Minimal replacement or complete upgrade of sda crs crossovers

wrhifinut

Currently trying to decide if I should replace all caps with the newer metallized poly or similar caps or replace with a mix of electrolytic and metal poly. To give a little background, the speakers appear to be the original crs series from 84 prior to the removal of external fuses and addition of internal safety guards. I purchased the speakers directly from the dealer. So there have been no other owners. I have noticed some deterioration of late, but had put off looking into it.

When testing the exterior connections (pins 1 & 2, +, and -,) the readings for the right channel appear to be ok based on the downloaded troubleshooting guide. Please keep in mind that these readings were taken with an older VOM. However, the left channel had 3-4 readings in the infinity range. While trying to read the cap labels, I made the mistake of loosening the nut that holds the dimensional crossover to the rear wall and it found it's way to one of the driver magnets. So now the wires are disconnected and it's difficult to confirm those readings. There appears to be no visible damage to the speaker and the drivers all appear to test at 6-7 ohm resistance. Cannot check the coils for induction but they appear to pass continuity. The 750 pf, 12 uf, and 20 uf caps appear to be bad on the dimensional crossover. These caps show infinity while others caps and resistors appear to show the overall 6 ohm reading.

I have read numerous postings about the benefits of the newer caps, but I have also read how complete changeout does not always improve the sound. While I am not looking to go with the more expensive brands, I would change all if I were confident about the results. Is it better just replace electrolytics in kind? If so, the choices for axial, non-polar caps appear limited. Can anyone suggest a good brand or vendor? If I decide to change all caps, should the crossovers be completely redesigned? Any suggestions would be appreciated.

wrhifinut

Thanks for the advice on the sonicaps and daytons. However, that may be more than I want to put in them right now. Also, thanks for the note about the testing. I did not remove the caps, resistors, etc. from the circuits. So those tests were probably not of value. Sorry, but I am new to this forum. Did you post a link to your crs+ refurbish? Regarding the version of crs that I have, mine are the earlier speakers with two tweeters per channel.

heiney9

Do NOT use electrolytics again. If Sonicaps are to much $$$ for the budget go with Clarity Caps, they are less expensive and do a better job than most other film caps in their price range. You will no longer need the 750pF bypass caps.

Clarity Cap PX for the high pass if you are on a budget
Solen or Axon or Dayton caps for the low pass

I highly recommend Mills non-inductive wire wound resistors as they are in the signal path and are much smoother and pleasing to the ear vs. the stock sandcast. You'll need all the taming hardware you can get in the new x-over if you are going to continue to use the stock tweeters. They are are a little harsh in and of themselves compared to what is available today as a direct replacement from Polk.

IMO, this is about as minimal that can be done that will give good results for the $$$ spent. Of course, you are always free to choose to use cheap electrolytics that cost next to nothing as you won't get much improvement, if any.

H9

heiney9

wrhifinut wrote: »

I have read numerous postings about the benefits of the newer caps, but I have also read how complete changeout does not always improve the sound.

What posts specifically? And who posted it? You'll find most, if not all, of us who are experienced and have done these upgrades multiple times on many different vintage Polk's won't ever say there is no improvement or that they are lesser than before the upgrade. You may find some noobs that have posted stuff like that, but in general, anyone who has been here a long time, done the upgrades and listened to them over a long period will always say there is a HUGE improvement.

H9

Joe08867

H9 considering how new he is to the site i am sure he read that on another forum. I have heard guys complain during break-in but never have I heard someone say there was no improvement.

Unless they are using the cheap electrolytics there should be some kind of improvement.

wrhifinut, if you don't have the cash to update/upgrade the caps to something better than electrolytic than I would wait. Considering how long you have owned them, don't they deserve the refresh. I will honestly say with hand on heart that you will indeed hear a marked improvement in the sound of those speakers with new caps.

wrhifinut

Thanks all for your help. Regarding the noted posts about preserving the electrolytic/mylar mixes, these posts were found on other forums or by general searches. Since I have one speaker disassembled, I hate to put off the upgrade further. However, I may just have to do a partial upgrade. The extra tweeters and having to pair caps for the 27 uF replacement causes the price to be much higher for the Clarity Caps. At this point, I am leaning towards a combination with Solens on the low circuit and Daytons on the high circuit.

Regarding the tweeter upgrades, that will be deferred but for future reference, do most go with the current Polk offering? Are parts prices available on line or does one have to call? I have seen a couple of tweeters by Goldwood and Audex that appear to be about the right size. Does anyone know about the general quality of these brands?

wrhifinut

Sorry, just noticed that I misspelled one of the names. That should have been Audax.

