First post: Questions regarding ALTEC 612 enclosure - DIY

Thanks Altec Best !

Just to get a second confirmation on what options I got I also sent an email to greatplainsaudio.

The Altec Lansing 604E Duplex speaker elements (the ones I got) has fins on the backside - this means that the 604E model in the Duplex series
only can be mounted from the rear.

This means that all previous messages regarding the bevel along the opening in the 612C cab with the use of the 604E model is useless.

This is because it is NOT possible to mount the 604E speakers from the front.

In the email I got back from great plains it was also explained to me that the bevel cannot be cut out with a rear mounted speaker ( 604E?s ) because in my case the of the use of 3/4 " plywood ; that is too thin - the mounting screws will go through the bevel edge in the plywood front.


- tralalalala

Quote:

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Originally Posted by Tralalalala

This is because it is NOT possible to mount the 604E speakers from the front.

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Not true, it just requires a bit more work by cutting notches to match the fins and using thick neoprene or similar closed cell sponge gasket. Adding a false baffle to both stiffen up/mass load the baffle and make it a ~flush mount is a good plan also.

GM

OK. my bad GM , understand that it is possible...

but, I think I will go for a rear mount solution. I have a gut feeling that I will be more than happy with a simple cabinet.

I?ve put in the correct mounting size for a Altec Duplex 604 E ( rear mount ) in a new drawing.
+ additional correct measurements of the inside braces given by Altec Best earlier in this thread.

+ just skipping the front edges of the original 612C cab.

This is a very simple draw plan, but I think this is what I?m going to do in the end...
then I as mentioned before will only need two whole 3/4 inch birch plywood plates instead of three...

http://img600.imageshack.us/img600/7...converted0.jpg

Posting a drawing of my previous suggestion of cabinet build...

Just for reference.

This drawing is made for 604 E rear mount speakers.

http://img841.imageshack.us/img841/8717/diy612cab01.jpg

Hello !

I have now started to build my 612 DIY cabinets.

I have choosen 19mm MDF as material for these cabs.


Any other people out there that has built or heard Altec Duplex speakers in MDF cabinets ?

Reason for using MDF instead of Birch plywood :

1. Birch plywood in 19mm (3/4 inches) thickness is almost not possible to find where I live.
2. Birch plywood compared to MDF in price : you can triple the amount between the MDF and the birch plywood.

I will paint the cabinets battleship grey :)

Will add pictures later on !


- tralalalala

Battleship Gray is the only choice....Chicks love battleship gray, definitely...

After all of the work and expense you already invested, don't let a few Kroner influence your material choices.

Arguments can be made for MDF or plywood. I'd go with the ply. Might even be tempted to go with the 15mm. I find that Altecs sound good in somewhat live plywood boxes, although I had a pair of very heavy MDF Onkens that worked well.

I don't now how many people soaked in modern design practice will agree with me but, within limits, I say "Lively cabinet equals lively sound."

Quote:

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Originally Posted by Tralalalala

Hello !

I have now started to build my 612 DIY cabinets.

I have choosen 19mm MDF as material for these cabs.


Any other people out there that has built or heard Altec Duplex speakers in MDF cabinets ?

Reason for using MDF instead of Birch plywood :

1. Birch plywood in 19mm (3/4 inches) thickness is almost not possible to find where I live.
2. Birch plywood compared to MDF in price : you can triple the amount between the MDF and the birch plywood.

I will paint the cabinets battleship grey :)

Will add pictures later on !


- tralalalala

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Your leaving out the Biggest consideration. Of What sounds the Best.. I also agree that (Baltic Birch) Plywood is what sounds the Best IMHO...

Good Luck with your project.

Quote:

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Originally Posted by Tralalalala

Any other people out there that has built or heard Altec Duplex speakers in MDF cabinets ?

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Yes.

?? MDF cabs have a low Fs due to their higher mass, damping, usually in the lower mids BW, so tend to ?suck the life out? of some speaker?s critical mids, especially low Qt ones like most Altecs.

If driven with a ~matching impedance or the driver has a high Qt though, the cab?s damping tends to reduce any under-damped driver ?ringing?.

19 mm BB or similar no-void ply OTOH tends to have a high enough Fs due to its extreme rigidity to be above the cab?s gain BW, so only minimal damping is required to keep the driver from exciting the cab, ergo any ?liveliness? in the response is all driver generated and most Altecs are known for their ?liveliness?.

A decent compromise is to make the baffle and top out of 19 mm no-void ply and the rest out of MDF and use some ply scraps to reinforce the MDF panels. If stand or wall mounted, then make the bottom out of ply also.

GM

Hi again people

Thank you all for the response !

GM: thanks !
I will take into consideration your suggestion about building the front and top ( maybe the bottom also ) plates in 18 mm baltic birch x-finer.


Will keep you updated !


- tralalalala

OK. Done some research: I will need one birch x-finer 18mm to do what GM suggested.

I have some questions:

1. frame ( blue surface on the first attached photo below ) : I have seen DIY 612 cabs with this type of construction before.

a good design ? ( will be built out of 18mm birch ply)

http://imageshack.us/scaled/thumb/842/hostboard01.jpg

2. front frame ( made out of MDF ) mounted to the the front baffle with wood pins.

again - the design - will it work ?

http://imageshack.us/scaled/thumb/4/hostboard02.jpg


all inputs will be appreciated !


- tralalalala