Were I to need a cabinet for an altec 420a and a horn...

[lexx21]

Here is my situation...

I only run tube amps (both pp and se), so a high-ish spl is desirable. What I want to do is this... I want to acquire a pair of Altec 420a drivers and pair them with 811 horns and compression drivers for the higher end.

The problem is that I have never designed speakers before and trying to hunt down which cabinet to use with the 420a driver is proving to be very confusing.

The room that I have as a "listening room" is my record library/work shop/general disaster area. Luckily my wife is understanding and doesn't mind me using what would be a spare bedroom as my "he-man bo-hunk man cave" in which I nerd out in regularly and listen to vinyl. However being of the "spare bedroom" variety of room, it is somewhat small; along the dimensions of 14 feet by 10 feet.

I really don't listen to music that loudly, but what I do what is great representation of the music that is there (vinyl only).

So... were I to buy these drivers, what cabinet would I need to build? An open baffle really isn't in the cards since I have 2 Ikea expedits in the room, one 5x5 to hold records and one 2x4 to put my turntables on. Between that, my work top, and diy stereo stand, the back space just isn't there.

What do you good folks suggest? I have wanted Altec drivers ever since I knew what good sound was so I am really hoping that you guys can help me out.

Thanks in advance,

John

 

[Don Hills]

The 420a was originally used in the Santana, Madrid and other sealed cabinets with volumes from about 3.5 cu ft to about 5 cu ft. These sizes are smaller than optimum for the 420a, which has a very high Vas. The apparent intention of a small enclosure was to limit the cone excursion because the driver has an underhung voice coil with relatively limited travel. I had mine in 6.8 cu ft ported enclosures tuned to 40 Hz, it minimised the excursion for the classic rock/prog/metal I favoured at the time, which rarely contained music below 40 Hz. Optimum ported enclosure size is 17 to 22 cu ft tuned to 20 Hz, and sealed is around 50 cu ft...
So basically, just build the biggest sealed cabinets you have room for.
Also, the 420a performs well in the midrange. You should try just pairing it with a small tweeter crossed over at 3 to 5 KHz instead of the 811 and tweeter.