# Altec 416 8A box requirements?



## nelsondog

Is there someone who can suggest the size of ported enclosure for this woofer?
Thanks for looking!


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## GPM

Greets!

Yes, but...... these are old drivers that are often re-coned and with the wrong kits to boot, so while I have some measured T/S specs they may not be worth much beyond giving you a possibly too large cab. Anyway, Altec used it in a variety of cab alignments ranging from around 3.1 - 12 ft^3 depending on how much LF gain BW was desired and/or how much output impedance it was driven with, so how big can you 'afford' and what will you be driving it with?

Also, are you wanting some specific dims such as width or height, i.e. standalone 'sub' or tall cab (aka MLTL) to mount a horn either in or on top of it or prefer to just build one of the factory designs?

GM


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## nelsondog

If I were to guess I would say one of the drivers I have has been re-coned. 
The cab size I can afford is only dictated by the height and depth 25" H x 23" D. I would like to keep in the 5 cf area for ascetics alone.
I'm using a solid state class A amp with around 15~20w/p/c
I want to reinforce the open baffle set-up I have in our garage / workshop. Maybe ported is not the correct way to go, I don't know for sure. One thing I do know is I don't think I'm up to building a horn.
I just want a bass life in my music and I have these woofers to hopefully complement my Altec 420A.
Think you can help me?
Brian


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## GPM

Well, in ~5 ft^3 net it will only have a ~50 Hz F3 when placed out away from walls/corners, so assuming that's acceptable:

H = 23.5"
W x D = 21.375" x 18.25" 
driver down 11.06"
dual 4" diameter x 4" long vents down 21" on either side of the driver

All dims i.d. and approximate. Line the top, back and one side wall with 1" acoustic fiberglass insulation or similar.

GM


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## nelsondog

What would it take to get 35 ~ 40Hz, cabs placed in corners and against wall?


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## GPM

A speaker's F3 doesn't change with boundary loading, though due to my poor wording I can see how it can be interpreted this way. What I meant to imply is that with shelving EQ its effective F3 can be lowered by trading increased acoustic efficiency for more 'flat' gain BW. 

To lower the proposed speaker alignment's F3 requires it be a T/S max flat one since above/below it all others result in a higher F3 and since its increased Vb yields a bit more in-room tuning flexibility I recommend increasing it to at least ~6.67 ft^3 and preferably Altec's 8 ft^3 net recommendation if for no reason than these are 'mystery' drivers WRT their measured specs and potential for enough mismatch that they may require different alignments to sound equal.

Anyway, since the 5 ft^3 cab is tuned in the high 30s, using EQ and lowering its tuning a bit will get you there if up against a wall, ergo in a corner a tuning around Fs will lower it even more, though the vents will have to be quite long, increasing the cab size a bit, so it may be better overall to use it sealed in this location.

GM


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## nelsondog

Same volume for sealed then?


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## GPM

Without knowing the driver's actual specs and the room gain curve, don't have a clue. All I can say is that with my specs it's a ~0.62 Qtc alignment and that the theoretical room gain curve is +12 dB/octave below the room's 1st axial mode (~565 divided by the room's longest dim in feet if rectangular), ergo the ideal sealed alignment is a T/S max flat 0.707 Qtc with the appropriate driver Fs to inversely mirror the room curve.

As a general rule-of-thumb though, a low Fs/~0.6 Qtc alignment can be tuned 'close enough' to most average size rooms by adjusting its box volume (Vb) if you don't want to use digital EQ for whatever reason, so if my specs are ~accurate then the short answer is yes with ~3.625 ft^3 being its 0.707 Qtc alignment.

GM


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## nelsondog

Ok then, 3.625 cf, sealed, I'll try...
I could have guessed my way through trial and error and eventually being disheartened I would have given up. Thank you very much!
I the case you have never heard about Lampizator, I'd like to pass on this website: http://www.lampizator.eu/
I find it quite interesting.
Please let me know what you think about it.
Brian


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## GPM

Youre welcome!

??? I didn't say build the small cab, just progressively downsize the 5 ft^3 one if need be, though frankly, it probably will need to be larger unless the drivers spent their life in acoustically small cabs or horn loaded.

