one Altec Lansing Model 15 sounds muddier than other

[clashradio]

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.

[Earl K]

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 ).

:)

[clashradio]

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.

[Earl K]

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. (https://great-plains-audio.myshopify.com/collections/diaphragms/products/diaphragm-original-gpa-288-8-ohms)

:)

[clashradio]

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.

[Earl K]

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.

90997

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. ).

90998

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 ).

:)

[clashradio]

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.

91003
91004

[Earl K]

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 ?

:)

[clashradio]

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.

[Earl K]

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 (https://www.google.com/search?q=Great+Plains+Audio+phone+number&rlz=1C1CHBD_enCA823CA823&oq=Great+Plains+Audio+phone+number&aqs=chrome..69i57j0i390l2.11449j1j7&sourceid=chrome&ie=UTF-8#)

:)

[clashradio]

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.

[Earl K]

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 ?? ).

:)

[clashradio]

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?

[Earl K]

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

[rusty jefferson]

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

[clashradio]

@ Earl: Not being harsh at all. I can take the truth. I'm more of an automotive repair guy than delicate stuff like this. Yes I'll probably send it in the GPA depending on what Bill says when he replies to my message.

@ Rusty Jefferson: I'm sure the crossover is fine since I switched the complete horn assembly and got great results.

[clashradio]

Ok Earl K;

I sent the driver to GPA (which had the new GPA diaphragm that I mangled). I got it back about a week later, tested and sounds just as muddy as before. I was expecting them to replace the diaphragm since I thought I destroyed it by soldiering the wiring direct to the posts. Ends up the diaphragm was still good. Unhappy with those results, and as another test I bought a new diaphragm from a place called Midwest Speaker Repair. Same results; muddier than the other speaker. This diaphragm had the same wiring method as the original; not the push-on, newer style GPA has which made installation much easier.

One thing I didn't notice until today when I installed this newest diaphragm is the one I got from GPA is 3.5". The original, and the one from Midwest is 3" diameter.

I called Bill at GPA and explained my situation. I asked if it's possible my driver is bad. He didn't think so. He said he recharged the magnet while it was at the shop. Keep in mind for years I was an idiot and had two amps connected to the same pair of speakers and accidently turned on both amps at the same time which blew one of the amps and blew the same diaphragm from the driver I'm having the muddier sound with.

What I don't understand, and I think is a major deal is when I switch horn assembly's from speaker to speaker and put the good horn (from left speaker) into the right speaker (which has the muddier sound), I get crystal clear bright highs (and sounds as good as the left speaker) . And conversely when the right-side horn is in the left speaker, it sounds muddier. I think this proves the crossover from the right (muddier) speaker is good.

Since there are some highs coming from the muddier horn, it passed whichever tests they might do at GPA. But when you hear how much brighter the other horn sounds, it's night and day.

Bill wants me to send the driver back. Just wondered what else you might recommend? Should I try a new driver? At almost $400 I'd like to confirm that that's the problem.

[DerekTheGreat]

Greetings from a fellow Michigander!

If I understand your post right, you've already tried swapping the "bad" horn assy with the "good" assy and the poor sound follows the "bad" horn. Since these were your dad's, I'd bite bullet and spend the $400 on a new driver.

Edit: Another question that just hit me is what parts are in the "good" driver? Are they indeed the same? Because what if a "new" driver shows up and sounds just like the muddy one?? :blink: At that point I think all I could do is laugh at myself.

[clashradio]

Hi DerekTheGreat, also from Michigan nice!

Yes, muddier sound follows the bad horn. A few tests I haven't done yet are swap horns and drivers (put good driver on bad horn) and install the good diaphragm on the bad horn/driver.

I do have one more cheap, new, aftermarket diaphragm coming hopefully today. This time the part number is: 26420.The GPA and the Midwest Speaker diaphragm numbers are: 34647.

When you say to replace the driver, are you thinking because I had two amps connected to the same pair of 15's and had both amps on at the same time which fried one of the amps, and one diaphragm?

I don't know exactly which parts are in the good horn assembly. I think only the one diaphragm got replaced in 2012 (the same one I'm having issues with now). When I remove the good diaphragm to swap test, I can look at the part number and see if it matches the other side.

