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Thread: Tom Danley mods for Altec VOT A7?

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    Tom Danley mods for Altec VOT A7?

    I understand Tom Danley once proposed some mods to the A7 which are supposed to improve the sound greatly. I couldn't find anything on the net, and paging Tom on AA brought no result.

    Anybody happen to know where I could find further info?

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    Senior Member louped garouv's Avatar
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    there's an old Sound Practices article by Jim Dickinson that you may want to search out also....


    if you can still buy the Sound Practices Archive CD on Ebay, I thought it worth the admission price....

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    Quote Originally Posted by louped garouv View Post
    there's an old Sound Practices article by Jim Dickinson that you may want to search out also....


    if you can still buy the Sound Practices Archive CD on Ebay, I thought it worth the admission price....
    Thanks, I'm aware of the Sound Practices article as I have a full collection of the mag. However, according to an old thread on this very forum, Tom Danley said somewhere that his mods take several hundred degrees of phase distortion out of the design, an aspect which is not covered in the SP article.

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    Senior Member JBLRaiser's Avatar
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    What do you know and ....

    Quote Originally Posted by mcds View Post
    Thanks, I'm aware of the Sound Practices article as I have a full collection of the mag. However, according to an old thread on this very forum, Tom Danley said somewhere that his mods take several hundred degrees of phase distortion out of the design, an aspect which is not covered in the SP article.
    what do you need to know?

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    Here's the info that can be found on the Altec User Board:

    A-7 mods

    Replace stock drivers with JBL-2226 and BMS 4550.

    Replace lower vent panel with one having 4 , 4 inch dia ports, 5 inches long.
    Pic #60

    Reinforce 15” horn flares, glued in with construction adhesive not wood glue or epoxy.
    I used boards which were 5 ½ inches by 12 inches with one side cut to a 20 degree angle to better mate with the horn flare.. These are way too live.
    Shown in pic # 62
    Before and after is shown in measurement, gets rid of a few dips.

    Optional, it wouldn’t hurt to put a 2X2 diagonally on the lower cavity side walls with a 2X2 added to tie the sides (from one side to the other) together.
    I would use construction glue to adhere the 2X2’s to the walls and when dry, use screws to attach the cross brace.

    Apply damping to the under side of the final bell of the 511 (not visible).
    Mount the horn on the rear side of the wood, setting it back from stock.

    Mount the 15’s with an extra front gasket for clearance at Xmax.

    Use foam tape to seal all removable panels and replace the wood screws with 1 5/8 drywall screws.

    Drizzle some extra glue at the front edge of the flare on the interior (the glue joint at the front where the bent plywood attaches. Use that gorilla glue (polyurethane) for this as it fills gaps. On this one there was a gap in the wood (on the inside).

    Remove and remount the horn mounting board, remount 2 ¾ inches rearward and use the foam tape under it (which dampens the box top panel).
    I'd love to see the pics, of course, but most importantly, I can't imagine that TD did not make any suggestions for the crossover.

    Also, which version of the 2226? Not sure I'd go with the BMS, but TD usually knows what he's talking about.

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    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by mcds View Post
    Not sure I'd go with the BMS, but TD usually knows what he's talking about.
    Unity horns are built with BMS 4550s, I do believe....

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    I've used the JBL 2226 and various Altec VOTT woofers including the 411 and 416. Its weird to me that he would suggest replacing an Altec woofer with a JBL but, weirder things have happened, I suppose.

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    Senior Member spkrman57's Avatar
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    I don't think JBL 2226 is good choice for A7 driver!

    The cabinet is way too large for a small Vas driver like the 2226(I think about 7 ft from memory).

    I think there are better drivers to use in the A7 VOTT cab.

    Regards, Ron
    JBL Pro for home use!

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    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by spkrman57 View Post
    The cabinet is way too large for a small Vas driver like the 2226(I think about 7 ft from memory).
    Allegedly, it is a horn.

    The friend he did that for already had the drivers; Danley said he'd have used something cheaper. That narrative is on Audio Asylum, as I recall....

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    TD's original post from AA which Zilch alludes to, and which is quoted somewhere in the archives of this forum can be found here:

    http://db.audioasylum.com/cgi/m.mpl?...t=2226+4550&r=

    Since TD specifically mentions "several hundreds of degrees less phase shift through crossover", I'm thinking he must have done something to the crossover as his work on re-aligning the BR wouldn't change the response at the crosover point.

    Now, to my mind, there's two possiblities: either TD found that with the existing crossover but different drivers, the phase shift through crossover was less; unlikely.

    Or he changed the crossover schematic. This is what I'm trying to find out. Any help is very much appreciated.

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    Quote Originally Posted by Zilch View Post
    Unity horns are built with BMS 4550s, I do believe....
    The original Lambdas had TAD 2001 or B&C DE25 (what mine have). The current Synergy's use the 4553 and other BMS from all I have read.

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    Senior Member Russellc's Avatar
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    Quote Originally Posted by mcds View Post
    Here's the info that can be found on the Altec User Board:



    I'd love to see the pics, of course, but most importantly, I can't imagine that TD did not make any suggestions for the crossover.

    Also, which version of the 2226? Not sure I'd go with the BMS, but TD usually knows what he's talking about.
    Well I can tell you one thing, when you hold a 2226H or 2225H driver up to the hole in my 828 A-7 cabs, you're going to need a hole shrinker! Driver aint quite as big as the original I have, 416 8C and 515 8G anyway......

    Russellc

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    RIP 2011 Zilch's Avatar
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    Re: BMS 4550

    Danley posted this two days ago:

    http://www.diyaudio.com/forums/showt...78#post1870178

    The larger issue is the HF response, and Don McRitchie documented A7's "haystack" tuning. That keyword will find Don's post.

    My best answer to the crossover question is the reconfiguration of the Model 19 crossover I did in Skywave's 9844 thread here, but even the "HF capable" Altec drivers exhibit a significant ripple when compensated, at least the 802s and 902s I measured. The BMS is higher sensitivity, so to bring it into the operating range of the dual controls, an additional fixed L-pad may be required.

    No, I never ran it with 2226H as the woofer, and no I don't have any A7s to try that.

    I extensively documented how the Model 19 crossover works here. Keyword "Gary" by Zilch will find it, "Here go, Gary...."

    Bottom line, based upon my analysis, upgraded A7s begin with empty cabs, and after all of that, they'll still need subs....

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    Quote Originally Posted by Zilch View Post
    Bottom line, based upon my analysis, upgraded A7s begin with empty cabs, and after all of that, they'll still need subs....
    Then they're not A7's, they're 828 cabinets with a variety of purposely chosen components installed.

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    Quote Originally Posted by Goodwill_HiFi View Post
    Then they're not A7's, they're 828 cabinets with a variety of purposely chosen components installed.
    Naw, they still have Altec sectorals, but we can work on that part, too, of course....
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