SDA 2B placement

rhythm

Hi, I currently have my stereo equipment in a location where one of my Polk SDA 2B speakers backs up to a wall where there is a return for our air conditioning (pic attached). From what I understand, these speakers really need ideal placement in order to get the best from them, and the open cavity behind this speaker certainly is not what you want. My SDA 2B's are pretty old, and I'm thinking about spending some money to upgrade them. But if I have to keep them placed like this, is it worth doing? Or should I consider a different model speaker in this room?

Thank you,
Greg

pitdogg2

Upgrade them and do the 4.1tl mod on them for super excellent results. 3 to 6 inches off the wall gives good bass results and minimum 3 to 4 feet of side clearance is good rule of thumb.

DaveHo

I don't think the return will significantly impact the performance. Upgrade as you see fit!

Nightfall

I wouldn't be worried about that vent either, upgrade away.

BlueFox

I used to have the SDA 2B speakers. Unfortunately, the sides warped off, so I bought PSB Synchrony One speakers to replace them. That was a good upgrade. Speaker technology is like other technology. It improves.

rhythm

Thank you for the replies. In general, the room they're in is not as good as where they were in my previous house. I know that I am not enjoying the sound of the SDA 2B's as much as I used to. What I don't know is how much of that is due to the room change and how much is due to the speakers being older and needing component replacement on the crossovers. I guess that question will be answered if I replace the components and hear the results; I just hope that the room itself is not mostly to blame because this is where they're going to stay. Aren't these speakers more picky than many others about the room they're in? That's my main concern about keeping them.

Greg

F1nut

Rooms make a huge difference regardless of the speaker. SDA's are not that picky, but there are certain guidelines one should follow for the best results. 5 to 6 inches off the back wall, at least 3 feet from the side walls, 6 to 8 feet apart and no toe in. Other speakers may need to be 3 or 4 feet off the back wall, yet others need various degrees of toe in, etc., etc. Basically, every speaker requires careful set up for the best results.

Square rooms are a complete nightmare, so if yours is all I can say is get used to headphones.

CH46E

As mentioned above. That 3 to 4 ft side wall clearance is crucial. Because I could not make that clearance I had to let go a mint pair of SDA SRS 2. I will probably regret that move in a few years.

Inscrutabl0915

CH46E wrote: »

As mentioned above. That 3 to 4 ft side wall clearance is crucial. Because I could not make that clearance I had to let go a mint pair of SDA SRS 2. I will probably regret that move in a few years.

Looks like I’m in the same boat with the same speakers at the current house. Sigh ...

rhythm

Thanks again for the replies and advice. Even though my room is not ideal (kind of reflective/bright sounding), I am able to have my SDA 2Bs 6-8 feet apart, 6 inches off the back wall, and have a few feet of open space on each side. So I'm going to go for it and upgrade the crossovers and tweeters. I've never heard what the TL version of my speakers sounds like so I'd have to assume that I'll like the sound better, but with all of the positive reviews about the TL mod I feel like I should go for doing that also.

CH46E

Oh man. I feel so bad right now letting my SRS2 go. I did get a fully acoustic treated room from the owner, designer and mixer of Studio IMA305 for them. Im going to reach out and see if I can get them back tomorrow.

It looks like he does not have them in optimal position anyways. He did tell me he was looking for a large presentation speaker for looks in his studio.

I hope I can get them back.





Those are my old SRS 2 in a Miami Studio.

CH46E

rhythm wrote: »

Thanks again for the replies and advice. Even though my room is not ideal (kind of reflective/bright sounding), I am able to have my SDA 2Bs 6-8 feet apart, 6 inches off the back wall, and have a few feet of open space on each side. So I'm going to go for it and upgrade the crossovers and tweeters. I've never heard what the TL version of my speakers sounds like so I'd have to assume that I'll like the sound better, but with all of the positive reviews about the TL mod I feel like I should go for doing that also.

