Hello everyone,
I've recently inherited a pair of Altec Lansing VOTT A7 speakers (with 511B HF horns) and would like to restore them. The previous owner made some modifications, including adding insulation inside the cabinet and moving the HF horn inside. They were originally purchased around 1975.
One speaker works fully, but the other has no sound from the HF horn. Suspecting a bad HF compression driver, I found both drivers labeled 802-8D, but one is marked "Symbiotik." Upon inspection, the diaphragm and voice coil in the working driver (labeled Symbiotik) were easily removed, while the non-working driver’s assembly seemed fixed due to attached terminals. I did not force this assembly apart. Testing showed faint sound from the faulty driver; both drivers read 2-3 Ohms on a multimeter. Swapping the drivers confirmed the crossover is not the issue.
I've contacted Bill at Great Plains Audio about replacing the diaphragm and re-magnetizing both drivers, but have yet to send them in. Additionally, I'm interested in refinishing the cabinets and would appreciate any advice or tips.
Here are some images for reference: VOTT A7 Album
Thanks,
David
I've recently inherited a pair of Altec Lansing VOTT A7 speakers (with 511B HF horns) and would like to restore them. The previous owner made some modifications, including adding insulation inside the cabinet and moving the HF horn inside. They were originally purchased around 1975.
One speaker works fully, but the other has no sound from the HF horn. Suspecting a bad HF compression driver, I found both drivers labeled 802-8D, but one is marked "Symbiotik." Upon inspection, the diaphragm and voice coil in the working driver (labeled Symbiotik) were easily removed, while the non-working driver’s assembly seemed fixed due to attached terminals. I did not force this assembly apart. Testing showed faint sound from the faulty driver; both drivers read 2-3 Ohms on a multimeter. Swapping the drivers confirmed the crossover is not the issue.
I've contacted Bill at Great Plains Audio about replacing the diaphragm and re-magnetizing both drivers, but have yet to send them in. Additionally, I'm interested in refinishing the cabinets and would appreciate any advice or tips.
Here are some images for reference: VOTT A7 Album
Thanks,
David
Welcome to the forum!
I've been down that A7 road a few times. It's best to call Bill, GPA aren't the best on email.
Adding thickness and/or bracing to the inside of the box is a good idea. Also bracing and damping the back of the woofer horn is a big improvement. The thin plywood of the bass horn likes to sing along with the music. 🙂
The stock crossover is "OK" but you can make a better one if you want to DIY it.
I've been down that A7 road a few times. It's best to call Bill, GPA aren't the best on email.
Adding thickness and/or bracing to the inside of the box is a good idea. Also bracing and damping the back of the woofer horn is a big improvement. The thin plywood of the bass horn likes to sing along with the music. 🙂
The stock crossover is "OK" but you can make a better one if you want to DIY it.
I'm going to have to take a look inside for the woofer model once I can move them off the wall they're against this weekend, and yes, the lower half is currently just a full cloth grille. I'm assuming the biggest reason for moving the horns inside was form factor and aesthetics? That mod seems pretty common, although I'm sure there is impact to acoustics.
I agree with bracing the woofer, although I'm guessing I wouldn't want to narrow the BR port with the horn inside?
I gave GPA a call on the drivers and they're currently at least two months out on completing orders due to them moving locations, so they recommended I call back in several weeks.
I agree with bracing the woofer, although I'm guessing I wouldn't want to narrow the BR port with the horn inside?
I gave GPA a call on the drivers and they're currently at least two months out on completing orders due to them moving locations, so they recommended I call back in several weeks.
Of you wil be using these at home, putting the horn on the top and reducing the port will be the best options. Those metal horns tend to ring so it’s best to attach them a frame.
The voice coil in your faulty driver might have fried and swollen up. If it’s rubbing, you might find continuity from the coil to the metal of the driver. Worth a check.
The voice coil in your faulty driver might have fried and swollen up. If it’s rubbing, you might find continuity from the coil to the metal of the driver. Worth a check.
