JBL 4345 DIY project of a complete Rookie

[buutinie]

Dear folks,

hello from Berlin! This is my first post so I wanted to say hello first (for those who are not interested - there will be a question later on). So I am a 30 years old music lover that went to Japan this year and had the chance to listen to some of the bigger JBLs in so called Hifi-Bars (Vinyl-Bars). I was absolutely stunned and now, sad thing: I want to have something like this. My personal Hifi-Equipment is not top notch but it was sufficient enough for the last years (Marantz 2250b and B&W 683 speakers). As I am now moving to a new place with a bigger living room I can actually get bigger speakers. Nice to have I thought. And I like to build things in my spare time, as I am working in an office. So I kinda got obsessed with the idea of building my own 4345. I have been chatting with a really nice guy on another forum (hifi-forum.de) who recommended this forum for me. I have been reading quite a lot, but: I am a complete rookie - please forgive me. I don't really understand the details etc. But I think I can managed if I can rely on the help of you guys. It would mean the world to me.

So to my questions:

I have the parts list in front of me right now. It says I need the 2245h, 2122h, 2425J, 2405, 2307, 2308.

So I did some digging and found the 2240h for a really good price. I read in this forum that you could recone the 2240h into a 2245h - any thoughts on that?

I also found some le10a that need reconing - and read here that these could be reconed into the 2122h. Same applies to the le10h to my understanding. My question here is: Can I use the le10a/h without reconing into the 2122h in "my" 4345? I know that I would have to change the network in oder to use them.

If you have any suggestions, help, information: please let me know. Again, I am a real rookie, so it would be highly appreciated if you take that into consideration when answering!

Thanks so much and have a great day!

Max

[Odd]

Some of the items you have to buy are hard to find.
Would recommend you and read this thread and follow it.
It gives guaranteed good results.

2245H
2123H
2445J/2311/L94 with D8R2452H-SL diaphragms
2405H

[buutinie]

Hello,

thank you for your replay. I have read the thread, but thanks for pointing me in the right direction. Can you maybe tell me, why he did not use a 2425j? Because on the reference chart it says that this is the one to use. Also the horns that are sold online seem to be different to the 2307 - any thoughts on this?

Can you maybe shed some light into my questions of using the LE10a/h?

Thanks again and have a nice day!

[buutinie]

Oh, and what about the 2426j?

Thanks a lot!

[Ian Mackenzie]

Hello,

thank you for your replay. I have read the thread, but thanks for pointing me in the right direction. Can you maybe tell me, why he did not use a 2425j? Because on the reference chart it says that this is the one to use. Also the horns that are sold online seem to be different to the 2307 - any thoughts on this?

Can you maybe shed some light into my questions of using the LE10a/h?

Thanks again and have a nice day!

As time has moved on and availability of the original matched components for the JBL 4345 become more difficult to obtain and people have started to try some alternative options.

After some experimentation the larger more expensive 2 inch HF drivers were evaluated.

Some people have a preference for the larger 2 inch HF drivers and variations of the original network were trialled.

If you look and search carefully the details are in some older threads but there appears confusion over exactly what you need to do for the network with particular drivers.

Historically there are a number whys and wherefore questions on how to implement the network depending on the actual components you have available.

This excellent thread was a condensed work in progress at the time.

http://www.audioheritage.org/vbullet...5-quot-Project

When I get time I will sim the 2123 model I have in LEAP to clarify what the diy person needs to know.

The 2 inch driver with an acquaplas coated diaphragm is excellent but its not a drop in replacement in the original 4345 network (3145)

The "sensitivities" and the "tilt"in the response of the specific drivers (mid 2123/2202 - HF 2445J/2311/L94 with D8R2452H-SL diaphragms) needs to be accounted for so you get the end result you are paying all that money for.

When I get hold of the 2 inch driver mentioned in the above thread I will post a reference to this thread to help clarify some f the questions some people have been asking.

I would refer to that as an advanced project for an existing 4345 diy user.

The 2425 is a lower cost (original component) and the crossover network is more straightforward.

There is the Consumer Version of the JBL Professional 2307, the Consumer HL 91 and the 2308 Lense (the parts are identical)

The LE10A/H question

Originally the 10 inch mid driver was based on the LE10A/H

The LE10A/H is a woofer.

