CRS+ placement

quadzilla

I've been mucking about with my (new to me) CRS+, and really loving the SDA effect. There's a however in there. I was thinking that something in my set up, most likely my amp from various comments in various threads on here, was causing a some bass bloat. Well, finally figured it out tonight after buying another amp and figuring out that that wasn't it. It basically comes down to I ended up moving the speakers so that the front of the speak is ~58 inches from the wall. The speakers are 36" from the side wall. Is this considered a normal placement? Or is it just the room, which is 8x15x18 and opens into another area about 8x8x35? Would bass traps be likely to help with this and let me move the speakers a bit closer to the front wall than a 1/3 of the way into the room? I'm sitting nearly in the breakfast area to get back a bit further than the distance between the speakers.

SDA effect is really nice though.

Thanks for any recommendations that don't involve me contorting myself and/or bending various parts of my body into impossible positions in order to achieve some bizarre sexual act. :biggrin:

F1nut

Your room is almost square, you can't get much worse when it comes to audio. Anyway, are they on the original stands? Are they on the long or short wall? Are the stands spiked? What is between the stand and the speaker? What's the amp? What cables are you using? What is the source?

Mr Glide

Hi,

I am in the process of getting Polk Monitor series speakers (70,30,cs2) and FxiA4s. I am looking at following 2 Polk subs to replace my 10" Velodyne sub.

Polk PSW125
Polk PSW505

The monitor series page on Polk site recommends PSW125.

However, PSW505 (vintage line, was top of the line in its series) is much more powerful and going for about half in price compare to PSW125.

http://www.polkaudio.com/homeaudio/specs/recent/psw505/
http://www.polkaudio.com/homeaudio/psw/index.php?s=psw125

Which sub would you recommend? Will PSW505 cause any mismatch with rest of these speakers?

Please advise.
Thanks.

quadzilla

Granted, the room is almost square, but the 7x7 opening should effectively couple this room to the other area as far as bass is concerned, yes?

Original stands, spiked per the manual.

On short wall. Long wall isn't much of an option.

Stands have a thin foam tape across the top.

Currently using a NAD 270 for the amp and a PAS-3 with tone controls bypassed.

Cables are Signal Cable Silver Reference.

Happens with all sources. Tried a Pioneer Elite 45A multi-disc player, CT-W59 cassette, as well as my Empire 208/Shelter 501/Aural Thrills phono stage.

F1nut

but the 7x7 opening should effectively couple this room to the other area as far as bass is concerned, yes?

I do not believe it would.

The long wall is always the better choice when it comes to SDA's. Just saying.

Instead of the foam tape, try some thicker rubber 'bumpers."

Have you tried them at 5 or 6 inches off the back wall?

quadzilla

I'll try the bumpers. I'm guessing the soft-ish vinyl ones from home depot should work?

I did get them 8 inches off the wall. That didn't seem to work, but I didn't go as low as 5-6. I thought bass response got stronger as you got closer to the wall?

Thanks for the suggestions.

F1nut

Yeah, those will work. Although, I'm not really sure they will help with your problem, they are better than a thin foam strip.

You are correct, the bass gets stronger, but it may tighten it up for you.

Is the PAS-3 is good working order? Do you have a different pre amp to try?

I'm trying to think of anything that might help. I mean, I've heard a lot of CRS+'s, but never with the bass issue you are having.

Have you checked for air leakage...make sure all the screws are tight. Also, if you have the pin/blade version with the plug in the back of the cabinet where the original blade/blade connector was, it may be leaking air and need to be sealed from the inside.

One other thing to check, pull the PR's out and check that rear hasn't separated from the front.

quadzilla

OK, thanks. At about 8" the problem was getting worse so I stopped going closer, then got better out to about 14", then got worse again until I got out to nearly 5 ft. It really seems like they're sitting in a node

I haven't checked for leaks yet, but did try tightening everything up. I was also going to order some of the Armacell tape that people have been talking about lately. I'll also pull the PR out and double check that.

