You are going to set this once and not tough it for a decade. Imho, not worth the reliability issues. Bypass with fixed.
@eriksquires
I totally agree that once they're set I'll never touch those controls again. However, since they let you set mids and highs independently of each other, something that can't be done with preamp tone controls, I feel that they do offer value during the setup process.
Otherwise I would have to do some fairly extensive critical listening to determine my preferred mids and highs levels, so that in turn I can order the correct fixed value resistors. But that process would be time-constrained (because I want the darn things fixed already), and compromised by the fact that the existing mid pots are busted.
It's also a one-shot deal; if the speakers are moved to a different room the levels could not be adjusted again.
I like the simplicity and cleanliness of fixed resistors, but i lean towards maintaining operable tone controls because of the flexibility they offer.
I totally agree that once they're set I'll never touch those controls again. However, since they let you set mids and highs independently of each other, something that can't be done with preamp tone controls, I feel that they do offer value during the setup process.
Otherwise I would have to do some fairly extensive critical listening to determine my preferred mids and highs levels, so that in turn I can order the correct fixed value resistors. But that process would be time-constrained (because I want the darn things fixed already), and compromised by the fact that the existing mid pots are busted.
It's also a one-shot deal; if the speakers are moved to a different room the levels could not be adjusted again.
I like the simplicity and cleanliness of fixed resistors, but i lean towards maintaining operable tone controls because of the flexibility they offer.
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That sounds like a sensible solution. The crossover panel is 3/4 particle board so I need the 1-inch version...
...it's the only one out of stock 😂
@PKI
For me at least, the value of forum posting is in a) writing my thoughts longhand is helping me sort and clarify them, b) feedback from folks who've done the job before is invaluable, and c) perhaps most importantly, my posting may help someone in the future who's looking to do the very same thing I'm doing today 🙂
For me at least, the value of forum posting is in a) writing my thoughts longhand is helping me sort and clarify them, b) feedback from folks who've done the job before is invaluable, and c) perhaps most importantly, my posting may help someone in the future who's looking to do the very same thing I'm doing today 🙂
So I busted out my caliper and started measuring my components, something I probably should have done sooner.
First a correction: The pots are NOT mounted on 3/4 material, but on a 3mm plastic plate
However, a new pot (or L-pad) with a 1" threaded stem could be mounted high enough off the base plate to clear the small pot (which is only 12 mm tall) and the big pot's diameter becomes irrelevant. The space above is open, so this could work
Meanwhile, the Australian pot won't work because its 10mm stem is too short, and the Parts Express 15 watt L-pad w/1" stem is out of stock
So I got this pair of 8 ohm 15 watt L-pads from ebay:
https://www.ebay.com/itm/352509648977
I will update when they arrive. Thanks again @olsond3 for the reminder to measure 🙂
First a correction: The pots are NOT mounted on 3/4 material, but on a 3mm plastic plate
- Original pots are 33mm and 24mm in diameter, respectively, with a 4mm space between them.
- Both the Parts Express 15 watt L-pad linked by @chrisng and the Australian 15 watt pot are 41mm in diameter
- A 41mm part would be a friction fit at best, so less than ideal
However, a new pot (or L-pad) with a 1" threaded stem could be mounted high enough off the base plate to clear the small pot (which is only 12 mm tall) and the big pot's diameter becomes irrelevant. The space above is open, so this could work
Meanwhile, the Australian pot won't work because its 10mm stem is too short, and the Parts Express 15 watt L-pad w/1" stem is out of stock
So I got this pair of 8 ohm 15 watt L-pads from ebay:
https://www.ebay.com/itm/352509648977
I will update when they arrive. Thanks again @olsond3 for the reminder to measure 🙂
The new L-pads arrived. They look a lot like the ones Parts Express sells:
They're quite a bit bigger (41mm diameter) than the old pots (33mm), but they will fit just fine
Despite being larger, the L-pads fit in without interference from the other components. Thanks to their 3/4" long stem they hover 3 or 4 mm above the tweeter pots.
