SDA1 vs. SDA1c

SDA1C

I'm sure I just haven't figured out the correct lingo for searches here cause I haven't been able to find a comparison on these two.

What is the main difference between the 1 and the 1c? They look identical to me.

Thanks for all the info, 1C

renowilliams

The difference is in the drivers used in each. Here is a link that shows a pdf file on parts and drivers. Just scroll down the page to the parts list.


http://www.polkaudio.com/forums/showthread.php?t=55888

SDA1C

OK so if I'm reading this right it seems you would get more high frequency dimension out of the 1's than you would from the 1c is this correct? Also why the change? What was laking to initiate the change?

renowilliams

No idea...I think they were experimenting at the time.

SDA1C

Well its got me curious. I'd really like to hear a set of 1's. There is a set in Portland on cl by a fellow named Scott. Does anybody know who this might be and if they are a member. I have a truck being delivered to the airport for me. Wouldn't it be sweet to have a set of SDA1 waiting for me when I get there as well?

heiney9

Drivers, cabinets, x-overs, tweeters........you name it, they are completely different speakers. In the 4 generations they were improved upon vastly.

Take a read here it explains some of the differences:

http://www.polksda.com/sda1creview.shtml

SDA1C

In light of that article I would say my assessment is correct in that the higher frequencies would carry more dimension. However, if the dimension is out of the range for hearing then I suppose it doesn't matter much eh? lol.

Dennis Gardner

SDA1C wrote: »

In light of that article I would say my assessment is correct in that the higher frequencies would carry more dimension. However, if the dimension is out of the range for hearing then I suppose it doesn't matter much eh? lol.

Your assessment is flawed. Dimension is added not by adding more sound, it was done by cancelling out unwanted sounds by reversing phase in the dimensional drivers. They realized that the additional drivers and costs involved weren't needed to achieve the same effect. That is why later versions carried fewer tweeters in some models.

heiney9

SDA1C wrote: »

In light of that article I would say my assessment is correct in that the higher frequencies would carry more dimension. However, if the dimension is out of the range for hearing then I suppose it doesn't matter much eh? lol.

Incorrect. Re-read page 42, middle column towards the bottom. Limiting the freq of the dimensional array surprisingly enhanced the spatial information. The dimensional tweeter is not needed and could tend to sound "phasey" at times compared to later SDA models without it.

H9

SDA1C

Yea it seems were saying the same thing just different ways. The crossover design in the 1 allowed the dimension to the tweeter which was not only not needed but actually detrimental. The fact that it was unwanted and measurable sort of proves it was there. I suppose the assessment that it doesn't matter much could be incorrect though. It clearly does matter and seems it matters in a measurable way.

SDA1C

heiney9 wrote: »

Incorrect. Re-read page 42, middle column towards the bottom. Limiting the freq of the dimensional array surprisingly enhanced the spatial information. The dimensional tweeter is not needed and could tend to sound "phasey" at times compared to later SDA models without it.

H9

I get it heiney. The frequencies were reduced in the 1c to achieve better overall effect. That seems to me proves that whether it was desirable or not the sda1 had more dimension at the higher frequencies. Maybe not to the compliment of the overall sound but nonetheless it was there.

Dennis Gardner

Dimensional driver placement is a big factor in the success of cancelling crosstalk and using a tweeter along with a mid-woofer in the same plane with highs traveling faster than lows created artifacts in the high range that weren't too good. Newer versions put all tweeters in the same plane/array to avoid time alignment issues, and the SDA cancelling needed could be done at mid freqs just fine.

The placement of dimensional drivers side by side with main signal drivers was intentional to duplicate the spatial properties of ear spacing on the listeners head. This is why my CRS+ models with more space between dimensional and stereo drivers (same spacing as the big arrays) give better SDA imaging than my SDA1Cs.

I guess I got a big head..........

Toolfan66

Just in looks alone my vote goes to the 1C's.. LOL..

Dennis Gardner

TOOLFORLIFEFAN wrote: »

Just in looks alone my vote goes to the 1C's.. LOL..

True that......

Dennis Gardner

I know you just picked up some 3.1s, but I personally have steered away from the SDAs that use odd driver arrangements like the 3.1 or 2.3. Something makes my head hurt when I look at them, kinda like they are lopsided.

SDA1C

Did they ever make an sda1 that had the vertical tweeter arrangement?

Dennis Gardner

SDA1C wrote: »

Did they ever make an sda1 that had the vertical tweeter arrangement?

The 1Bs and 1C both have the tweeters arranged vertically above the mid-woofers, but they weren't ever placed between the mids in the 1 models like they were in the largest Reference models SRS, 1.2 etc. The array of tweeters placed vertically were never used in producing SDA though. They were used in the largest SDA towers in a way that used them at different power levels. The more power needed, the more tweeters kicked in. Too cool huh?

heiney9

The vertical tweeters on later SDA's are referred to as a progressive point source. Each tweeter plays at a different output level.