You don't need them off the wall behind them. If you have 2ft from side walls its worth a shot buddy. Do it!

rhythm

I haven’t soldered much and the little that I did was a long time ago. So I may be looking to have someone do the crossovers for me. I like doing projects myself but I’m not sure I want to use my crossovers for soldering practice.

F1nut

Contact member westmassguy, he'll take care of you.

rhythm

F1nut wrote: »

Contact member westmassguy, he'll take care of you.

Done. He got back to me with a lot of helpful information and bunch of options regarding component choices. Regardless of which options I go with on the components, I'll be doing the 'TL mod' and buying some RD0198 tweeters from Polk. Looking very forward to having this done and having a 'new' set of speakers in my house!

Inscrutabl0915

rhythm wrote: »

Thanks again for the replies and advice. Even though my room is not ideal (kind of reflective/bright sounding), I am able to have my SDA 2Bs 6-8 feet apart, 6 inches off the back wall, and have a few feet of open space on each side. So I'm going to go for it and upgrade the crossovers and tweeters. I've never heard what the TL version of my speakers sounds like so I'd have to assume that I'll like the sound better, but with all of the positive reviews about the TL mod I feel like I should go for doing that also.

So how has that worked out? Figure if yours not so great, then I am screwed.

After 2 house moves, I have a FROG now, roughly 12x20 with 5.5’ vertical knee walls and 2.5’ 45* angles/fillets to the 8’ h ceiling. So I am even more constrained for width on the (preferred) short wall, and the long wall will have built-in equipment shelves behind them, only 8’ or so depth to a seating position, which then blocks built-in record racks. Sigh ...

I know 7 billion people would trade places, and grateful for what I have, but this downsizing sucks and I do miss my 500sf listening room and 900sf HT.

rhythm

Sorry I never reported back on this. I did have David (westmassguy) re-do the crossovers with new components and the TL mod, and I also replaced the tweeters with the 198's. It was definitely well worth it - the speakers sound much better (much 'fuller' sound now). I did do the leak test and I suspect some improvement can be made here also. When I push and hold, the mid-drivers pop out right away, but only seem to take between 1-2 seconds to retract back to where they stop. I also can clearly hear some air 'hiss' where the mid-drivers are when I push. Is that normal? And I still have a bit of a 'boxy' sound, rather than a nice 'tight' sound that I had before, and the reflectivity of my room may be to blame for that. I'll need too throw down a rug and maybe hang something over the sliding glass door since I have no window treatment right now.

Greg

Gardenstater

Nope. Not normal to hear air hissing. You definitely need to check all those gaskets to make sure there are no breaks. I would highly recommend @xschop semi rings (1/4" thick by 1/2" wide steel) JB-welded behind the MW's. Also, 1/8" steel square washers under the heads of the machine screws you will use help enormously. In a pinch you can use #10-32 square nuts drilled out and one edge ground / filed down to clear the surround rubber. You will not be one bit sorry you did this.

F1nut

Round washers work perfectly.

Gardenstater

They're OK but I found the square (1/8" thick!) ones allowed me to increase the surface area substantially, doing a better job of preventing the metal basket from being distorted under the heads of the screws. @JayCee mentioned a similar phenomenon observed by him as well. I have found I can get more torque on the screws without distortion and they don't need to be re-tightened. To each his own. 👌 Oh and I should add that the bass with @xschop semi-rings and the square thick washers is tighter and with more slam than I could've imagined I'd get out of these speakers. Very pleased.

rhythm

Yeah, I'll pull the MW's out this week and take a look at the gaskets. That seems to be where I'm hearing the air. If the gaskets seem OK, I suppose the air leak may be due to the MW drivers not being tight enough up against the baffle/bezel? If so, I guess the rings, or at least better fasteners, are in order.

Gardenstater

If the particle board (maybe mdf on some models?) of the baffle is not stripped out, good sound gaskets and the OEM screws should get you leak free. The mods I was mentioning get a stiffer baffle and help to couple the MW to the baffle better and are geared towards better sound, although the square washers do give a bit more even pressure since they help concentrate the force out near the flanged rim of the basket where it is most rigid. If you had stripped particle board or screws that just aren't really getting snug, the rings would definitely be the way to go then. If you do hurricane nuts, then you can't do the @xschop semi rings so I wouldn't. The semi-rings go in top and bottom in a horizontal configuration to stiffen up the wide baffle.

