DIY "4345" Project

[ivica]

The issue is the 2345 has more tendency to couple boundary reinforcement than the 2235.

The ports are tuned to 28 hertz so they are only going to impact in the low bass , not bass boom frequencies.

The issue is baffle realestate and where to if the ports, they can go anywhere.

The most effective was is the eq the woofer flat

Hi Ian,

I only wonder, may be, mid-bass (doggy box) with the back box wall would produce a kind of acoustic duct, so a kind of higher frequency box resonance can occur as such duct would divide internal volume into two smaller boxes. May be when the ports are somewhere in the middle between these boxes, such influence is less pronounced. All these are my speculations, and it would be interesting (for me, for sure) if someone nearer the JBL technical older stuff can put some "light" on such issue.

Measurements with 2242 drivers, in the box of about 220Lit, tuned on 26Hz with two ports near the bottom plate of the box, are shown.
These measurements are from (in) one vent . So the combined response bass+ driver would be as shown.
Interestingly that AkAbak simulation would predict such behaviors.

regards
ivica

[Ian Mackenzie]

I don't feel that is likely. Sorry.

When l stuff (sex with a JBL) my head in the 4345 there is lots of space.(box)

The ports a not far from the woofer.

Only a port on the rear bottom would make it different due to the wall floor junction.

The problem is port noise and compression if the port is restricted in any way?

Bo has proven well done EQ in a home cures all these issues of the 4345.

[BMWCCA]

. . . all these issues of the 4345.

There are issues with the 4345?

Not in my house!

[ivica]

There are issues with the 4345?

Not in my house!

Hi BMWCCA,

I would not expect such with 4345, as vents are somewhere in the middle of the box, as Akabak simulation has shown too, but it would be interesting to be seen (for me) the FR response from the port ONLY

Reagrds
Ivica

[Dr.db]

4344Mk II network on the left, 4355 (equivalent) network on the right. Both are bi-amp only. These aren't fancy at all, just built as quickly as possible to get the job done.

There are only four outputs on the boards since the rest of the 4344MK II network components come after the L-Pads. The second photo shows the L-Pad board with the 3.5 mH 7.5 ohm and 1.0 mH 7.5 ohm inductors.

Attachment 46971Attachment 46973Attachment 46972

Did you use the 3.5 mH 7.5 ohm and 1.0 mH 7.5 ohm inductors together with the 4355 (equivalent) or with the 4344 network?

Thanks a lot for your help!

[Ian Mackenzie]

see my post here
http://www.audioheritage.org/vbullet...l=1#post408762

I hope to have some clarity on the soon

[Dr.db]

Thank you, but I can´t find anything regarding the inductors in your posts...

[Ian Mackenzie]

Thats because I have not done it yet.

Cant you tell I am out clubbing!

I will try and look at this over the next few days

[Ian Mackenzie]

Okay

Based on the voltage drives use this schematic without the conjugate.

The caveat is I am not sure 4313B optimised the 3155 for the 2123H so its a work in progress

http://www.audioheritage.org/vbullet...l=1#post292188

Use a bi amp 3rd order 18 db HP filter @290 hz.

At some stage when I have a 2445 driver handy I will look at the whole system in Leap with some 1/2 space LMS measurements

[Dr.db]

At some stage when I have a 2445 driver handy I will look at the whole system in Leap with some 1/2 space LMS measurements

That would be very kind of you, thanks in advance!

So your assumption is there are no such 3.5 mH 7.5 ohm and 1.0 mH 7.5 ohm inductors used in the 4355 network, right?

[Mannermusic]

Okay

Based on the voltage drives use this schematic without the conjugate.

The caveat is I am not sure 4313B optimised the 3155 for the 2123H so its a work in progress

http://www.audioheritage.org/vbullet...l=1#post292188

Use a bi amp 3rd order 18 db HP filter @290 hz.

At some stage when I have a 2445 driver handy I will look at the whole system in Leap with some 1/2 space LMS measurements

Ian: See post 132 re 2123 LEAP analysis vs 2202, etc. Giskard covered all that, several of us use it.

[Dr.db]

The caveat is I am not sure 4313B optimised the 3155 for the 2123H so its a work in progress

I think initially 4313B was going to adjust the 3155 equivalent network to mate the 2123h 10"-driver. But than he tried the 2123h with the untouched network and was suprised how similar it behaved to the 2202h and left it by that.
To my knowledge he never changed the lowpass, so the 2,4mh inductor and two 36mf capacitors remained...!?

[Ian Mackenzie]

Yep,

This thread takes some twists and turns. You can't just read one post to get it hence the questions back then and now.

In summary forum member 4313B ideas evolved after trialling several networks, the 3144mk11 , the 3145 equivalent, and the 3155 charge coupled.

Given this was a new enclosure build 4313B had flexibility to try the larger 2 inch 2446 compression driver (that won't quite fit with the standard stock mid range enclosure) and swapped out the 2122H for the 2123H.

It was easier to use the 3155 network to incorporate or shoe horn these ideas into a system and that is where it ended up with the modified 4345 enclosure (to fit 2445/6 compression driver).

In terms of what direction you want to take its real diy audio here. You are not cloning a JBL 4345 or the JBL 4344 here and it comes down to what's important to you, component availability, budget and of course you have to be able to make it work.(Pm me if you need support)

Essentially the quest was for greater system sensitivity for the upper three drivers so the Mid L pad was removed.
Its important to understand the 2445/6 won't fit in a stock and cloned 4345 enclosure.

I plan to get hold of the 2446 with the D8R2452H-SL diaphragm to evaluate.

[Ian Mackenzie]

I think initially 4313B was going to adjust the 3155 equivalent network to mate the 2123h 10"-driver. But than he tried the 2123h with the untouched network and was suprised how similar it behaved to the 2202h and left it by that.
To my knowledge he never changed the lowpass, so the 2,4mh inductor and two 36mf capacitors remained...!?

On reading the thread several times I think member 4313 was talking to those who he as making networks for and they kind of got it.

It sounds like a fun idea to try out.

I must say the presentation of the 4355 using the 3155 network with the 2 inch compression driver and the 12 inch 2202 never really impressed me the way the 4345 does. Yet others like the 2202.

Maybe the 2123 works better then the 2202?

I need to obtain a 2202 and try to out!

[ivica]

On reading the thread several times I think member 4313 was talking to those who he as making networks for and they kind of got it.

It sounds like a fun idea to try out.

I must say the presentation of the 4355 using the 3155 network with the 2 inch compression driver and the 12 inch 2202 never really impressed me the way the 4345 does. Yet others like the 2202.

Maybe the 2123 works better then the 2202?

I need to obtain a 2202 and try to out!

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