Since I was a teenager I've wanted an Altec A7 based stereo system, but space has never allowed such monsters in my home. That is still the situation, but the dream lives on. I've decided to build my own Altec system with a footprint that will allow me to continue living with my wife in the same space. I've collected the following components so far:
- A Pair of 416-8Z woofers in near perfect condition, one of which has just returned from GPA for a complete recone.
- A pair of 511B horns - one of which is NOS brand new from the box, the other in storage since the 1960s
- One 802D driver (as new) and one 808-8A driver, unused and fresh from the factory box. Both of these will be refitted with new 8-ohm diaphragms from GPA.
The cabinets will be furniture-grade 7 cubic foot pieces with the usual over-bracing, yadda, yadda, designed from computer program and vented. Loosely based on the Model 19. Narrow cabinet width will be compensated by greater height. They will be v-shaped to fit in the corner of the room.
Two questions:
- The horns will be mounted on top of the cabinets simply because I want them to be seen. Should I position the woofers at the top of the cabinets as well in order to keep them as close to the horn mouth as possible?
- My biggest concern is crossover design. I want to take advantage of the recent research done by a number of Altec enthusiasts to smooth the horn driver"s frequency response - especially in the 500 - 5000Hz range. My first inclination was to go with a version of the Zilch-designed Z19 crossover, but he favored changing the horn drivers to another brand. I recently ran across the Hiraga-designed network (http://web.archive.org/web/200502060...s/HiragaA5.pdf). Complete background article at: http://wajonaudio.webs.com/Voice%20o...%20theatre.pdf. Although Hiraga's crossover is specifically designed for use with the 288 drivers, it seems that the frequency response modifications are identical to those required for smoothing the 802 drivers.
(I'd like to advise in advance that I have no technical training in electronics, so my understanding of electronics is quite rudimental. I can build crossovers from diagrams, but beyond that I'm at loss.)
I'd appreciate any thoughts you guys have on this project, especially the crossover question. Thanks in advance for any help.
GeeDeeEmm
OK, guys, I know I'm the newcomer here, not part of the club, but surely some of you are willing to share your thoughts on the direction I'm intending to go. I'm sixty-three years old - too old to be learning to be an electrical whiz in order to design these crossovers. I've done the searches here and see no other discussions to guide me in this build when it comes to a non-stock Altec crossover. How 'bout some love for the new kid?
GeeDeeEmm
I don't think anyone is ignoring you. I think the board is a little screwed up right now. And it gets slow around here. But be patient. There is a lot of good help.
Sonic Barbarian
You should do a bit of preliminary work on the size and orientation of the parts. A 511 is 23 1/2" wide across the flange and with an 802 is about 23" deep, horn lip to back of driver or 17 3/4" from the flange to the back of the driver. I just placed mine in a corner and measuring diagonally, I get about 30" across the mounting face to the wall on each side. That's the width of a model 19 and doesn't include the depth of the box. If you make them 7 cuFt they will be shorter than a 19 and may still have the same footprint. It would appear that making them triangular to fit in a corner would move the front face out or reduce the cross sectional area.
Have I misinterpreted the concept?
Here is the corner cabinet I dreamed up a while back, it might give you a little perspective of a corner box and maybe a little inspiration.
http://www.hostboard.com/forums/f700...r-speaker.html
"James, a little knowledge is a dangerous thing!" World's scariest Volvo: [url]http://www.youtube.com/watch?v=AKn-LTNa4rc[/url]
No, you are right on target. After posting, I had the feeling that my initial cabinet dimension estimations were way off, so I did some measuring, as well. What I've come up with is a variation on a cabinet that I already have. The front is (surprise!) 30" wide, 12"deep sidewalls which then taper into a v-shaped rear for corner placement. Height is 16." The cabs are 3.83 cu ft. Eye balling these cabinets, I could easily triple the height while keeping all other measurements intact, for an approximate capacity of 11.5 cu ft - considerably above my original estimate. (Other considerations such as bracing, driver displacement, and double walls would allow me to easily lower the interior volume as needed, if needed.) So, cabinet wise, I'm back to the drawing board.Originally Posted by zelgall
My primary concern at this point, though, is the crossover design. Having no first-hand experience with the frequency curves produced by the Hiraga or Zilch designs, I'm wondering what your thoughts are. I've heard these components using the stock Altec 500Hz crossover, and the in-your-face midrange frequencies are just too much for my taste. What's your opinion?
GeeDeeEmm
- - - Updated - - -
Thanks so much for that thread! Lots of excellent info there.
I'm appreciating all the input, guys. I've been building seat-of-the-pants speaker systems for over forty years now. Only in the last ten or so have I been exposed to the procedures for doing it the right way - thanks to the interweb. Now my bookshelves are filled with speaker-building books, and I have several great sounding builds under my belt using conventional hi-fi speakers built from scratch. But the dream has always been a classic Altec system with a horn on top. Considering my very limited budget and the expense of components, I'd like to do this one right the first time!
GeeDeeEmm
Yeah, I posted some yesterday, then went to this one and was locked out from posting, so tried others and was locked out also; finally gave up trying around 2 am EST after a number of browser reboots, thinking it might be my 'customer no service' AT&T DSL since I've never had this particular problem with Hostboard.
Anyone got any idea why Todd insists on keeping it here?
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Well, thanks for trying to reply, GM. I was looking forward to what you might have to say.
The problem I keep having here is that if I stay on the site long enough, the printed material goes completely blank. Pictures still come through, but no text. I happens on another site using this host, too.
GeedeeEmm
The Zilch crossover uses the same components as a model 19 version but is rearranged to allow bi-amping. It still has the stock model 19 1200 Hz crossover point which may not be the best choice for 511s. It could be reworked but then you would need to basically re-do the whole design. Better to start from scratch or get a crossover designed for the combo and loading you have.
You complain when nobody responds to your specific question within 20 hours (your first and second post were about that far apart) and then don't respond to the solutions presented in response for days. My life is busy and full but when I ask someone else for assistance I always provide an appropriate response for their help.
Perhaps it's different where you live.
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