Recommended Altec 604 Cabinet Designs

Recently I was able to obtain a pair of Altec Lansing 604 G8 drivers with original crossovers (not at a reasonable price). They were in pretty nice shape but enclosed in 3/4 inch plywood 18 x 18 x 30 boxes. At least the enclosures were baffeled. Now, I'm a pretty good woodworker and cabinet maker, so difficult is not a problem. But when it comes to the physics of designing an enclosure to best display the fine sound attributes of these drivers, I'm an idiot.

I'm sure Altec Lansing designed enclosures for these drivers and I would love to know what they were. More importantly where I could get copies of the detailed plans. Also I would welcome thoughts on a good enclosure designs from those of you familiar with the Altec 604 G8.:confused:
604 cabinets


Welcome to diyAudio. There are many possible enclosures for Altec 604. Since this is a 50+ year old design many different cabinets have been used over the years. A good starting place is the Altec 620 cabinet. Then you should try other cabinets. Your second set of cabinets could be the MLTL design that has been discussed here and elsewhere on the web. It is the newest cabinet design I've seen for the 604. Then you should build some vintage cabinet designs. I suggest some Jensen cabinets like the Imperial. I used the 'built-in' version with my Altec 605a but only in mono. I liked it but it was large at 30 cu. ft. I'm now going to try the 605 with an added woofer as was done in the Urei 813 and 815. I hope these keywords and google will get you started. Let me know if you have more questions.

Thanks! This is all great info. The freeware looks neat, I'll need to study it for awhile. I found the plans for a 620A cabinet but nothing on the types of materials used, such as what kind of wood (does it matter)? what if anything was used for sound damping inside of the cabinet..foam? fiberglass insulation? Polyurethane foam? Maybe I should just play that part by ear.

Others on this site have done some pretty amazing box designs. The technical expertise makes me feel pretty humble.


Joined 2003
No, either find a Baltic Birch or Appleply supplier or ask the special order folks at Home Depot if they will order it for you, which is how I've gotten mine. Note that 19 mm (3/4") BB ply normally only comes in 5 x 5 ft sheets. If you can't get either, then see about premium marine grade.

There's enough demand from american/canadian contractors to make standard 4X8 sheets instead of 5X5 but they had to make another adjustment to the machinery to provide it, so it is costlier per sq.ft than the 5X5

But they have it. It wouldn't surprise me if they have it in the USA

Over the years Altec changed the T/S parameters of the 604 drivers, plus over the years the magnet strength on one or both of your speakers could have changed. You will need T/S parameters for each speaker for the best build results. It is not uncommon for old speakers to need a magnet re-charge for optimum performance, or you may accept a modest motor drift identified from simple measurements. Naturally, you could build one of the common BIG cabinets, and trust that the large volume provides enough tolerance for acceptable performance with your best-guess T/S specs. If you Google "measuring speaker T/S parameters" you will find a few good presentations on the method and simple equipment(DVM... resistor... weight) required. This data will assure a great design for your money and hard work.

Do you favor any one specific cabinet shape? The older cabinets were just "BIG" and proportioned to look like furniture, and avoid nasty resonances. There were general rules for horn height, cabinet shapes, and port location. Newer cabinets, like the Mass Loaded Transmission Line (MLTL) are TALL with precise dimensions and port location. Folks here can run design simulations which deliver optimum sound once you have T/S parameters for your speakers.