Cheap, temporary midwoofers for Heathkit/Altec 811b horns and 401-105 drivers

Hi All,

I just purchased a set of Heathkit/Altec 811b horns and 401-105 drivers (I think they were parted out from a Heathkit AS-101).

Eventually, I'd like to use these to put together something like a Valencia, Model 19, or A7 clone, but I can't afford genuine Altec woofers right now.

Is there anything fun and cheap I could build so I could at enjoy these horns/drivers until I can save up for the real deal woofers?

I was thinking of getting a mini-dsp anyways, so bi-amping and experimenting with crossovers is an option.

Thanks!
 

GM

Member
Joined 2003
Don't need to nowadays, there's an inexpensive (at least relatively speaking) near enough clone of the 416-8B nowadays except with higher power handling to offset its bit lower efficiency, just can't even remember the brand name, much less the model # at the moment. :cuss::headbash::scratch1::sigh:
 

GM

Member
Joined 2003
Any chance it's the Acoustic Elegance TD15M mentioned in this thread?
https://www.diyaudio.com/community/...z-600hz-for-passive-hi-fi-2-way.375230/page-2

What about JBLs? I have a lead on some affordable 2226hs...

If you do think of it, let me know!!
Eh, they somewhat have their roots in vintage Altec, etc., but business wise not a good plan, so seem to have fine tuned their designs to what Altec, etc., might have wound up with over time for its 'top drawer' HIFI/studio monitors they were once known/revered for.

If wanting to 'keep the faith', then use these measured specs to guide you.

That said, to go true vintage you'll want the 803A or 803B/416A 16 ohm drivers or the later 8 ohm 416-8A (measured specs attached)

The late Bill Eckle kindly did a 'cheat sheet' of drivers for the various large, small format speakers.

Having built some, the 2226H is one serious horn driver, but wouldn't use them at home without a separate sub system of equal quality performance, i.e. big/expensive with low Fs, Qt, high Vas such as my 20 ft^3 dual 515B, but that's just me as I got 'spoiled rotten' early on by super high efficiency systems.

Regardless, there's apparently more options available than I recall, so now you've got enough references to make an intelligent decision for the needs of your app. ;)
 

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Eh, they somewhat have their roots in vintage Altec, etc., but business wise not a good plan, so seem to have fine tuned their designs to what Altec, etc., might have wound up with over time for its 'top drawer' HIFI/studio monitors they were once known/revered for.

If wanting to 'keep the faith', then use these measured specs to guide you.

That said, to go true vintage you'll want the 803A or 803B/416A 16 ohm drivers or the later 8 ohm 416-8A (measured specs attached)

The late Bill Eckle kindly did a 'cheat sheet' of drivers for the various large, small format speakers.

Having built some, the 2226H is one serious horn driver, but wouldn't use them at home without a separate sub system of equal quality performance, i.e. big/expensive with low Fs, Qt, high Vas such as my 20 ft^3 dual 515B, but that's just me as I got 'spoiled rotten' early on by super high efficiency systems.

Regardless, there's apparently more options available than I recall, so now you've got enough references to make an intelligent decision for the needs of your app. ;)

This is all so great! thank you.
 
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I might try these "GRS K-33" they only make a 4ohm version though (maybe fine with miniDSP?):
https://www.parts-express.com/GRS-K...oofer-for-Klipsch-Speakers-292-830?quantity=1

Or, super bargain basement "GRS 15PT-8":
https://www.parts-express.com/GRS-1...-Woofer-3-Voice-Coil-8-Ohm-292-808?quantity=1

The idea being to get experience putting something together and testing without breaking the bank. Then save up for the real deal woofers and materials for a nice enclosure.

I'm using the specs from Great Plains Audio's 416-8B to guide me, and still figuring out how all the T-S parameters influence each other and what they work with, so bear with me if these are way wrong!
 
Horns and drivers came today. Very cool, tried them out (no woofers, just wanted to make sure they worked) with a dsp highpass at 800hz , and then 1200hz. I see why people call them shouty. I was pretty excited by what I heard nonetheless, crisp transients, very lifelike.

I ordered a used pair of B&C 15 PH 40s today off reverb for the woofers:
https://www.bcspeakers.com/media/W1siZiIsIjIwMTcvMDQvMjcvMTVfNDZfMDdfMjE5XzE1UEg0MC5wZGYiXV0

Seems like they're relatively close in spec to the 416 8b - though I haven't found a speaker that has anywhere near the Vas of the 416... Is there a reason for that? Plus they were pretty cheap.

