my new 604 cabinets I'm building.

**Panomaniac** · October 11th, 2011, 12:00 PM

Thanks Bowtie. I guess I've seen rolls of the stuff but never used it. It looks very fancy.

**cradeldorf** · October 11th, 2011, 12:59 PM

Thank's Guys, Yep I used the Iron on stuff went on real easy but bubbled up when I polyurethane'd it but a little heat from the heat gun and the heavy rubber roller sank it back home. Scrubbin those toilets gives me lots of time to daydream Bowtie.

Vott I'm putting a 65 SqIn port in the bottom of the back panel That way It should do a little better job of keeping any midrange freq's from canceling out.... I hope the source knew what he was talking about. I got my port size numbers straight from the Altec "Speaker Enclosures Their Design and use" bulletin, quite a handy guide.

I'm thinking of adding a board across the front of the baffle about 2-3 inches below the speaker hole so I can do a black cloth grill across the top and still see the wood on the bottom half. Plus it will add a little more bracing to the baffle.

GM · October 11th, 2011, 10:20 PM

~12 ft^3 with a 65"^2 vent x 3/4" tunes it to ~41 Hz, kind of high for a modern HIFI app unless a sub system is used.

GM

**cradeldorf** · October 12th, 2011, 02:13 AM

Originally Posted by GM

~12 ft^3 with a 65"^2 vent x 3/4" tunes it to ~41 Hz, kind of high for a modern HIFI app unless a sub system is used.

GM

That's what the Altec bulletin suggested for the 604? I haven't cut the ports yet, if you got a better suggestion.

**VolvoHeretic** · October 12th, 2011, 03:27 AM

I'm still quite confused on this, especially after reading my Radio Shack "Advanced Speaker Design" book three times and doing all of the math long hand. Isn't the only frequency coming out of the port the box/port resonance and at Fb the speaker is motionless and all of the air motion is in the port and in faze with the woofer? Doesn't aiming the port out the rear, bouncing off of the wall make it out of faze with the woofer?

**cradeldorf** · October 12th, 2011, 05:35 AM

Originally Posted by VolvoHeretic

I'm still quite confused on this, especially after reading my Radio Shack "Advanced Speaker Design" book three times and doing all of the math long hand. Isn't the only frequency coming out of the port the box/port resonance and at Fb the speaker is motionless and all of the air motion is in the port and in faze with the woofer? Doesn't aiming the port out the rear, bouncing off of the wall make it out of faze with the woofer?

This is where I got my info from Volvo, otherwise I probably know less about understanding this stuff than you do.
TA Speaker Topics: Vent FAQ's

**voice of the theater** · October 12th, 2011, 11:17 AM

I would wait to cut the ports until you hear from GM and others here as far as their recommended size and location of the ports. I don't know much about building cabinets, but I think there's a reason that all of the Altecs I've ever seen had ports in the front of the cabinets, not in the back. Also, the page you're referencing (in your post number 30 of this thread) shows a picture of an 846A Valencia. Again, I'm far from an expert on DIY cabinets, but if that picture is any indication of the date/year of the "Altec bulletin" you're using as a reference then it's a very old reference (from the 60's) and I know that the cabinets Altec used back then were tuned much higher than later Altec cabinets like the Model 19 cabinets. I think by the later 70's Altec had a much better "handle" on cabinet tuning as far as how to get really deep bass out of a cabinet. I wouldn't use the port size that Altec recommended in the 60's if you want to get deep bass (more modern "hi fi" tuning) out of those cabinets. As I mentioned before, I'd wait and get recommendations from GM and others here (regarding port size/location) based on your exact cabinet dimensions and 604's that you're using (or in lieu of that, find a much more modern source/reference to achieve a more appropriate/modern cabinet tuning that will allow significantly deeper bass)......

Originally Posted by voice of the theater

Wow--those are beautiful cabinets--nice job!! Have you/how are you going to determine the port size/location/cabinet tuning?

That's why I asked you this question earlier in this thread. I suspect the problem you're having with the AS 101 cabinets is that they're not tuned for 604's (and someone apparently also failed in their attempt at DBR tuning with the "shelves" they installed in the cabs). I think these new cabinets will be much better for your 604's IF "appropriately" tuned/ported. You're at a crucial step right now that will "make or break" the success of this project IMHO.....