I should add that as a stopgap measure, if you have screws that don't snug up correctly, there are ways to fix that like some epoxy like JB-Weld in the screw hole with a toothpick applicator and then put the screw in but don't tighten fully until it cures. I would spray some dry teflon lube on the screw and let it dry beforehand so epoxy doesn't stick to screw.

rhythm

Well, I pulled out the MW drivers on each speaker and the gaskets all looked like they were in good shape. No tears, holes, creases, bends, etc. They are paper thin, but I think that's the way they are supposed to be, correct? The screw holes in the particle board all seem good and I was able to tighten everything back down really well. I was a bit surprised. After doing the leak test I thought I was going to find issues with those gaskets. I was pretty certain that I heard air leaking from the MW driver area.
I know that the stock gaskets are normally very thin, but is it possible that they've now been compressed long enough that they're a bit too thin? I mean, they seem almost like notebook paper.

While I was at it, I took some resistance measurements across the driver terminals. I removed one lead from each, and measured 6.8 ohms on the 6503's and 3.1 ohms on the 6511's. From what I was told a while back on what to expect, the 6503's are reading fine, but the measurement on the 6511's seems a bit low. (3.8 - 3.9 is what I was told was good). Am I OK with the 6511's?


Thank you,
Greg

F1nut

They're supposed to be paper thin, keeps the basket snug against the bezel. Anything that creates a cushion has a negative affect.

Gardenstater

Those 6511 are good Greg, at least with respect to DC resistance. 1 to 2 secs is way too fast for the leak test though. Is it still that fast? Did you check the crossover/binding post cup screws and gaskets?

1 Driver Type Q BL Compliance DC Resistance Fs

3 MW 6501 1.47 5.96 N 3.25 E - 3N/M 7.75 Ohms 31 Hertz
4 MW 6502 1.97 5.16 N 1.47 E - 3N/M 3.52 Ohms 44 Hertz
5 MW 6503 1.82 5.24 N 3.55 E - 3N/M 6.54 Ohms 29 Hertz
6 MW 6509 2.1 4.57 N 3.54 E - 3N/M 8.97 Ohms 30 Hertz
7 MW 6510 1.39 6.32 N 3.41 E - 3N/M 6.57 Ohms 31 Hertz
8 MW 6511 1.405 4.34 N 3.496 E - 3N/M 3.13 Ohms 29 Hertz
9 MW 6512 1.905 4.99 N 1.588 E - 3N/M 3.466 Ohms 40 Hertz

Easy Runnin

Hiss from the MW could be from the dust caps. I believe that is normally where the air will escape from.

rhythm

Thank you again for the comments and the help. The leak test seems about the same after reinstalling the MW's. One speaker seems just barely better, but still seems to retract too quickly. I will check out the crossover/binding post cup screws and gaskets this week. I had not yet done that.

Just curious on the leak test. When the drivers pop out a bit when the PR is pushed on, should they stay "fully out" for a just a bit before starting to retract back in, or is it normal for them to immediately start slowly retracting?

Thank you!

F1nut

They pop out and slowly recede immediately.

rhythm

The gaskets on the binding post cups appear to be in pretty good shape too. I attached a picture of each. There are some notched-out areas in the gaskets near the screw holes, but there was no gasket material stuck to the back of the speaker so I figure nothing had actually torn off since initial assembly. There is one little suspect area near a screw hole in the second picture, but I'm not sure it is bad enough to be causing any problem.

From what I remember, there is no gasket on the back of the spool inductor housing. So I didn't pull those to check anything for leaks. Or is there something I should check there?


Greg

rhythm

While I'm at it (posting pictures), figured I'd post something much overdue - some pics of one of my overhauled crossovers.

Greg

F1nut

The gaskets look perfect. Nice neat job on the crossovers.