The 604-8G's

[jmarkwart]

Mark,
As far as I know it is. All my Altec promo lit says that the 604-8G requires a 9ft^3 enclosure with exterior inch dimensions of 40 by 26 by 18 called the 620A. The Altec construction plans in AN-11 label it as 620 - but it is clearly a 9ft^3 enclosure of the dimensions above. The 620 cabinet superceeded the 612C that was recommended for the 604E by Altec, and which was about 6.6ft^3 with a 23in^2 vent.
Altec could change product suffixes at the drop of a hat - but I believe the 620 plans are applicable to the 604-8G and H only. Anybody have any more info?
Jeff

[selmerdave]

Weren't the letter designations for the size of driver used? I thought an "A" cabinet was for a 15" driver, a "B" cabinet was for a 12" driver and so on. The plans I have don't show any "C" cabinets, but "A" and "B" refer to the size of the hole you cut for the driver.

Dave

[billfort]

I use 604-8G?s in cabinets of 9ft3 internal volume & 40Hz vent tuning. I tried to use the important parameters of the 620A cabinets (volume, tuning and baffle width which I think is critical) but wanted something a little more attractive that could get the driver up to ear level and allow corner placement if the room can accommodate.

There are some details of my attempt at a cabinet here.

The results have been very satisfying with great bass performance and none of the lightweight upper bass/lower mids I sometimes hear with these drivers in narrower cabinets. I think the 620A, or a design that follows the lead of the 620A, is the way to go with the G.

Billfort

[Murray Keidge]

Hello Mark,
I would have to aggree that the 620 cabinet is the best one for the 604-8G. I have a pair of them in my home and they perform excellently.

I have compared them with nearly evey model of 604 available and my personal preference is the 604-8G in the 620 cabinet.

Mine are powered by a Crown DC300a amplifier with a Crown IC150a pre-amplifier.

I also use the standard 604-8G passive networks. They are not in the cabinet but run externally.

I do not run any sub-woofers with them at home, I have however, given them a bit of assistance in the low end by the use of some very specifc eq.

This technique may not be considered "perfect" or "correct" by some but the result is excellent.

The comment from friends is that these loudspeakers must be the latest available as they have not heard anything else like them, particulay for movies.

If you want to talk further give me a call, being in Queensland I am not too far away.

Murray.

[thevott]

EQing a system is 'correct' and an embraced proceedure for achieving a flat system. Many people are opposed to any processing at all though I find this approach impractical in most normal listening environments (parallel walls Etc.).
MP

[joyspring]

VOTT:

You're quite right with 604/5s; EQing is a MUST because 604/5s are anything but flat. Stock Altec crossover networks are hardly optimal.

Mark:

If you would like to try out the UREI Time-Align crossover networks from the schematics in the PDFs I linked to above, there are a pair of blue UREI 800H horns currently on Ebay:

http://cgi.ebay.com/ws/eBayISAPI.dll...EBWA%3AIT&rd=1

These are correct for the original 811/813/815 UREI monitor series that utilized the Altec 604-8G.

The response correction alone in this crossover makes this effort worthwhile - it is a VAST improvement over the stock Altec unit. The time domain correction also sets it apart from the Mastering Lab units as well.

BobR

[thinking]

I have a question that is related to the topic of building cabinets for the 604-G. When you calculate the box volume, the driver takes up part of the space inside the box. Does anyone have a value to use for this volume? I saw a suggestion on one web page about wrapping the thing is plastic and dunking it in a full bucket of water, and measuring how much water it took to refill the bucket. Hmmm. First, a 604 would take a pretty good size bucket, second, I really don't like the risk of putting one of these things anywhere near water. Bill at GPA did way too nice of a job reconing them! Also, it would make a difference whether you mount them on the front or the rear of the baffle. Any thoughts appreciated!

[jmarkwart]

Thinking,
Altec published .33ft^3 as the volume of an alnico 604, .24ft^3 for the ferrite.
I prefer to front mount the 604 on the baffle; it's a lot easier and quicker to remove/install the driver than having to remove a rear or side cabinet panel first. Also, if you build your baffle to front mount the older, narrower basket (604 thru 604E) then you can utilize it for the later 604G thru K, as well.
Jeff

[thinking]

Thanks for the reply, I see the numbers in the chart now, and don't know why I didn't figure it out for myself. I knew that Vd was not the number I was looking for, but didn't even contemplate what the Vid was. Now I need to recheck my calculations.
On the rear or front mounting, what I meant was that when you move to the front, you effectively change how much of the speaker is inside the box. It's a fairly simple calculation, simply the volume displaced by the thickness of the baffle, and the mounting flange flange thickness. But I don't know which way the spec is intended for, front or rear mounting.

[thinking]

I sat down and measured up a 604E, and roughly calculated out the volume that it would displace. My conclusion is that the published number is for rear mounting on the baffle. Also by my calculations, front mounting will reduce that volume by approximately .1 cu ft.