604-8G cabinets to build

[Morfeas]

I'm new in the board and the Altec universe.

Just received my 8Gs.


What cabinet would you recommend for them? Looked at the 620 plans but any suggestions from more experienced users are welcome.



A second question is regarding the magnetic field. It seems very weak. Both LF and HF cannot even hold a screw driver. Is this normal? Are they magnetically shielded?



Thanks

[speakerdave]

The housings of the magnets act as shields, although I think the intention was more to focus as much as possible of the magnetic field in the gap. It is possible for Alnico magnets to lose some of their force, but this results from the flux modulation of large inputs and is far more likely in a woofer than a tweeter. If you are concerned about this possibility you can get the magnets regaussed.

Cabinet recommendations for this driver can be found at the Great Plains Audio web site devoted to Altec classic equipment. The 620 was actually designed for earlier versions of this speaker, but it has been used with the 8G to good effect. One plan they don't seem to mention often there is the one published by Lampton and Chase in Audio Amateur sometime in the mid seventies. This was one of the early designs using Theil Small parameters and filter theory. It is a 5 cubic foot box that is -3 dB at 40 Hz. With this driver you need to go a lot larger to get much lower--like ten cubic feet. Dr. Gizmo and others figured it was best to use a subwoofer with this driver. If you want VLF commensurate with the output of the 604 and have room enough for 10-12 cu fit total I would suggest using a large efficient subwoofer driver like the JBL 2242 in addition to the 604 (in its own subenclosure).

David

[Morfeas]

Thanks

[Wardsweb]

Checkout Bill's thread on building his 604-8G cabinets over on my website.

http://www.wardsweb.org/Billfort/

[speakerdave]

You're welcome!


And, yes, that Billfort box is one I have read about on the web and should have mentioned specifically. It is an adaptation of the 620 volume to a shape that may fit better in many rooms.

David

[mazort]

I want to build billfort's Altec speaker box design after seeing his website for my 604-8G's. Does anybody know how to querry billfort or know the dimensions of the triangular vents, side and rear panels?

Thanks for any assistance, I'm new to this forum. :wave:

[Zilch]

Are you reading this other thread?

http://audioheritage.org/vbulletin/showthread.php?t=5707&highlight=billfort

[Morfeas]

Working on the 620 cabinets I do have a couple more questions:

1. What is the stuffing used. I have some info that in the original ones it was rockwool.

2. I do not get a detail in the cabinet drawings. In the attached image I have marked board A that goes from front to back and board B that goes from side to side. What's the stuff between A and B? Is it an extra board from side to side?

Thanks:)