MAH Assembly

**mah** · October 4th, 2011, 09:54 PM

Thanks for the compliments. Photo enhanced by blurriness.

**mah** · October 15th, 2011, 01:38 AM

Another small step. 416s mounted and wired. Enclosures in position. Gawd they look big.

Jig to be made for routing the holes for ports.

Plumbing supplies for the ports.

**Panomaniac** · October 15th, 2011, 02:38 PM

Originally Posted by mah

Gawd they look big.

Cause they are!

**Altec Best** · October 15th, 2011, 02:49 PM

Originally Posted by mah

Enclosures in position. Gawd they look big.

You should see what 20 cubic ft. cabs look like.I'm going to have trouble getting them through the door !

**Panomaniac** · October 15th, 2011, 06:20 PM

U R Krazee!

**VolvoHeretic** · October 15th, 2011, 06:49 PM

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.

**Panomaniac** · October 15th, 2011, 08:01 PM

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

**mah** · October 15th, 2011, 11:14 PM

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.

GM · October 15th, 2011, 10:08 PM

Originally Posted by VolvoHeretic

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