Joe08867

You are much better off with the current Polk Tweeter than any aftermarket brand. The tweeters were designed with SDA crossovers in mind. It is truly a no brainer as far as the tweeters go.

I would shoot for Clarity over Dayton but if money is the issue and you really need these speakers than Daytons will work. The Daytons can be a bit harsh though, just so you know.

CNWDI

wrhifinut, good luck with your CRS's - I've got an early pair of B/B CRS+ with two crossover boards per speaker (which therefore can't natively do the TL upgrade) and I've been trying to figure out my options which are somewhat similar to yours:

1. Use existing PCB and components, replacing only the electrolytic caps. Consider replacing tweeters with RD0194-1 from Polk (which should still be available). Price ~$150 to $250 depending on capacitors, add another ~$100 for two tweeters.
2. Redo entire crossover keeping only PCB, Molex connectors, and inductors. Replace tweeters. Cost ~$400 for Sonicaps
3. Completely replace crossover using gimpod's new PCB and all new components (except source the inductors from vintage Polk crossovers). Update tweeters to RD0198-1. Cost ~$600

Option 3 gets me the full 4.1 TL mod, which otherwise won't be possible with the speakers I have. I'm seriously considering Option 3 if I can get all the inductors I need--replacing the large 16mH inductors (that my older CRS+ don't have) with current "very good" such as North Creek parts could add another $250 or more to the cost of option 3 above what I hope to pay using vintage inductors.

Bottom line, if you start updating you can spend over $1000...or much less. Right now I have "champagne taste and a beer budget" so I'm just keeping my eyes open for parts that could make option 3 realistic.

wrhifinut wrote: »

Thanks all for your help. Regarding the noted posts about preserving the electrolytic/mylar mixes, these posts were found on other forums or by general searches. Since I have one speaker disassembled, I hate to put off the upgrade further. However, I may just have to do a partial upgrade. The extra tweeters and having to pair caps for the 27 uF replacement causes the price to be much higher for the Clarity Caps. At this point, I am leaning towards a combination with Solens on the low circuit and Daytons on the high circuit.

It sounds to me as though doing *something* to these at this point is reasonable, and I would expect that the Solens/Daytons you outline above won't make anything notably worse--if after listening to them you're unhappy, then you can make further changes later.

Regarding the tweeter upgrades, that will be deferred but for future reference, do most go with the current Polk offering? Are parts prices available on line or does one have to call? I have seen a couple of tweeters by Goldwood and Audex that appear to be about the right size. Does anyone know about the general quality of these brands?

If you've got _really_ old CRS I think you might have the Peerless tweeters for which I don't know if there's a one-to-one replacement. Trying to replace a tweeter (actually a pair per speaker) with other ones "about the right size" is unlikely to be very successful--you really want a replacement that has a sufficiently similar response curve across the frequency range. The SL2000/SL3000 tweeters do have replacements that are available from Polk--I'd suggest calling or e-mailing with the S/N info off your speakers, stating that you're a Polk Forum/Club Polk member, and asking about pricing/availability of replacements.

Joe08867

He can't do the 4.1TL mod on original CRS speakers.

CNWDI

Joe08867 wrote: »

He can't do the 4.1TL mod on original CRS speakers.

He sort-of-can...only he has to do a more severe version of what I'd have to do with mine. In my case the crossovers are radically different, two of the MWs are different, and the IC cable is different (besides having to replace the tweets). To do the full 4.1TL on mine I need new PCBs (or two sets of scavenged ones that are the right vintage), two new MWs, new tweets, and a heck of a lot of components to populate the PCBs.

In his case, he'd also end up disconnecting two tweeters...but since the dimensional tweeters aren't a feature of the later SDAs I don't see that as a significant issue. If he actually has Peerless tweets, which I believe is possible, then last I knew there was no easy one-for-one replacement anyway...

So my statement is that if your goal is 4.1 TL it *is* possible to build it inside an older carcass, and re-use at least some of the parts. Note that I'm not trying to say it's worthwhile...that depends strongly on goals, budget, and personal preference. I do note that there's at least one other TL conversion that was done on an older B/B CRS+ pair like mine, though. I also know that even though I'm still pretty doggone happy with my unmodded, original-owner, 1986 B/B SDA-CRS+ pair I'm planning to open them up within the next six weeks, replace gaskets, install Larry's rings, and probably replace the SL2000 tweets with RD0194-1s. That will cost less than $200 and probably give me a fairly good ROI (and keep me "happy" for another few years while the budget gets spent elsewhere.)