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Thread: Drivers from 1966 825 cabinet compatible with 828 cab?

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    Hostboard Member kipduff's Avatar
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    Drivers from 1966 825 cabinet compatible with 828 cab?

    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......

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    Senior Hostboard Member Elitopus1's Avatar
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    Re: Drivers from 1966 825 cabinet compatible with 828 cab?

    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.

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    Hostboard Member kipduff's Avatar
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    Re: Drivers from 1966 825 cabinet compatible with 828 cab?

    Quote Originally Posted by Elitopus1 View Post
    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.

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    Senior Hostboard Member Elitopus1's Avatar
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    Re: Drivers from 1966 825 cabinet compatible with 828 cab?

    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

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    Senior Hostboard Member LOUDER's Avatar
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    Re: Drivers from 1966 825 cabinet compatible with 828 cab?

    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.

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    Hostboard Member kipduff's Avatar
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    Re: Drivers from 1966 825 cabinet compatible with 828 cab?

    Quote Originally Posted by LOUDER View Post
    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.......

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    Junior Hostboard Member lokie's Avatar
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    Re: Drivers from 1966 825 cabinet compatible with 828 cab?

    Is it OK to just make your own mounting board for the 15" woofer.

    Changing the horn opening etc.. is probably not doable... and maybe the different size woofer won't load correctly??

    Probably adding more questions than answering... food for thought.


    vott.jpg

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    Senior Hostboard Member Elitopus1's Avatar
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    Re: Drivers from 1966 825 cabinet compatible with 828 cab?

    You could change the mounting stud spacing, but I wouldn't change the size of the opening. I think the opening has more to do with properly loading the horn, and less to do with the woofer that is installed.

    I don't think the opening size is different in any of the 825/828 cabs. I don't see why it would be different, when the different Altec woofers meant to go in that cab all have the same size cones. Pls correct me if I am wrong about this.

    My 828 cabs a short motor board like the above pic. Meaning it doesn't go across the whole cab and seal off the horn flares. At least that cab has a plywood motor board. Mine is particle board like the rest of the cab. Makes me worried to hang a heavy 515 on there.

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    Hostboard Member kipduff's Avatar
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    Re: Drivers from 1966 825 cabinet compatible with 828 cab?

    Quote Originally Posted by lokie View Post
    Is it OK to just make your own mounting board for the 15" woofer.

    Changing the horn opening etc.. is probably not doable... and maybe the different size woofer won't load correctly??

    Probably adding more questions than answering... food for thought.


    vott.jpg
    I don't think there's gonna be any problem here- as Elitopus says, I'm pretty sure these 825/828 boards are all cut at same diameter (13 1/4"). I will not be able to use the 4 existing captive T-nuts because they are on a larger (15") circle. I will draw a new 14 9/16" circle indexed on original opening and use my 416A to mark 8 locations to pre-drill from back for eight #10 pan head wood screws.

    - - - Updated - - -

    Quote Originally Posted by Elitopus1 View Post
    You could change the mounting stud spacing, but I wouldn't change the size of the opening. I think the opening has more to do with properly loading the horn, and less to do with the woofer that is installed.

    I don't think the opening size is different in any of the 825/828 cabs. I don't see why it would be different, when the different Altec woofers meant to go in that cab all have the same size cones. Pls correct me if I am wrong about this.

    My 828 cabs a short motor board like the above pic. Meaning it doesn't go across the whole cab and seal off the horn flares. At least that cab has a plywood motor board. Mine is particle board like the rest of the cab. Makes me worried to hang a heavy 515 on there.
    I think you're right- so far, I see no evidence that all 825's and 828's were not cut at 13 1/4" diameter. And the seller has confirmed that these are also- and I bought the cabinets. They are a later model 828 without rails, 5/8" material represented as MDO (medium density overlay), and has the full width motor board. This is stronger than MDF. He seems to be pretty knowledgable. For better or worse, they are refurbished and look pretty good and stock. He has used the type of paint that has the "spatter" pattern which I've seen in pictures of later A7's. I'm gonna see if I can attach some of the pics off the eBay listing and post to this thread so you guys can see them.

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    Senior Hostboard Member Elitopus1's Avatar
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    Re: Drivers from 1966 825 cabinet compatible with 828 cab?

    Very cool! Good to hear you were able to make the deal

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