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Thread: Altec Custom VOTT Somethings

  1. #1
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    Altec Custom VOTT Somethings

    I found a nice set of custom built speakers loaded with Altec goodies and cabinets that were allegedly built to some Altec build plan about 30 years ago. The cabinets are relatively well built with an internal 1" thick wall surrounded by 3/4" oak ply.
    The driver contingent is as follows:
    Altec 802D HF Drivers
    Altec H-811-B Horns (Gold in color)
    Altec 414A woofers - 2 in each
    Altec N-500-E Network.

    All 16ohm

    External cabinet size is 39" high, 26.5" wide, 21" deep.
    Internal size is 8.4 CF

    Port is 4" x 11.5" deep.

    Rotary switch on back for network adjustment.
    No insulation.
    NO internal bracing.
    Back panel is removable and needs more screws.
    Cheap Screw terminals.

    The Oak is not my cup of tea, but once buffed out again should look fine.
    Came with fairly primitive grilles that need new material if I keep them in the same configuration.

    Sound quality is impressive. Big and lively being run with my Dynaco St70.
    Two of the woofers have cracks in the seem of their accordion surrounds that will need to be addressed unfortunately.

    So what do I have the makings of here? I really am digging the sound so far and gotta think with some other refinements these could be really good. I am not sure what if anything has been done with the HF drivers over time.
    Attached Images Attached Images      

  2. #2
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    Nice setup!




    I would add some 2" fiberglass insulation/batting ( or the UltraTouch stuff maybe ) on 3 of the 6 inner surfaces ( to begin with ) > since that's how Altec did it.

    Re; your splitting of the 414's surrounds.

    Personally I'd keep it ( at least the cones & coils ) all original and simply fix the splitting from the backside with applied plasters ( WWI-style wound dressing ) made up of cigarette papers ( which is very thin ) and lightly applied rubber cement ( to glue the paper into the existing surround goop ). Consider that many surrounds are made from linen cloth and you get another type of backing material ( if paper seems too marginal ).

    That would be my first course of a DIY type of fix .


  3. #3
    Dang. Amateur speakerdave's Avatar
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    The 811 horn and 500E crossover are a mismatch, based on Altec and general recommendations to crossover at least an octave above physical cut off. Not sure exactly where that horn unloads, but it us called an 811 for a reason.

    The fact that the woofer surrounds are damaged suggests that the speakers have been cranked all the way to eleven and the bass tone control twisted up by a wannabe DJ. That could also mean that your CD diaphragms have been stressed as well.

    What you have there are some really nice speakers that would reward a little careful tweaking with hours and hours of very acceptable sound reproduction.

    I think the cabinet may be wide enough to retrofit the 511 horns.
    "Audio is filled with dangerous amateurs." --- Tim de Paravicini

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    Thanks Speakerdave for identifying the conflict between horn model and network model. I will check measurements etc and see if I can find enough room to expand the opening in the baffle for the larger 511. Looks like it will be close, but then again the horns on my Santiagos go near side to side. The height might be the bigger challenge. As far as positioning it forward or back, should it be mounted back in the cabinet more than it is now where the horn is mounted on the baffle and then extends out from there. Again, most others I have seen are set back so the point of the horn is about the same as the baffle face.

    I am uncertain how these were run prior to my purchase, but based on what I saw at the sellers house, yes, they could have been pushed and by not so great power. The splits in the surround are at the bottom of the woofers so it could also just be aging as they seem a bit dry and were pretty dusty etc. I need to check and make sure the diameter of the cut-outs for each woofer are actually large enough. It appears some of the surround is hidden behind the edge of the baffle there. Hmmm

    Earl K, Interesting fix formula! I have emails out to GPA and Gordon W to see what they think about it as well. I would much prefer to keep as much original in-tact as possible of course.

    Insulation for sure. Would like to here from folks what the best material is these days for these etc.

  5. #5
    Senior Member gdmoore28's Avatar
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    Those are some nice-looking speakers.

    And I would second Dave's suggestion about swapping out those 811B horns (rated for 800Hz crossover) for the 511B horns (rated for 500Hz crossover). These are the horns that should have been used with your crossover. This is the recommended configuration. But, if you are satisfied with the current rig, carry on. (The 511B horns measure 24" across the front if you want to measure for room.)

    As for repairing the splits in the surrounds, there is a guy on ebay that sells the proper sticky mixture for repairing these. It never hardens, as opposed to any other commercially available mixture. Just use a small piece of linen and repair the cracks from the back, like Earl suggested. A repair using the proper sealer and a piece of linen will be a permanent repair. If the speakers and horn drivers sound OK, I wouldn't worry about them.

