1" Compression Driver & 1st Order Crossover Capacitor Choice?

At long last, I am acquiring some parts for a two-way Altec build. I have 32a horns on the way, 414A in the house, 614 cabs still needed, and a pair of B&C DE250 8 ohm or Altec 902 8 ohm. Here are a few quick questions:

* your preference for 1st order crossover point 5-8,000 hz and capacitor type(oil or film)/brand (414 runs wide open, only the cap on the highs)

* Which driver have you preferred of any of the following: 802D or G, 902, B&C 250, or Emilar EA175

I'm in La Crosse, WI, and I'm looking for some 614D cabinets ready to go, but I'll seek out a builder if I can't find a pair.

I'm hoping this system will be a worthy substitute in my 8x14 room. I used to have A7 and at another time a split 210 cab w/ EVHR9040A horns. Want the sound without the size.

Thanks for your thoughts!
 
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I just went down this road with slightly different components…414z and 32c in an open back cab (just over 11” on each side of the 414z) I like what OB adds to the sound stage.

I started with 902-8 drivers and later picked up a pair of mint 807-8 both with Symbiotik phrams. These are slightly less efficient than the 802 drivers, but I think they are a better match to the 414 by allowing to do away with the L-pad. The Symbiotik diaphragms roll off on the top end (which I can’t hear). The GPA critical listening diaphragm that je2a3 recommended may be a better choice.

I started my crossover at 5uf/4000hz which is in the area of where the 414 rolls off. I slowly increased capacitance with long listening cessions in between. I’m at 7.8uf and 7.4uf which is 2700hz. At 7.8uf the horn starts to dominate the 414 on the top end …more in the room. At 7.4uf I have a wider, deeper sound stage.

This is for my system, I’m sure yours will sound different. The fun is finding the sound you like.
 
Thanks so much for the detailed reply - lots of great information. Are you satisfied with the bass? My room is so narrow, that it is tough to get a large enough panel in the room. I think I will buy some inexpensive caps to find the best range, and then I'll try a few flavors at that value. Also great to know about the 807 as I hadn't really considered that driver. So many options, so little time... Thanks again!
 
Bass…NO…haven’t gone there exactly. I have my 605Bs in H-frames powered by sub woofer plate amps. (Not the horns) I like the sound of the bass, but I’m not sure of where the 414z rolls off in an open baffle configuration. I will have to lean on the wiser here to get me in the ballpark.

Buy some inexpensive .47uf and 1.0uf caps to parallel with some larger caps to walk your way around your crossover point.
 
Bass…NO…haven’t gone there exactly. I have my 605Bs in H-frames powered by sub woofer plate amps. (Not the horns) I like the sound of the bass, but I’m not sure of where the 414z rolls off in an open baffle configuration. I will have to lean on the wiser here to get me in the ballpark.

Buy some inexpensive .47uf and 1.0uf caps to parallel with some larger caps to walk your way around your crossover point.
This is what I would suggest as well. Get some inexpensive pp caps, and find the right ~frequency. Then buy some nice high voltage oil caps, maybe bypassed with very small value, high voltage pp caps like the CDE 940/942, etc. I use this basic recipe on my emilar ec-175/ea-175s, and de-250's.

Cheers,
Gable
 
Gable - thanks for weighing in. I have a pair of 902, a pair of B&C 250, and I see some Emilar EA175 that I might try to pick up. That should be a great start for drivers. I'll gather up some resistors and caps for a range of crossover points and 5-12 db of attenuation. Can't wait to get my 32a horns in the house!
 
Gable - thanks for weighing in. I have a pair of 902, a pair of B&C 250, and I see some Emilar EA175 that I might try to pick up. That should be a great start for drivers. I'll gather up some resistors and caps for a range of crossover points and 5-12 db of attenuation. Can't wait to get my 32a horns in the house!

If you can, I highly recommend autoformer attenuation, intact audio makes some very nice units, and there's the Werner Jagusch(sp?) ones on ebay some times. I have some of Werner's, and they are phenomenal. Lots of threads talking about those and how to implement.

Cheers,
Gable
 
I have thought of using autoformers. I think I still have a pair (possibly Werner's) from an abandoned Klipsch project. I'll have to dig those out. Not sure how to terminate with resistors to keep a steady impedance, so I'll have to look for those conversations.
 
Not sure how to terminate with resistors to keep a steady impedance, so I'll have to look for those conversations.
If you go the fixed L-pad route, here’s a calculator I’ve used in the past.


Fun project, keep us posted on what you end up doing!
 
I have thought of using autoformers. I think I still have a pair (possibly Werner's) from an abandoned Klipsch project. I'll have to dig those out. Not sure how to terminate with resistors to keep a steady impedance, so I'll have to look for those conversations.

This helped me when I was experimenting with mine:


There is an 'rshunt' calculator on that page as well.

Cheers,
Gable
 
If you go the fixed L-pad route, here’s a calculator I’ve used in the past.


Fun project, keep us posted on what you end up doing!

The fixed l-pad route can be a great one, inexpensive and easy to experiment. Get some values figured out ahead of time, order a handful of values and solder until it sounds right :D
 
These Russian XO caps are excellent for XO experimentation.

My two DIY "final" XO's have vintage PIO "oil cans" and the other has Mundorf MCap Supreme.

The old PIO's are good for helping the horns play nice with direct radiators. The 32 horn doesn't need much help as it integrates so naturally so, I use the Mundorf on those.... which seem to do everything right with my ears.
 

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