New 604 Cabs

**cradeldorf** · September 22nd, 2012, 01:46 AM

Hi guys, I had a

**juniper** · September 22nd, 2012, 08:40 AM

Nice work Cradeldorf those look great!!! Is it the pictures, or is the speaker hole offset slightly? What are the dimensions of the cabs and the interior volume? That port looks very similar to a big red...Please give us your listening impressions once dialed in. Thanks for posting!!!!

**donaldpatten** · September 22nd, 2012, 08:47 AM

Very nice
Did you cut the double baffles with different diameter speaker mounting holes , to give the step when the boards are assembled ?

**Alien_Shore** · September 22nd, 2012, 11:05 PM

wow - mad skills!!
That's impressive. It's a shame though that your stain didn't work out. The tops look great.

I gotta get a router (or find a friend with one)...that's great how you did the inset baffle cutout. Maybe I can get some plans from you or some help with construction for the newbie...

So what frequency are you tuning them?

**voice of the theater** · September 23rd, 2012, 07:45 AM

Those turned out great Cradeldorf! I like how you not only offset the speaker hole (which, from what I understand, helps to prevent reflections inside the cabs cancelling each other out), but you offset them the opposite of each other so you have a "right cabinet" and a "left cabinet". I really like that approach--when purchasing a pair of factory Altec cabinets (with offset holes), they were always identical so there was no "right" or "left" cab. I'm sure that made it a lot easier to sell them (in pairs and as singles)--you didn't have to order a "right" and a "left". Anyone know if Cradeldorf's approach will enhance stereo imaging compared to the "traditional" Altec approach?

EDIT: It's a shame you had to paint those beauties. I really like the look of the grain just as it is in the photos. If they were mine, I would have been tempted to just put a clear coat on them. But then again, I've always been a sucker for blondes!

GM · September 23rd, 2012, 11:29 AM

Originally Posted by voice of the theater

I like how you not only offset the speaker hole (which, from what I understand, helps to prevent reflections inside the cabs cancelling each other out)

Anyone know if Cradeldorf's approach will enhance stereo imaging compared to the "traditional" Altec approach?

EDIT: It's a shame you had to paint those beauties. I really like the look of the grain just as it is in the photos. If they were mine, I would have been tempted to just put a clear coat on them. But then again, I've always been a sucker for blondes!

The insulation inside the cab is for damping down its reflections, so at best, the offset will allow less internal damping, which is a good thing normally.

What the offset [or heavily rounding over the cab corners] is for is to average out the eigenmodes [standing waves] between the driver output and edges of the cab, so that the peaks/nulls are much lower in amplitude.

It enhances stereo only to the extent that there's less 'dilution' of the signal arriving at the listening position [LP] due to comb filtering of direct to reflected sound across the driver.

With an effective acoustical baffle width around 34", it will have a ~200 Hz eigenmode with both even and odd harmonics, so offsetting the driver in a golden or acoustic ratio is a good plan on wide baffles when it will have output down to the baffle?s fundamental.

Then there?s the speaker/room boundary eigenmodes to contend with. The horizontal ones can be dealt with adequately by toeing the speakers in as long as the angle is > 6 deg/channel.

Vertically, it gets more complex unless you slope the baffles a like amount to deal with the floor, ceiling eigenmodes and ?floor bounce?, which is the angular reflection between the speaker and LP, with the latter best dealt with by placing the driver at floor level.

A compromise to deal with all this is to locate the speakers up off the floor at some golden or acoustic ratio and angle them up/down and left/right at least 6 deg.

Since imaging/sound-staging is perceived principally in our acute hearing BW, just outputting the phone BW [~250-3500 Hz] in these locations is usually sufficient, so a suspended/angled studio monitor with a separate sub system consisting of at least one sub/room mode is about as good as it gets without building an acoustically ?neutral? room.

GM

edit: Me too, though when used in an HT app, they need to be a very dark color and preferably a matte finish.

**Panomaniac** · September 23rd, 2012, 09:49 PM

What are you using for a crossover?

GM · September 23rd, 2012, 10:25 AM

Looking good!

Just noticed your 604C measured specs and FWIW, these are early 605 specs, which is based on the 803 series, not the 515 series based 604. Seems like you've got one of the relatively rare transitional '604' series from when Altec tried unsuccessfully to get the recording/monitor playback industry to embrace a 'weaker' motor/cheaper to make '604', though AFAIK not at a cheaper price.

GM