Cabinet Design

I am looking to build cabs for my recently purchased Mod 422-8z woofers (15")I also own a pair of N-1201-8A network units purchased new in the late 70's still in box. I also have a pair of 802-8D drivers and I looking to purchase 811-B horns I think they will be more suited for home even though I owned 511's in the 70's and I still remember the sound. I'm new to the board but need some specs to build these cabs I am not looking at horn loaded, so whats the next efficient design? Does anyone have info on my woofers they are not listed on the site?
Thank you

Probably the design you would want is the old classic bass reflex. Or ducted port as they are called today.
You will need to know the Thiele Small parameters of the driver to design it. You might have to measure them yourself. See my recent post about measuring this below.
To design the box, there are a few good shareware programs available on line. I used Box Plot with good results. Others here might have other favorites.
I think the 422-8Z is a musical instrument speaker????
Ron

The person I bought them from said they were removed from a voice of the theatre enclosure I can even see the faded area where they were exposed. Thank you for your reply.

I suggest the 861 : about 3 cubic ft. It sounds great with a 605A . I built one for a center channel and omitted the rectangular port ( 2? X 3 ?) and put 3?dia X 7? tubes in the two other ports .See below for plans :

http://www.lansingheritage.org/html/...1968-plans.htm

Altec 1968 Enclosure Design Guide

Model 861
Don

Sorry I got the wrong Question
Don

Hi, Tranquil,
The 422-8z was used in the 1200 series VOTT cabs in the 70s, marketed mainly to the PA/musician user. They used the same coil/cone assy. as the 423-8z, and were combined largely with 807 and 808 drivers, on 811s and 511s, none of which, I'm sorry to say, really tells you much. I've got a pair, and to my ear, I'd call them a match to the 418B (still little help). They're obviously suited to horn loading, though have a wider BW than the 416 or 515. My pair is now in some 5 cu ft sealed boxes, crossed at 1200 hz to 909s. I'm sure the bottom end could be improved by venting, but as stage monitors they fill the bill nicely, and are very sweet with vocals. For HIFI, I'd definitely go vented, either by measuring and calculating, or trial and error, the former being a great way to learn how to juggle relationships and tradeoffs, the latter giving results if you don't care "why".
"Till the Wheels Fall Off and Burn!"
BFISH

Thank for the info Bfish. It's strange that these are not listed anywhere I'm not sure if I will use them but knowing where and what they were used for is definately going to help with my decision. My project is still on the drawing board.

Tranquil

Tranquil,
I hope I get corrected if wrong, but from the limited info you mention, and some personal experience, I consider the 422-8Z the equivalent of the 418B, and the 423-8Z the equivalent of the 421A. Although most of Altec's MI speakers are generally pooh-poohed for HIFI apps, keep in mind that much of our favorite music was MADE with them, so it can be easily PLAYED with 'em too, and it doesn't take extreme EQ'ing to do so! Since I'm about to slip into the topic of musicians, their gear, and their treatment by so-called audiophiles that claim to love music, a subject that I'll save for a later and greater post, I digress..........Good Luck!

"Till the Wheels Fall Off and Burn!"

Greets!

>I consider the 422-8Z the equivalent of the 418B, and the 423-8Z the equivalent of the 421A.
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Interesting! I've messed with many Altec MI speakers and have never seen/heard of these.
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>Although most of Altec's MI speakers are generally pooh-poohed for HIFI apps, keep in mind that much of our favorite music was MADE with them, so it can be easily PLAYED with 'em too, and it doesn't take extreme EQ'ing to do so!
====
This is the very reason you don't want to use MI drivers for HI-FI since the object is to reproduce the signal, not add another layer of distortion to it. That said, many CDs are very 'dry' sounding so the added distortion can be pleasing, but a good recording can be 'colored' enough to screw up vocals if you like to listen occasionally at ~live levels (been there, done that with 421s).

Anyway, if they are drop in replacements for 418s, then using the 418-8H specs here on the site should get you 'close enough' WRT cab Vb/initial vent dims.

GM

After reading all your comments and giving this some carefull thought, I have decided to trade in my 422-8Z and start looking for a couple of 416-8B's. I owned four of these a long time ago and I will always remember how efficient they were especially when listening at low levels late at night.WOW! I have been away from Altecs for some time kept my new N1201 and my drivers in a closet for years, but I could never stop talking about Altecs. Years after here I am I want to reunite with my Altecs! Could someone please send me the prints for the Model 19 I know it's out there somewhere.

Greets!

WRT Altec's MI drivers Vs their cinema/HI-FI drivers, a steeper XO slope and/or applying a removable damping compound such as rubber cement to the metal DC will offset most/all of the frequency response differences at very moderate SPLs, but it's their distortion generating rapidly rising response suspensions/reduced Xmax that causes them to be unsuitable for HI-FI IMO unless you BW limit them to within their Xmax in a compression horn or EQ'd sealed or listen to them at very moderate SPLs.

