Anyone Prefer the Dimensional Tweeter?

falconcry72

I'm in the market for SDA's; having never heard them I've been doing a lot of reading. As you can tell by my sig I like the vintage Polk sound. These SDA's will be for a dedicated 2-channel rig that will use a separate power amp and preamp that I don't own yet.

I have read many past posts about this, but I'd like to hear some more.

People here generally think that the dimensional tweeters on some of the earlier SDA's don't sound as good as the later SDA's that don't have the dimensional tweeters.

Thoughts?

I have a local line on some original SDA 2's, but I'm trying to decide if I should hold out for 2B's or 1C's. I've already been holding out for a few months, so I'm getting a little anxious. :mad:

Thanks!:D

nooshinjohn

Hold out for the 1C's... many here consider them to be the best of the non-sig SDA's. I wish I held on to mine sometimes.

ben62670

Some 2B's, 1C's, or 1B's would be worth waiting for.

cnh

+1, I run the 2Bs in a smaller space....the largest I'd go are the 1Cs.

cnh

Bobsama

*hand up for preferring dimensional tweeter*

I actually prefer the sound of my original SDA-1's (with SL1000 tweets) to CRS+'s and 1.2TL's. Though to be fair, at least on the 1.2TL comparison, the loudspeakers were much too large for the room and were overpowering... and I'm not entirely familiar with them either. The CRS+'s I used for quite a bit longer and would be a bit of a tie. I like the sound of the SL2000 tweeters (brighter than the SL1000's) but I miss the effect of the dimensional tweeters. I'm actively looking for SDA-1A's; my SDA-1's are a bit unique (very early production). If I can find SDA-1A's, I'm going to be a very happy man. (Plus, gotta stock of ~8 good SL2000 tweets)

It's a bit tough to select SDA's without listening to them first. I am lucky in that regard; my uncle owns the 1.2TL's and the CRS+'s, and I purchased for myself the SDA-1's. If you can find a good price on SDA-1's or 1A's or 2's, I say go for it. While there are quite a few pairs of SDA's on sale at any given time, it's a question of what's available in your area. One of the reasons I have the SDA-1's is because they're what was available; I found the seller's ad on CL after a few failed attempts to buy CRS+'s and then Monitor 10's. As I'm sure you've noticed, it's fairly easy to get Monitor 5's, 7's, and 10's on eBay.

Anyways, I prefer the dimensional tweeters. Not everyone will. It's probably more important for you to match the loudspeakers to the room. If you have a large room, try for SDA-1's or SRS's. If you have a medium room, CRS's or SDA-1's. And a small room is almost entirely regulated to CRS's.

falconcry72

cnh wrote: »

+1, I run the 2Bs in a smaller space....the largest I'd go are the 1Cs.

cnh

The space I have now is big. I could run 1.2's no problem. Well, actually there are 2 problems: 1) I can't afford them 2) my next place will be much smaller.

So even though I could run the big boys now, I'd like to get something smaller that I could take to my next place.

So who's got some extra 1C's? I'm in Richmond, VA, and I'd be willing to drive a couple hundred miles for the right pair:o

falconcry72

After months of looking, last week I found a local pair of 1C's for sale, and I thought my prayers had been answered. They were in good shape, but the guy wouldn't let'em go for any less than $750:eek: I told him what they were worth, and he was appreciative of the info, but he said at any less than 750 it wasn't worth it to him to sell'em.

Too bad:(

cnh

Don't worry they are more around the corner. The SDA game is a 'waiting' game....keep looking for them and be patient.

Here's a site that one of our members accessed that allows you to see/search all craiglistings in your area for Polks and across the country--if you wish.

http://craiglook.com/electronics.html?q=polk+audio

Good Luck!

cnh

falconcry72

cnh wrote: »

Don't worry they are more around the corner. The SDA game is a 'waiting' game....keep looking for them and be patient.

Here's a site that one of our members accessed that allows you to see/search all craiglistings in your area for Polks and across the country--if you wish.

http://craiglook.com/electronics.html?q=polk+audio

Good Luck!

cnh

Patience certainly is the key. I've been checking craiglook, craigslist, audiogon, ebay, and the flea market here daily for the last 4 months.

I thought I had finally won when I found the 1C's I mentioned earlier, but 750?! too high for me. I would have done 400.:rolleyes:

Good news: just last night I got a line on some very local 2B's (pics below). They appear to be in great shape, and the guy says they work perfectly and have the IC. I don't know what his price is yet, but I'll be checking them out this week, and if the price is right I'll grab'em for sure. I'm pretty psyched thinking about it . I just hope he isn't asking way too much like that other guy.

cnh

The 2Bs are a nice speaker in a mid-sized room. And these look very good. Don't forget to do the mid-driver test to see if the drivers are frozen and/or the seals are good! Push them in gently and see if they return forward 'slowly'...take a couple of seconds or more.

