4320 Project

[jbl4ever]

Hello hjames, can you post a picture of the 2405 diaphrams front and back. They look like aftermarket by the one picture. Hard to tell. If they
are aftermarket ones the impedance will most likely be different than stock. A impedance curve would be needed to properly design the new circuit for this.

[hjames]

Hello hjames, can you post a picture of the 2405 diaphrams front and back. They look like aftermarket by the one picture. Hard to tell. If they are aftermarket ones the impedance will most likely be different than stock. A impedance curve would be needed to properly design the new circuit for this.

Not easily - I'd have to pull the woofers to gain access to the drivers, unmount the 2405s, then tear down a working driver.

In truth, I'd rather build the crossovers as if they were the right (JBL) diaphrams - once money is a bit less dear I may send the 2405s out for JBL pro rebuilds anyway, and if I build networks specifically for the aftermarket parts, I'd just have to redo the networks when I change.

I got the 2405s on ebay - the deal was they needed diaphrams installed and a new pair of diaphrams were provided to install. Knowing that any set I bought on eBay have worn or tired diaphrams anyway, they were cheaper than most others pairs offered. From the price of JBL diaphrams, (provided free with the 2405s) I'll assume they are aftermarket.
The diaphrams were sealed in clear plastic trays numbered DWT044S-8.


3110 Crossover LF out to 2215 woof, MF out to L166 Crossover
L166 Crossover LF leg (choke) removed - MF & HF only used
2215 15" woofer
2420 MF driver
2405 HF driver

[hjames]

I've got a quick question. I've seen the reference to Charge Coupled crossover networks quite a few times in these forums - this is something you do for bi-amped systems right? I mean, you are doing this fancy crossover at a 1v P-P preamp output signal level, correct?
The crossover pictured on the perfboard at http://audioheritage.org/vbulletin/s...1&postcount=28 doesn't look beefy enough for the 200+ wpc power levels you folks run these speakers at ...
I ask because I want to build crossovers for the L300 equivs I am building from my 4320 speakers (2215, 2420, 2405) - and I want to be sure I'm using the right specs to do so.
Thanks for the info!

[Mr. Widget]

I've got a quick question. I've seen the reference to Charge Coupled crossover networks quite a few times in these forums - this is something you do for bi-amped systems right?

Nope.

The charge coupled crossovers are standard passive networks being powered by your amplifier. The charge coupling means that they have a DC offset voltage that is reported to lower some forms of distortion caused by the capacitors. I have no personal experience with them, but the people who have tried them really do rave about them.


Widget

[hjames]

I just ordered the parts to build Giskard's 4333/S300/L300 equivalent bandbass circuit - (the regular, not the Charge Coupled design)
see - http://audioheritage.org/vbulletin/s...42&postcount=3

After reading a number of threads here, I've also followed Giskard's design
trick and put the Lpad and load resistors for the MF HF legs on an external board and mounted that on the back of the baffleboard. I even created a "foilcal" lookalike in photoshop, based on the 4333A foilcal that spirou38 offered here a while back. see - http://audioheritage.org/vbulletin/s...ead.php?t=9544

I bought a cheap Ryobi tablesaw ($99 - Home Despot) that I can clamp into my Shopmate and I've cut down some lumber to build grills with ... got some Zilch cloth to cover the grills with, and a pair of metal JBL Logo badges to slip discreetly into the corner of the grill. I don't have a shed/garage so I just need some less cold weekend time to set up the saw outside and notch the ends of the boards so I can clamp/glue them together. More pictures later ...

I'm hoping to get all this completed by mid-April ... and get the speakers off the floor so I can have my TV room back.

[remusr]

One thing that will change the sound vs a 4333/L300 is the use of your tighter 2215's vs the deeper extension/longer throw 136A/2231A's.

[hjames]

One thing that will change the sound vs a 4333/L300 is the use of your tighter 2215's vs the deeper extension/longer throw 136A/2231A's.

Ok - should I gather that tightness is not a good thing? Should I just bite the bullet and start looking for a pair of the newer speakers. At the moment, its an all alnico system (for whatever thats worth), but my plan to update the crossovers should indicate I'm willing to do updates to improve the sound.

[Chas]

I just ordered the parts to build Giskard's 4333/S300/L300 equivalent bandbass circuit - (the regular, not the Charge Coupled design)
see - http://audioheritage.org/vbulletin/s...42&postcount=3

I can certainly vouch for this network, it works just fine over here. BTW, I think there was a typo in the schematic, one of the resistors was labeled 40 Watts, I can't recall what I am using - I can check if you want. Maybe Giskard could chime in - but I think 40 W is overkill.

Initially I used Solens, now they are Hovland (except in the low pass portion) in my non-CC version. Expensive, but well worth it to me.

[hjames]

Thanks for the tip! While talking of crossovers in other threads, Giskard has said to just stack up 10w resistors to get the higher wattage numbers - so I ordered all 10 watt resistors. Worst case, maybe I'll have a few too many, but they're the cheaper part of the networks.

Anyway - thats next weekend's job - today is dedicated to building grilles.

The speakers didn't have any grills when I bought them, but the basic design is similar to one I saw in one of Zilch's pictures here: http://audioheritage.org/vbulletin/s...75&postcount=1

Last weekend I got one of those $99 Ryobi table saws at Homedespot, and a 60 tooth finecut saw to put into it instead of the default 24tooth saw it came with (basically, more teeth = finer cut). I thought we'd get rain this weekend so Friday after work I got the parts sawed out. But Saturday was a clear day. I glued and pinned the wood together, and cut 8 mid-side spacers - then put them into position. Everything went so well that by 4pm I had time to l spray them with flat black paint and I'm ready to glue the grill cloth.

For cloth options I've got a light tan (similar to L300 color), black, and some of the JBL Blue cloth I got from Zilch (which looks black but is actually more like Navy blue). We decided to pass on the black, but we can't figure if we like the deep blue or the tan - the speakers will be up on the shelf and partly block the window - so the light color may be more appealing. Anyway, as you can see in the botom picture, I loosely covered one grill with each - and we'll look at them for a week or so before deciding which one to glue into place.