smoothness of these systems progressed from the early 43xx to the later JBK4344mk11.
The measurements show subtle and no doubt audible variations.
At some stage l will post a series of measurements.

Hi Ian,

From MY experience with 2311 & 2308 & 2441 (Radian dia), I have to agree with You that some small variations in the FR occur

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=63555&stc=1&d=14153588 66


or 2445 (Ti-no-rib) 2311 &2308

http://www.audioheritage.org/vbullet...1&d=1381156032

or 2445 and 2311 NO 2308

http://www.audioheritage.org/vbullet...1&d=1363271915


and some of the forum members have said that combo is leak of 'imaging' but if looking on the horn size (including the lenses) I have
to say it is very "compact size" horn with quite large horizontal dispersion, and ALMOST flat FR response from about 1kHz to over 10kHz.
As in its construction there are large numbers of sharp edges, it is expect-able that a kind of reflections are present, so small amount of bouncing
in FR response is present.

regards
ivica

[1audiohack]

Hi All;

A question if I may:

Is there any signal shaping on the 2245 in the 4345?

I am running a dimensionally same box tuned right at 30Hz here in half space tonight and mine needs some boost in the bottom octave ie 30-60Hz.

Surely this will change in an enclosed space but I rarely test indoors but I am curious.

Thank you one and all.
Barry.

[Ian Mackenzie]

No

Only the low pass filter

The voltage drives are posted on the 4345 system reference forum

A loudspeaker is said to be in “half-space” when it is placed next to a large solid surface such as a wall or on the floor.

http://www.jblpro.com/pages/components/2245H.pdf
See page two for jbls measurements

(Check they are not out of phase...it’s easily done)

[ivica]

Hi All;

A question if I may:

Is there any signal shaping on the 2245 in the 4345?

I am running a dimensionally same box tuned right at 30Hz here in half space tonight and mine needs some boost in the bottom octave ie 30-60Hz.

Surely this will change in an enclosed space but I rarely test indoors but I am curious.

Thank you one and all.
Barry.

Hi Barry,
can You show some measurements

regards
ivica

[1audiohack]

No

Only the low pass filter...

Thank you. I just wanted to be sure.

Yes half space, on the ground with no other significant boundaries and just one box and driver.

Honestly it’s been a long time since I had a direct LF radiator out doors and it just seems, weak.

I did not save any measurements, thought about it but didn’t.

Thank you guys.
Barry.

[ivica]

Thank you. I just wanted to be sure.

Yes half space, on the ground with no other significant boundaries and just one box and driver.

Honestly it’s been a long time since I had a direct LF radiator out doors and it just seems, weak.

I did not save any measurements, thought about it but didn’t.

Thank you guys.
Barry.

Hi Barry,

Have you done so called "near field measurements " or several meters away from the speaker.
I am not sure how near field measurements behaves in 2pi or 4pi environment.
Regards
Ivica