It has low frequency extension and medium efficiency.

The LE10A/H was re designed for the JBL 43XX 4 way systems for higher efficiency and a smoother response with later versions of this driver like the 2122-2123.

You can certainly try the LE10A/H as a diy project.

I recommend that you consider a 4 way active crossover network to avoid the difficulty of modifying the original passive crossover if you decide to go this route.

[buutinie]

Hello Ian,

thanks for your thoughts.

So if I understand you correctly: I could either use the 2425 or the 2445 - it doesnt harm the whole build, right? Its just a question of the crossovers in the end. Therefore Id go for the ones that are cheaper. Did you also mean that the 2426 is an option?

Regarding the Le10 thing: I could also use the LEs, again, nothing wrong with them? Whats your personal opinion on this? Would you (given that time and money is somehow an issue, more the latter) try our the Le10?

My next steps will be: Finding the parts and then starting to work on the networks - or at least try to figure out how to do em - is that a good approach?

Again: Thanks for helping!

Max

[Ian Mackenzie]

Hello Ian,

thanks for your thoughts.

So if I understand you correctly: I could either use the 2425 or the 2445 - it doesnt harm the whole build, right? Its just a question of the crossovers in the end. Therefore Id go for the ones that are cheaper. Did you also mean that the 2426 is an option?

Regarding the Le10 thing: I could also use the LEs, again, nothing wrong with them? Whats your personal opinion on this? Would you (given that time and money is somehow an issue, more the latter) try our the Le10?

My next steps will be: Finding the parts and then starting to work on the networks - or at least try to figure out how to do em - is that a good approach?

Again: Thanks for helping!

Max

Hi Max

This is your diy journey with JBL.

Take your time and enjoy.

It becomes a consultative and a somewhat time consuming process that my wife says deserves compensation with a bottle of her favourite red wine!

In short to answer your questions:

Yes but remember the 2445 requires the 2311 2 inch short horn. The space for the larger 2445 along needs to be factored in to the actual box build.

Its also a high cost item generally.

The implication is the 2426 is a one inch driver and is way cheaper and the passive crossover network is different.

You can try the LE10A/H BUT you will have to realise the result will not be the same as the 2122 or the 2123.

It will work and that might be okay for a start.

It depends of you are happy to let the project evolve or just go straight to the final design.

This is all going to require some time and effort in your part.

FWIT I originally did the former over 20 years ago and evolved my diy project from an Altec two way to a 3 way with a JBL 2405.

Then I got an Audax mid driver and made it a 4 way.

I sold my Altec 515b and bought the JBL 2245 woofer. That was the easy part.

I then replaced the Audax with a JBL 2122H and got it into my head I wanted to make a JBL 4345.

I previously made a diy JBL 4343 21 years before that and thought building a 4345 would be an interesting if somewhat ambitious project.

That was really hard because there was no information anywhere back (2003) then like you have here now.

Its actually harder to replicate an original design because you are held to some rigid requirements.

The diy journey or more fun because you appreciate the journey more and the changes you make as you more forward.

If you actually have a LE 10 in good order I would definitely try it out . It one of JBL most highly sort after vintage drivers.

Pm me if you want to digress further

[just4kinks]

I went with the original drivers when I built mine, 2245/2122/2425/2405.

The 2123 was more obtainable even back then, but I decided to go with 2122's because I thought they would be a better match for the 2245's with their soft suspension and lower resonant frequency. I'm sure the 2123's are great too.

For the compression drivers, I really wanted 2421's but I couldn't find a decent pair. I was never that happy with the 2425's and I was going to swap the diaphragms for aluminum ones, or get 2440's, or aquaplased 2450's, but I never found any of those things and I ended up getting TAD's instead.

FYI, if you want the option of a 2445 or similar, you will need to modify the dimensions of the midrange chamber.

[ivica]

I went with the original drivers when I built mine, 2245/2122/2425/2405.

.....
FYI, if you want the option of a 2445 or similar, you will need to modify the dimensions of the midrange chamber.

Hi just4kinks,
but, mey be, 2450 is the solution ?????

regards
ivica

[Ian Mackenzie]

Hi just4kinks,
but, mey be, 2450 is the solution ?????

regards
ivica

I think it depends on the important details.

