Can someone help me build Altec 620 cabinet for 604-8H III

Hi,

I live in Houston, Texas, and I'm looking for someone to build me a very nice pair of 620 cabinets for Altec 604 8H III drivers from Great Plains Audio. I'd like grills to be made for them except with magnets instead of velcro.

Edit: I'm not using the driver in these photos, but I love the color.

Best regards,
M.K.
 
Administrator
Joined 2004
Paid Member
Hi Lioh,
You're putting a lot of responsibility on the part of the builder. Any cabinet maker could build a very nice set of speaker boxes, but you must spec the project for them. They can then build to your spec and not worry about complaints for some error.

So, if you want someone to build these boxes, figure out all the dimensions and put them on paper. Include anything unusual about the construction and assume they know zero about speaker boxes. Details like "air tight" construction is required information. Any terminals or panel to fit in the box somewhere must be spec'd. So do the mounting holes and any "T-nuts" you intend to use. You will be required to provide any special materials, such as damping material.

Asking for someone to build you a pair of speaker boxes without anything to guide them is asking for a big disappointment. That's if you have any takers. On the plus side, that woodworker is likely to be a local person. Additionally, since you are asking for a furniture grade pair of boxes, expect them to be priced higher than the boxes that are advertised. A lot higher.

Your best bet might be to simply purchase the enclosures that are being sold, then drop those off to a carpenter and have them professionally veneer them. You might even be able to have the boxes laminated with 1/4" finish material. Those boxes would be substantially heavier and stiffer, so a clear upgrade from the items being sold.

-Chris
 
Hi Lioh,
You're putting a lot of responsibility on the part of the builder. Any cabinet maker could build a very nice set of speaker boxes, but you must spec the project for them. They can then build to your spec and not worry about complaints for some error.

So, if you want someone to build these boxes, figure out all the dimensions and put them on paper. Include anything unusual about the construction and assume they know zero about speaker boxes. Details like "air tight" construction is required information. Any terminals or panel to fit in the box somewhere must be spec'd. So do the mounting holes and any "T-nuts" you intend to use. You will be required to provide any special materials, such as damping material.

Asking for someone to build you a pair of speaker boxes without anything to guide them is asking for a big disappointment. That's if you have any takers. On the plus side, that woodworker is likely to be a local person. Additionally, since you are asking for a furniture grade pair of boxes, expect them to be priced higher than the boxes that are advertised. A lot higher.

Your best bet might be to simply purchase the enclosures that are being sold, then drop those off to a carpenter and have them professionally veneer them. You might even be able to have the boxes laminated with 1/4" finish material. Those boxes would be substantially heavier and stiffer, so a clear upgrade from the items being sold.

-Chris

I'm hoping to find someone who's built them before and knows the little things. The Altec 620 plans are online and easy to find, and I've got $2,000 give or take. I don't see how that's not enough money?
 
Administrator
Joined 2004
Paid Member
Hi Lioh,
I didn't say anything about a certain amount of money, just that you should expect it to be a lot more than the boxes you can currently buy. Now you have mentioned a target amount of money, which is more than anyone had previous to your last post.
The Altec 620 plans are online and easy to find
It's up to you to present the plans. That is not a difficulty for you, so another bit of information has fallen out of the sky. Did you post a link to the exact plans you wish to be your finished product? If not, please do. However you should look them over to the best of your ability before using them as your plans.

My own read is that the money is probably reasonable, and the plans are forthcoming soon. See how far you have come in one post? Now someone can read about what you want and decide for themselves if they want to become involved. Before that they had very little to go on.

Why not edit your first post to include all this information? You're bound to have better luck now.

-Chris
 
Hi Lioh,
I didn't say anything about a certain amount of money, just that you should expect it to be a lot more than the boxes you can currently buy. Now you have mentioned a target amount of money, which is more than anyone had previous to your last post.