Yes, thanks, I'm familiar with Lukasz's site, some good stuff there. BTW, there's a dedicated forum for real Altec equipment: http://www.hostboard.com/forums/altec-users-board/

Anyway, would appreciate an update once you get them dialed in.

GM


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## dnaples

These woofers were once used in the Voice of the Theater speakers. They were my first DIY speakers. I had the 16 ohm versions including the 511B horns and 802 drivers. I later built two more pair using the 8 ohm drivers for a neighbor to use with his band. I think I may still have a copy of the plans that includes other cabinets Altec made that used these woofers. I'll check.
Don


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## GPM

FYI, for some factory plans/suggestions: http://www.lansingheritage.org/html/altec/plans/altec-plans.htm

If you can add any, it would be much appreciated since AFAIK EV destroyed all the plant's records after the buyout except for then current products. 
GM


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## dnaples

The plans I have are from the 1968 manual listed on the site you referenced.
The copy I scanned of the Altec 861 is clearer than what is shown on the link you provided. See:
http://woodartistry.com/external/Altec/Altec1.jpg
I think this design meets the requested specifications.
Don


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## 1Michael

The actual, original box dimensions for the voice of the theater studio monitors was H 4Ft W 3Ft D 2.5 Ft according to my measuring tape...


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## GPM

dnaples said:


> The plans I have are from the 1968 manual listed on the site you referenced.
> 
> I think this design meets the requested specifications.
> Don


Ah! Yeah, that's not the best of scans. I have the original, but have never gotten around to scanning it. 

I believe this cab would need to be tuned lower for corner loading and for sure much better constructed for best performance.

GM


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## GPM

buggers said:


> The actual, original box dimensions for the voice of the theater studio monitors was H 4Ft W 3Ft D 2.5 Ft according to my measuring tape...


Interesting, which model are you referring to? The largest Altec studio monitors I'm aware of is the bit smaller 9848, though AFAIK it wasn't marketed as a VOTT studio monitor. 

GM


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## dnaples

buggers said:


> The actual, original box dimensions for the voice of the theater studio monitors was H 4Ft W 3Ft D 2.5 Ft according to my measuring tape...


You are close with your measurement estimates.
The drawing I posted is in response to the original request for a vented enclosure that could be used with the 416A woofer. This is not the VOTT drawings. The VOTT speakers are 42" x 30" x 24" but had two configurations. One was with the 511B horn on top (I made mine enclosing the top mounted horn, so they were taller). The other was with the speaker turned upside down and putting the horn in the port (with one panel removed to compensate for the space the horn displaces). For such a large bass reflex speaker, you would think the bass would be good. It was muddy, and the horns ring. Taping the horns did help some. 

I next moved to making some JBL-S8 Studio Monitors that were much smaller and had much cleaner bass. These were the same drivers JBL used in the Paragon speaker system. With a passive radiator added, these were the Olympus and Sovereign speakers. (I still have these plans as well) I prefered the vented enclosure. JBL later made them available as a commercial speaker. I don't recall the model but a less expensive version that was close was the L-200. It used less expensive drivers but had the same cabinet.


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## jean

Hello,
i just saw this thread and i want to give an advice based on personal experience. A perfect enclosure for the Altec 416 is the Onken enclosure, which i've been using since 1984 and IMO has not been outdated.
The response is very flat and goes down to 40 hz easily. You can see a measurement i published in the REW forum one week or two under the name of Jean ( http://www.hometheatershack.com/forums/rew-forum/20950-first-measurement.html) = look at the second graph, the first one is not well made. . It's a Japanese design and is very popular in France. The magazine "l'Audiophile" directed by Jean Hiraga introduced it and published plans. Here are a photo and the first article. If you have trouble reading french, i can help you, but the plan is clear enough, use 25mm good plywood. Big and heavy, but very subtle, not for a PA system. 
Best egards, 
jean.


