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Altec XO recap experience anyone?

Zilch said:
I believe those are plastic conduit clamps Wojo used there.... :yes:
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Zilch, you have good eyes and know what you're talking about, plastic retainers, aluminum fasteners and ferrules, no ferrous inductance interference here!! There's not enough real estate on those crossovers plates to lay them out any different so horizontal mounting is not an option. :sigh:
 
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dgwojo said:
Personally I wouldn't do that to N1209's, the 1209's had some EQ built in EQ for the A7 cabinet, the model was the 1236, I bought a pair of 1236's new in 1977, still have them. If building a simple 2nd order Butterworth, I'd just mount everything to a piece of wood, just my thoughts, Dave.
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Thanks Dave.
Is it advisable to add an L-pad to this XO if building from scratch?
 
Russellc said:
Details & schemo much appreciated. Always on the lookout for a good A7 crossover.

Thanks,
Russellc
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That will take some effort since they're in the cabinets and I might not be able to measure the inductors while in-circuit. Dave.
 
Zilch said:
N1209-8A is the basis of the improved crossover Dc270 built.

Everyone should be using HF comp to shut down A7 midrange "shout" and extend the VHF.

N801-8A must be followed with 30904 or 30923 for similar effect.

See Markwart.... :yes:
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Zilch

how do you shut down de midrange shout as you state? thats my problem. i am rebuilding the 1209 xovers and i would love to decrease the shout on the horns. what changes do you recomend?
thanks
 
Djsergei said:
Zilch

how do you shut down de midrange shout as you state? thats my problem. i am rebuilding the 1209 xovers and i would love to decrease the shout on the horns. what changes do you recomend?
thanks
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Sadly and unfortunately, Zilch passed away some years ago. He has lots of info along those lines in the econowave thread on this forum, various threads on the Lansing Heritage site. His last designs for these types of crossovers can be seen on the Parts Express forum, a thread called "Flex your PCD Meddle" or something like that.

The compensation is usually specific to theHF driver, and the horn or waveguide used, and the woofer mid it is being mated to. You will notice that typically the HF driver is quite a bit more efficient that the woofer/midrange. Because of physics, these HF drivers (compression drivers like Altec) have a "Hay stack" response pattern which gives the shout...the compensation doesn't really boost the ends of the haystack up, but pushes the midrange down. this not only flattens the frequency response, but also lowers the efficiency to match the woofer/ mid efficiency, and eliminates the shout.

Some High frequency drivers also have spike that must be filtered out, Altec HF drivers typically don't have this, at least not the 802 and 902 series.

I would suggest you read the entire gigantic econowave thread which covers this theory nicely. More modern methods were worked out for compensation in the "PCD meddle" thread on Parts express.

Russellc
 
Pick up a set of 30904 attenuation boards and just use the HF part of it or simply build a set. May not be perfect but made a big difference for the better on my Valencia copy's. I'm using 902 drivers on the horn.

BillWojo
 
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