H9

Dennis Gardner

heiney9 wrote: »

The vertical tweeters on later SDA's are referred to as a progressive point source. Each tweeter plays at a different output level.

H9

Is that true of the dual tweeters on the 1Cs too, or just the 3 and 4 driver models of the SRS line? I'm not up on the crossover design.

heiney9

True for all multiple (vertical) tweeter SDA's......just to a lesser degree than the big boys.

SDA1C

Dennis Gardner wrote: »

The 1Bs and 1C both have the tweeters arranged vertically above the mid-woofers, but they weren't ever placed between the mids in the 1 models like they were in the largest Reference models SRS, 1.2 etc. The array of tweeters placed vertically were never used in producing SDA though. They were used in the largest SDA towers in a way that used them at different power levels. The more power needed, the more tweeters kicked in. Too cool huh?

Yea I'll say! Guess thats why tweeters in certain positions wear out first. Would it be a good idea then to rotate tweeters?

heiney9

SDA1C wrote: »

Guess thats why tweeters in certain positions wear out first. Would it be a good idea then to rotate tweeters?

Why would that be? How did you come to that conclusion for SDA's? No, they don't wear out differently. Rotating tweeters because of an imagined wear pattern is not necessary. I'm not saying that multiple drivers of any kind don't wear unevenly, it can happen, not all the time, but it is possible, just not for the reason you state.

H9

heiney9

The Crystal Clear Imaging of Polk's Line Source Array

Even the best of conventional loudspeakers suffer from blurred imaging and tonal coloration caused by unwanted floor and ceiling reflections of midrange frequencies. Reflections reaching the listener within 5 milliseconds of the original signal will "smear" the image. Polk, however, minimizes the damaging effects of undesired reflections with its Line Source Array technology.

By controlling the vertical dispersion of these frequencies, a much higher level of imaging purity is achieved. The sound becomes more "open" by reducing the effects of undesired room interactions. Consequently, the listener is given a wider range of optimum listening positions in the room.

Additionally, Polk's Progressive Point Source technology to maintain a Constant Vertical Directivity of mid and high frequencies, which prevents undesirable beaming. As frequencies increase, the tweeter array adjusts its radiation area and eventually becomes an ideal point source at the very highest of frequencies, eliminating high frequency interactions and reflections between multiple drivers.

SDA1C

Just put together the multiple output levels you spoke of and the fact that the bottom two tweets went out first on my set. Really just a guess as it were...sorta why I said guess lol

heiney9

There is probably another reason they went out, not simply because they are in a point source array. It is possible to overdrive and damage the tweeters that have the slightly higher output before the tweets with lesser output. But, that has everything to do with improper gear vs. because of the array. Which model do you have? The tweeters have a thermal poly switch in some models to protect them from being over driven, after tripping those a few times they become easier to trip or with age they start to trip prematurely interrupting the signal to the tweeter. They are self resetting unless they aren't working properly. 20+ year old Polks have this issue a lot. Some replace the poly switch with a small value resistor or another poly switch.

H9

SDA1C

The ones that went out were the sl2000. I have a good feeling they were the original tweets. I'm fairly certain they had seen their day I just thought it odd that the same position went out first. The dome was literally hanging by a thread and the other blew off completely (no jokes about not being able to hear it at the time please). It is entirely possible that there were problems with the upper tweets as well I replaced them all and didn't look back. When I bought the rdo I got new poly switches but haven't put them in. I bridged the old ones and haven't had any problems.

FTGV

It appears that in the 1c the bottom tweet is operating at the same level (minus the small amount of DCR in the .4mh series coil)as the top tweet but with reduced bandwidth.In other words the two tweeters are operating together over the (approx)2k-6k range,above which the bottom tweeters response is slowly rolled off leaving only the top tweet to cover the top octave and abit.The effect of which as As Brock's Polk quote indicates is reduced flloor/ceiling reflections in the upper midrange and lower treble whilst leaving the highest treble unaffected.

SDA1C

Just so people don't think I'm either blind or completely clueless. Heres why I thought they were identical.

http://portland.craigslist.org/mlt/ele/2412072517.html

1c

michaeljhsda2

Those are studio version SDA 1C's. Sonically they are indentical to the ones with the wood caps on the top and bottom.

heiney9

SDA1C wrote: »

Just so people don't think I'm either blind or completely clueless. Heres why I thought they were identical.

http://portland.craigslist.org/mlt/ele/2412072517.html

1c

They might look the same, but that doesn't mean they are. 1's, 1A's, 1B's, 1C's and 1C Studio versions are all different. The difference between the 1C's and 1C Studio is mostly the cabinet, with the 1C's getting the nod having a better cabinet.

The difference between all earlier versions and the 1C are vast, with later 1B's not being all that different, but still different.

H9

SDA1C

OK. So even though they are the vertical array the ones linked to could still have the SDA1 crossover and driver compliment? Making them SDA1 not 1c? If they are 1c I'll snatch them up...(if the guy hasn't sold them and would get back to me) From what has been said it doesn't sound like the SDA1 can keep up with the 1c

1C