SDA 2A placement and crossover questions

cascius · August 2017

Hi there,

I've been playing around with the placement of my SDAs and right now they're about 5 inches from the wall. I believe that's supposed to be right, but I've found all sort of recommendations from half a foot to 3 inches off the wall... Any recommendations? Unfortunately they're on spikes and moving them on a thick carpet is a PITA...

Also, I've been playing around with the crossover setting and keep going back and forth between 50 and 80Hz. Depending on the song I get better or worse results... Any tip there?

Thanks!!!

- Olivier

pitdogg2 · August 2017

Run them full range. Why are you not doing that? 4"-8" off the wall can be the sweet spot

cascius · August 2017

I had them set as Large prior but a couple weeks ago I tried them as Small and it seemed like the bass response improved.

I just switched back to Large and it seems fine... Go figure...

F1nut · August 2017

The bass response will vary with the distant from the rear wall. Too close and it gets boomy, too far away and you lose bass. Get it just right and the bass is deep and tight. I've found 5 to 6 inches works best.

cascius · August 2017

Thanks for the info. I just hung the tv, redid the ht cabinet so it's not as wide, and now the sdas have at least 3 feet on the sides.

I also used a CD to measure the distance from the wall. I think it was slightly better an inch closer to the wall. I'll have to try again...

Anyway, here's how it looks.

cascius · August 2017

inscrutable · August 2017

Have you played with distance apart? Hard to tell but looks little less than 6 ft? If you have the side room, you might like a little further ... found mine best around 7 ft

gmcman · August 2017

@cascius ....looks like you have a have a decent room to work with, placement of SDA's is critical...welcome to the world of speaker tweaks....

You really need to use a tape measure and a level if you have one. I would start with 5" from the rear wall but make sure its exactly 5", measure each corner of the speaker and make sure they are all 5", not 5 1/4"...it really makes a difference.

They need to be facing straight, also check the bottom of the cabinets if you don't have a level handy.

I see you have a sub, are you using it? I assume you're using an AVR, if so, when you change the speakers to small, the sub is likely turned on, when set to large, it may be set to only work in the small setting and not Large + Sub.

I would temporarily remove the sub, use the large setting with no sub, set speakers to full range...those 2A's will play below 30Hz.

Also, do you have the interconnect cable hooked up?

Schurkey · August 2017

cascius wrote: »

Wild Guess: Either remove the trinkets from the tops of the speaker cabinets so they don't vibrate and rattle, or use one of the many anti-vibration compounds (Blu-Tack is often recommended, but there are others including rope caulk) to dampen their motion. Even a heavy cloth between the objects and the speaker may be enough.

I've found that glass and ceramic decorations generally don't sit completely flat, any motion upsets either the bottle or the lid. You may not hear it directly, but on heavy bass it's probably adding "clutter" to the soundfield.

Do be careful. I've heard of Blu-Tack and rope caulk weeping out some kind of liquid as they age--the oils that keep 'em supple, I suppose--and the liquid discolors what it's been touching for the last six months.

pitdogg2 · August 2017

Schurkey wrote: »

cascius wrote: »

Do be careful. I've heard of Blu-Tack and rope caulk weeping out some kind of liquid as they age--the oils that keep 'em supple, I suppose--and the liquid discolors what it's been touching for the last six months.

Silicone stick on bumpers would be better or stick on felt circles.
Both of the above will discolor the tops of the speaker.
I'm also not a fan of anything on my speakers.

pkquat · August 2017

cascius wrote: »

Hi there,

I've been playing around with the placement of my SDAs and right now they're about 5 inches from the wall. I believe that's supposed to be right, but I've found all sort of recommendations from half a foot to 3 inches off the wall... Any recommendations? Unfortunately they're on spikes and moving them on a thick carpet is a PITA...

Also, I've been playing around with the crossover setting and keep going back and forth between 50 and 80Hz. Depending on the song I get better or worse results... Any tip there?

Thanks!!!

- Olivier

The crossover frequency and phase can be tricky with a sub due to room resonances and the passive radiators in the 2B's (passive radiators in general). Sub placement is another factor.

I too recommend leaving them full range, and only use the sub for HT duty. If you can have the sub and front speakers on at the same time, and have some source material that covers a wide bass range or ever better some test tones, you can find where the combo can be boomy and cancel each other. Find want crossover and phase setting works best for the lowest frequencies, even it it boosts them a little and then use those settings as a start for HT with the sub only producing the LFE, meaning you are no longer mixing the sub with the mains for regular listening.

cascius · August 2017

Thanks for all the feedback everyone. I've been swamped at work but as soon as I have some time I'll give you an update.