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## nelsondog

Hi Jean, that is exactly what I'm looking for! Fantastic! But, I don't read French 
Did you build the enclosures in the photo! Very Nice indeed!
Thank you for your contribution.
The cabs I built are not working for me. I just bought a pair of 416-8Bs I was thinking of another attempt with a different driver but now this plan appears... I will look for a matched pair of 416-8As and build these. Is there a chance you would have the X/O schematic for the system including the horn tweeter?
Brian


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## GPM

??? Oh really?! It's way bigger than your limits listed here and more in line with what I was recommending: http://www.hometheatershack.com/for...altec-416-8a-box-requirements.html#post172192

GM


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## jean

Hi,
the picture is taken from an ad, but mine looks approximatively the same. It's been said that it's better to put the driver inside the box like in the plan. It's a big box but it's only 40 liters (dm3) bigger than the Altec's 8ft^3 quoted by GPM. The vents on the side add to the stiffness.
You can use the 416-8Bs, i'm using 416-8Cs.
The crossover will depend on which mid and tweeter you will use. For the bass/medium X/O, after many tests it has been decided that the simpler was the best: it's said in the article i joined at page 5: 3MH and 24microF for a 600Hz cut. For the low cut of the mid it's the same components: 24 microF and 3MH. Of course you can cut lower (around 300hz) but you will need a mid-bass driver and go 4 way; the interest of this enclosure with this driver is that you can use it in a 3 way system with a 2" driver (Radian, Altec, JBL, TAD,...) and a horn tweeter (JBL, Fostex,..). 

Jean


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## nelsondog

GPM said:


> ??? Oh really?! It's way bigger than your limits listed here and more in line with what I was recommending: http://www.hometheatershack.com/for...altec-416-8a-box-requirements.html#post172192
> 
> GM


GM, I built the 5 ft^3 boxes and played with the internal volume by adding 0.25 ft^3 of wood at a time to reduce the actual volume also changing the amount of damping material. I listened each time I made a change and was never satisfied with the result. I will take your advice and try a much larger cabinet in the form of the Onken. 
I have read a little about the Onken and seems they may fill the bill by providing me with the bass I'm looking for.
As for my initial size requirements, I guess I'll have to compromise my bench area in my shop to accommodate the lager design. I do appreciate your help very much, and I hope I didn't waste a great deal of your time.
As for the mid and upper band, I would like to stay with the arrangement I have now. I'm using an Altec 420A as midrange on an open baffle. I really like the way it reproduces the midrange. 
I would like to try an Altec 811B horn with 806-8A driver (reason being; the x/o is something I can build from the schematic) like used here: http://www.lampizator.eu/SPEAKERS/PROJECTS/P23/Aaltec_Rusinos _Maximus_Lampizator.html 

I have no idea if I can use a different Altec driver like the 802-8D or 808-8A and keep the x/o the same as on the Lampizator page. I'm pretty sure it would not work.
It seems the the other drivers are more readily available than the 806 
I will most definitely need help with that!
It will be a little while before I am able to start the project. In the meantime, I will try and collect the needed parts.
Brian


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## Bruno13

nelsondog said:


> What would it take to get 35 ~ 40Hz, cabs placed in corners and against wall?


I'm interested in the Onken designed cabinets for my Altec 416A's any suggestions??
Thanks,
Mike


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## jean

Bruno13 said:


> I'm interested in the Onken designed cabinets for my Altec 416A's any suggestions??
> Thanks,
> Mike


here: the original article :

http://www.asrr.org/biblioteca/Revue Audiophile/FICHIERS/02/ONKEN/ONKEN.html

Jean


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## GPM

Altec' specs varied quite a bit over the decades due to the transition from very high output impedance systems to very low ones, so increased Qts and often lowered Vas, balancing them as required to take advantage of more current cone assemblies, ergo without measured specs of each driver, then all that I can recommend is to build the Onken 360 and either add some series resistance if it's too bass 'shy' due to being too big or damp the vents as required to reduce any 'boom'/'flabbiness' from being too small.

To ensure the cab will likely be large enough for the later, higher Qt, Vas variants/re-cones it will ideally need to be ~25-35 ft^3 tuned to Fs or below and may need to be sealed while an original circa 1971 only needs ~ 6 ft^3/40 Hz if driven with a typical very low output impedance, so quite a range to choose from!

GM


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