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In Reply to: RE: Questions for Salectric and Lokie re P15LL posted by bald2 on March 10, 2017 at 10:53:39
What compression driver are you going to use on the 32 horn?
I can send you some cabinet and crossover information later this weekend after I return home from a trip.
Hi, sorry to butt in but am i right in thinking you have your 32 horn mounted inside the cab, and that you previously had altec 414s in the same cab?
Im looking at building a bigger cab so i can house everything inside. Im currently using a 614 cab with 414, 32 horn, gpa902 and jelabs crossovers and its not popular with the wife having the horn on top!
I saw quite an elegant solution where a french chap made a bigger cab in the style of a shindo speaker but having the port on the bottom is a bit beyond me...
Maybe I'm telling you something you already know, but what we are making here is a poor mans Western Electric 753C. In my opinion, one of the most beautiful speakers on the planet.
Mint condition will get $20k per speaker.
Yes, that's right. My 32 horns have always been mounted in the same cabinet as the woofer, similar to the Western Electric 753. I started with the 414 woofers in a 3.2 cu ft cabinet, and later replaced them with the 15" Jensen P15LL in the same cabinets. I eventually built new cabinets that were 5 cu ft thinking I would get deeper bass. Unfortunately the bigger cabinets just never sounded as good as the 3.2 cabinets. I am not sure why, but this could be due to other differences and not just the cabinet volume. In any event, the easy solution was to go back to the 3.2 cabinets which is still what I am using today.
While I have never tried the 32 horn outside the woofer cabinet, I did try an Emilar horn both inside and outside the woofer cabinet, and I thought it sounded better when mounted directly to the cabinet. The sound was more coherent, more like a single driver, than when the horn was on top of the woofer cabinet.
I think the cab im using (the 614) is about 3.2cf and after reading a comment on the jelabs blog last year i was convinced a larger cab would be better and at the same time allow me to get the horn hidden away, and now that i have some room i was going to give it a go.
Back to the drawing board then...
My cabs are 4.5 cubic feet but I'm not going to put the 32 inside, as the magnets prevent close alignment of drivers. Center to center distance would be acceptable yet this places the 414 too low for listening, even on stands.
I'm also going to compare the 32 with a pair of Edgar salad bowl horns before making a decision and mounting on top will be helpful for starters...
The JE Labs crossover models at about 1150hz with my drivers, incidentally (16 ohm EA 175s and 16 ohm 414Zs). The DCR on all is between 11 and 12 ohms but my understanding is that AC is more important, in actual application...
I gather that having the magnets in close proximity isnt a problem, the altec 9849 was designed this way.
My plan now is to try and remove my speakers front and make a new one copying the altec 9849 as the dimensions are otherwise the same. I still cant help feeling a bigger cabinet would be better, and have found discussions on a french forum where somone is reccomending 150-180 litre cabinets (about 5.2-6.3 cubic feet.
Your cabinet of 4.5 sounds promising, id be very interested in how they turn out.
I'm probably going to use the Emilar EA 175 or Altec 802Ds, if I can find some at a reasonable price.
My email is harryzweben@yahoo
I sent you an email. Let me know if you didn't receive it.
"Reasonable Price" is relative. The current benchmark is the GPA 802G at about $500 a pair. They are new and guaranteed to meet spec. If you find used 802's on Ebay you may need to replace the diaphragms ($90 from GPA) or even remagnetize them. Unless you get them really cheap you'll end up spending the same price. However you may get lucky. I found a pair of 802D's with new diaphragms for a good price from a fellow enthusiast who was looking just to get his money back.
There is currently a pair of 802D's on Ebay with a field coil conversion. They are very tempting. But with more than two days to go they are at $385/pair. I can see them going for some silly money.
The field coil conversion, may, or may not be better than the original alnico. Do not assume, because its a field coil, that it is automatically better than the alnico !!
More than a dozen RCA filed coil drivers ( MI-1428B and MI-1443s ) I have personally owned, and have passed through my hands. I was an early user and proponent of these, ( and I owned six RCA Ubangie Bass Horns, all at one time ). Today, I am VERY happy having ALTEC alnico 802Ds, remagged and GPA re-diaphragmed. YMMV.
There are other areas where we can gain performance. IMHO, "I" would NOT ever buy a magnet "converted" 802 unless I was able to A-B them in a relaxed manner, over time, on my system. No-knowing - WHAT will sound best. You better have a GOOD amp and a good source, and optimized wiring / a truly optimized crossover, when you compare 'em, to make a good determination.
My post's point is " a field coil is NOT necessarily automatically better , AND, it may be automatically worse."
See if anyone here can figure out why this might be so, technically. I know someone, very experienced with early movie theater W.E. RCA, etc, who has this figured out.
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