Yesterday I finally scored a new center: SC350. Can't wait to test it out tonight!

Next step will be to keep tinkering with the placement of the SDAs. Which brings up an interesting question: what settings should I use to test placement? I'm thinking large, pure direct, no sub. What do you think?

Ps: I have a ghetto idea on how to be able to move the sdas for testing purposes. I'll post some pics!

gmcman · August 2017

cascius wrote: »

Next step will be to keep tinkering with the placement of the SDAs. Which brings up an interesting question: what settings should I use to test placement? I'm thinking large, pure direct, no sub. What do you think?

There have been some good suggestions so far, really need you to try what has been stated and report back.

SDA's are designed to be setup a certain way, believe me when they are just a little bit off it does make a difference.

Are you using them for HT or mainly music? I had a sub for my TV/stereo usage, once I put the SDA's in the front, I have since retired the sub.

Now for HT use, I would likely only use it for movies if that's what you desire, but not supplement it for music.

Properly setup SDA's, like yours, especially when they have been recapped, are pretty good for low bass in movies.

cascius · August 2017

Hi everyone,

I agree with everything that has been said. There are a few things I've already done with those:
- Completely redid the crossover + changed all internal cabling
- Upgraded tweeters
- Spiked them
- T-Nuts upgrade + Mortite
- Speakon connectors for the SDA cable
- Upgraded speaker terminals
- Added felt materials to the trinkets on top of the speakers. Kinda need those for the WAF...

i still have a slight air leak in the left SDA though. I've been battling it for a while now, and can't seem to find the issue. I wish I could just fill up the speaker with smoke and observe where it leaks...

So in order to test the different distances from the back wall. I'm thinking about putting them on some sort of round bars so that I can roll them closer/further form the wall until I find the distance I like. With the spikes and my carpet it's just a nightmare to even get both of them at the exact same distance.

Regarding the distance in between each of them: Unfortunately it's only 5 feet. I could increase it but then they will be completely off centered with the couch. Other option would be to lose the minimum of 3 feet from the left wall. Room configuration can be such a pain....

I run these as large with 2 modes:
- Stereo (no sub)
- Extended stereo (sub + center/surrounds @ 40%)
Both modes are actually quite nice depending on my mood.

I do feel the SDAs can be a little dull at times. I have no clue what might be causing the issue though. I wonder if it might be my amp, but short of buying a new one I don't have a way to test it... I'll keep playing with placement.

Finally: the SC350 is a very nice match, I'm very pleased! I will order the parts to upgrade the crossover in the next few days.

Thanks for all the inputs!

- Olivier

cascius · August 2017

Alright, I just found a major culprit: standing wave settings were sucking the life out of the SDAs... Turned that crap off, all WAY better! Still need to play with the distance from the back wall... I'll keep you posted.

RandyCroissant · August 2017

I believe you mean CS-350 as your center, just a correction for others who are tuned in carry on

cascius · August 2017

RandyCroissant wrote: »

I believe you mean CS-350 as your center, just a correction for others who are tuned in carry on

Correct! Thanks for catching that.

westmassguy · August 2017

cascius wrote: »

RandyCroissant wrote: »

I believe you mean CS-350 as your center, just a correction for others who are tuned in carry on

Correct! Thanks for catching that.

Awesome center, and a great match for the SDA/SRSs. Easy x-over upgrade too.

stones89 · August 2017

Oliver, experiment with placement if you have room to do so. Even though Polk SDA's were designed with near wall placement in mind, no speaker can deliver full potential being too close to room boundaries with regard to imaging and tonal purity. Also, experiment with the SDA interconnect, listen with it in and out. If you need the "SDA" effect then it can be rewarding in most rooms. In a well treated room with good upstream components it is not necessary. I have not heard your speakers but the ones I have heard and have experience with, are good speaker systems in their own right.

westmassguy · August 2017

SDA is not an "effect"

pitdogg2 · August 2017

stones89 wrote: »

Oliver, experiment with placement if you have room to do so. Even though Polk SDA's were designed with near wall placement in mind, no speaker can deliver full potential being too close to room boundaries with regard to imaging and tonal purity. Also, experiment with the SDA interconnect, listen with it in and out. If you need the "SDA" effect then it can be rewarding in most rooms. In a well treated room with good upstream components it is not necessary.

The above in bold is completely untrue.

stones89 · August 2017

"The above in bold is completely untrue."