The online price of the driver on GPA's website shows $900. Talking to Bill yesterday he mentioned something about $400. Yes would be a real bummer if I replaced with a $400 part with no difference in sound.

[Mike Caldwell]

If you had two amps connected directly to the speaker as in the outputs of each amp were going directly to the terminals of the speakers that is VERY BAD for not only the amps but the speakers. If you wanted to switch between amps you need to use a selector switch between the amps and speakers.

Connected like sounds like the amps were each amp is seeing what appears as almost a dead short from the loading of the other amp. Depending on the amp some have the output grounds isolated from the main chassies ground and that could cause issues as well.

I'm thinking you need to do a driver by driver test and double / triple check the crossovers.

[clashradio]

@Mike Caldwell:

Last year I bought an amp/speaker switch box, so the two-amps-to-one-pair-of-speakers debacle is no longer an issue. And I've replaced the amp that blew.

Today I was able to switch the left driver diaphragm (good side) into the right driver (bad side). Not sure what happened, but the voice coil leads came separated. I really didn't want to mess with the good diaphragm, but I figured it was a great test to confirm if the right-side driver was bad. Earl K. is going to really lose confidence in me now :crying:.

But by taking the left driver apart to get to the diaphragm, I noticed the round center piece (not sure what it's called) is orange and the right side is black. Maybe the right-side driver was replaced back in '12 and not just the diaphragm?

I still have one good aftermarket diaphragm so I tested that with both drivers, and to my ears it sounds like the black driver (right-side) has a little restricted high frequencies than the orange (left-side). Of course this is about ten minutes between each test so I can't tell if it's my imagination or not. At this point I'm fried. I'm more than happy to dish out $400 for a new driver if that's what the issue is to get matching highs/treble out of both drivers.

[Mike Caldwell]

Post some pictures of the drivers, inside and out and the crossovers if possible.

[clashradio]

Post some pictures of the drivers, inside and out and the crossovers if possible.

91166
91167
91168
91169
91170

Please keep in mind when I swapped the good horn assembly from the left cabinet and placed in the right, I got the same higher frequencies that are in the left. I believe this proves the right cabinet crossover is good?

[RMC]

Looks to me like you have a Tangerine phasing plug in the left horn but maybe not in the right one?

Richard

91171

[clashradio]

Oh wow! This has to be my problem then. Bill from GPA said the new diaphragm is working but he wasn't able to hear both in comparison.

I dug a little deeper in my checkbook register from 2012 and found I paid for a new diaphragm at $17.29 I don't want to name the company but I wonder if they replaced the Tangerine phasing plug with an aftermarket? But that price wouldn't include return shipping of the driver. Remember the driver had a label with my name and date and that date matches my register so that means I must have mailed the driver to get the diaphragm replaced. Sorry I didn't save any receipts for some reason.

This Tangerine phase plug must really do what's advertised. I was beginning to lose hope getting matching highs from both drivers. I'm going to try to locate one.

Thanks Richard (and everyone else) for your help. I'll report back.

[Mr. Widget]

That was my first thought when I saw the bright orange phase plug, but looking at the black one it is also segmented in the same manner as the tangerine. It is not a traditional style phase plug with concentric slots. I am no Altec expert, but I wouldn’t jump to the conclusion that your phase plugs are mismatched.

I would send both drivers back to Bill and ask him to rebuild them as necessary to bring them both up to spec. I assume he has the capability of testing and verifying performance.


Widget

[clashradio]

Ya after doing some research on the phase plugs, the ones that aren't Tangerine look totally different. As you mentioned this black one has the same design. I'm hoping it's aftermarket and not quit the same build quality. I was able to find an Altec Tangerine so hopefully Bill can install. I plan on sending both drivers in for new diaphragms anyways.

[Mr. Widget]

Ya after doing some research on the phase plugs, the ones that aren't Tangerine look totally different. As you mentioned this black one has the same design. I'm hoping it's aftermarket and not quit the same build quality. I was able to find an Altec Tangerine so hopefully Bill can install. I plan on sending both drivers in for new diaphragms anyways.Hopefully with both drivers in hand, Bill can sort this out.

IIRC: Not all Altec "Tangerine" phase plugs were orange.


