Help identifying Altec cabinet/model/plans

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zdw11

Member
Joined 2021
#1
Long time listener, first time caller...

I've been looking to start an Altec project.

These cabinets have really gotten my attention.

They claim they're 820's, but the only info on 820's I can find is about corner loaded 821 or 820a/c. Those were driven with 2x803 for LF and 802/H808 for HF. Nothing about this style cabinet. They say the dimensions are Cabinet Dimension(each): 29 3/4" x 23 3/4" x 48"(inches), and the ~24" depth is very appealing to me.

Anyway, I'm looking for any info on these as I'd consider building a pair if I had more to go off of. Maybe this cabinet could benefit from reflex porting like the 817? Has anyone seen cabinets like this? Or similar plans?

If any of you are familiar with these, would you search for 803LF drivers? Would 416s or 515s "work"?

Thanks!
z

Here are the photos from the ad
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#2
Not seen those before. Those are seriously cool looking cabinets.
The 803 drivers were the precursor to the 515 and the 416 which seemed to have a little bit of each in them IIRC. Those cabinets look to be suitable for both them and even the 421. You would be hard pressed to find the 803 and I think it wouldn't be as good as any of the more obvious choices.

Nice find but are they asking a lot for something you could have built for less than that. Either way, you could end up with your own version of a Stanley Screamer type system that I have put my sights on for some time.
 
#4
I remember these from an oldschool "balzaal" (=club) here in Belgium, where older people went dancing on daytime. I did a student job as bartender there about 27 years ago. They did sound good for the old muzik (waltzes, polka's, foxtrot, flemish folk music and dutch/flemish schlager music....) that were played there as far as i remember. They were amped with old Philips amplifiers if i remember right and a pair could easely power a hall for about 250 people in that setup.
 
#5
Thanks everyone. I was a little disheartened to see the plans describe the cab as "a straight horn with 80hz rolloff"

Frankly I'm a bit confused as the cabinets I posted are definitely ported at the bottom, and it's hard to tell if that's included in the plan illustrations. Need to do some more digging...
 
#6
Interesting cabinet, I haven't seen that one before - though I have seen and heard a few 828 cabinets with an extra woofer or subwoofer. But those did not have the second woofer horn flare.

The box does look reflex, judging by the slot on the bottom, and it seems to be meant for an 811 horn.
 
#9
Have you found the internal volume listed somewhere?
How have you calculated that?

I'd imagine that the volume of the "square" 29 3/4" x 23 3/4" x 48" box in the listing would match the volume of the corner horn but who knows?

I really like the look of the cabs and I'm more comfortable going with something taller than a larger footprint like the 817.
 
#10
No, I just looked at external dims for this one and the 828 which I have owned. I'm not even sure that the real internal volume of the 828 cabinet is - but GM and I have both found that it models as if it's 11 cubic feet. I don't think that's the actual volume, but sims are fairly accurate using 11 cubic feet.

IME one nice thing about big cabinets like this is that you have plenty of wiggle room, they aren't super sensitive to modest changes. Very much unlike puny bookshelf speakers or the current anorexic slim towers, the big boxes are not sailing right on the edge of the design envelope.
 
#14
Yeah I don't know about the "tuned to" part. My 828 with 416 woofers didn't go below 60Hz with the original giant port. Closing it down to a slot and putting the cabinets in the room corners got me down into the mid 20s - very solid at ~32 Hz IIRC. With some searching I could figure out what the port tuning was. With two woofers you have more room to play with response shaping.
 
#18
Pano said:
I'm not even sure that the real internal volume of the 828 cabinet is - but GM and I have both found that it models as if it's 11 cubic feet. I don't think that's the actual volume, but sims are fairly accurate using 11 cubic feet.
Click to expand...

Yeah, near enough, but for the record; long ago worked it out to a fare-thee-well and got 17,861.825"^3 = ~10.3367 ft^3.

The factory spec for the 825 = 12.56 ft^3 since the horn flares aren't blocked in, but don't recall ever confirming it, though seems reasonable relative to the 828's.
 
#19
Alas I could not find the measurements - seems I left all that back home. Sorry. I tuned my cabinets ports with near and far measurement and by ear for the best low end extension in my room. The actual tuning frequency is long forgotten.
 
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