    The biggest (and cheapest) modification that you can make to them is installing the Altec 30923 circuit to your horn leg. This circuit dramatically lowers the mid range "honk" and accentuates the hi frequencies. It's a change that moves the horn's sound more to a Hi Fi characteristic instead of a ProSound curve.


    You need to build only the top portion of this circuit. (The bottom portion is a Zobel network not made for your system.) If your 802D driver is still 16ohm, you will need to use the following values:

    C1 3mF
    R1 7.8 ohms
    R2 13 ohms

    GeeDeeEmm

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    Excellent! Thanks GeeDeeEmm.

    I have the 30904 in my Santiagos that I recapped recently so I am familiar enough with it to be comfortable to make the change. Makes sense.

    I will switch out the horns, as long as the larger 511's will fit. It's gonna be close. Will head over to the marketplace section to see if anyone here has any before hitting up EPay where there seems to be a plenty.

    Cool fix on the surrounds. Sounds simple enough as long as I can find that ebay seller with the goop.

    David


    Quote Originally Posted by gdmoore28 View Post
    Those are some nice-looking speakers.

    And I would second Dave's suggestion about swapping out those 811B horns (rated for 800Hz crossover) for the 511B horns (rated for 500Hz crossover). These are the horns that should have been used with your crossover. This is the recommended configuration. But, if you are satisfied with the current rig, carry on. (The 511B horns measure 24" across the front if you want to measure for room.)

    As for repairing the splits in the surrounds, there is a guy on ebay that sells the proper sticky mixture for repairing these. It never hardens, as opposed to any other commercially available mixture. Just use a small piece of linen and repair the cracks from the back, like Earl suggested. A repair using the proper sealer and a piece of linen will be a permanent repair. If the speakers and horn drivers sound OK, I wouldn't worry about them.

    The biggest (and cheapest) modification that you can make to them is installing the Altec 30923 circuit to your horn leg. This circuit dramatically lowers the mid range "honk" and accentuates the hi frequencies. It's a change that moves the horn's sound more to a Hi Fi characteristic instead of a ProSound curve.


    You need to build only the top portion of this circuit. (The bottom portion is a Zobel network not made for your system.) If your 802D driver is still 16ohm, you will need to use the following values:

    C1 3mF
    R1 7.8 ohms
    R2 13 ohms

    GeeDeeEmm

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    So I know my options, is there a network I can use instead of the N-500-E that will work with the 811 horn and 414A's? 16ohm.
    I am not sure I will be able to modify the baffle within this cabinet to fit the 511 horn.

    Also, is the surrounds goop mentioned below the same as the AR stuff?

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    Here's the schematic for the N500-E.

    I wouldn't be in any rush to swap it out ( see below for my reasons ).



    Notice the 4uF (MFD ) cap used in the horn circuit.
    - This starts a highish roll-off for a 10-12ohm driver ( such as this 802d > assuming it has the original 20275 diaphragm ).

    This 4uF cap also somewhat negates the need for the 30923 circuit.

    Here's a ( very rough ) XSim of this network ( using Zilch's .frd and .zma files for the 414Z woofers, along with some of my HF files > from a custom 802D combo ).
    - One can see that when using this collection of drivers the actual crossover point is nicely above 1K.

    - Drugolf, your crossover point ( with your speakers ) won't be that much different than what I'm showing here.


    That's why I suggest that you shouldn't be in any rush to change it out.




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    Drugolf,

    Another thing, the current box tuning of that pair is way way too low ( dangerously low ).

    A single 4" ( i.d. ) tube that is 11.5" long, gives a box tuning of @ 17hz. ( the light blue line seen in the picture below )

    Tuning a box below the woofers Fs is a great way to destroy the woofers compliance ( and this helps explain your cracked surrounds ).

    I'd suggest you take the tuning up to around 40hz ( you'll end up with a more usable bass response ).

    2 x 4" ( internal diameter ) tubes that are @ 2-3/8" deep will offer an @ 40hz tuning .



    I'd place the second port ( diagonally offset to the first ) below the upper woofer ( ie; for visual symmetry ) .

    You have enough "extra" length of ducting to create these new ports.




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    Great stuff Earle, and thanks for taking the time to go through all that. Good to see Zilch's name come up too!.

    This would be really good because while I may be able to widen the baffle opening for the larger 511, there isn't enough height and I run into the top of the higher woofer. Plus the work would not be all that simple to do correctly not knowing how this cabinet was pulled together beyond what I can see upon inspection. Cutting in a single new port hole shouldn't be all that difficult as it looks like there is enough surface area there to run the router on. ( I am working with a master wood craftsman on some KHorns right now and he will be a big help).