Widget

[Mike Caldwell]

For what it's worth the right driver (is that the driver that sounds bad) in the picture with the black phase plug appears to have a shim spacer for the diaphragm.
Maybe that space is not needed for the new replacement diaphragms.
Sometimes shims are needed to compensate for either a diaphragm or driver being slightly out of tolerance.

It may not be needed with the replacement diaphragms.

[clashradio]

@Widget: Bummer; I was hoping all Altec Tangerine plugs are orange. Then maybe the fact that mine is black might be my problem.

@ Mike Caldwell: there are in fact two spacers on the right driver. I just figured it was a gasket. I kept them in place when I installed both GPA's and Midwest Speaker's diaphragm. I didn't notice the left driver didn't have this until I removed the diaphragm.

[DerekTheGreat]

Interesting! It seems like perhaps we are onto something by tearing into the drivers. (And yes, by "drivers" I meant the whole horn dealio and what parts were in each). But like Mr. Widget said, both phase plugs look similar. Not sure what gives but this is certainly progress.

[clashradio]

Interesting! It seems like perhaps we are onto something by tearing into the drivers. (And yes, by "drivers" I meant the whole horn dealio and what parts were in each). But like Mr. Widget said, both phase plugs look similar. Not sure what gives but this is certainly progress. Yes but from what Widget is saying, I'm thinking the black phase plug won't make any difference since this also seems to be a Tangerine model. I was hoping it was aftermarket and maybe not as good of build quality.

[DerekTheGreat]

Indeed, but maybe there is a difference? Perhaps someone got some trash in there or the black one isn't made from the same materials and thus accounts for the differences in sound? Just throwing ideas out there..

[clashradio]

I'm going to send both drivers to Bill once I receive the used Tangerine plug. Now that he'll have both, maybe he'll be able to hear the difference between the two. In the meantime I bought two used 802-8G drivers. Once they arrive I'll be able to compare those with my good driver that has the Tangerine plug.

[Mike Caldwell]

As for "muddier" sound, is it from lack of high frequency extension or just lower in level when compared to the other driver?

[clashradio]

The best way I can describe it is, lower in level when compared to the other driver. I can hear highs in the right, but pales compared to left

Both drivers had 23744 diaphragms, but only the left-driver has an orange Tangerine phase plug. The right has a black plug, which may still be a Tangerine? The right-side is also the side I have less high-end frequency response.

The muddier sound follows the horn when I switch from cabinet to cabinet. To me that says the right-side cabinet's crossover is good, and something is wrong with the right-side horn assembly, possibly the driver.

Remember for years I had two amps feeding the same pair of Model 15's. When one amp was on, I could see the VU meters moving in the amp that was off. Wondering if any backfeeding destroyed the right-driver?

[Mike Caldwell]

Since the diaphragm has been replaced maybe the shims are no longer needed. With those in place it could raise the voice coil in the gap just enough to lower the output.

Changing diaphragms should include cleaning the voice coil gap in the driver, using some sticky tape to grab dirt ect. running something like a business card around the gap to get anything loose, using more tape to pick up anything, some clean compressed air to blow anything loose and then repeat all the above.

Then when putting the new diaphragm in before snugging it down run some test tones to it loud enough to easily hear and a starting around 400hz and move the diaphragm as much as you can with the screws in place to find the spot where you hear the cleanest pure tone with no over tones and snug it down in that spot.
Those diaphragms have centering guide pins it may not have much if any play to move and may be good to go as is.

It is not unheard of to slightly enlarge the centering pin holes in the diaphragm to allow for more play to fine tune the centering.

[clashradio]

@Mike Caldwell: At this point I'm going to send both drivers to Bill, once I receive the used Tangerine plug. I've already fried three diaphragms, including the two rare 23744's. I did try to clean the voice coil gag when I installed the GPA 34647. Like you mentioned; there isn't much if any play due to the centering pins. Maybe Bill can run some frequency tests when he has both drivers and compare the two. He said the right-side was fine but didn't have both drivers at that time.

Between the right-driver not having the orange radial plug and having two diaphragm spacers, maybe is enough to have the muddier sound compared to the left-side.

What's weird is if the left-cabinet didn't sound so good, I probably would have never known the right is muddier.