Is it wrong to not use putty to seal old AR speakers?
- Thread starter retreatwi
- Start date
Single piece or linear strip gaskets will work just fine as long as there is a consistent ring of compressed material under the driver flange.
The original HF controls used in classic AR's are potentiometers, not L-pads, and may or may not be suitable for re-use. It will all depend on their condition and your evaluation. Also, many AR-2's employed oil-filled caps which very well might not require replacement. Please show pics as your project progresses.
The original HF controls used in classic AR's are potentiometers, not L-pads, and may or may not be suitable for re-use. It will all depend on their condition and your evaluation. Also, many AR-2's employed oil-filled caps which very well might not require replacement. Please show pics as your project progresses.
WaynerN
Addicted Member
How are they not L pads? They put resistance in series and resistance in parallel. Its an L pad.
OK....no resistance from me.
The metal baskets are very robust, but the original putty can sometimes be very tenacious, so back each screw out carefully and then begin to find a willing spot to pry up the edge of the woofer and work around the circumference until it becomes free.
In an acoustic suspension the seal must be tight to prevent leakage of the backwave. Whatever is used should not deteriorate over time. Mortite is butylene rubber with a filler and it does not harden for many, many decades. That's what AR and KLH used, among others.
Amazon ships stuff in a thin kind of wrapping, I don't know what it's called: it's an expanded polythene "micro-bubble" wrap, maybe 1/8" thick, the "bubbles" being cellular in size. I've used it for gaskets, it compresses and seals very well. Easy to cut circles with a razor or scissors, with no seams. It's white, but a use a black marker around the outer edge and it's invisible.
Best, it's free and there's tons of it — my neighborhood is Millennial, they only seem to shop on Amazon, and there's dozens of "empty" Amazon boxes on the sidewalk on garbage day. The boxes are full of the stuff, huge sheets of it — if you don't mind scavenging in public — I wear my Armani suit so no one thinks less of me
— like I care — they're all glued to their iPhones anyway and don't even know there's a "real world".
The free boxes are also useful if you do any selling/shipping — a huge range of sizes and shapes. Better than the $5–6 I sometimes pay for one amp-sized box at Box Depot or whatever it's called. For storing stuff too — I have my audio odds and ends organized in these boxes — connectors, tubes, screws/nuts/bolts/washers etc — and they stack neatly on the shelves.
Best, it's free and there's tons of it — my neighborhood is Millennial, they only seem to shop on Amazon, and there's dozens of "empty" Amazon boxes on the sidewalk on garbage day. The boxes are full of the stuff, huge sheets of it — if you don't mind scavenging in public — I wear my Armani suit so no one thinks less of me
— like I care — they're all glued to their iPhones anyway and don't even know there's a "real world".The free boxes are also useful if you do any selling/shipping — a huge range of sizes and shapes. Better than the $5–6 I sometimes pay for one amp-sized box at Box Depot or whatever it's called. For storing stuff too — I have my audio odds and ends organized in these boxes — connectors, tubes, screws/nuts/bolts/washers etc — and they stack neatly on the shelves.
spark1
Lunatic Member
Hmmmm. The difference, to me, is that a pot uses one resistor, while an L-pad uses two. They therefore have different effects on system impedance.
Based on this distinction, the attenuators in the classic AR speakers, such as the 2a, are pots (not l-pads).
Of course, none of this has anything to do with the OP's question about sealing the woofer...but I couldn't help but reply, given your response (or more specifically, its tone).
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moebuster
Super Member
Just this past week I recapped and serviced the "things in the back with a knob that is turned to add or take away stuff"
and I went in through the dual mid hole and never removed the woofer.
One might consider this method since the woofer can be difficult to remove from the front .
and I went in through the dual mid hole and never removed the woofer.
One might consider this method since the woofer can be difficult to remove from the front .
tyella
Super Member
I use dental tools to pull woofers stuck in place with putty (usually something like Ductseal). After pulling the screws, I'll insert the 90 degree dental pick around the woofer and twist to loosen the old stuff. Then do the same inside the screw holes, if necessary. I then pull out with the dental pick in one of the screw holes so I don't dent the wood.
There are lots of substances you can use, but you should use something to maintain the air seal. Often, the old putty can be peeled off and warmed in the hand. Then roll it into thin "snakes" and line the wood where the woofer will touch. When you put the woofer back, tighten the screws like you would lugnuts on a wheel. Do one first, but not fully tight, then do one on the opposite side. Zig zag like that, and tighten them all gradually more.
But I digress. To answer the OP's question: Foam will be fine. Just make sure you get off enough of the old putty that you get a good, clean seal with the foam.
There are lots of substances you can use, but you should use something to maintain the air seal. Often, the old putty can be peeled off and warmed in the hand. Then roll it into thin "snakes" and line the wood where the woofer will touch. When you put the woofer back, tighten the screws like you would lugnuts on a wheel. Do one first, but not fully tight, then do one on the opposite side. Zig zag like that, and tighten them all gradually more.
But I digress. To answer the OP's question: Foam will be fine. Just make sure you get off enough of the old putty that you get a good, clean seal with the foam.
I LIKE MUSIC
Super Member
Not necessarily.
Both of the above have three terminals. The top one is an L-PAD and the lower one is a potentiometer.
It is true that an L-PAD will provide a somewhat constant impedance load to the particular section of the crossover network. It is also true that not all speaker manufacturers used L-PADs for crossover controls.
A simple out of circuit Ohm meter test will identify the type of control.
centsless
Super Member
I find that good ole duct seal is great for the drivers. Cheap and readily available. Never hardens. It is not mortite.
https://www.rectorseal.com/wp-content/uploads/2013/08/dctseal.jpg
https://www.rectorseal.com/wp-content/uploads/2013/08/dctseal.jpg
'Zactly. And it is further true that the L-pad is often wired as a rheostat and used in place of one. This is often a good solution to obtain higher power at moderate cost.
I have purchased Russian mil-surplus ceramic rheostats—look like scruffier versions of the old ceramic Clarostat controls, if you're old enough to remember those—which, delivered, cost me the same as Chinese rheostats or L-pads. The wipers on many of those Chinese products (probably all from the same factory) are reported to be troublesome. My tweeters don't care about the porcelain defects so neither do I.
Likely the same material with a different pigment.
The inert additives used to provide bulk are likely identical. Mortite is mostly butylene rubber with some calcium carbonate added, plus a little titanium dioxide for color.
Carbon black could, however, be added for color. This is what makes materials black. Titanium dioxide is white, just like in white paint.
So it may be the same material. No way to know.
What I do know is that all of the accounts of AR and KLH putty are identical to Mortite, and the discussions over at CSP all discuss butylene rope caulk as the suitable replacement.
The inert additives used to provide bulk are likely identical. Mortite is mostly butylene rubber with some calcium carbonate added, plus a little titanium dioxide for color.
Carbon black could, however, be added for color. This is what makes materials black. Titanium dioxide is white, just like in white paint.
So it may be the same material. No way to know.
What I do know is that all of the accounts of AR and KLH putty are identical to Mortite, and the discussions over at CSP all discuss butylene rope caulk as the suitable replacement.
I find them to be different in many ways.
While the butyl rope caulk is always pliable, the Mortite is stiff in comparison.
During cold weather applications, the Mortite needs to be softened up with a heat gun otherwise it won't stick and even warp the frame of a woofer if not tightened down properly.
Shelf live of the butyl rubber caulk is superior to that of Mortite.
The 3m rope calk looks like the AR sealant, the Mortite doesn't.
This is what I've observed.
