Interesting Variable

[bowtie427ss]

All the usual caveats.

These appear nicely preserved and unmolested as well as sporting some more of those symbiotik 802's.

http://cgi.ebay.com/Altec-A7-500-8-V...QQcmdZViewItem

Notice the difference in heigth/location of the vents, what gives?

[edfallon]

Originally posted by bowtie427ss:
All the usual caveats.


Notice the difference in heigth/location of the vents, what gives?

<font size="2" face="Verdana, Helvetica, sans-serif">Even worse, look at the differences in the attachment points of the horn throats. One appears to have a wider throat opening. Quality control was not job one when it came to cabinet construction. At least they appear to be plywood and not MDF.

[LICORNE]

The bass reflex vents are not identical on both units. As long as the drivers sound the same .

I would call this a minor adjustment to be made.

....................

[GM]

Greets!

FYI, the cab on the right with the smaller area LP filter (not throat, which is the baffle board area) is for an A7-8 using the 803B/416 series woofer due to their different specs/response, while the larger one typical of all later cabs is for the early A7-8/803 and all A7-500s as well as the 825/828 based A5 with 500 Hz XOs. Not sure when they quit building the two different versions or when they quit using the upper glue block for what I assume were cost cutting measures as the A7-8 wasn't nearly as popular around here as the A5 and A7-500, all I know is that a circa 1970 A7-8/A7-500-8 cut sheet still shows the small filter cab without the glue block on both models, so apparently the marketing dept. was already getting a bit sloppy.

WRT the different vent locations, the baffle board sizes changed somewhere along the line and my SWAG is with the introduction of the A7-500 to get the desired tuning when the larger horn is mounted in the vent since I've only seen the 'high' vent on A7-8s. From a performance POV the higher vent will only fractionally raise Fb, so strictly a cosmetic issue.

Anyway, as I've periodically noted, for the tweaker there's some minor performance gains to be had by experimenting with reducing the LP filter's area when using various woofer, horn, XO combinations (mostly response smoothing), which holds true for all the other woofer horn combos too.

GM

[drummerwill]

This pair looks identical to the pair of A-7 ccabinets I got from a St Louis araea Cinema service dealer's warehouse. One cabinet had the High vent the other the lower vent. Although the had different sizes they were supposebly from the same installation.
Thats the reason I sought out info on the optimal size vent, to DIY. I did notice better imaging maybe better sounding when both were the same.

Have fun
Willie