Still plan to bi-amp with a mini-dsp. Thinking it would be fun to power the horns with tubes. Are there tube amp kits folks recommend?

Now to figure out cabinets. No Windows machine at home, so using speaker box lite for now...

IMG_4304.jpeg IMG_4306.jpeg
 
Woofers should be here Tuesday, I also picked up a Motorola Push Pull 12ax7/EL84 rebuilt console amp to power the horns (not the three channel one, but a stereo model). Planning on using a McIntosh MC2125 for the woofers.

Dimensions for the woofer cabs:

W 23.5, H 33, D 16.75 for a net internal volume of 5.9 ft^3 (Vb = 8.6/1.44 and rounding down so I can fit all my cuts on to two sheets of ply).

Two ports, 3" diameter, 2.2" long. I have no idea if that's right. I had to use speakerbox lite to design the cabs, as I don't have access to a windows machine.

Look ok? This is my first attempt at designing an enclosure...

Screen Shot 2023-08-27 at 3.48.08 PM.jpeg Screen Shot 2023-08-27 at 3.58.21 PM.jpeg
 
Hmm, FWIW I get a bit less net Vb, but well within +/- 10%, so based on your math, Hornresp (HR) 'says' dual 3"/38 Hz = 1.35" long vents, so currently tuned too low and response looks much more like I expected + IM(limited)E vetting SBL it's best to avoid unless willing to spend some quality time fine tuning the vent, cab damping preferably 'in situ' (final location).

That said, while the pioneer's decreed tuning to Fs was best, they stipulated that it meant having equal amplitude impedance peaks based on high output impedance tube systems which doesn't necessarily mean free air Fs, but in box Fs, so for this, HR calcs 35.6 Hz/1.97" long, so your call what tuning to use, though if you eventually go SET tube, then suggest actually tuning via the classic way of measured equal amplitude impedance peaks to max out its (mid) bass response.

Since yours is a classic alignment, hence 'voiced' to be a bit 'lively', it in theory only needs the pioneer's back, top, one side wall opposite the driver, i.e. no need to cover the whole panel, just ~71% centered around the driver. Still, best to add a removable panel just in case you want to reduce/increase damping.
 
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After all that, the woofers arrived yesterday damaged from shipping, and both magnets are seized. Bummer.

So, I ordered a pair of Lavoce WXF woofers from Parts Express.

My experience with most online calculators/box designers has been mixed at best, I might have access to a windows machine when I start back up at school in the fall, but in the meantime, is there a way I can calculate this stuff by hand? Even if it's cumbersome and time consuming, I'm up for the challenge.
 

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Using ajdesigner.com and double checking by calculating manually using the information here: https://audiojudgement.com/bass-reflex-alignments-explained/ I get:

Vb = 2.6ft^3, Fb = 35hz with a port length of 7" at 4" in diameter.
This is for the SBB4 alignment, as a mix engineer, low frequency transient response is important to me, so this felt like the best fit.
(red curve on the attached chart)

Screen Shot 2023-08-30 at 11.39.40 AM.png

Manufacturer recommended enclosure is Vb = 4.1ft^3, Fb =45
Using the vintage guidelines (Vb = Vas/1.44, Fb = Fs) I get Vb = 6.3ft^3, Fb = 35 with two ports at 4" x 6"

ajdesigner.com doesn't allow me to change Vb, only gives recommended Vb based on chosen alignments, so I still had to use speakerboxlite to draw curves and calculate the manufacturer recommended Vb and the 'vintage' Vb.

both of these looked pretty good too, the 'vintage' having the best low frequency response, however:

Ergonomically, I'm leaning towards the 2.6ft^3 enclosure option as I'll potentially use these once a month for a hifi-happy hour DJ set at a fancy restaurant in town, and will be making subwoofers anyways.
I can make a 19" by 28.5" by 12" enclosure with 3/4 ply, and a 19" wide box for the 811s would fit perfectly on top.

Screen Shot 2023-08-30 at 11.35.47 AM.png

Do I need to worry about port chuff or compression with one 4" diameter port, should I get flared ports?

Woofers just got dropped off by UPS, fingers crossed they arrived in good shape!!

Thanks for all your help!!!!
 
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