You can search ebay for "altec 802 diaphragm"; replacements are surprisingly inexpensive. Not a bad investment even if just to get things "sorted" until you can get real vintage Altec parts if those are knockoffs. I believe the diaphragms were, by design, easy to replace in the field, so one "being stuck" may mean something's going on.
It's hard to imagine just one magnet losing its "tism" to the point where it wouldnt speak with a good diaphragm. I'd swap the one good one into the other magnet structure to check. Your pictures seem to show space between the diaphragm and that machined flat surface, to which I think "no way!". Could the plastic part be warped? Some of the securing screws missing?
One thing I know was done is to place a wad, or fitted piece of fiberglass or other thick damping material into the rear cup cover. You can imagine there's a lot of sound bouncing around in there. I didnt see any absorbent material within the cups in your pictures; I think they would have been glued to the inside back. Obviously, this material cannot touch the diaphragm domes.
Totally unsure what increasing the volume of that cap/cup would do regarding power handling, or removing it entirely for a rear firing radiation effect. I've seen that trick's been done in some high end OB with horns.
Many moons ago I had the Altec "Valencia" model, with similar if not same horns and drivers. I did the opposite; took the horns out of the cabs and set them on top. I remember a couple - few watts was all they needed for an entirely comfortable listening level. You could probably get away with messing with the cap cup at that power handling.
Just dont take them out for a rock band sound reinforcement and forget to put the original caps back in place ;') It's pretty clear the diaphragms would need the backpressure provided by compressing that small sealed space, in order to survive high power levels, using the original crossovers.
It's hard to imagine just one magnet losing its "tism" to the point where it wouldnt speak with a good diaphragm. I'd swap the one good one into the other magnet structure to check. Your pictures seem to show space between the diaphragm and that machined flat surface, to which I think "no way!". Could the plastic part be warped? Some of the securing screws missing?
One thing I know was done is to place a wad, or fitted piece of fiberglass or other thick damping material into the rear cup cover. You can imagine there's a lot of sound bouncing around in there. I didnt see any absorbent material within the cups in your pictures; I think they would have been glued to the inside back. Obviously, this material cannot touch the diaphragm domes.
Totally unsure what increasing the volume of that cap/cup would do regarding power handling, or removing it entirely for a rear firing radiation effect. I've seen that trick's been done in some high end OB with horns.
Many moons ago I had the Altec "Valencia" model, with similar if not same horns and drivers. I did the opposite; took the horns out of the cabs and set them on top. I remember a couple - few watts was all they needed for an entirely comfortable listening level. You could probably get away with messing with the cap cup at that power handling.
Just dont take them out for a rock band sound reinforcement and forget to put the original caps back in place ;') It's pretty clear the diaphragms would need the backpressure provided by compressing that small sealed space, in order to survive high power levels, using the original crossovers.
I have a vague memory of seeing a nicely documented rebuild years ago with IIRC perforated ply struts or panels and some sort of reworking of the cavity between the horn and the outer cabinet walls. Would that have been yours?
Greets!
Horn in port layout is for stage, studio monitor apps, definitely affects horn performance, so in home we normally want the horn centerline either at desired ear height or up high, angled down and either way, toe'd in to 'taste'.
If the horn is located per factory specs, then it's tuned properly, though for in home some folks will add some form of damping to tone down its prosound reflex 'boom'.
Interesting! There's many folks on the various Altec Facebook threads getting no response since Bill retired.
Funny enough my context for using them is not strictly in-home, but rather live sound for neighborhood holiday events. Most of the intended audience will be situated ~100 feet from the speakers at minimum, and they do sound lovely at those distances. This is not to say I wouldn't consider modifications to improve the overall sound and reduce ring.