If all this fails, I'll probably move to rebuilding the xovers. It's on the agenda anyway, and the bass improved greatly on the last set I rebuilt and had in that room.

In the end, if this is where the speakers end up needing to be, I can live with it. It just struck me as weird having them 1/3rd of the way out into the room. And then there's always room treatments, which I expect that this room needs anyway, due to the aforementioned squareness.

Loud & Clear

You could also add a sub and cross the speakers over at roughly 80 Hz, or whatever frequency removes the bloat. Equalizer?

quadzilla

Thanks, but he point is kind of not having a sub. Besides, I'd have to crossover closer to 160 Hz. Really don't want an EQ either. Going for a more retro vibe, with a 60's PAS-3 pre, a phono stage built from a design done in the 50s, TT is from the early 60's, etc.

Anywho... I'm leaning towards a leak right now. The PR test says 2 seconds at most for the drivers to return to their original positions with the PR fully depressed. No leaks/tears/holes in any of the surrounds.

Sadly, the depot of home by work was out of armacell. Have to get over to another one this weekend and pick some up. Everything else seems tight.

Failing that, I'll try the xover rebuild since I'll be doing it anyway, sooner or later.

quadzilla

Armacell tape from home depot did seem to help. Also found that at some point, someone had removed one of the drivers and not got it screwed back in right, or else the front baffle was just giving out from age. When I pulled the driver, the particle board was disintegrating around two screw holes. Filled the holes with wood putty, spread some wood glue over the whole mess, and redrilled the holes. Now I'm getting tight seals and the bass is improved, which let me move the speakers back closer to the wall and farther apart, giving a better SDA effect.

A side benefit was that I found that whoever installed the RDO-194s in these did not bother with scraping the red lacquer off the back of the positive terminal. I did that, and the detail is much improved now.

newrival

The typical SDA rules of thumb in regards to relative distance to the back wall do not apply with CRS's since their PR is rear-firing. As you noted, the CRS's are the exception to the rule wher you want to get them farther into the room to get appropriate bass response, clarity, and detail. I had mine right around 18"-20" from the back wall. Bass was exaggerated as I brought the closer to the wall, but bloated. As with any speaker placement, your room will have its own effect on the sound, but trust your ears. I'm with you on bringing them out into the listening space.

Additionally, "The long wall is always the better choice when it comes to SDA's" is an over-generalization as I'm sure you can tell, and not always true. the ideal setup for some situations is along the shorter wall due to reflections, etc. What F1 may be referring to is that it's important to adhere to the SDA rule of keeping at least 3' between the speakers and a sidewall. so the if you sit 8' away from the vertical plane of the speakers, you'd need an 18' wide wall which is not often the short wall in the average owner's listening room. Is the long wall the best wall? not always. The case is that it ends up being the only way to meet the dimensional requirements of the SDA's. (this is all just generally speaking in no specific dimensional terms, as far as what is better or best, etc.)

DollarDave

quadzilla wrote: »

Armacell tape from home depot did seem to help. Also found that at some point, someone had removed one of the drivers and not got it screwed back in right, or else the front baffle was just giving out from age. When I pulled the driver, the particle board was disintegrating around two screw holes. Filled the holes with wood putty, spread some wood glue over the whole mess, and redrilled the holes. Now I'm getting tight seals and the bass is improved, which let me move the speakers back closer to the wall and farther apart, giving a better SDA effect.

A side benefit was that I found that whoever installed the RDO-194s in these did not bother with scraping the red lacquer off the back of the positive terminal. I did that, and the detail is much improved now.

Interesting, the RDO's had been put in there just before I got them. The guy I bought the speakers from was a fan of the SL-2000's (understatement of the day). He advocated all sorts of crazy things and eventually got banned...At any rate, he must have pulled a driver at some point also. I was always going to open them up and upgrade the cross-overs and all that, but I never did. I'm glad you are getting them tweaked up. Do the drivers mount with screws, or t-nuts and threaded bolts?

