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Thread: one Altec Lansing Model 15 sounds muddier than other

  1. #1
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    one Altec Lansing Model 15 sounds muddier than other

    Hello,

    Newbie here. I have a pair of Altec Lansing Model 15 and one sounds a little muddier than the other.

    I’ve confirmed it’s the speaker & not the amp, cables, etc. One of the tests to confirm was to switch the L/R rca’s from the cd player (you know how some recordings have different instruments, eq settings in each channel). I wanted to make sure I heard; say the hi-hat, or crash cymbal in the good speaker first. When switching the L/R channels into the bad speaker, the same hi-hat/crash was not as pronounced.

    A little background: These are my dad’s speakers that I inherited in the 90’s so I am the second owner. I had the woofers re-coned in ’98 and again in ’15. Don’t think anything’s been done with the horn diaphragms or the crossovers. A little research shows the caps in the x-overs might need to be replaced.

    Having the M.F. Level at max (on the bad speaker) seems to help a little with the highs, although it says the optimum level is in the middle. I currently have the H.F. Level centered even although optimum says ¾ to max.

    Questions:
    -how do I know if the problem is with the horn diaphragm or in the crossover?
    -if it caps are bad in one x-over, is it better to replace both sides even though only one speaker is muddy? The other speaker sounds incredible.

    Thanks in advance for any help or suggestions.

  2. #2
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    Quote Originally Posted by clashradio View Post
    Hello,

    Newbie here. I have a pair of Altec Lansing Model 15 and one sounds a little muddier than the other.

    I’ve confirmed it’s the speaker & not the amp, cables, etc. One of the tests to confirm was to switch the L/R rca’s from the cd player (you know how some recordings have different instruments, eq settings in each channel). I wanted to make sure I heard; say the hi-hat, or crash cymbal in the good speaker first. When switching the L/R channels into the bad speaker, the same hi-hat/crash was not as pronounced.

    A little background: These are my dad’s speakers that I inherited in the 90’s so I am the second owner. I had the woofers re-coned in ’98 and again in ’15. Don’t think anything’s been done with the horn diaphragms or the crossovers. A little research shows the caps in the x-overs might need to be replaced.

    Having the M.F. Level at max (on the bad speaker) seems to help a little with the highs, although it says the optimum level is in the middle. I currently have the H.F. Level centered even although optimum says ¾ to max.

    Questions:
    -how do I know if the problem is with the horn diaphragm or in the crossover?
    -if it caps are bad in one x-over, is it better to replace both sides even though only one speaker is muddy? The other speaker sounds incredible.

    Thanks in advance for any help or suggestions.
    Swap the "bad" horn/driver combo over to the opposite cabinet having the "good" crossover ( to see if the problem follows that horn-driver ).


  3. #3
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    I'm a dummy. Good call didn't even think of that part of the test.

    Ok I did that and you're right; the problem is in the diaphragm, not the x-over. By moving the complete horn assembly into the other speaker, I get the same muddier sound.

    Also discovered that I've had this diaphragm repaired back in 2012 (there was a sticker with my name and date on the magnet). Thinking back it seems like I did have this problem before and had one or both horns/diaphragms repaired. Looks like I only had the one repaired.

    Usually I save receipts or keep track of this sort of stuff. Can't remember where I had this done or what quality of parts were used. Any particular high-quality parts I should ask for? Money is (sort-of) no object.

  4. #4
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    You'll need to take the bad driver off of the horn.

    A visual inspection is now in order ( of the diaphragm ).

    Remove the back-cap of the driver and then post a pic of the diaphragm ( you might have an aftermarket diaphragm in there > visually, those are quite identifiable ).

    Also, measure the DCR of that (bad ) diaphragm ( to make sure it's the 8-ohms model ).

    GPA ( Great Plains Audio ) is the only place I know of to get good replacement diaphragms. The 8 ohm model is their # 34647 diaphragm.


  5. #5
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    Thank you, Earl K; much appreciated!

    I think I found the problem. Upon your advice I took apart the diaphragm and saw both the little leads that run from the silver portion of the diaphragm through the black plastic outer ring were separated. Needless to say my meter didn't read 8 ohms. I ordered from GPA.

  6. #6
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    Quote Originally Posted by clashradio View Post
    Thank you, Earl K; much appreciated!

    I think I found the problem. Upon your advice I took apart the diaphragm and saw both the little leads that run from the silver portion of the diaphragm through the black plastic outer ring were separated. Needless to say my meter didn't read 8 ohms. I ordered from GPA.

    If you haven't already tossed it ( or further damaged it with rough handling ) I would recommend holding onto that particular diaphragm for possible resale.

    I'm assuming what you have is the original model ( which is a 23744 type ) and not some later model.

    The model number is visible ( typically ) on the inside of the voice-coil former if its a 23744.

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    These 50+ year old diaphragms typically break their leads-ins + outs ( from some traumatic event has occurred such as a turn-table needle dropping causing a loud thump, etc. ).

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    There's the occasional person who can fix those separated leads who might be interested in the purchase /// so it might be worth selling the broken diaphragm to an interested party ( found usually over at Audio Karma ).


