MAH Assembly

[Panomaniac]

Externally the 828 (A7) is about 17 cubic feet. Big speaker for home use.

[GM]

So I think that I remember that my A7 cabinets are something like 12.5 CF. I could easily add a 7.5 CF box extension onto the back upper half of my enclosures. I just need some numbers-cubic feet total volume, cubic inches port volume.

IIRC, the 825 is ~12.65 ft^3 net and the 828 with its closed off horn cavities are ~11.42 ft^3 net. Which do you have?

Regardless, to keep from getting multiple band-pass cavity resonances you would need to make the whole cab deeper, i.e. remove the entire back except for a mounting flange to bolt up the addition.

GM

[mah]

Remember, guys, this is work in slowgress. I hope to be listening by Christmas.

Recap:

Originally intended to build 848s(as A7-500s). After the panels were cut I decided to go with bass-reflex using the same outer panels - so size is the same as an A7. Luckily, I managed the build using the original panel material.

External volume is 17.5 cu.ft.

Internal volume is13.7 cu.ft. (14.55 internal - 0.60 cleats/braces - 0.25 416-8B)

Bracing inspired by bridge roadway construction.

416B mounted as high as I dared with baffle rigidity in mind. Happily it is at seated ear level.

Poly lining: 20mm on both sides, 30mm on the back, folded back up a foot or so, and a 20mm curtain mid-way between the 416B and the back panel, 50mm at top. The curtain drops to about a foot from the bottom panel. I hope this is beneficial to port action.
This gives about 0.1lb per enclosure internal cu.ft.
Could be light-on( GM??? ).

Some constrained layer damping material added here and there to panels and to where the casters are bolted.

Ports: two 4 inch dia. PVC pipe. Front bottom mount.

Speakon socket on back.

Finish: some day ~ er, black, a cross between flat and satin. Think Hi-Fi components.


Yet to happen:

* Complete port panel.

* Instal GPA #34647 diaphragms into the 808s. Omit loading caps and put felt in rear covers.

* Cobble together N501 type crossover to use until I service some old classic SS amps for active DCX setup.

* Use an in-service amp to commission and tune the system.

* Grills or screens.

Thank you for your support, Marshall.

[cradeldorf]

Have fun with it Mah, The first time you fire em up makes it all worth while.

[Altec Best]

U R Krazee!

Nah ! Just a little Audio Nuts ! Altec crazy maybe ?

I never seen a dual 15" woofer cabinet that wasn't LARGE !

As per GM's Recommendations I asked for Stellar.So I got Stellar Humongous Cabs !

[Altec Best]

Remember, guys, this is work in slowgress. I hope to be listening by Christmas.

Marshall I know the feeling ! Your not alone there. Damn work gets in the way.

[GM]

This gives about 0.1lb per enclosure internal cu.ft.
Could be light-on( GM??? ).Thank you for your support, Marshall.

You're welcome!

From a strictly technical POV it's whatever it is with whatever is used that removes the 'ring' in an impulse response, but all that really matters is, does it sound 'right' [life-like WRT vocal's, music's attack/decay AKA 'PRAT': pace, rhythm and timing] to you and everyone else that's going to listen to them on a regular basis.

GM

[mah]

Cabs completed with 'test' ports fitted. All cables/interconnects assembled. Should be hooked up for commissioning by new year. Has it really been nearly 3 years(don't answer)?

Let me tell you a funny story(weep). Some time ago, I was talking to a guy who works in a store in town and he said he had a dilemma. His adult son had given him a model aircraft kit for Christmas and kept asking him if he had built it yet. Well, this guy confided to me that he didn't have a clue about putting things together. I hadn't put together an Airfix, or similar, kit since I was a kid and heard myself saying " I'll build it, just drop it around to me".

This is what he provided: Build a Fokker Triplane

Being a man of my word, I am still building it.

Best wishes, to all, for the festive season.

Marshall

[mah]

Help! I have mounted the Al frams into my re-magged 808s but cannot find the screws to fasten on the rear covers. What type of screws are they?

Marshall,

[GM]

Mine are 6-32 x 5/8" Phillips round head: Machine Screw #6-32 x 5/8" Phillips Round Head Stainless Steel, Pack

GM