Model 19 vs 604

I Have joined the 604 club and am finally ready to start a cabinet build. I have found a source to purchase 3/4 sheets of cherry plywood.

The plan is to build a slightly larger version of the stonehenge III cabinet. I have a pair of 604-8G speakers. I have a pair of original Altec Stonehenge III crossovers but after reading several posts here and throughout this site I think I need to keep them on the shelf and purchase some Great Plains XO's?

So the preliminary plan is to build cabinets that are 48H X 23W X 19 1/2D. This will create a cabinet with a internal volume of about 11.3 Cubic FT. I am guessing that the speaker and bracing will subtract about 1.5 Cubic feet?

So My friend who builds cabinetry and furniture has agreed to take on the project and I will assist him to the best of my ability. He is suggesting to dado the side, top and bottom panels. Thereby creating a cabinet that the front, back and top pieces are recessed by about 1/2 inch.

I like his idea and it would create a cabinet without visible screws. Except for the front mount screws for the speaker. My thought is if we go with internal xo placement then the only access will be through the speaker opening or port area.

I would not mind either a rear panel mount xo arrangement or external xo setup (sitting on top of the cabinet in dedicated boxes).

So the plan is taking shape and wood is to be purchased this week (Dec 10 - 15)

I am hoping some of the forum regulars chime in with some advice for a 604 rookie...
 
1. http://www.wardsweb.org/Billfort/
2. outboard your XOs for maximum flexibility (and consider active XOs -- analog or via DSP, at least as something to try).
(not that I can find a photo of the back of my cabinets -- but I just brought the woofer and tweeter wires out to two pairs of 5-way binding posts on the back panel)

mine aren't - at least currently - really being used as 604s any more, though (in full disclosure):

DSC_9984 (3) by Mark Hardy, on Flickr

current morph of the crossovers (not 604-friendly at this point):

DSC_9780 (3) by Mark Hardy, on Flickr

FWIW, I use the ML XOs when both sections of the 604Es are in use:

604Etest2 (2) by Mark Hardy, on Flickr
 
One of the guys on the JBL forum just gave away a pair of cabinets as you describe, except cut and ported for a JBL 2245. Here are the pics so you can get some ideas on how a cabinet should be done. He paid $800/pr to have them made.

I was going to take them but thought they were a bit big. From the "giver."

"They have a curved sides. The front is 22"W and the rear is 16"W and is curved not straight. That helps the design in several ways both visually and acoustically. They are 48"H and 23"D."

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Thanks for the replies and the links, the more responses the better!

Port size and position is another subject and discussion I would like to have.
I found a Speaker Enclosures Their Design and Use booklet online from Altec. On page 3 was Table III that showed the relationship between Fr, Internal Cubic feet and port size in a base reflex cabinet. looked like great info and unless someone here thinks it unwise to follow I think I will use it to determine the port size of my cabinets.

In the paragraph of text before Table III it mentions that the location of the port in relationship to the speaker opening was not critical. Nor was the shape but to keep the height to length ratio below 5 to 1...So I was thinking a conventional rectangle port 3 or so inches below the speaker and about the same width would keep things symmetrical. It would also stay within the 5 to 1 ratio based on a approximate port size of 60 square inches. Say a 4 X 15 inch port?
 
So I just read the 604-8G free air resonant Frequency is 30Hz. I was assuming in was 25Hz like other in the 604 series. Glad I caught that...not that it makes a huge difference.
 
One of the guys on the JBL forum just gave away a pair of cabinets as you describe, except cut and ported for a JBL 2245. Here are the pics so you can get some ideas on how a cabinet should be done. He paid $800/pr to have them made.

I was going to take them but thought they were a bit big. From the "giver."

"They have a curved sides. The front is 22"W and the rear is 16"W and is curved not straight. That helps the design in several ways both visually and acoustically. They are 48"H and 23"D."

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here're the images FWIW -- for anyone not logged onto the lansingheritage forum or those without accounts there.

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source: http://www.audioheritage.org/vbulle...18-quot-Driver&p=418892&viewfull=1#post418892
 
The program is easy to use and far better than using literature values.
But, but, but...

Literature values are exactly what the database is generated from. ;)

Many drivers, not just Altecs went through changes and revisions over the course of their production that effectively changed their parameters. Time/age of the driver is also an often overlooked factor.

Has it been driven hard enough to accelerate discharge of the alnico?

