Altec 604E Port size

[mflaten]

I am looking at having a cabinet maker make a pair of enclosures for the 604E. They will be about the size of the Stonehedge (9 ft3) but in an art deco style similar to the 605 or 607. I have quite a bit of Altec literature and have the graph that reflects resonance frequency, enclosure size and port size but I am not sure if it is still relevant. Given the enclosure is 9 ft3 and the resonance frequency is 27.10 what size port should be used?

Second anyone try the Iconic DN604E-16U crossover?

[GM]

Yes, it's still relevant, though a calculator is more accurate than a nomograph, so allowing 0.5 ft^3 for driver and basic bracing: Speaker Box Enclosure Designer / Calculator

Attachment 3304

GM

[endeeinn]

GM, I'm confused. You plugged in 8.5cuft for the Vas which I assume is the 9cuft of the enclosure minus the .5cuft of the driver. Is this correct? However, when I go the the unofficial Altec site and get Vas for a 604E it is stated as 15.75cuft. Can you please help me understand the why as I plan to build a similar 9cuft enclosure but use a pair of 605B's instead. Thanks.

[mflaten]

I am looking for the necessary port size with a given size enclosure using the specs of the 604E. It used to be you simply cut out the necessary port size and you were all done. Is tuning the port recommended using a tube? Is there a calculator to perform this?

[GM]

No, did this 'on the fly' between some other tasks and screwed up! I used Qts to 'fudge' a desired result since box size was a given, just inputted the wrong gross Vb [Vas]. Should have inputted 9 ft^3 to get a ~8.5 ft^3 net Vb, hence a 6" dia. vent ~7.75" long.

I could have 'fudged' it using the correct Vas, but didn't want to take the time to look it up.

Thanks for pointing it out!

GM

- - - Updated - - -

I am looking for the necessary port size with a given size enclosure using the specs of the 604E. It used to be you simply cut out the necessary port size and you were all done. Is tuning the port recommended using a tube? Is there a calculator to perform this?

Yes, there's programs that do it, though can't think of an on-line one ATM.

Ducted ports are better damped, hence damp the driver better, though a simple baffle thickness vent can do it by adding one or more layers of a tightly stretched cloth. The pioneers factored this in when choosing grill cloth densities and the main reason why they're much denser than modern day ones.

Anyway, a ~26.2"^2 square/rectangle or 5.78" dia. hole in a 3/4" [18-19 mm] baffle will work.

Really, unless you will drive it with a high output SET amp or similar, then no need to tune it to Fs, though 'in the ballpark' is usually a good choice for a HIFI app with Altec drivers in general; and if you are, then ideally you need to tune it to the driver's actual Fs for best overall bass response, rendering all this moot.

GM

[mflaten]

The speakers are finished in the style of the 605. Wood is African Sapele.

[mattvandyke]

Very nice - Great work.. Where did you get the Altec emblem? What crossover did you use?

Matt

[Steve Schell]

An ex-Altec engineer I knew years ago (long gone now) maintained that the 604 was ideally paired with a 15 cubic foot bass reflex cabinet. He never said anything about the port area. He was running 820 systems at the time which really blew my socks off along with his Altec 1530A industrial amps!

[mflaten]

I got the Altec decals from Radio Daze. I have the Great Plains N1600-16 crossovers and I also have the original Altec crossovers.

I always was fond of the art deco look of the 605 cabinets. I also had the same cabinet maker build a record cabinet in the same style and a couple of diffusers.
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[mah]

WinISD - Linearteam Calculator/ designer - download WinISD 0.44(2002). This version has most Altec drivers, the others only two.