My new JBL 4345 build.

[fencki]

Sometimes the older Alnico drivers loose a bit of magnetic properties and the throats maybe dirty.

The newer Ti diapgrams are not an exact drop in fit in the older 24202470. The pin holes may need slight filing out.

I would be careful of any old drivers as there are no guarantees.

Mr Widget is right

The scarcity of re cone kits and older drivers is a risk in terms of the original result.

Talk to a JBL service agent like Jands in get them to check all your drivers.

It will eliminate a lot of headaches.

My advice is dont rush it. Its a really big job. Allow 6 months at least.
If you have dont have background in electronics get someone to do the passive crossover, the discrete active crossover and wiring up (me-I accept donations like a case wine)

Dont skimp on the active crossover if you have high expectations

Setting then up can take a while.

But when the are they give the newer systems a run for their money

ian you are totally right.
i took my time and it was the very fun part of the building...
i enjoyed the hours of the build and planning. even if i was confused and frustrated...

thx again for your help...
:-))

[fencki]

beautiful work.. look like an original..I wouldn't pick it.. do you have any frequency response measurements?

i will post some measurements in a few days when i am back home...
i made one measurement from listening position when i fired them up and made my config and setup....

and i feel like the passive crossover is getting better from day to day... i think i can hear very small improvements from the beginning.
but maybe i am only fascinated by the result of my built.

[Ian Mackenzie]

I have offered XRT22 an audition and support when my new new house is completed in 3 months

I made sure main room is 9.5 x 5 x 3.3 (L x W x H m) is big enough.

We will do it when my wife is away.....Lol

[berga12]

Rush in those Kind of project it's risky...

I started my 4355 only with my 2441 coming from previous system.

It took....3 months for the 077
6 months for 2202h
nearly 1 year to find 2235 in Europe with Original Cone never reconed.

An hell of research, demand, questioning, checking, waiting and...........Sweating after huge payments and waiting for the parts all over the world!!!


Finally, this was a funny part of the project

[fencki]

An hell of research, demand, questioning, checking, waiting and...........Sweating after huge payments and waiting for the parts all over the world!!!


Finally, this was a funny part of the project

i can remember when i was buying the 2245 and 2405 and waiting for them
didn´t know if they were good or not.

but everything was fine in the end.

and i found original 2122 after 6 months of search.
this was the hardest path....
now i have all the original parts.

i still want to try out 2421b to compare with the 2425j..
but i can wait.

[XRT22]

I have offered XRT22 an audition and support when my new new house is completed in 3 months

I made sure main room is 9.5 x 5 x 3.3 (L x W x H m) is big enough.

We will do it when my wife is away.....Lol

Looking forward to it Ian! Question is... do I bring with me a red or a white? Or one of each?

If you are interested, I'm happy to repay the favour and have you audition my Mac XRT22's. They're no 4345's but they're pretty good.

My 2245's and 2122's have now arrived and look awesome! No turning back now! :-)

[Ian Mackenzie]

One of each...Lol

It's great to see that these older vintage designs garner an going popularity since l first looked at the 4345 15 years ago.

A bit of history........

The consensus was the 43xx were harsh and glarey.

Back then there was not much information on the 43xx four ways and l busy working on the crossover for the 2344 bi radial with Robert Hamel. Robert and l were arguing how it should work as all l had was the 4430-35 white paper and no schematics.

It sounded pretty good on my diy Pass Aleph 2s burning 600 watts at idle.

At the time l had built a three way monitor with Altec 515 woofers, an Audax eight inch paper mid and a pair of 2420 drivers for my 2344s l found on eBay.

I was not happy with the woofers so l got hold of some 2245 woofers

At time considering a 4345 clone was only an idea.

But it was something l had to do having built a pair of 4343s when l was a young 20 year old about in 1979.

I did try and get details of the 4343 crossover but Gary Margulius politely declined!

So l build my 4343 crossover using text books graphs and adjusted it by ear. They quickly got a reputation as being way better than anything at the TV station where my brother worked.

We were all a newish Lansing forum members back in 2002 and l asked Bo Putnam to place a tape measure on his authentic 4345s so l could draft up a drawing for the enclosures.

Bo was actually really good about it.

With a basic box design l soon found a pair of 2122h mid cone drivers on a jbl tent sale

Because the drivers were NOS I was unaware the cones were starting to delaminate about 3 months after l installed them

I had them recone by Jands under warranty by JBL Northridge because they were for all intensive purposes replacement drives for a JBL monitor. I got lucky.

The message here is you can't be too careful with old drivers.