Good luck.

cnh

falconcry72

cnh wrote: »

The 2Bs are a nice speaker in a mid-sized room. And these look very good. Don't forget to do the mid-driver test to see if the drivers are frozen and/or the seals are good! Push them in gently and see if they return forward 'slowly'...take a couple of seconds or more.

Good luck.

cnh

Thanks for the luck; I really hope these work out. I'll definitely be checking the drivers. Such an easy and revealing test. For some reason the cabinets on my RTA12C's are sealed much better than my Monitor 5's or 10's. On the RTA's, when I push the passive in all the way, the drivers stick way out and stay all the way out, even after 30 seconds, then they immediately go all the way back when I let go. On the Monitors the drivers go back in about half way after 3 seconds, and the rest of the way after I let go.

If these 2B's work out, I'll need to find a good amp and preamp ASAP. luckilly I have some money saved up, as I've been hoping to find myself in this predicament.;)

Bubinga99

Back to the original question, what was the reason Polk gave for reducing the bandwidth of the difference signal in more recent SDA models? There must have been a pretty strong consensus among Polk's designers that rolling off the difference signal at about 1kHz (and therefore below the tweeter's response) gave an overall improvement, or they wouldn't have done it.

I've never heard an SDA model with a dimensional tweeter, and probably never will, but it would be interesting to know how the sound evolved. Is this described in that SDA compendium document that is no longer available?

gdb

I've got a pair of SDA-1As with real walnut veneer that aren't in service right now, I kinda' liked the dim. tweeter effect myself. After a while one of the 4 tweeters stopped working and I was preparing to upgrade the XOs and tweeters when I found some SRS2s that I really prefer more than the 1As. I like the looks of the 1As way more than the SRS2s but the 1As have a LOT of parts to replace in their crossovers and I don't know whether I'd end up keeping the dimensional tweeters or possibly getting the XO modified to use a single tweeter instead.For now I'll stick with the SRS2s and put my upgrade dollars into them first.Not sure if I'll ever get back around to the 1As, maybe someday if I live long enough!
One thing to keep in mind is that all of the first SDAs had dim. tweeters, and people loved their sound and bought a lot of them before the later,improved models were introduced. IMO.... you have to have a pair of the earlier models for a little while at least, if only for the sake of comparison and education !

Bubinga99

In case anyone else is interested, I found Matthew Polk's description of the effect when the dimensional signal was changed to only use the midwoofers. I figured it might be described in an early Polk patent, and sure enough, it's described in US4630298, filed May 30 1985, granted in December 1986:



Since it references application 616249, which later became US4569074 that was filed June 1, 1984, it was apparently some time between June 1984 and May 1985 that they discovered the benefits of a dimensional signal just to the midwoofers.

comfortablycurt

falconcry72 wrote: »

Thanks for the luck; I really hope these work out. I'll definitely be checking the drivers. Such an easy and revealing test. For some reason the cabinets on my RTA12C's are sealed much better than my Monitor 5's or 10's. On the RTA's, when I push the passive in all the way, the drivers stick way out and stay all the way out, even after 30 seconds, then they immediately go all the way back when I let go. On the Monitors the drivers go back in about half way after 3 seconds, and the rest of the way after I let go.

If these 2B's work out, I'll need to find a good amp and preamp ASAP. luckilly I have some money saved up, as I've been hoping to find myself in this predicament.;)

That's odd. When I do the press test on my 7A's and SDA 2A's(which are pretty similar cabinet wise to your RTA12's), I get completely opposite results. My 2A's(even after applying Mortite) only stay extended for about 4-5 seconds, but my 7A's(also Mortited) will basically stay extended for as long as I feel like sitting there holding the PR in...lol

dorokusai

Nope.

falconcry72

comfortablycurt wrote: »

That's odd. When I do the press test on my 7A's and SDA 2A's(which are pretty similar cabinet wise to your RTA12's), I get completely opposite results. My 2A's(even after applying Mortite) only stay extended for about 4-5 seconds, but my 7A's(also Mortited) will basically stay extended for as long as I feel like sitting there holding the PR in...lol

I know; I thought it was odd too. The RTA12C's have much larger cabinets then my monitors, so I figured they'd be less effective at holding air; shows what I know!:p

g-man

I have a pair of SDA 1A's serial# R SDA 1A1822 and L SDA 1A1866,and I'm in need of two SL2000 and two MW6501's.

Does polk have these in stock or does someone here at CP have some for sale?

I live in Norway and here it's very hard to get spare parts.

If someone have these items for sale,and have a Paypal account I'll be happy to do business.

Cheers.

hearingimpared

falconcry72 wrote: »

I'm in the market for SDA's; having never heard them I've been doing a lot of reading. As you can tell by my sig I like the vintage Polk sound. These SDA's will be for a dedicated 2-channel rig that will use a separate power amp and preamp that I don't own yet.

I have read many past posts about this, but I'd like to hear some more.

People here generally think that the dimensional tweeters on some of the earlier SDA's don't sound as good as the later SDA's that don't have the dimensional tweeters.

Thoughts?