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

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 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. But people are using the more advanced compression drivers than in the stock 4355 such SL version of the titanium diaphragm in the 2446. (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 it's an option.

Of course each to their own desires, needs and resources.

Do what makes you happy😊.

[buutinie]

Hey guys,

thanks for all your insights, it has been very helpful.

I am just wondering about the crossovers. If I am not mistaken, the 3145 crossover was switchable, meaning that you could either go active or passive, is that right? If so: is there any schematic on how to build these? Or am I just being stupid and missing something here? I thought the option of doing both would be a nice something...

And the bi amping has one big downside, which is the WAF. I have to say it was already hard getting my girlfriend to believe me that I do ned the 4345, but it might actually become impossible to convince her that I do need 2 more amps and an active crossover laying around.

If I really do need the bi amping: What would be your (budget!!!) thoughts on the amps? Srsly, I kinda spend everything on the 4345s, so I cannot really spend 10k on amps. Even though I would like that.

Thanks a lot and have a great weekend you all!

Max

[just4kinks]

And the bi amping has one big downside, which is the WAF. I have to say it was already hard getting my girlfriend to believe me that I do ned the 4345, but it might actually become impossible to convince her that I do need 2 more amps and an active crossover laying around.

Girlfriend? Dude, you are fine. Stock up before you put the band on the hand!

If I really do need the bi amping: What would be your (budget!!!) thoughts on the amps? Srsly, I kinda spend everything on the 4345s, so I cannot really spend 10k on amps. Even though I would like that.

Many of us have used Crown PS-200/PS-400 for our 4345's, great amps and just a few hundred bucks.

[BMWCCA]

Many of us have used Crown PS-200/PS-400 for our 4345's, great amps and just a few hundred bucks.

I second that. I've used Crown DC300A-II and D150A-II but now use Crown PS-400 and PS-200 with the crossover design from the 4345 thread here made without provision for using a single amp. The designer felt the switch was a bad compromise only offered for marketing reasons and that bi-amping really worked much better on the 4345.

I've paid as little as $100 for my most-perfect PS-400 and I don't think I've spent over $200 for any of them. Oddly the little PS-200s cost nearly as much. Just look for one that hasn't spent a hard life on the road and you'll be fine. So, to reiterate, you might have to spend $600, but certainly not $10k, to make them sing.

[ivica]

Hey guys,

thanks for all your insights, it has been very helpful.

I am just wondering about the crossovers. If I am not mistaken, the 3145 crossover was switchable, meaning that you could either go active or passive, is that right? If so: is there any schematic on how to build these? Or am I just being stupid and missing something here? I thought the option of doing both would be a nice something...

And the bi amping has one big downside, which is the WAF. I have to say it was already hard getting my girlfriend to believe me that I do ned the 4345, but it might actually become impossible to convince her that I do need 2 more amps and an active crossover laying around.

If I really do need the bi amping: What would be your (budget!!!) thoughts on the amps? Srsly, I kinda spend everything on the 4345s, so I cannot really spend 10k on amps. Even though I would like that.

Thanks a lot and have a great weekend you all!

Max

Hi Max,

for 'normal home listening' I would suggest Rotel RB980 (second had round 300$) for bass section, and for the rest smaller Rotel BX970 (round 150$), pre-amp Rotel RC-8xx or 9xx (about 100~ 150$) and active (DSP driven ) network such as some stereo 3-way such as DBX Driverack PA (expected about 200$) or Behringer DCX2496 , miniDSP, ........, may be even analog two-way active network ca be applied. but I would suggest DSP driven digital, as EQ would be included.

regards
ivica

[buutinie]

Hellohello!

Thanks for the thoughts. We are really talking about home listening. It might get loud sometime, but I live in an apartment building with neighbors that will probably kill me anyways. The Crowns look good, but I prefer the Rotels I really like a sleak pure design... Ill see what I can get there. We are talking about the RB-970BX, right?

What are your thoughts on the old Yamaha? I really liked the M2/C2... If I went that route, would I go for an M4 to take the upper range?

Any thoughts are really welcomed here. Maybe old NAD?

Thanks so much, I really appreciate your help!

Max