You can see the L-pads are wired like pots, not L-pads, as the ground pin (pin 1) is unconnected. In that mode they actually only measure 7 ohms at full attenuation, which is fine since the old pots were 5 ohms.
While I was in there, I swapped the old dinky factory binding posts for nice ones I cannibalized from a ProAc project that won't need them anymore 🙂
Old vs new posts. I'll call it an improvement 🙂
That completes the crossover refurbishment!
Here they are, before and after:
![crossover [after].jpg](https://www.diyaudio.com/community/attachments/crossover-after-jpg.1404981/ "crossover [after].jpg")
The tweeter pots tested fine and they're not scratchy at all, so they're staying for now. I may replace them later.
I'm glad I kept adjustable controls in place. I probably won't touch them again after they're set up properly, but they do need to be set up properly in the first place.
Since the old crossovers showed so many signs of overheating, I drove the speakers pretty hard for an hour or so (PIL's album Album at 75% volume), then checked component temperature. The big resistors and the L-pads were steady at 72 deg F vs 70 deg room temperature. Meanwhile the amps' rear heatsinks hovered around 130 deg F while they're normally around 90-95 deg F at idle.
I've been listening to the speakers for the past 6 - 7 hours. I have to say that they sound really great, now that they're driven by a proper pair of Classé monoblocks. The Carver M500 was pretty much on its knees trying to keep up, but the Classés are proving to be a good match.
I bought the RS-II as in-betweens, to allow me to listen to music while I figure out which speakers I really want, a process that has taken months already and is nowhere near done.
While I am looking, I am growing really fond of the RS-II. I think that driving them properly is essential to revealing their true potential; but with the right amps, they really shine. I may be a little biased, but honestly at age 43 they still measure up to and beyond any speakers I've heard up to $10 - $15K. Arnie Nudell was a genius and truly one of the best speaker designers ever.
Thank you again to everyone who chimed in in this thread, I really appreciated your help and feedback!
They're quite a bit bigger (41mm diameter) than the old pots (33mm), but they will fit just fine
Despite being larger, the L-pads fit in without interference from the other components. Thanks to their 3/4" long stem they hover 3 or 4 mm above the tweeter pots.
You can see the L-pads are wired like pots, not L-pads, as the ground pin (pin 1) is unconnected. In that mode they actually only measure 7 ohms at full attenuation, which is fine since the old pots were 5 ohms.
While I was in there, I swapped the old dinky factory binding posts for nice ones I cannibalized from a ProAc project that won't need them anymore 🙂
Old vs new posts. I'll call it an improvement 🙂
That completes the crossover refurbishment!
Here they are, before and after:
The tweeter pots tested fine and they're not scratchy at all, so they're staying for now. I may replace them later.
I'm glad I kept adjustable controls in place. I probably won't touch them again after they're set up properly, but they do need to be set up properly in the first place.
Since the old crossovers showed so many signs of overheating, I drove the speakers pretty hard for an hour or so (PIL's album Album at 75% volume), then checked component temperature. The big resistors and the L-pads were steady at 72 deg F vs 70 deg room temperature. Meanwhile the amps' rear heatsinks hovered around 130 deg F while they're normally around 90-95 deg F at idle.
I've been listening to the speakers for the past 6 - 7 hours. I have to say that they sound really great, now that they're driven by a proper pair of Classé monoblocks. The Carver M500 was pretty much on its knees trying to keep up, but the Classés are proving to be a good match.
I bought the RS-II as in-betweens, to allow me to listen to music while I figure out which speakers I really want, a process that has taken months already and is nowhere near done.
While I am looking, I am growing really fond of the RS-II. I think that driving them properly is essential to revealing their true potential; but with the right amps, they really shine. I may be a little biased, but honestly at age 43 they still measure up to and beyond any speakers I've heard up to $10 - $15K. Arnie Nudell was a genius and truly one of the best speaker designers ever.
Thank you again to everyone who chimed in in this thread, I really appreciated your help and feedback!
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