The next challenge was the crossover

There was no information

I took a punt to sent a email to JBL at Northridge asking if they could provide details of the crossover ?

To my amazement Greg Timbers kindly emailed me the engineering data sheets and advised on how to tune the bass enclosure and set up the 2234a active filters. Greg was chuffed someone was actually interested in making a pair

Then Giskard and Greg worked together on the original equivalent 3145 crossover as the tapped crossover inductors were no longer available

I found the other drivers and bought a Jasper circle jig.

The baffle was a real challenge.

The crossover used Hovlands as l recall and that crossover ultimately found its way into Robert's system.

Back this was radical a daring project. Most people were focusing on the 4333 or the 4355.

I actually compared the 2344 and the 2307/2308 and slot back and forth and arrived at the conclusion l preferred the later on my genre of music (jazz)

I did a very similar comparison at John Nebels home where John had both the 4343 and the 4435 in one large room . I arrived at the same conclusion and as l recall we agreed the 4435 was better on classical music.

I later learned the 4435 had the dual 2234 woofers which are 2235 without the mass ring. The 2234 has significantly better midrange articulation than the heavier 2235.

With really good amps (diy Pass Aleph) and good caps (the Hovlands) the much maligned reputation of the horn, lens and slot was not present to my ears!

But of course who else had a diy Pass Amp and was mad enough to spend $600 on Hovlands.

Getting the Lpads set was a pita. Eventually l came up with a scheme to adjust the Lpads using a Tandy spl meter

That was the start of unleashing the potential of these systems.

I then put more thought into the active crossover and built a discrete class A design that porschedman has in CA has.

After much collaboration and listening Ed agreed with my appraisal that all things being equal a high quality full passive crossover was inherently more musical than attempting to bi amp with a less than optimal active crossover (a PA crossover)

https://www.passdiy.com/gallery/proj...-low-crossover

Note we were and are using Pass Labs amp through out that are audibly a brilliant match on these JBLs as Kent at Pass concers based popularity among other JBL owners. You don't of course need to buy a factory amp if you go the diy route.

This is of course our opinion but blind testing suggests it's not placebo.

[XRT22]

One of each...Lol

It's great to see that these older vintage designs garner on going popularity since l first looked at the 4345 15 years ago.

A bit of history........

The consensus was the 43xx were harsh and glarey.

Back then there was not much information on the 43xx four ways and l busy working on the crossover for the 2344 bi radial with Robert Hamel. Robert and l were arguing how it should work as all l had was the 4430-35 white paper and no schematics.

It sounded pretty good on my diy Pass Aleph 2s burn 600 watts at idle.

At the time l had built a three way monitor with Altec 515 woofers, an Audax eight inch paper mid and a pair of 2420 drivers for my 2344s l found on eBay.

I was not happy with the woofers so l got hold of some 2245 woofers

At time considering a 4345 clone was only an idea.

But it something l had do having built a pair of 4343s when l was a young 20 year old about in 1979.

I did try and get details of the 4343 crossover but Gary Margulius politely declined!

So l build my 434 crossover using text books graphs and adjusted it by ear. They quickly got reputation as being way better than anything at the TV station where my brother worked.

We were all a newish Lansing forum members back in 2002 and asked Bo Putnam to place a tape measure on his authentic 4345s so l could draft up a drawing for the enclosures.

Bo was actually really good about it.

With a basic box design l found a pair of 2122h on a jbl tent sale

The next challenge was the crossover

There was no information

I took a punt to sent a email to JBL at Northridge asking if they could provide details of the crossover ?

To my amazement Greg Timbers kindly emailed me the engineering data sheets and advised on how to tune the bass enclosure and set up the 2234a active filters. Greg was chuffed someone was actually interested in making a pair

Then Giskard the and Greg worked together on the original equivalent 3145 crossover as the tapped crossover inductors were no longer available

I found the other drivers and bought a Jasper circle jig.

The baffle was a real challenge.

The crossover used Hovlands as l recall and that crossover ultimately found its way into Robert's system.

Back this was radical a daring project. Most people were focusing on the 4333 or the 4355.

I actually compared the 2344 and the 2307/2308 and slot back and forth and arrived at the conclusion l preferred the later on my genre of music (jazz)

With really good amps (diy Pass Aleph) and good caps (the Hovlands) the much maligned reputation of the horn, lens and slot was not present to my ears!

But of course who else had a diy Pass Amp and was mad enough to spend $600 on Hovlands.

Getting the Lpads set was a pita. Eventually l came up with a scheme to adjust the Lpads using a Tandy spl meter

That was the start of unleashing the potential of these systems.