Has somebody tried to take it apart? (disassembling most alnico motors will at least partially discharge them)

The only empirical way to know your driver's parameters is to measure them.

With even the youngest 604-8G now being 40+ years old, several examples are likely to have important parameters 10% or more out of spec with the original design. If it has been re-coned at any point, the parameters may have changed significantly when a different type cone was installed.

Factors like de-magging of the motor, suspension fatigue, viscosity changes in the surround dope as well as migration of the dope on drivers living in warm climates can impose parametric changes that grossly affect tuning or the prediction thereof via modeling programs.

It's not unheard of with older 604s to have a condition where the compliance of the spider has loosened up while at the same time the viscosity of the surround dope has increased making the surround less compliant. It changes the tonal characteristics of the cone completely.

This ugly little reality is never talked about because it very realistically de-values what are otherwise pristine and immaculate appearing 604's. It is also part of the reason why the early models with paper hinges and phenolic spiders in clean working condition bring such premium prices.

Just my .02 y'all understand.........................
 
Well...I am going to order the wood for the cabinet project. I will post the exact dimensions of the cabinet when they are finished. I am shooting for about 10 cubic feet after subtracting for the interior bracing and speaker volume.

At that point If anyone wants to help with port size, or at least verify that my calculated port size is good. That would be great.
 
WinISD says flattest response is tuned to 42.09 Hz using 4.51 cu ft box space. A 4" tube should be 1.22" long.

For 10 cu ft you would want to tune it to ~40 Hz, but the vent is "too short" until you get down to about 33 Hz, which will produce a roll off from about 150 Hz down.
 
Have you considered a construction method that would allow for adjusting/tuning the port on the fly?
I have given it some consideration. But haven't really come up with a good design as of yet. I am leaning towards and would prefer to stay with a traditional basic port structure...My thought is to not use a tube port. Altec didn't use tubes and seemed to do a good job without them. I am open to suggestions and would value your input.

BTW I'm also a vintage Chevy guy...
 
WinISD says flattest response is tuned to 42.09 Hz using 4.51 cu ft box space. A 4" tube should be 1.22" long.

For 10 cu ft you would want to tune it to ~40 Hz, but the vent is "too short" until you get down to about 33 Hz, which will produce a roll off from about 150 Hz down.

From what I have been reading (mostly Altec and JBL speaker design documents) if I understand it correctly...A 10 cu ft cabinet with sufficient depth (front panel to rear panel of say 18 inches) a 604-8G (30hz Fr) and approximately 50 - 60 sq in rectangular port will create about 20db per octave roll off either up or down in freq. from 40hz tune? Of course the speaker can only reproduce down to 20hz or so. I think the 620 studio monitor and model 17 both using the 604 -8G had a 40hz tune and close to this roll off?

I am fairly new to bass reflex design but...the above is my general understanding.

Tube ports I'm sure work a bit differently and are a bit more complicated in the way they "store air" for the lack of a better term. I have only read a little on their characteristics?
 
I think it comes down to area and length regardless of shape. Download WinISD or something similar and try to run what size/tuning you prefer. IIRC, it does allow for rectangular ports.
 
Why not go with the "Big Red" style Mastering Labs boxes? They already did the heavy lifting including crossovers.
 
Or "Big Red Supers" like I got last week. These are 5'2" tall x 24" wide x 18" deep with a volume of over 12 cu ft. Mine are set up for tri-amping and included the electronic crossover, high frequency contour units (extremely rare), and cables. Note there are no ports on these cabinets. In fact, I've seen five different sets of Big Red Supers (including two sets here at the house), and none were ported.

Big_Reds1.jpg

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Or "Big Red Supers" like I got last week. These are 5'2" tall x 24" wide x 18" deep with a volume of over 12 cu ft. Mine are set up for tri-amping and included the electronic crossover, high frequency contour units (extremely rare), and cables. Note there are no ports on these cabinets. In fact, I've seen five different sets of Big Red Supers (including two sets here at the house), and none were ported.

Big_Reds1.jpg

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DSC_00027.JPG

DSC_00045.JPG

Wow that is some nice gear! Your a lucky guy toddalin.

They don't have ports because they literally don't need ports. At over 12 cu Ft (more like 14) and with a additional 15 in speaker for more bass no real need for a bass reflex cabinet. They must sound incredible/
 
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