It's up to you to present the plans. That is not a difficulty for you, so another bit of information has fallen out of the sky. Did you post a link to the exact plans you wish to be your finished product? If not, please do. However you should look them over to the best of your ability before using them as your plans.

My own read is that the money is probably reasonable, and the plans are forthcoming soon. See how far you have come in one post? Now someone can read about what you want and decide for themselves if they want to become involved. Before that they had very little to go on.

Why not edit your first post to include all this information? You're bound to have better luck now.

-Chris

It won't let me edit after 30 minutes I believe, otherwise I would (sad face). Also, I'm at a complete loss. None of the plans for the 620A or B cabinets look readable. That's unfortunate(...). At this point, I'd be looking for someone who's built cabinets for these drivers before.
 
Lioh, Lioh, use the Force...the Resonant Force!

The Altec 602 cabinet is a basic big box bass reflex port design. Advanced computer modeling software now allows accurate design of more complex speakers enclosures. Every cabinet shape has resonances. To control them a well designed ported bass reflex box will use a combination of: prime ratios for W*D*H; bracing materials for strength and resonance control; and stuffing.

More refinement.... MLTL = Mass Loaded Transmission Line
The MLTL enclosure can be thought of as a form of tuned transmission line where quarter wavelength standing waves are used to provide the spring force for the mass of air in the bottom port. A speaker with a Fs under 30Hz requires a tall cabinet to generate the long quarter-wave required to extend ported bass.

The Altec 604 has: moving mass, mechanical restoration force, magnetic motor force, etc.. which model best in a transmission line with a 419sq_in internal cross-section area.

If the driver is offset at 1/3 the length of the straight transmission line, the 3/4 wavelength standing wave can be totally suppressed, and in addition the impact from every other quarter wavelength mode (3/4, 7/4, 11/4, ...) will also be essentially removed from the system SPL response.

Using this 1::2 ratio, a 39"� ear level driver position would require a ~58.5" line height with the driver center 19.5" down from the line top. Total internal line volume of 11 cu_Ft with a 419 sq_in line section area,2" long x 6" diameter port, 7" above the line bottom.

419sqin =22” x 19”
~200Hz initial baffle step
=======
Read up at: Quarter Wavelength Loudspeaker Design. Quarter Wavelength Loudspeaker Design

GM has designed a few MLTL cabinets for Altec 604 coaxials which a Google will find.
 

Attachments

  • MLTL.jpg
    MLTL.jpg
    128.4 KB · Views: 729
604 speaker cabinets

Ok here you go was looking for this guy but could not remember his name then it just hit me Michael ChristThis guy dose super high quality work but i promise you he is not cheap. Back in the day i saw Jensen imperial cabinets he built they looked stunning if i remember they cost the owner $3500.00 a pair. This guy makes Dr Bruce Edgar's horns. I really think unless you want to spend 2k with Michael find a local cabinet shop build them with 3/4" MDF and then veneer them MDF is arguably the best speaker cabinet material and with so many different veneers out there you will have so many options on looks. To be honest i think such iconic and beautiful speakers deserve something like burled maple or maybe birds eye maple.
 
To illustrate MLTL cabinet size and shape......

Legendary Jean Hiraga displaying his Altec 604 MLTL speaker. Port air exits out of bottom slots.

Typo in my original note .... The ferrite magnet GPA Altec 604-8H III T/S parameters best match a transmission line with a 405sqin cross section. Jean Hiraga uses Alnico motor 604 speakers which have slightly different T/S matching a 419sqin line.
 

Attachments

  • Jean Hiraga 1.jpg
    Jean Hiraga 1.jpg
    111.1 KB · Views: 715
  • Jean Hiraga 3.jpg
    Jean Hiraga 3.jpg
    102.9 KB · Views: 664
i'm having model 19 cabinets built from the amish here in ohio...which should be almost finished.. they do a really great job with wood.... I wanted solid 3/4 inch wood.... no one else would build it the way I wanted because they said it would take to much time and cost to much..and if you seen my video center... it nice !!.
I had a few things made there.. starting from 4 years ago i just wanted a nice pantry to put some extra things in... but when it was done ,,my wife took over and put all her things in it..