I then put more thought into the active crossover and built a discrete class design that porschedman in CA has.

After much collaboration and listening Ed agreed with my appraisal that all things being equal a high quality full passive crossover was inherently more musical than attempting to bi amp with a less than optimal active crossover (a PA crossover)

Note we were and are using Pass Labs amp through out that are audibly a brilliant match on these JBLs as Kent at Pass concers based popularity among other JBL owners. You don't of course need to buy a factory amp if you go the diy route.

This is of course our opinion but blind testing suggests it's not placebo.

That's some fascinating history Ian! With stories like that, I'm gonna have to bring 2 of each!

[Ian Mackenzie]

I have edited my previous post to add some additional comments and a link

It's a better read now.

Of late there have been a number of pms seeking technical support about the 4343-4345 and other things to achieve nirvana.

I am at a point now where l am in a position to spend more time researching on the 43xx four ways and the 443x bi radial monitors with a focus on how to obtain the absolute pinnacle of performance.

This may include providing a dedicated support via a web site that specializes in this specific area with new insights, a consolidation and update of my previous posts and articles re written specifically for the JBL 43xx and 443x owners and of course links to key existing Lansing forum data.

[focalguy]

Ian,
That website would be a great idea! You may want to publish all the schematics for charge coupled versions for the 43xx.
crossing my fingers!

I have edited my previous post to add some additional comments and a link

It's a better read now.

Of late there have been a number of pms seeking technical support about the 4343-4345 and other things to achieve nirvana.

I am at a point now where l am in a position to spend more time researching on the 43xx four ways and the 443x bi radial monitors with a focus on how to obtain the absolute pinnacle of performance.

This may include providing a dedicated support via a web site that specializes in this specific area with new insights, a consolidation and update of my previous posts and articles re written specifically for the JBL 43xx and 443x owners and of course links to key existing Lansing forum data.

[tjm001]

For use in a 4345 clone it is apparent that 2123s are easy to come by, but 2122s are becoming extremely rare and expensive. My question is to those that have started out with 2123s and then switched to 2122s. What was your perceived and/or measured sonic difference if any? Other than for strictly purist reasons do you think it is worth the expense and effort to go with the 2122s?

Thanks.

Tom

[Ian Mackenzie]

That is an excellent question and a response requires diplomacy and a considered approach

Another persons opinion is not always useful.

You should refer to GTs comments in the designers post.

Link to designer post

http://www.audioheritage.org/vbullet...esigner-s-Post

I have used both but do not have the 2122 on hand to make a direct comparison

When set up correctly the 2123 is excellent. Getting the crossover right and careful setting up is often the unpredictable factor when attempting to compare drivers.

I would then try and hear another members system with the 2122 and decide from there.

Otherwise l would stick with the 2123.

Ian


Greg Timbers comments

Quote

" I noticed a comment earlier in this string regarding the 2122H. It is a really good voice transducer. It always has been and always will be. Things just sound really natural through it. Another one that might be slightly better is the 2123. It is a little less smooth but perhaps a little more realistic on voice. Either are really good for that critical range from a few hundred Hz to about 1500 Hz."

[Chas]

The great thing about the 2123 is there no foam surround that would suffer from degradation over time. Both are great drivers, with the appropriate crossover and set up.

[tjm001]

That is an excellent question and a response requires diplomacy and a considered approach

Another persons opinion is not always useful.

You should refer to GTs comments in the designers post.

Link to designer post

http://www.audioheritage.org/vbullet...esigner-s-Post

I have used both but do not have the 2122 on hand to make a direct comparison

When set up correctly the 2123 is excellent. Getting the crossover right and careful setting up is often the unpredictable factor when attempting to compare drivers.

I would then try and hear another members system with the 2122 and decide from there.

Otherwise l would stick with the 2123.

Ian


Greg Timbers comments

Quote

" I noticed a comment earlier in this string regarding the 2122H. It is a really good voice transducer. It always has been and always will be. Things just sound really natural through it. Another one that might be slightly better is the 2123. It is a little less smooth but perhaps a little more realistic on voice. Either are really good for that critical range from a few hundred Hz to about 1500 Hz."

Thanks you pretty much reinforced my gut feelings on this issue. I'd still like to hear from a few others that actually did this.

Tom

[Ian Mackenzie]

Beware

Of course nothing can stop a 5 year kid pocking the dust cap.

They love doing it like it was meant to happen

Out comes the vacuum cleaner suction pipe.....Lol
OMG