  7. #7
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    The diaphragm that has the broken lead-ins is the one that has a sticker that has my name and date on the magnet (placed there by whichever shop I must have dropped it off to). Therefore I know this one was replaced back in 2012. I originally forgot that one (or both) of the diaphragms were replaced. The part number on the inside is: 391846 and a symbol next to it (see attached picture).

    Which leads me to my next question; Both diaphragms have modern crimp connectors (see attached picture). Did they have these in the late 70's? If not than that means both of the diaphragms have been replaced.

    I think I know what caused the blow-out. For years I had two amps connected to the same speakers. This seemed to work out until my dumba%@ turned on both amps. I've since bought one of those 2-way amp switcher/splitter boxes.

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  8. #8
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    The pictured diaphragm is too far gone to ever repair ( just toss it ). It looks like a vacuum sucked it forward into the phase-plug ).

    The older Altec drivers used green + brown wires ( changing to red + black in a year that's not known to me ).

    Your new diaphragm will have male spade ( push-on ) lugs ( meaning those wires won't directly attach ).

    GPA used to ship an adapter kit ( of new wires ) if they knew the diaphragm was going into an older type driver.

    Did you tell GPA this replacement diaphragm was for an 802-8G ?


  9. #9
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    When removing the diaphragm from the magnet, I accidently pushed on the center, so that's why it looks more damaged that it originally was. I tried to pop out the indentation but that only made it worse.

    Sounds like both diagrams were replaced since both sides have newer red & black wires (with crimp connectors that I don't think were around in the late 70's).

    No, I didn't let GPA know about details. I just ordered part number 34647 and added to cart from the web site @ $130. Is there anything I need to contact them to adjust? I imagine they will send it out Monday the 12th.

  10. #10
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    It's best ( at this point ) to phone them and ask them just what internal wiring is needed for your driver.

    +1 405-789-0221


  11. #11
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    Hi Earl,

    Is it safe to say that since both diaphragms have red and black wiring (you said stock was green and brown) and both have what looks like modern crimp connectors (not sure if these existed back in '78) that both of the diaphrams have been replaced? The sticker from the repair shop that's on the magnet with my name and date was only on one of the magnets. Obviously one of the diaphragms has been replaced. I'm just trying to determine if both have been replaced.

  12. #12
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    I believe that red and black wiring you have ( inside the back-cap ) is original to your 802-8G

    I'm guessing that the green + brown predated that model.

    I have an 802-8T with red and black wiring ( same as a "G" with an additional loading-cap under the back-cap ).

    My older 802-8D's do have the green + brown wiring.

    What's a bit strange about your decade-old repair experience is that the munched diaphragm you've shown ( replaced back in 2012 ) is of the older style diaphram which stopped being made in about 1980 ( so, NOS ?? ).


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    Diaphragm arrived yesterday and I still have the same amount of muffled high-end. More to the story. It’s lengthy I’m sorry.

    I did get sent the newer style diaphragm (with wiring kit) that has a vertical post for the wire connection. My original has a Phillips screw (like you said maybe these were new old stock when I had them replaced in ’12 and according to GPA’s website this style might be pre-’83). When using the new wiring, you can’t close the outer diaphragm cover (the leads are bottoming out on the cover, even with the connectors being horizontal 90-degree). It does close if I don’t have the wiring connected. The vertical post-style adds almost 1/2” height (when the wiring is connected) and is why the connector is bottoming out on the cover.

    I ended up stripping the end of the wire that attaches to the diaphragm and soldiering directly to the vertical post. Due to the heat of the soldering iron, this caused one of the binding posts to come loose from the black plastic portion of the diaphragm. The voice coil wire was still intact and I put some Gorilla Glue to help hold the binding post in place.

    After re-installation, at first I was getting absolutely no high-end. Took apart and saw one of the leads came un-soldiered. I re-soldiered and tests showed the exact same amount of muddy sound I had with the original defective diaphragm.

    Assuming the diaphragm is still good (after being exposed to heat, etc) could this mean I have something else wrong? Perhaps some obstruction in the horn? Or do you think I fried the new diaphragm? Just odd how there were no highs whatsoever when one lead was disconnected yet I had some highs (same level as original bad diaphragm) when both leads were connected.

    I double-checked the cross-over again by switching the complete horn assembly from the [good] speaker to the [bad] and got all the highs in the world when switched so that confirms the x-over is good. And of course I now get muddy sound with the [good] speaker.

    GPA’s site does say if you have the pre-‘83 you must send it in for repair. I sent a message to Bill explaining the situation. I hope they can rebuild the old diaphragm. But you said to toss it because the silver coil portion got sucked in (my fault).

    If GPA can't repair, and don't have the older style, I did see a company called Simply Speakers that their website shows they have the older style. Anyone have any experience with them? Quality of parts?

  14. #14
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    Hmm,

    Sorry to sound a bit harsh here , but since you've twice proven yourself to be all thumbs in the handling of your driver during repair attempts;

    ( IMHO ), You should either pack up the driver and diaphragm and send it in to GPA for proper installation ( or find someone local who can maybe salvage your installation mistakes ).

    Earl K

  15. #15
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    Have you tried to clean the contacts on the mid/high L-pads with some contact cleaner?

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