I had screwed up and had light gray stained glass in the doors..(thats why she took it.)(but at the time... I think it was 525 dollars because it was a custom item...) I looked around and I think its worth at least 1,000 dollars..But why I can get things built there at a good price is this small amish company does everything from growing the trees to delivery of the finished product....

I dont know if it makes any difference
in building with mdf,,, plywood or solid wood,,?? I am sure someone on this site knows.. I just wanted the speakers to match my ELM wood tv stand......SO IF ANYONE IS INTERESTED ..???

I HAVE TO GO BACK TO SEE IF MY SPEAKER CABINETS ARE DONE IN THE NEXT FEW DAYS..(the amish does not have phones)...
The only drawback i can see is it usually takes 3-4 months to get something custom built from them...I would be willing to help anyone that would like something like that built.. and I could crate it and have it shipped....I am not looking to make money,,But only willing to help anyone if they can wait the time it takes to get it done...I cant drive the hour down there every week to see when they have it finished..lol.. it takes time....
 
Last edited:
Building MLTL cabinets for 604-8H

Lioh, Lioh, use the Force...the Resonant Force!

The Altec 602 cabinet is a basic big box bass reflex port design. Advanced computer modeling software now allows accurate design of more complex speakers enclosures. Every cabinet shape has resonances. To control them a well designed ported bass reflex box will use a combination of: prime ratios for W*D*H; bracing materials for strength and resonance control; and stuffing.

More refinement.... MLTL = Mass Loaded Transmission Line
The MLTL enclosure can be thought of as a form of tuned transmission line where quarter wavelength standing waves are used to provide the spring force for the mass of air in the bottom port. A speaker with a Fs under 30Hz requires a tall cabinet to generate the long quarter-wave required to extend ported bass.

The Altec 604 has: moving mass, mechanical restoration force, magnetic motor force, etc.. which model best in a transmission line with a 419sq_in internal cross-section area.

If the driver is offset at 1/3 the length of the straight transmission line, the 3/4 wavelength standing wave can be totally suppressed, and in addition the impact from every other quarter wavelength mode (3/4, 7/4, 11/4, ...) will also be essentially removed from the system SPL response.

Using this 1::2 ratio, a 39"� ear level driver position would require a ~58.5" line height with the driver center 19.5" down from the line top. Total internal line volume of 11 cu_Ft with a 419 sq_in line section area,2" long x 6" diameter port, 7" above the line bottom.

419sqin =22” x 19”
~200Hz initial baffle step
=======
Read up at: Quarter Wavelength Loudspeaker Design. Quarter Wavelength Loudspeaker Design

GM has designed a few MLTL cabinets for Altec 604 coaxials which a Google will find.

Greetings to you all. This is my first time posting on the forum but I am a frequent visitor.
I replied to this thread because I am in the process of building MLTL cabinets for my Altec 604-8H drivers. The quote above has given me some valuable information and cleared things up to some extent. However, My cabinet inside dimensions are 19"x 22"x 47" (WxDxH) ~ 11.3 cubic ft. The 19x22 gives me the suggested cross section area 419 sq. ins but I do not have the suggested line length of 58.5". i am at 47". I also looked at the 39" air level driver position and in a 47" line 1/3 the length will be ~15.5" from the top to center of the driver and 31.5" to the lines end. A stand of ~8" could put my drivers at ear level.
Question. How do i complete this project? Can this length line work for this driver? How do I size/tune the port?
The science behind the design. I looked at Mathcad, read the tutorial, read it again but a full undestanding of cabinet design using Mathcad is going to take me some time. I will be very appreciative if someone with the knowledge of MLTL design will help with some suggestions.
Anthony