F1nut

The typical SDA rules of thumb in regards to relative distance to the back wall do not apply with CRS's since their PR is rear-firing. As you noted, the CRS's are the exception to the rule wher you want to get them farther into the room to get appropriate bass response, clarity, and detail.

Hogwash. I've run my 4.1TL's in various rooms in two different homes at 5 to 6 inches off the back wall with exceptional bass response.

quadzilla

@newrival

I'm currently at 5.5 ft between the speakers, 19.25 inches off the back wall, and 3 ft off the side wall. I'm thinking I might need to come at least 2-3 inches further off the back wall, as it seems like just a bit of bloat might have creeped back in. But at least they aren't almost 5 ft off the back wall any more.

@DaveMuell: It's just screws, which is what made is so easy for the baffle to come apart. It looks like about the cheapest particle board (not MDF) I've seen. As in "chunks of wood glued together" board. I'm also debating on whether at some point I want to try fashioning new boxes for these made a little more solidly. It'd be an exact duplicate as far as dimentions, just made out of MDF and maybe finished with a nice veneer. I think a black baffle and a birds eye maple veneer would look pretty sharp.

I also want to make it clear that I'm not in any way saying this was your fault or something you should have known about. I'm quite happy with the speakers. Thrilled even. And they're paying huge dividends for each little tweak. I can't wait to get time to rebuild the xovers.

newrival

F1nut wrote: »

Hogwash. I've run my 4.1TL's in various rooms in two different homes at 5 to 6 inches off the back wall with exceptional bass response.

Awesome, glad you like it. It Doesn't mean I have to. I'm just offering another perspective.

I've done equal amounts of placement experimentation and came out with a different result. Of course you're going to get more bass response as you bring them closer to the back wall due to bass loading, but the loading characteristics of the CRS+'s were far different than that of my SRS's, 2b's, or 3.1tl's. In my opinion it sounded less defined. I preferred the sound of them being into the room further.z

quadzilla

4.1tl? Is that the CRS with the TL treatment?

DollarDave

quadzilla wrote: »

4.1tl? Is that the CRS with the TL treatment?

Yes.

http://www.polkaudio.com/forums/showthread.php?t=40577

I'll buy the RDO-194's from you if you decide to do the 4.1..

newrival

you have to make sure you have the pin/blade CRS+'s from after DEC. 1988.

quadzilla

After looking through that thread, it appears that the differentiating factor is whether mine use a MW6510 for the stereo driver and a MW6511 for the SDA driver. Mine do, and my xovers are laid out exactly as in F1's pics, so I should be good.

@Dave: Man, you know I have to. Even without the xover upgrade, the one and only complaint I have about these is that sometimes the vocals do seem a bit pushed back. I thought it was my imagination, but I feel better knowing I'm not the only one to have this impression. I might sell those 194s back to you. Or I might stick them in my 10Bs That's also kind of tempting. But I'll probably end up selling them, as I don't really use the 10Bs any more, especially since upgrading the xovers in the LS50s, which now have the bass of the 10Bs, but with a much more refined top end and midrange.

newrival

quadzilla wrote: »

After looking through that thread, it appears that the differentiating factor is whether mine use a MW6510 for the stereo driver and a MW6511 for the SDA driver. Mine do, and my xovers are laid out exactly as in F1's pics, so I should be good.

Rad, go for it! I ended up selling mine before I did the upgrade, but it seems to be a fairly nice upgrade and well received.

quadzilla

Ordered xover parts for the TL mod today. Missed the parts guys, so have to call them first thing in the morning.

On a side note, I think I figured out what happened to the speaker cut out. Looks like the original owner replaced the MW6503s with MW6510s according to the schematic I was just looking at, and munged it when **** the driver back in.