SDA-CRS conversion

[NeilGabriel]

Would it be possible to convert the CRS to CRS+ by disconnecting the dimensional tweeter....or is that just too easy?

One other question that I think I know the answer to....but maybe not...

If the interconnect is not used on these (and other SDA speakers), I assume that leaves each speaker with one functioning tweet and mid?

[stubby]

Yeah, it would be a little too easy. The crossover is completely different. The MWs are different, but other than that.....

Second question, you are correct.

I have a pair of two tweeter CRS speakers that I have installed the "+" crossover in, and it doesn't sound too bad. Need to get the proper drivers, but I'm in no hurry. Would like to make a pair of CRS style cabinets myself and get the tweeter centered the way it should be. Another no hurry thing.

stubby

[FTGV]

Would it be possible to convert the CRS to CRS+ by disconnecting the dimensional tweeter....or is that just too easy?

Try it,thats essentially what they have done with the CRS+ though as mentioned above used different drivers so required a reworking of the crossover.Rumour has that the SDA effect is enhanced when the dimentional signal is limited to the midband and below.

[F1nut]

I'd suggest that if you want CRS+ speakers, find a pair.

[heiney9]

As far as your 2nd question..........not on all SDA's. Later models if you disconnect the cable the drivers still function, just no SDA signal. Earlier models if the disconnect the cable you loose the entire mid.

H9

[FTGV]

If the interconnect is not used on these (and other SDA speakers), I assume that leaves each speaker with one functioning tweet and mid?

From the schematics it looks to me like the dimensional mid and tweet in the CRS will not be function with the cable removed, but the dimensional driver in the + will still operate as it gets fed the low bass from the stereo signal through a big inductor.

[dorokusai]

Yes, you may simply disconnect the dimensional tweeter but I'd look for a pair of SDA CRS+.

[NeilGabriel]

Yes, you may simply disconnect the dimensional tweeter but I'd look for a pair of SDA CRS+.

I have a very nice pair of CRS+ (with great stands from Stubby)....

but there is a nice pair of CRS in the neighborhood that I have a chance of getting at a good price....was going to try the 4 in the HT system....not sure how using CRS+ in front (which I do now) and CRS in back would work...maybe they would be fine together without modding the CRS??

[Bobsama]

My input in here is that Polk designed SDA-1's, 1A's, 2's, and CRS's with two tweeters for a reason. If they sounded better without the dimensional tweeter, they'd have left the dimensional tweeter out entirely. For SDA's of that vintage, leave all tweeters connected.

[NeilGabriel]

Well, I am not the expert (not close), but that would sure surprise a lot of the modguys who think you can improve on a design even if it was manufactured and sold to the public....

I guess my question while the bigger debate rages is whether using CRS+ as fronts and CRS as rears presents any inherent flaws given the difference in design.

[analog97]

I had my ears on the original 2-tweeter CRS for over a year. They are a fantastic speaker system IMO. Although I have never heard the single tweeter model, it strikes me that there is a lot of negativity directed toward the CRS. I can't imagine why. With good equipment, they are magic. With a little luck, I'll get a chance to hear the CRS+, but I'm from Missouri on night and day improvement. Best wishes. SDA is magic.

[heiney9]

My input in here is that Polk designed SDA-1's, 1A's, 2's, and CRS's with two tweeters for a reason. If they sounded better without the dimensional tweeter, they'd have left the dimensional tweeter out entirely. For SDA's of that vintage, leave all tweeters connected.

The reason the early SDA's have two tweets is because Polk didn't know any better at that stage of the game. I really don;t care for any SDA with the dimensional tweeter.

H9

[heiney9]

I guess my question while the bigger debate rages is whether using CRS+ as fronts and CRS as rears presents any inherent flaws given the difference in design.

Nope not in an HT set-up, go for it.

H9

[heiney9]

I had my ears on the original 2-tweeter CRS for over a year. They are a fantastic speaker system IMO. Although I have never heard the single tweeter model, it strikes me that there is a lot of negativity directed toward the CRS. I can't imagine why. With good equipment, they are magic. With a little luck, I'll get a chance to hear the CRS+, but I'm from Missouri on night and day improvement. Best wishes. SDA is magic.

The single tweet models are even better ,as in a more natural and realistic presentation but still with all the SDA magic possible.

