4688 TCB Monster Subwoofer

[4343]

It felt like someone fired up something like that over here last week. Fortunately it was for only a few seconds and at reduced volume. They kept it under a 6.0.

That wasn't me! Although, come to think of it, it was the day I got my "new" SB-5 running, maybe the straw that rattled the fault loose?

[Wolf]

Hello,

a happy and healthy new year to all!

In the meantime i am a happy owner of an old 4685; at least i believe it's a 4685...

Here is a picture of that cabinet. Does anybody know this box? There is no label on the backside but i'm sure it's an original JBL cabinet. May be a predecessor of the established 4685?

Best regards
Wolf

[Zilch]

Three chambers inside, with mounting for two drivers in the middle one?

[Wolf]

Yes. I hope you can identify the cabinet with the following fotos.

Thank you in advance for your help!

Best regards
Wolf

[Zilch]

It certainly looks right, but the square port was apparently not used on the production models.

The metal bracing between the woofers is of considerable conceptual interest. Until we see an actual production version, or plans for it, we won't know if that was part of the final design.

It would be interesting if someone would order a pair from the JBL Pro custom shop. This might generate some head-scratching in Northridge....

[johnaec]

Those look like 15" baskets to me - JBL's 18's have a completely different spoke assembly, don't they?

John

[Zilch]

Those look like 15" baskets to me - JBL's 18's have a completely different spoke assembly, don't they?

I believe Wolf said he had the 15" version, 4685.

Three sizes were available, actually. Links to the smaller ones are in this early post:

http://audioheritage.org/vbulletin/s...5266#post65266

[Wolf]

Hello,

yes, it's the 15"-Version. I bought it as a 4685. Later i found out that the dimension are quite different to the dimensions stated in the flysheet (mine: H/W/D=57/114/87cm; original: H/W/D=75/125/51cm).

There is no model code at the input panel. But it is an original JBL-panel.

The quality of the construction is absolutely professional and analog to my other JBL gear.

The bracing looks good but i am not shure being original. Maybe someone of my predecessors had a good idea...

ASAP i will offer better pictures of the cabinet.

Best regards and thank you for your help
Wolf

[Wolf]

Hello,
here are some new pictures. I hope they are not too large, sorry if so.

The front, the back and the rear input panel. There is no model number written on the panel. Funny.

Thank you very much in advance for your help.

Best regards
Wolf

[Rudy Kleimann]

Looking at the pics, it sure does look like something built by JBL. Perhaps it was a custom shop cabinet to fit in a certain space?
Does it have the right metal grilles over the openings? Do they look like they were installed professionally?

RE: the metal braces and that square hole that Zilch commented on: seems to mee like it is an access port to install the woofers and braces on the backside, and then you put a cover over it...?

[hmolwitz]

The center port looks correct, this design is 3 chambers with port(s) on each chamber, it is just square instead of round as the literature states.
It looks like the area of the center chamber porting is equal to the area of the outer chambers ports combined, which makes sense to me.
Harry

[Wolf]

Hello,

there are no metal grills covering the openings; there ist no grill at all.

The cabinet has two access ports, one above and one downside, leading to the backchamber (of course). At the front of the backchamber for the two 2225 is one square port (18,7*18,7cm, length 100cm). The volume of the backchamber is about 75litres (net).

The frontchamber of each 2226 has about 155litres (net) and one round port with a dia of 15,1cm and a length of about 18,3cm.

@Zilch:
What kind of software do you use for the simulation of the 4685 and the 4688? I would like to simulate my "4685" and compare it to your simulation.

Thank you all for your advice and best regards
Wolf

[Zilch]

BassBox 6 Pro. It has a triple-chamber bandpass option....

[Wolf]

Hello @ all,

it seems to me i'd found the big brother of my custom JBL 4685:

http://cgi.ebay.de/JBL-Bandbassgehae...QQcmdZViewItem

It is a TCB cabinet too, but with square hole instead of the round one's of the 4688/4788. The same as mine (see above, 4685/4785), but for 18" driver.

Is there anybody who can tell me something about these cabinets?

Best regards and thank you in advance
Wolf

[subwoof]

Looks like JBL ( harman ) had a cabinet shop and sold low-profile versions of the TCB's in the EU. The input plate wood cutout is the same as all the concert series cabs I bought back in '97 and the plate / jacks / printing look identical.

It sure would be nice to get plans for the cabinets since getting LF boxes under the stages and such is an advantage in cramped installs.

At the current price you can't go wrong and if you get it please share the specs!

sub