Midrange for a mybrid JBL/Altec system

[sekess]

Hi All,
I just finished going from a passive crossover for an Altec 416-8C(vented box) -- 802-8G/511 horn to an active crossover (1200Hz 2'nd order). This was a huge improvement in the blending of the 2 drivers -- much more punch. Plus, the highs are cleaner. Before I was using an Altec 1285 xo of which I replaced all the caps, coils and resistors with premium parts. I also had that crossed at 1200Hz (can be set to 500Hz, 800Hz, or 1200Hz). But, I just never could get the level of the 416 up to that of the horn (I had the L-Pad almost all the way at the end). Anyway, I went active and it's much better.
But, I would like more.
So, for my next experiment: I have a pair of JBL 2245H's. I am going to replace the 416's with the 2245's. I'm curious to hear how they will blend with the 802/511 horns. I have a pair of large (about 14cu ft. boxes tuned to around 18.5Hz). I am going to pop the 2245's in there and then cross them at 500Hz to the 802's. I'm expecting a lot more oomph out of these guys.
However, in snooping around in various threads here, I see that 300Hz or so is the highest that most of you guys go with the 2245's. So my question is: When I set this up, is I feel that the midrange is a little muddy (which I think might be a possibility) and/or the 802 is crossed a little low, what would you guys recommend for a good JBL midrange driver in between the 2245 and the Altec 802-8G/511? I like articulate. But, I must have chest punch as well.
Thanks,
Steve

[sekess]

oops -- mispelled the title. I meant to write:

Midrange for a hybrid JBL/Altec system

not "mybrid"

sorry bout that,
Steve

[Zilch]

Your woofer's not the problem, and you're digging yourself into deeper doo-doo with your plan.

Are you using HF compensation on the compression drivers?

Start with Altec 30923 bridged "T" filter, maybe; make R-2 adjustable, if required....

[sekess]

Hey Zilch,
Well, I also have a 2404 on top of the 802. So, my high frequencies are not bad. So, I didn't use the 30923 compensation filter. Now that I have the active setup, I just dialed down the level on the 802's amp and the blending seems pretty good between the 416 and the 802.
My issue now is that the 416 could have a little more snap (upper mids). It's tough to describe. But for example, when there is a quick rip through a drum solo, I feel like it could be a little more accuracy. I get the chest punch. But, there is some lack of precision.
Do you think it's possible to get the sound I'm trying to describe out of the 416?

Thanks,
Steve

[Zilch]

Look at the 802 curves. You still need comp:



You might move down to 800 Hz on 511, but no lower....

[sekess]

Hey Zilch,

Hmmm, I see what you mean. Ok, so compensation it is for now. This is another reason why I feel that a computer based digital xo is the way to go. That compensation can be taken care of with the software. Then you wouldn't have to waste amp power on the padding down of the driver. It's an efficient driver. But still, the signal would be cleaner.

Too bad about the 800Hz lowest cut off frequency though. I'm really dying to try out these 2245's.

Thanks for the graphs and info. Zilch --much appreciated.,
Steve

[Zilch]

Too bad about the 800Hz lowest cut off frequency though. I'm really dying to try out these 2245's.

Build subs:

http://www.lansingheritage.org/html/.../1983-subs.htm

30923's not gonna make dirty, just kill the "Shout...."

[sekess]

Hey Zilch,

Do you find that the Zobel sedction for the woofer from the 30904 would help the sound of the 416 in any way?

Thanks,
Steve

[Zilch]

Never used it; it's for 411 woofer, as I recall....

[sekess]

Hey Zilch,
Do you happen to have the 802 curves with the compensation circuit applied?

Thanks,
Steve

[Zilch]

Yes, they're in the "Babies" Valencia thread.

Search word "Tangerine" will get you to the relevant posts....

[sekess]

Hey Zilch,
Thanks. That dip at 16K is an easy one to hear. A few days ago I was running through the pink noise bands and just listening to them. At 16K the level just dops off to nonthing. Your plots confirm what I was hearing.

Thanks again -- nice work,
Steve

[sekess]

Hey Zilch,
Thanks for the heads up on the compensation circuit. It worked out nice.
I will now try to reproduce circuit actively. Currently, there is a bypassed protection cap and this compensation network on the midhorn. I also need to pad down the midhorn so as to better match the tweeter. So, the passive components are starting to add up. By reproducing this network (or similar) plus the padding actively, there will only be the protection cap in line.

Anyway, thanks for the push in the right direction,
Steve

[A9X]

Too bad about the 800Hz lowest cut off frequency though. I'm really dying to try out these 2245's.

As you asked about a midrange, something like a 2123 would fit nicely in between an 18 and a 1" CD.