H9

[dorokusai]

My input in here is that Polk designed SDA-1's, 1A's, 2's, and CRS's with two tweeters for a reason. If they sounded better without the dimensional tweeter, they'd have left the dimensional tweeter out entirely. For SDA's of that vintage, leave all tweeters connected.

As Heiney stated above, it was an eventual design change by Polk Audio which is well documented in the forum and verified at every Polkfest since 2004.....by the Polk Audio Engineering department. It's also in the SDA Compendium if I'm not mistaken.and talked about in depth before the forum changed many years ago. There's no dis-information happening here Bobsama, sorry.

[codyc1ark]

Very interested in this post, as I have a pair of CRS's. I've done some reading about disconnecting one tweet to improve sound. From what I understand, which may be wrong, the best way to go is to have the xo modded for one tweet. (Which is something I'm dying to do, but don't know anybody who is willing to do it.) If you try this, I'd like to see how it comes out. The biggest, and only mod, that I've done is replacing the posts as the ones I got broke right away. Good luck!

[FTGV]

From what I understand, which may be wrong, the best way to go is to have the xo modded for one tweet.

No extensive mod would necessary,simply removing the resettable fuse (polyswitch)from the dimensional tweeters circuit will remove it from the signal path.

[Bobsama]

As Heiney stated above, it was an eventual design change by Polk Audio which is well documented in the forum and verified at every Polkfest since 2004.....by the Polk Audio Engineering department. It's also in the SDA Compendium if I'm not mistaken.and talked about in depth before the forum changed many years ago. There's no dis-information happening here Bobsama, sorry.

Which then goes against most everything I've heard around here about early SDA's. My point is that it'd be pretty stupid (and unlikely) that early SDA's were tested exclusively with dimensional tweeters. Simply put, why make a product more complex than necessary? The dimensional tweeter costs money, the additional crossover components costs money, the time to setup the additional hole in the cabinets costs money, the time to install the additional tweeter costs money, and finally the additional complexity of the product (and especially additional points of failure) costs money. Maybe I'm wrong here, but changing or disabling active drivers changes the sound product.

Go on and make whatever modifications wanted. I sure as hell wouldn't.

[F1nut]

Which then goes against most everything I've heard around here about early SDA's.

No, it does not.

You keep missing the fact that Polk went to a single tweeter and/or multiple tweeters in a progressive point source because it sounded better. That fact alone should tell you that the dimensional tweeter idea wasn't the best idea.

Have you actually tried disabling the dimensional tweeters in your speakers?

[Bobsama]

No, it does not.

You keep missing the fact that Polk went to a single tweeter and/or multiple tweeters in a progressive point source because it sounded better. That fact alone should tell you that the dimensional tweeter idea wasn't the best idea.

Have you actually tried disabling the dimensional tweeters in your speakers?

I've listened to SDA-1's (w/ SL1000's), CRS+'s (w/ SL2000's), and 1.2TL's (w/ SL3000's).

I agree that it wasn't the best idea and that point source sounds better in the majority of situations. However, the point I'm making is that Polk originally designed & manufactured loudspeakers with dimensional tweeters. If SDA-1's and 1A's and CRS's sounded better without the dimensional tweeter, then why include it at all? I would make an educated guess and say that they included it because, using the technology of the day (drivers, crossovers and cabinets), the speakers sounded better with the dimensional tweeter enabled than disabled.

[F1nut]

Polk thought at the time that they needed to include the high frequencies to fully obtain the SDA "effect". Polk discovered later that they did not and that the dimensional tweeter actually imparted a phasey effect that folks did not like. Many owners of early SDA's saw that Polk did away with the dimensional tweeters and followed suit by disabling theirs.

Polk also used very inexpensive caps and resistors in all of the SDA's. That doesn't mean they did it because it sounded better. They did it because they wanted to meet a certain price point and even more so because exotic caps and resistors were either not available or not available in vast quantities. That doesn't mean we need to continue to use those original parts. I do not recall one person that after upgrading their crossovers went back to the stock parts.

[NeilGabriel]

In other words, one can make a mistake and correct it in a later deisgn....that seems to happen all of the time. I think Bobsama has a good point that existing technology might put constraints on the design...but this sounds like a case where further research indicated that a design change was appropriate....at any rate, they are what they are...and as we are reminded....if you think it sounds good, it sounds good.!