I have a local line on some original SDA 2's, but I'm trying to decide if I should hold out for 2B's or 1C's. I've already been holding out for a few months, so I'm getting a little anxious. :mad:

Thanks!:D

The dimenstional tweeters on my original CRSs are fun to listen to and are a novelty as instruments seem to fly over your head and come from behind you but for serious listening, I don't use them.

gdb

g-man wrote: »

I have a pair of SDA 1A's serial# R SDA 1A1822 and L SDA 1A1866,and I'm in need of two SL2000 and two MW6501's.

Does polk have these in stock or does someone here at CP have some for sale?

I live in Norway and here it's very hard to get spare parts.

If someone have these items for sale,and have a Paypal account I'll be happy to do business.

Cheers.

Try calling Polk at 1-866-764-1801 to see about replacement MW6501s and also look in the "Flea Market" section for some SL2000s, there's usually some for sale in there. Good Luck !:)

Click Here:
http://www.polkaudio.com/forums/showthread.php?t=99674

g-man

thanks

On3s&Z3r0s

From the posts it sounds like I may be in the minority in that I own a pair of original SDA2's with the dimensional tweeter, and I've never had the opportunity to hear any SDA's without dimensional tweeters. So, I can't offer a direct comparison, but I will say that the SDA's do sound more echo-y than any other speaker I've ever done an A/B with.

On good recordings and in the sweet spot, the echo effect goes away and the stereo imaging is prefect. Outside the sweet spot it's not bad, just a fuller sound. On bad recordings with echo or reverb added by the recording engineer (out-of-phase program information, as another forum poster put it) it's unpleasant. I have to imagine that this effect would be a lot less pronounced without the dimensional tweeter.

However, I will say that the 3rd midwoofer (without a dimensional counterpart) in the original 2's gives you great bass detail and probably a little more punch. So, if I was picking and choosing, I'd definitely go with 1C's for the extra midwoofers and no dimensional tweeter just based on reputation alone, then I'd probably go with these original 2's cause I likes me some good bass presence, then the later series 2's. Again, I haven't heard the 2b's and maybe the use of two different midwoofers gives the same bass output as the 3 MW's in the original 2's.

Falconry, let us know if you ended up picking up the 2b's and how you're liking them!

heiney9

Bubinga99 wrote: »

In case anyone else is interested, I found Matthew Polk's description of the effect when the dimensional signal was changed to only use the midwoofers. I figured it might be described in an early Polk patent, and sure enough, it's described in US4630298, filed May 30 1985, granted in December 1986:



Since it references application 616249, which later became US4569074 that was filed June 1, 1984, it was apparently some time between June 1984 and May 1985 that they discovered the benefits of a dimensional signal just to the midwoofers.

I believe it was even futhur refined (no add'l patent necessary) with the introduction of the SDA 1C and "TL" series of SDA's.

ben62670

On3s&Z3r0s wrote: »

From the posts it sounds like I may be in the minority in that I own a pair of original SDA2's with the dimensional tweeter, and I've never had the opportunity to hear any SDA's without dimensional tweeters. So, I can't offer a direct comparison, but I will say that the SDA's do sound more echo-y than any other speaker I've ever done an A/B with.

On good recordings and in the sweet spot, the echo effect goes away and the stereo imaging is prefect. Outside the sweet spot it's not bad, just a fuller sound. On bad recordings with echo or reverb added by the recording engineer (out-of-phase program information, as another forum poster put it) it's unpleasant. I have to imagine that this effect would be a lot less pronounced without the dimensional tweeter.

However, I will say that the 3rd midwoofer (without a dimensional counterpart) in the original 2's gives you great bass detail and probably a little more punch. So, if I was picking and choosing, I'd definitely go with 1C's for the extra midwoofers and no dimensional tweeter just based on reputation alone, then I'd probably go with these original 2's cause I likes me some good bass presence, then the later series 2's. Again, I haven't heard the 2b's and maybe the use of two different midwoofers gives the same bass output as the 3 MW's in the original 2's.

Falconry, let us know if you ended up picking up the 2b's and how you're liking them!

Just unplug the dimensional tweeters. If you like the sound you can easily mod the crossover to bring the single tweeter up to the volume level of the mids.
Ben

On3s&Z3r0s

ben62670 wrote: »

Just unplug the dimensional tweeters. If you like the sound you can easily mod the crossover to bring the single tweeter up to the volume level of the mids.
Ben

Thanks for the tip, Ben! I didn't realize the tweeters were connected via plugs vs soldered connections. (The speakers at least still have fantastic seals and I've been paranoid about messing them up just for the sake of exploration.) As for the permanent mod, one man's easy is another man's self-inflicted burn wound. I've done some work with a soldering iron, but not sure if I'm ready to tackle crossover mods, especially those that change the characteristics of the crossover rather than just replacing like with like. Plus there's always the resale consideration although I guess in the eyes of true Polk aficionados I may be improving the speakers.

But thanks again, I may have to try the quick tweak if a pair of SDA's without the dimensional tweeter don't magically materialize sometime soon.