    I opened up the Network last night and of course found all the tar coated contents. I hope I don't have to dig into that! I did deoxit the switch. Also quickly replacing the terminals to better 5-way posts for now. Of course the "in" screw terminals on the top of the network box do not have positive or com marked. Ugh. the old wire running from it to the old screw terminals also wasn't marked. Do I go with right is red?

    Also, do you also concur on adding some insulation on a few of the internal walls? I still need to dig up info on that aspect.

    Quote Originally Posted by Earl K View Post
    Drugolf,

    Another thing, the current box tuning of that pair is way way too low ( dangerously low ).

    A single 4" ( i.d. ) tube that is 11.5" long, gives a box tuning of @ 17hz. ( the light blue line seen in the picture below )

    Tuning a box below the woofers Fs is a great way to destroy the woofers compliance ( and this helps explain your cracked surrounds ).

    I'd suggest you take the tuning up to around 40hz ( you'll end up with a more usable bass response ).

    2 x 4" ( internal diameter ) tubes that are @ 2-3/8" deep will offer an @ 40hz tuning .



    I'd place the second port ( diagonally offset to the first ) below the upper woofer ( ie; for visual symmetry ) .

    You have enough "extra" length of ducting to create these new ports.



  11. #11
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    Quote Originally Posted by Drugolf View Post
    Great stuff Earle, and thanks for taking the time to go through all that. Good to see Zilch's name come up too!.

    <<<SNIP>>> Of course the "in" screw terminals on the top of the network box do not have positive or com marked. Ugh. the old wire running from it to the old screw terminals also wasn't marked. Do I go with right is red?

    Also, do you also concur on adding some insulation on a few of the internal walls? I still need to dig up info on that aspect.
    Your welcome!

    Yes, add some insulation.

    Use a multimeter ( in continuity mode ) to determine the common input ( measure between either of the 2 black output wires and your choice of the 2 input tabs ).
    - One of those 2 input tabs ( measured to the black output wire ) will give a very low Z reading of less than 1R ( ie; showing continuity ).



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    Got it.

    Add cross braces? Diagonal strip on back panel?


    Quote Originally Posted by Earl K View Post
    Your welcome!

    Yes, add some insulation.

    Use a multimeter ( in continuity mode ) to determine the common input ( measure between either of the 2 black output wires and your choice of the 2 input tabs ).
    - One of those 2 input tabs ( measured to the black output wire ) will give a very low Z reading of less than 1R ( ie; showing continuity ).



  13. #13
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    Quote Originally Posted by Drugolf View Post
    Got it.

    Add cross braces? Diagonal strip on back panel?
    I would add ( full length ) diagonal strips ( 2x3's, glued + screwed with the 2" dimension contacting the plywood wall ) on the back panel and the two sides.

    Top, bottom and baffle board I would leave alone for now.

    This is definitely minimal bracing >> but I currently follow the creed that form needs to follow function ( + since these are very light-weight cones unlike JBL 12's > with limited XMax > they will pressurize the box a lot less than many other brands of woofers ).

    - Less overall box pressure equates to less ultimate need to brace ( in my way of thinking > which of course can still be changed ).


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    So the issue with the surrounds is worse than I thought. Removing all 4 woofers I can now see the full extent of how bad the surrounds are and for the most part the surrounds are pulling away from the the cone. I think the goop has mostly fallen to the bottom edge leaving the surrounds exposed and weak. plus, each woofer cut-out is slightly too small (about 10' instead of the specified 10.25) and the surround probabaly was hitting the edges at times or was at least being restricted. it's also where all the goop had settled and I had to heat it up with a hair dryer to get the drivers off.

    I will probably talk to Bill at GPA tomorrow to see if they have the surrounds for these, but I do see some at Simply Speakers that are identified for 12" JBL, but they are the same dimensions as the 414 with the flat cone edge. Will these work?
    https://www.simplyspeakers.com/jbl-s...k-jbl2213.html

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    Will these work?
    Bummer, about the fully cracked surrounds.

    FYI, I'm not aware of anyone in any of the forums ( that I frequent ) who's replaced an Altec or JBL linen or paper surround ( although maybe I'm just not paying close enough attention ).

    Therefore I'd also say that you're in unchartered territory here.

    The other surround source ( mentioned over at AudioKarma ) looks to be the better choice for surrounds.

    Some advice; keep all the hardened goop that you collect ( including the stuff still on the old surrounds ).
    - You may need to reconstitute it ( if possible ) so that you have a backup supply of something original.

    The stuff mentioned in this other link might turn out to be a formula that leaves the new surrounds too stiff ( with a higher than desired Fs > that would need to be measured by doing an impedance test ).

    Also, it might be a lot more straightforward to simply make new baffle boards with the correct woofer cutouts ( than to shave back the existing holes > though I don't really know if there's a nifty router bit made for just that job > hopefully ).


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