Drivers from 1966 825 cabinet compatible with 828 cab?

[kipduff]

I have an opportunity to buy some pretty decent Altec 828 cabinets within driving distance (these don't have the protective exterior braces on back- but other than that, look like the drawings of 828's I've seen)- then realized A7 cabs had variations. I have components from 1966 A7-500's: 416A (16 ohm), 802D (16 ohm), 511B, and N-500-E that are looking for a home. I noticed from the drawings, that, for one thing, the LF baffle hole on the 828 is smaller at 13 1/4"- while the bolt circle diameter on the 828 is larger at 15". Looks like the port size on the 828 can be modified by placement of different size retangular boards to partially block the port.

Can my 1966 components work OK in the 828's? I'm just starting to research this (and I'm guessing there's a lot of threads on this), but was wanting to get these soon- so time sensitive. So far it looks like it's a GO. Thanks......

[Elitopus1]

They changed the screw spacing when the 16" frame drivers were out. I don't know numbers (bowtie told me and I forgot) or how many cabs have the larger spacing. All I know, is with the smaller spacing (for the 15" frame Altec woofer), the 16" frame will also fit.
And so will the commom frame JBL and EV woofers.

I would think that your components would fit as long as the cabs were built with the 15" woofers in mind. My later 828 clones (particle board) were made with the smaller bolt spacing.

[kipduff]

They changed the screw spacing when the 16" frame drivers were out. I don't know numbers (bowtie told me and I forgot) or how many cabs have the larger spacing. All I know, is with the smaller spacing (for the 15" frame Altec woofer), the 16" frame will also fit.
And so will the commom frame JBL and EV woofers.

I would think that your components would fit as long as the cabs were built with the 15" woofers in mind. My later 828 clones (particle board) were made with the smaller bolt spacing.

I guess two issues to think about.

1) will woofer fit physically?
The key issue that I'm aware of at this point is: is the opening in the 828 baffle for the woofer too large to mount the 416A? If I knew what speakers were used in later 828's, it would help. It's possible that the opening is too large: I see data for Altec 416-8B and 416-8C woofers specifying 14 1/4 dia openings. According to drawings I have, the opening on the 825 is 13 5/8" with bolts on 14 9/16" diameter (these are also the dimensions listed in the Altec data sheet for 416A). The baffle opening in the drawing I have for the 828 cabinet is smaller at 13 1/4" with bolt holes on a larger 15" diameter (these are also the dimensions listed in the Altec 515 and 515B data sheets). Anyway, can the 416A be mounted in the 828 cab? I don't see why not if the 828 cab baffle I'm buying is cut at 13 1/4" diameter. I would just draw a new 14 9/16" diameter circle indexed on the existing opening, place the 416A on the back of the baffle and make my marks for predrilling for eight #10 panhead screws. If any one can confirm that 828 baffle openings are 13 1/4" dia, I would appreciate it- the seller hasn't gotten back to me with that info yet.

2) is there something about the 828 tuning that would not be compatible with my 1966 A7-500 components? Sounds like not a problem. Adjust port area and/or internal volume.

[Elitopus1]

I believe the only difference between the two is the bolt spacing. The actual cutout should be the same, since both 15" and 16" Altec woofers use the same cone.

With the larger spacing the smaller 15" won't fit. I had some factory 817a cabs that I could only run 16" frame woofers in. With the smaller bolt spacing you can use either 15" or 16" spacing.

Can you get the seller to measure the mounting bolt spacing?

I believe with the old 825 cabs (with the two vertical ports) had a bigger port area. Personally I would retune the cabs anyways. So I wouldn't be worried about port size

[LOUDER]

I have 828's (g's ???) with 15" 421's. I don't know the year of manufacture. Why don't you take one speaker with you, and if it doesn't line up then make a decision. You could always offer half of what he's asking.

[kipduff]

I have 828's (g's ???) with 15" 421's. I don't know the year of manufacture. Why don't you take one speaker with you, and if it doesn't line up then make a decision. You could always offer half of what he's asking.

Well, seller is gonna measure the diameters of the openings and inform me. Easier than taking 300 mile trip to see for myself. Should get back to me later today.

So I looked up data on 421-8H speakers: 13 5/8" hole with 14 9/16" bolt circle. Same as 416A and 515B. So I'm assuming your baffle hole is 13 5/8. I know the bolt holes are not gonna line up- not worried about that. Just wanna make sure hole not cut for 416-8C. Thanks.......