GM

Gm,
I think I follow you, I laid out a 416 and a 418, and though I'd don't see any major differences in either the cone compliance, or the spider, (I think) the 418 feels tighter when flexed. Is there more difference than I'm seeing, or is it just that the MIs are more "doped up" (a description also commonly applied to those of us that use 'em)?
If (theoretically) suspensions were equivalent, would the MIs coil handle the extra 0.12" or so added Xmax without coming out of the gap? If the MIs are driven by a tube amp with reduced damping would their performance be a closer match to the others driven SS?
Sorry to be a pain, but these are issues I've long puzzled over.

GM,
Is the (minimally documented, but generally assumed) peaky, non-linear, response of the MI units the distortion you're referring to, or is there something else? Could you elaborate a little on the differences between the 418/421 variants, vs the 416/515s, or more simply put, MI vs HIFI, and possibly the associated design strategy?

Clarification of above post to all;
My reference to being "doped up" in my previous post was intended to be a joke. As a musician, (who's never blown a speaker in his life), I'm simply sick of being classified as a gear-abusing, doped-up hippy, by a limited number so so-called audiophiles that claim to love music, yet are only involved as a means of impressing their peers with their collection of over-priced "high-end" gear. Fortuneately, that's an issue that seldom arises on this board, whose members I have a great deal of respect for, and I apologize to any that may have been offended, especially to Tranquil, whose post I hijacked for my rant.

Sincerely

No offence taken Bfish. I'm also enjoying the conversation between you and GM.

Greets!

>Is there more difference than I'm seeing, or is it just that the MIs are more "doped up" (a description also commonly applied to those of us that use 'em)?

>If (theoretically) suspensions were equivalent, would the MIs coil handle the extra 0.12" or so added Xmax without coming out of the gap?
====
I don't know any of the driver's assembly details, so can only speculate. In today's manufacturing environment they would limit components as much as practical, relying on doping, etc., to make a different model, but these designs go back decades to a time when Altec had the majority market share and could afford to indulge in making many different designs with few interchangeable components, so I wouldn't be surprised if they had different motor details due to more robust VCs to go along with different spiders, DCs, etc..

A re-coner can tell you all the differences, but due to the suspension's rising rate, a MI driver is less likely to come out of the gap since it's designed to keep it from happening, and why the rapidly increasing distortion with excursion.
====
>If the MIs are driven by a tube amp with reduced damping would their performance be a closer match to the others driven SS?
Sorry to be a pain, but these are issues I've long puzzled over.
====
Somewhat.

I bought some 421-8Hs when they first came out in '72? because I was assured by the local Altec distributor that the only difference between them and the 416-8C was a higher power handling VC, paint job, labels. WRONG!

I wound up making quite a few frat house/pool party speakers with them, but HI-FI they ain't, so no need to apologize, these are valid issues that folks need to understand lest they make the same mistake as I.

GM

GM,
Thanks! I never did the frat thing, but did get to attend a few pool parties. Strange, isn't it, how or perception of BW and Xmax varies, depending on TOD and BAC?
I've written a new post to carry this on a little further. Thanks to Tranquil for the use of his!

"Till The Wheels Fall Off and Burn!"

BFISH

Is MDF/Particle board the material of choice for speaker cabinets.Could someone enlighten me on the advantages and disadvantages of using MDF instead of Birch or similar grade Ply.If this has already been discussed in detail please refer me to the thread? I searched and could not find a actual comparison or a reason for using one instead of the other.

MDF/particle board is a homogenous mixture of glue and sawdust formed into a 4x8 sheet. Plywood, birch or otherwise, is layers of real wood (with real voids) glued together. Not as dense or consistent. MDF is less likely to have internal resonances.

Take a solid piece of wood. Put one end to your ear and lightly tap the other end. How much sound do you hear. Take a comperable size piece of plywood and do the same thing. The sound should be much less.....Now take a comperable size piece of MDF or particleboard and do it again. The sound should be much less again.

The theory is to NOT ADD any sound that you can't control. Sounding comming from the wood itself as it vibrates because of the sound waves of the drivers can't be controlled. So the best thing is to eliminate/reduce the cabinet from vibrating by using MDF or particleboard.

Professional applications want to acheive this goal also....BUT they also have a goal of being very durable (especially if used in a road band). You don't want to move speakers made from MDF around alot. Plywood is more suited for this.

Altec Fan
From the info you gave me MDF is the material of choice because we are trying to avoid internal resonance in the system, the speaker should be heard and not it's enclosure, if the enclosure creates it's own sound this will be considered distortion, or is that every speaker cabinet will sound different because of the unique qualities of real wood? Reason why all acoustic instruments sound different.
Thanks

Quote:

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if the enclosure creates it's own sound this will be considered distortion, or is that every speaker cabinet will sound different because of the unique qualities of real wood?

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<font size="2" face="Verdana, Helvetica, sans-serif">The main thing is it can't be predicted WHAT the sound will be. Anytime you "Add" sound it isn't good. The speakers are to reproduce the sound as best it can from the musical source. If you start adding sound NOT from the musical source, then this isn't good.