Wrong. For me, I have used 2.3tl's in both situations extensively, normal living room, normal half finished basement and a Rives level 2 constructed room. My room is the biggest investment I had made in my hobby. It has worked for me through trial and error, so I am sharing that experience. There are no absolutes with stereo systems and experimentation is the only way to discover what works best for you.

I have always felt my Polk's with my components are a good speaker system in general, especially with updates, like new crossovers, blackhole 5, dyanamat. I prefer them without the SDA cable. I find them more relaxed with a more realistic sound stage. Thats just me - YMMV.

Schurkey · August 2017

westmassguy wrote: »

SDA is not an "effect"

If it wasn't an effect, it wouldn't have been deemed worthy of patent(s).

Of course it's an effect. SDA is the effect resulting from putting reverse-polarity crosstalk-cancelling speaker drivers and the attendant crossover-network circuitry convolutions in the same cabinet as the normal drivers.

I guess it's time to close this thread, too.

westmassguy · August 2017

Schurkey wrote: »

westmassguy wrote: »

SDA is not an "effect"

If it wasn't an effect, it wouldn't have been deemed worthy of patent(s).

Of course it's an effect. SDA is the effect resulting from putting reverse-polarity crosstalk-cancelling speaker drivers and the attendant crossover-network circuitry convolutions in the same cabinet as the normal drivers.

I guess it's time to close this thread, too.

I give up. It's just not worth it anymore.

cascius · August 2017

Yeah, let's try to keep this discussion "on topic" gentlemen.

F1nut · August 2017

SDA IS NOT AN EFFECT

It is a technology, which is why it has patents.

polrbehr · August 2017

Schurkey wrote: »

westmassguy wrote: »

SDA is not an "effect"

If it wasn't an effect, it wouldn't have been deemed worthy of patent(s).

Of course it's an effect. SDA is the effect resulting from putting reverse-polarity crosstalk-cancelling speaker drivers and the attendant crossover-network circuitry convolutions in the same cabinet as the normal drivers.

I guess it's time to close this thread, too.

So all this time I've been hoodwinked into thinking mine just sounded good because they were. Color me embarrassed, time to haul the 2Bs to the curb I guess... *sigh*

Gerres26 · August 2017

Same few people keep calling it an "effect" to try to get under the skin of some of the more knowledgeable polkies seems to me. It's annoying really, I've seen them post on other sites about it and laugh about saying it here.

F1nut · August 2017

Gerres26 wrote: »

Same few people keep calling it an "effect" to try to get under the skin of some of the more knowledgeable polkies seems to me. It's annoying really, I've seen them post on other sites about it and laugh about saying it here.

That's ok because we're laughing at their ignorance.

cascius · September 2017

Ok, so I'm currently extremely happy with the way the system sounds. One of the biggest highlight of this week: my wife told me that she hates our car sound system as it sounds like pure crap compare to the awesome setup in our living room. But when we initially got that car, she was amazed by the sound system in it... Everything is relative I guess!

A few notable things regarding the SDAs and this discussion:
- I've moved the speakers slightly father away from each others (almost 6 feet, but that's all i can do with the space I deal with)
- The left cabinet which has always given me grief with air leaks is now perfect. When I do the driver push test the passive stains in place until i release them. I think the hot weather must be helping there. Crazy!
- I've tried different distances off the wall and 5" 1/16 seems to be the best.
- There's plenty of bass without the sub! Finally!!!

What I'm working on this weekend: My CS 350
- Redid the crossover (Sonicap + Mills)
- Filled the various dings, sanded down, removed some of the veneer that peeling off
- Staining the front black
- Painted the Polk Audio logo gold to match the one on the SDAs

- Going to apply the same kind finish to the cabinet so it matches the SDAs' look
- Might redo the internal wiring (I have all the parts, so I might just go for it.
- De-oxit the crap out of all the connectors
- Might replace the seals with mortite, but i'm unsure it's necessary since the cabinet is ported
- Inside the cabinet there's various filling materials. I noticed the black ones weren't installed the same way on both sides. I guess one must have shifted over the years. I'll play with placement.

I will also play around with calibrating the rest of the sound system to the SDAs and the new center.

That's probably it for this weekend aside from jamming some great tunes!

Next diy projects might be:
- Custom audio rack
- If I make the above, I will also make a custom stand for the center, matching the same look and feel

Have a great weekend!

- Olivier

pitdogg2 · September 2017

Personally I wouldn't use mortite. Most have moved to this.

http://www.homedepot.com/p/Armacell-2-in-x-30-ft-R-1-Foam-Insulation-Tape-TAP18230/100539553

Cut to width and sticky side to woofer.

SDA 2A placement and crossover questions

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