Thank you for a wealth of information jj! The images depicting space between the diaphragm and aluminum housing were taken as I attempted to disassemble the driver, however the diaphragm became "stuck" while trying to remove it, and I wasn't sure if there was some delicate wiring I should be aware of. Sounds like whatever is stuck could be causing my issues! Perhaps a piece of the aluminum diaphragm bent up inside the housing "channel"? As I'll likely end up replacing the diaphragm anyway, I'll probably have another go at removing it with a little more force, as I feel that I'm unlikely to damage the housing 😆 I'll let you know how it goes, and I'll probably pick up that cheap diaphragm just to get things running!
This makes sense! Although as I mentioned above my use case is more stage/live sound, the horns could definitely use some bracing as they are currently just loose inside the cabinet. Would it make sense to build them a "platform" the horns could bolt to and fasten that platform inside the cabinet, if I wanted to keep the horns inside?
Depends in that with planned HiFi Vs prosound apps the tweaks, box tuning are counter productive, though in either case the horn would normally be on top and the factory two piece horn mount + rear adjustable bracket is adequate for bracing the woofer horn's flat top or cab bottom plate.
As for tweaks, the original design before the 'bean counters' took over required an HF horn baffle (800 Hz shown, 500 Hz baffle will be taller) and considering the 100 ft min. 'throw' distance it's needed to control directivity in the speaker's XO BW and ideally will require full height side 'wings' if the crowd is acoustically narrow (really need to do a scaled plan view to determine polar response angles).
Note that if the horn baffle, side wings are hinged, they can be used to fold forward to further control directivity/horn gain in both your apps.
Don't recall it, though a common way to do it nowadays, but Altec's OEM design is fine if you divide its curve span into 5ths to get plenty sufficient bracing/damping at an ideal odd harmonic. This also allows a thinner panel thickness and/or holes, cutouts for weight reduction.
Flow a bit of WD40 around the joint and locating pins and using some fine wire/fishing line wrapped around the joint and pull parallel to the driver surface to 'pinch'/break it loose without damage. Note that (assuming yours are) Bakelite is basically brittle, so can be cracked if flexed much.
Note that diaphragm choice for HIFI, prosound apps is apparently no longer an option based on the latest parts list, so need two new diaphragms, neither of which can handle high power prosound apps with your 500 Hz XO without some form of additional protection (DSP is most common nowadays) or converting yours to 800 Hz XOs.
Do you mean brace from rear of curve to box wall at those points? Maybe that's what I saw. Vertical walls (with large Swiss cheese holes) spanning from curve rear to cab wall. Maybe.
I have been looking for it but so many of the old self hosted web pages have disappeared over the years and without remembering whose page it was the archive can't help.
I have been looking for it but so many of the old self hosted web pages have disappeared over the years and without remembering whose page it was the archive can't help.
Correct: https://www.dropbox.com/scl/fo/5p11...rikf2328zpc003dfhvbd&subfolder_nav_tracking=1
Ditto, got a 'zillion' links to cover virtually any Q re Altec speakers and at one time had them on two HDs, but a set top board short/fire destroyed both while doing a BU.
😢😡
More recently, I was told that the internal discs? may still be good and just need new cases, etc., but at this late date the cost quoted back then wasn't worth it to me, so factoring in 20+ yrs inflated pricing, still don't care enough......
That said, I've occasionally found some on the net archive when I remember enough key words to search with, but unfortunately I can't recall the AUB forum's member name/moniker that did it or at least one similar to it.
Ditto, got a 'zillion' links to cover virtually any Q re Altec speakers and at one time had them on two HDs, but a set top board short/fire destroyed both while doing a BU.
😢😡More recently, I was told that the internal discs? may still be good and just need new cases, etc., but at this late date the cost quoted back then wasn't worth it to me, so factoring in 20+ yrs inflated pricing, still don't care enough......
That said, I've occasionally found some on the net archive when I remember enough key words to search with, but unfortunately I can't recall the AUB forum's member name/moniker that did it or at least one similar to it.
The horn flare in front of the woofer usually needs bracing and some damping. They do tend to vibrate badly, and at several frequencies. Tar or something less smelly like rope caulk will do the job. Look to see if yours are braced or not.