DIY 1200 Array

[4313B]

I should have replied sooner, I will (and planned on) taking one of mine apart this weekend to get you pics and dimensions. If that's not soon enough please let me know and spare me the trouble.

That sounds great. While I had planned on wrapping this up this weekend it turns out I'm off to Canada again so this project gets to wait another eight days. I had completely forgotten that you had a pair. Thanks!

[ivica]

Ok, .........................

The stock high pass networks are, on the other hand, a bargain in that all the inductors and resistors are 100% viable and reusable for charge-coupling.

BTW - Like Greg, I've switched over to using diodes instead of 9 volt batteries in all my charge coupling endeavors.

I have not seen mentioned "DIODE supported voltage supply" for charge-coupled network, but I can guess that (owing to almost no DC current loading of CC network) that there would be some kind of diode rectifier with some electrolytic capacitor as a filter (and battery). If SCHOTTKY diode(s) is used I can expect about 0.25V voltage drop on it, so in order to produce at least 1V for polarization for CC-Network capacitor it has to be 1.25V amplitude signal to be applied at the speaker box terminals. That would correspond to about of (1.25)^2/2/8=97 mW power to the speaker and for 90dB/1W speaker sensitivity that would be about 80dB level of sound, what is fare to be neglected. But for the signal level of about 66dB, (amplifier voltage of about 0.25V) there would be almost NO POLARIZATION voltage. So my question is what kind of improvements are expected using CC-network, for low level signals ( where, if "diode rectified" polarization is used, there is almost NO POLARIZATION) or for higher level signals ( where about 9.25V amplifier amplitude, would produce the same effect as 9V-DC battery, but that would correspond to 5.3W or sound level of about 97.3 dB/1m) ?
For more sensitive speakers ( over 90dB/1W/1m) such calculation would lead to even worse conclusion.
regards
Ivica

[JuniorJBL]

I have not seen mentioned "DIODE supported voltage supply" for charge-coupled network, but I can guess that (owing to almost no DC current loading of CC network) that there would be some kind of diode rectifier with some electrolytic capacitor as a filter (and battery). If SCHOTTKY diode(s) is used I can expect about 0.25V voltage drop on it, so in order to produce at least 1V for polarization for CC-Network capacitor it has to be 1.25V amplitude signal to be applied at the speaker box terminals. That would correspond to about of (1.25)^2/2/8=97 mW power to the speaker and for 90dB/1W speaker sensitivity that would be about 80dB level of sound, what is fare to be neglected. But for the signal level of about 66dB, (amplifier voltage of about 0.25V) there would be almost NO POLARIZATION voltage. So my question is what kind of improvements are expected using CC-network, for low level signals ( where, if "diode rectified" polarization is used, there is almost NO POLARIZATION) or for higher level signals ( where about 9.25V amplifier amplitude, would produce the same effect as 9V-DC battery, but that would correspond to 5.3W or sound level of about 97.3 dB/1m) ?
For more sensitive speakers ( over 90dB/1W/1m) such calculation would lead to even worse conclusion.
regards
Ivica

http://www.audioheritage.org/vbullet...l=1#post295666

[DavidF]

"I very nearly did the same but Greg urged me to build a charge-coupled pair of the low pass networks about a month ago if only for the sake of science. His argument is that the low frequency transducer goes up high enough to make a difference. I suppose one could argue that it wouldn't be as important for HT as if would be for dedicated two-channel..."

Thanks for relaying that suggestion. I did not consider charging the low pass section. Especially after buying air coil inductors. I used a mix of NPE and 10% poly for the trap in the mid/high section so I will do this in similar fashion for the two NPE in the low section. These xover thingies keep getting larger.

[1audiohack]

Like this?

The top board 1400 ARRAY P/N 360908-001 has a fastener hole layout as follows:

4.750" center to center wide

3.250" center to center down X2

The bottom board 1400 ARRAY P/N 360908-002 has a fastener layout as follows:

5.750" center to center wide

3.125" center to center down X2

Sorry for the glare, I have a big SLR that barely fits in the hole and pointing the flash where you want was impossible. The six inch rule is just there for a sense of scale. If you need more let me know.

All the best,
Barry.

[4313B]

Like this?

Perfect. Thank you very much.

It looks like that bottom board has a bit of room to grow to handle the extra cc capacitors.

[1audiohack]

It looks like that bottom board has a bit of room to grow to handle the extra cc capacitors.

Your very welcome and, yes it does. I didn't measure the floor dimensions but I will if it helps.


Barry.

[Mr. Widget]

Thank you to you both... one of these days (years) I will be using this info.

I am surprised to see such high quality components... in years gone by, JBL cut corners in the crossovers. I realise you can do better, but I imagine, you'd have to spend a lot to improve the sound just a little.


Widget

[4313B]

Thank you to you both... one of these days (years) I will be using this info.

I am surprised to see such high quality components... in years gone by, JBL cut corners in the crossovers. I realise you can do better, but I imagine, you'd have to spend a lot to improve the sound just a little.

True, but as was reiterated on Friday, they are a twelve thousand dollar pair of loudspeakers. There really is no excuse for non-biased filters in this quality of a system.

[4313B]

As luck would have it the 2206H efficiency is an excellent match for the 435Be using the stock 1400 Array network so there was no need to do anything with either the low pass or bandpass filters. In short, the 2206H is a bolt-in with the Be compression drivers. The 045Be is still a little too hot as I didn't increase the lead resistor as per Rob's findings.

The 2206H is surprisingly good in this application. Greg thought it would be and Doug did a great job desiging this particular driver. Too bad JBL never updated the LE14H core to this type of core.

As for the 476Be, it is definitely not a bolt-in with the stock 1400 Array network and I'm not interested in building Greg's 476Be networks to make it work (he used the 476Be in his final version of the 1200 Arrays before upgrading to the Everest II's). The 435Be works extremely well, is half the weight and a third the cost.

1200FE - ultra-low distortion, three-inch voice coil, outstanding midrange performance, good to 40 Hz.
2206H - four-inch voice coil, 4 dB more efficient, excellent midrange performance, good to 60 Hz.

In short, the 2206H is no slouch in any sense and can be easily obtained. Gotta love that extra efficiency. I see virtually no purpose for the SAM2LF, with its lower efficiency and greater cost. The Synthesis 8 drivers are really nice but they simply aren't in the same league as a 2206H.

[JuniorJBL]

I happened on a really good deal for some JBL pro gear about 2 months ago, 2 X AS2225's 2 X AS2216's 2 X SR4733a's and a pair of 2446j's/with 2385a's for less than, well almost free. I scooped that real fast so I have a pair of 2206's and that might be why I would want a second pair. Glad to know they work well with the 435Be!

[4313B]

Glad to know they work well with the 435Be!

Or readily available 2435H. Too bad Pro doesn't make the horns too. But that would be too perfect now wouldn't it.

[JuniorJBL]

Or readily available 2435H. Too bad Pro doesn't make the horns too. But that would be too perfect now wouldn't it.

[4313B]

I'm getting numerous requests for a functional network for the 1500AL and 476BE with H4338 horn. I haven't had time to work up a new one. Besides, it really matters how it is specifically being used, these parts are too good to settle with a generic version.

Still haven't had time to finish up the CC 1400 Array network either.

I did manage to move these things into a listening room after moving the 1200 Arrays out. I definitely do not like their bulk. And they're just stupid heavy...

[JuniorJBL]

Heavy but............ I bet they sound REALLY good though!! They sure would be fun to play with.

BTW looking forward to your CCed 1400 network.

I removed some of the padding from Rob's Be network as I found I like the horn a bit more "present"

Nice job 4313b