altec lansing 288c drivers

[tade]

ok, getting a bit of a hang at this crossover stuff. I have come up with based on the crossover on esp audio, and modified by the crossover component calculator there. I am going to power it with a 12v transformer and the simple power supply also pilched from esp.

i plan on using this schematic:
http://sound.westhost.com/p09_fig1a.gif

Here is the schematic for the power supply:
http://sound.westhost.com/project05.htm


I have selected a capacitance of 68nf and a resistance of 3.31k ohms.

 

[tade]

I built a tractrix horn for these drivers. Calculated for 450hz. It was the shortest horn i could build for the throat size. I believe that this will help minimize hornness. Made from pine "allwood" bought from lowes. I used the jigsaw glue and file method. they are very round.

Sound is lovely!

pic: http://img.photobucket.com/albums/v331/StilettoOne/Horn.jpg

 

[vuki]

Very nice!
Congratulations!!!

 

[tade]

thanks. later i shall take some better pictures. I am thinking about stainign them a deep royal purple and then polishing with wax for a smooth but not shiney surface.

Do you have any tips for finishing pine?

 

[GM]

http://www.sankey.ws/pine.html

 

[tade]

Thanks for the pine link, here are some more pictures:

http://img.photobucket.com/albums/v331/StilettoOne/Horn/Abyss.jpg
http://img.photobucket.com/albums/v331/StilettoOne/Horn/Corner.jpg
http://img.photobucket.com/albums/v331/StilettoOne/Horn/Side.jpg
http://img.photobucket.com/albums/v331/StilettoOne/Horn/Top.jpg

The horn sounds lovely but the twelve inch sounds boomy in its three cubnic foot unbraced sub cabinet. gona build nice two cubic foot sealed boxes for the woofers next. The object the horn is resting on is a two way bookshelf.

 

[KT]

Tade,

Awesome find! You are very lucky. There's something about the sound of good horns that's just mesmerizing.

Aren't unexpected dumpster finds great? Gotta love it.

I came upon a terrific find myself a couple of years ago: 6 pairs of Altec 755E drivers (12 in all) being thrown out by my workplace when they were revamping an auditorium. The 2 PA cabinets they were housed in had been replaced by another system years (decades?) before, but cabs were still hanging on the wall and the drivers turned out to be in mint-looking condition and they sound great.

I'm jealous of your horns, though. I love that involving horn sound when driven by 300B's.

Nice find!

Best,
KT

 

[tade]

300b? I assume a sweet tube amp? SE? What kind of options do i have with these horns in terms of tube amplification? I am using an NAD7175PE tuner/pre/power amp.

 

[KT]

Tade,

I haven't tried the VOT type horns with my tube amps, just the home audio types by Klipsch.

You do owe it to yoursef to try some good tubes with your horns, however. Depending on your listening tastes, they may very well blow you away for good!

SE is a top choice, but if that's too much of an investment to start off with, a good PP amp like the Scott 299B or 222C receiver, or the Dynaco ST-35 should sound really good with them.

Another choice you may want to try are some of the class-D amps, like the DIYparadise Charlize or a modified Sonic Impact.

The modded Sonic Impact is an interesting case. It has a fast, dynamic sound that's really lively, gripping, and even somewhat warm. But with the dynamic speakers I've used it on it has a slight edginess in the upper-midrange and treble that makes it, ultimately, hard to relax into. When I ran it into a pair Klipsch Heresies (horn mid and tweeter) that my brother is using, however, the synergy was magical. Fast, dynamic, lively, involving, extremely clear, but also warmish and musical. No hint of the harshness in the treble or upper-midrange. A very lively and involving sound that's fast, controlled, and tuneful with a nice dose of elasticity and bounce. My brother loves the pairing more than either a Dynaco ST-35 or an Audio Note Kit One 300B amp with the Heresies.

The Charlize is not as fast and lively sounding as the modded Sonic Impact, but it is overall more balanced, refined, and relaxing, especially with Blackgate N's replacing the Cerefine input caps. I haven't tried the Charlize with the horns, though, so I don't know which amp would come out on top with them.

On the dynamic speakers I'm listening to right now, the Charlize gets the nod for overall long-term listenability, but the Sonic Impact gets the nod for liveliness, high-rez sound, and excitement, but only for short doses. With the Heresies (with damping on horns and oil-caps in crossover), though, I think the modded SI can be a great long-term solution.

So you might want to try one of the above (and don't forget the UCD amps, either). Could be a good match for your cool Altecs.

Best,
KT

 

[tade]

hmm, perhaps in the interim i shall pick up and futz around with a sonic impact amp. What should i expect when using it to drive 24 ohm speakers? Understandably less wattage, a third as much as compared to eight ohm? So if the SI has a useable range of three watts that gives me one watt. Which gives me 115db. I suppose that is listenable. : )

I think these speakers being so efficient will allow me to experiement with amps without having to invest too much. I think the timeline should go something like this:

Bass box
second horn
second bass box
second half of crossover
(insert listening pleasure here)
crossover box
finish cabs (spikes)
build equipment rack
intergrate record player
tube amp for the horns
tube preamp for the record player/ general tube pre
stamp collecting?

: ) thanks

 

[KT]

Tade,

Hmmm... wasn't aware that the drivers were 24 ohms. I'm not sure what the effect of driving 24 ohms with a Sonic Impact will be.

But the SI is so affordable, there's really no reason not to try it.

Heresies were 8 ohms nominal, btw.

Best,
KT