I restarted the Altec A7 Voice of the Theatre renewal with Tim and Colin, soo to follow into the High Efficiency 2 way hot setups will be Joe I hope, he is going 2-way, but not VOTT but reflex and Altec horn/driver.

Anyways, this is about a 16" coaxial driver made by a Bill Hanshack who runs Great Plains audio. Bill was one of the last GOOD engineers working for Altec before they let the bean counters run them out of business.

The woofer cone is a 15" 515 variant and a 902 driver on a Mantaray horn lens. Crossover I am using is the N1500 (1500hz) with 2 different adjustable controls for HF compensation adjustment, and a MF adjustment.

I have mine in 4 cubic ft cabs tuned to 40hz(temporary until my cabinet make completes the 10 cubic ft enclosures for me(exterior - interior I am going to guess at around 8.5 cubic ft after bracing and drivers and ports are taken into consideration. I am thinking of going with a port of 6" x 10" x 14" deep for around 28hz(at least that is what my feeble mind is thinking).

Current evaluation using Yamamoto 45 SET amp/DeHavilland - Verve pre/Audio Note -cd21x cdplayer:

The pinpoint imaging is nice and the soundstage sets back well enough. The bass goes deep but is thin(tolerable - bigger box will help out here). The treble sounds decent enough even though the plastic Mantaray horn is thin plastic.

This is a speaker system for someone who don't want to tweak(other than crossover controls), imaging is good and I would recommend these if you have a large room.

Unlike most High Efficiency speakers, this speaker likes more power to come alive. The 2 wpc Yamamoto did not wake them up like my McIntosh MC-240(40wpc).

More on this will follow, time for more beers and currently listening to "Talking Heads live in concert CD).

If anyone has any specific questions to ask about the 704-8A or willing to travel to Columbus, Ohio to hear them, just drop me a line through the forum(e-mail).

Ron

The SV811-10 amp is coming along nicely. I should have it done in about a month. Might be a good time to have a gathering here in Cinci......Colin

So far if things keep going the same direction, start with 811B horn and 806 drivers, 1.6khz crossover (ala Pi system) and trying to find out which 15" driver for the bottom will be used in the Bozak cabinets.

Ron

These speakers have given me the opportunity to compare a coaxial system vs separate horn systems. I have to say there is something about a larger horn that serves my listening preference. I believe that JBL's 15" driver offering meshes better with a horn crossed over at 1500hz than the Altec offerings.

At least owning these coax drivers for a short time was worth the trouble. Once finished with the new custom cabinets will go on loan to a few friends I have discussed this with. They all have larger rooms than me and different tastes in music.

I wish I had a pair of Jensen Imperial horns to play these with as I bet they would be very impressive.

Regards, Ron

Your room observation surprises me actually. I used Altec 19’s and 604’s in the same small 11 x 17 room (but at different times and systems) and felt the co-ax was much better suited to that small space. I love the 19’s but feel you have to get pretty far back from a large horn design before they really click in.

I’ll be building a larger horn system this summer (Altec 902 on a 400Hz round wood tractrix and Altec 416-8A woofer) so will get to try this comparison again. Results may be different in my current system and dedicated 12 x 22 listening room but I can’t see ever giving up my 604’s, even if demoted to another room.

Keep us posted on future ‘704’ observations.

I have found that Altec 1" drivers play much better at 1.6khz than at 800hz or 500hz.

The crossover on the 704's is a Altec N1500 (1500hz) and it seems very close from what I could see on the exposed side to resemble the crossover for the Model 19.

Bill Epstein is building my new cabs for the 704's. It will start out as a 10 cu ft (exterior) and will have approx 8.5 cu ft after subtracting the bracing and driver volumes. I told Bill I wanted a port size of 6" x 10" x 14" deep. Not sure how exact that will be, but I bet with that size cabinet it should work out okay.

Currently the 4.5 cubic ft cab tuned to 40hz has bass, but I would have to admit it is down approx 6db relative to everything else, so it sounds kind of thin.

This system will not replace my separate horn-loaded systems that I like to tinker with. As soon as I get some room in the house, I plan to install my 4 16 ohm 2226J's (JBL) in the 4648 cabinets and run a 399 (Altec 288K) 1.4" driver on 311-60 horn and see what happens at 800hz crossover. I have tried it out with a 1.6khz crossover and was surprised that it played the HF notes almost as good as my 1" drivers!!!

I would love to have a 1.4" throat round traxtix horn (ala Edgar) with a 650hz flare rate to be used at 800hz, and without using a adaptor like I did before with my 288C on 350hz Edgarhorn.

When is your next trip across the border here to Ohio???

Ron

• Altec gear in a Pi box

704-8A specs are as follows:

fs 30.9hz
Qts .261
Qms 8.49
Qes .270
Vas 16.35 ft
Eff 4.87%/98.5db/watt

I tried Pi-align and it gave me a 4 cu ft box, but I am still trying to figure out how to use it. Why does it ask for bottom cutoff, I would think the program would figure it out. I just used 40hz since I did not know what it was asking!

What do you come up with? Bill is building 10 cu ft box for me and that is exterior, I expect after bracing and driver accounted for that I will have approx 8.5 cu ft.

And yes, I used the port size from the 416 info since I figured it would be close!

Any comments here????

Regards, Ron

One place where my plans changed a little was the throat – I measured the 902 exit expecting 1” but found it’s more like .875” so my tractrix throat will start with that dimension. I know it’s not much but I think it might be best to have a smooth transition from driver to horn throat without a .063” step in there.

I know a bunch of the software models say 4 to 5ft3 for flat alignment with these Altecs but in my experience, if you want full range, larger is better. I think you are in the right ballpark with the cabinets BillE is building. What baffle width are you using? As much as they look prettier, I found narrow baffle cabs sounded a little ‘thin’ in the upper bass lower mids with the 604’s and a 26” wide baffle (as used in the 620) yields better balance making that famous ‘604 midrange shout’ a touch less noticeable.

I sure would like to hear a purpose built round wood tractrix on an Alnico Altec 1.4” driver, if I ever find a pair of these at a reasonable price I’ll consider building some but with the price of Altecs these days, I don’t see this happening anytime soon.

No plans for travel anywhere near your place right now Ron, I really have to get down there! Do you ever get anywhere near Toronto? I’d love to have you over.