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altec 604-168x build.

The Fuxtor

The Fuxtor

Addicted Member
Ok, I scored a pair of these drivers! Can't believe they just fell in my lap .. So naturally I'm making plans to build some cabs, when I realize something. At first I was just thinking about building something along the lines of a 620 cab but previously I had plans to build a set using a JBL L-200 woofer I picked up from another AKer. I was going to pair these with an 811b horn. Well that changed with my new purchase. Then I got to thinking... What if I could put the JBL's in the same cab as the 640's as helper woofers? I also have the stock woofers from an Altec 1204 ( where the 811b horns came from) so a couple options available. What does a guy do??
 
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The Fuxtor said:
What does a guy do??
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Homework, plenty of it.

Are the L200 woofers LE15's or 2235's? Regardless, for the proposed exercise of adding a helper woofer to the system, you should give strong consideration to having someone like GordonW modify them to 2236 moving assemblies or equivalent. This would give you the ability to go LOW in a reasonably sized(sealed) box.

Since you'll be running 604's with a distinct HFE advantage over the vintage alnico predecessors, wouldn't it be a hoot to have similar LFE to compliment?

With the mismatched sensitivities and impedances, a fully adjustable DSP speaker management system like a Behringer DCX2496 or DBX Driverack is going to be your friend in getting the system right, i really wouldn't consider doing it any other way.

Just my .02...
 
bowtie427ss said:
Are the L200 woofers LE15's or 2235's?
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@moray james
Ok, as a noobie in this realm, my thoughts are to go with solo 604's first... I have a Behringer cx-3400 which can do 3 way stereo, but probably lacks features useful in this proposal?
I could later in future plans add the helper woofers correct? As stated, having matching impedance on both drivers would allow me to use a civil sized cabinet? My original plan was to build a 7 cubic foot cab....
 
The DSP loudspeaker management gives you an array of filter types and slopes to choose from as well as the ability to gap/overlap crossover points, plus some eq, time delay/phase adjustment, and the ability to store settings.

Having all driver elements the same impedance simply allows "off the shelf" and other proven passive network solutions. I think you're further ahead in this case to go active. It allows far more flexibility

The CX-3400 can certainly give you satisfactory results. I recommend using a "safety" cap on the HF drivers until you are well versed in the settings and adjustments on the network(regardless of what active network you use).

For fellas that wanna dip their feet in a little deeper the DCX, the matching DEQ2496 RTA/EQ, and calibrated mic render a pretty comprehensive DSP based tool box that you could have only duplicated in a well equipped acoustic laboratory a couple decades ago. The DEQ + mic gives anyone the ability to take real world in room 1/3 octave measurements in real time. Not everybody wants to play this deep in the field, and i understand that. But, those that do will find that some of this gear pays for itself in the first project or two.
 
It would be a lot easier with a pair of 416's as helpers. the larger the cabinet the better. 16 cu ft would sound great and you wouldn't need any ports. You want the 604 at ear height almost making the cabinets 4.5 ft tall by 2 ft wide by 20 inch deep. Stuff the box to cut down on internal standing waves, to damp the woofers, and to extend the bass to 20 HZ. Yes the speakers will have to be placed closer to walls and corners rather than standing away from surfaces, but that will guarantee some spectacular bass you are not use to hearing from ported boxes. .
 
Quick question..
Safety cap should be in line with the positive speaker post and after the active crossover? What value?
 
use a simple 1st order calculator at the impedance of the driver you want to protect. choosing a value approx 1 octave below the intended knee point will keep it audibly "out of the way" but it's effect will be up high enough to protect the driver if you should inadvertently send it 150hz when you intended to send it 1500hz. In this case with an 8ohm HF driver i'd use a 20uF(1000hz) to 25uF(800hz) cap.

It doesn't matter which terminal you install the cap on, we're dealing with AC here.
 
Cut the frequency in half and calculate. Thats 800 hz for the HF section and 10 HZ for the woofers. Of course if you would use Mac amps you wouldn't need the caps. I'd want a MC 502 for the HR and a MC 7100 for the woofers. If you want power for the woofers a MC 7200. They don't use autoformers but have protection to prevent DC and clipping reaching the drivers. 502 about 70 watts across 8 ohms, 7100 about 140 watts rms and a 7200 about 264 watts across 8 ohms. The 7100 puts out over 300 at 2 ohms and the 7200 puts out close to 700 watts at 2 ohms.
 
twiiii said:
Cut the frequency in half and calculate. Thats 800 hz for the HF section and 10 HZ for the woofers. Of course if you would use Mac amps you wouldn't need the caps. I'd want a MC 502 for the HR and a MC 7100 for the woofers. If you want power for the woofers a MC 7200. They don't use autoformers but have protection to prevent DC and clipping reaching the drivers. 502 about 70 watts across 8 ohms, 7100 about 140 watts rms and a 7200 about 264 watts across 8 ohms. The 7100 puts out over 300 at 2 ohms and the 7200 puts out close to 700 watts at 2 ohms.
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Is a cap for the woofer nessesary? Mac amps would be nice but unfortunately out of my pocket book range lately....
I've got a Hafler DH-200 for the hf and a AB International Precedent 1110a for the LF.
At least for now...
 
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Quality cap for the woofers would be big bucks. You would need almost 2,000 mfd for 8 ohms at 10 Hz.
 
bowtie427ss said:
Negative.

Suppressing any turn on "pop" from the DH-200 is a good idea. Turn on transients really aren't a big deal for LF drivers, but not something you want to expose HF drivers to if you can avoid it.
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That's a good point! Would installing a thermistor (cl-40) be helpful..
I also have an Laochen E34 tube amp... That might be the ticket to get me going.
 
toddalin said:
A cap will pass a transient.
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Indeed, a good cap should pass it cleanly without imparting any more than a little phase shift.

Suppressing power on/off transients in older amps like a DH-200 is the most practical reason to add a protection circuit that includes muting/delay at turn on.

One could simply switch off or disconnect the load on the amp during each power up. But, humans are not good at being able to consistently remember little steps like that every time.
 
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More questions....
Is there any advantage to using 2 ports as opposed to just having one? Aside from the symmetry aspect?
 
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