SDA-1C Imaging troubles

nooshinjohn

hi guys...
with all the excitement of getting these in my home and reconditioning them, I have noticed that the 'sweet spot' for listening to them appears to occur to the right side of center. When sitting between the speakers most of a performance comes from the left side. My receiver's balance is properly set, both speakers are wired properly and are in correct phase. my interconnect was replaced by and rca jack on both speaker and is connected. I can hear a difference in sound quality when it is disconnected... any ideas?

Does somebody have a copy of the owners manual for these that I could get a copy of?

thanks guys for the help:cool:

danger boy

just for **** and giggles.. swap the two speakers around... left on right, right on left.. and take another listen.. it's rare, but sometimes people have ended up with two lefts, or two rights.

also sounds like one of your mid driver ain't working. it's tough to tell because even with the interconnect cable unplugged.. they still appear to be working. to be sure. take each driver out one at a time. and connect it to speaker wire with a low volume music.. and see if each one is working properly.

good luck though.

nooshinjohn

tried that and got no sda effect at all

comfortablycurt

Did you move the chair that was in front of one of the speakers? That could contribute to that a little bit...just an idea though. That probably isn't the problem, and I'm sure you already tried it.

ben62670

It's your room. You need to move closer to your speakers. If your speakers are 6 feet apart your head should be no more than 8 feet back. Also you should have 3 feet on either side minimum. Room treatments can help a lot. You want to add panels at the first reflection. I've tried to put 10lbs in a 5lb bag. It doesn't work:(

dudeinaroom

sorry for the thread jack, you guys would hate me. mine are 4" off the side walls and about 12" off the back wall. They are about 10' apart, and my listening position is about 10' back. room gain picks up below 40Hz, so my little sda2s do just fine in the low bass region, and imaging is till nice and tight.

dudeinaroom

what other gear are you running with your sdas

Marty913

Try everything else suggested and if you still want the manual I have one. It's actually an addendum to the 1B manual with technical spec changes. The placement options are in the 1B manual which I also can provide. Email me if you need them scanned and sent. I don't check messages that much but I'm always on email.

Marty

Face

comfortablycurt wrote: »

Did you move the chair that was in front of one of the speakers? That could contribute to that a little bit...just an idea though. That probably isn't the problem, and I'm sure you already tried it.

comfortablycurt

Face wrote: »

Yeah...that's the chair I was talking about. If that thing is still there...get it out! That is ruining your imaging. Your sound is getting fired right into the side of that chair, and being absorbed by it.

Conradicles

You can also get the user manual @ http://www.polksda.com/

inspiredsports

I know most people don't drop $90 on something rarely used, but if you really want to eliminate guesswork, a db meter is irreplaceable. I've had great results with this one:

http://www.amazon.com/exec/obidos/ASIN/B000EWY67W/websitementcommu

A calibrated Test CD with left and right test, dog barking, phase tests, pink noise, tones, etc. is also helpful. I got one of these free in 1990 when I subscribed to "Stereophile" magazine and use it every time I buy, tweak or modify a speaker setup:

http://www.amazon.com/exec/obidos/ASIN/B0000049XN/websitementcommu

You can then hold the meter right in front of each driver in the system and know for sure what it is contributing to the mix. Once you prove the signal sources are equal, you can move on to room treatments.

nooshinjohn

i did try moving the chair...that was my first thought, and did not have any effect. The imaging coming from the left speaker is stronger than the sound from the right. Both speakers are 5 inches from the back wall and 39" from the wall on the sides with 5'6" in between. My seating area is 10 feet back from the speaker... I have tried sitting closer to the speakers when listening and this did not help. Balance is set correctly between speakers and the settings on the yamaha are exactly the same for both channels. All drivers are functioning. When comparing left/right with test tones there is an audible difference in output between left and right even when my ear is placed within inches of each speaker. When the I/C is disconnected from the speakers there is no change in output. They are being listened to in pure direct mode two channel operation.
hope the added info helps... I was thinking there may be a phase issue with internal wiring on the right side. could this be possible?

ben62670

There is something wrong if you hear no difference with the IC cable disconnected.

nooshinjohn

by no change in output I am refering to volume only. I do here a difference in sound quality...

the left side also seems to has a slightly deeper tone than the right, could there be a variance in the crossovers?

nooshinjohn

ok... I have figured out that the left has about twice the output of the right side... at this point I am leaning toward either power problem or a crossover problem...

ben62670

If you have a multi meter set it for ohms. With all cables disconnected you should read about 1.3 ohms from the pin hole on the IC socket to the ground. That number is a rough one. I do not have my book with me. Just as long as both are the same you are good. Also you can check from the positive to the negative, and the pin hole to the positive. Let us know the numbers you come up with.
Thanks
Ben

nooshinjohn

i do not have an ohm meter... but will get one tommorow

Ron Temple

I've gone through a similar problem. Thought it was an amp, thought it was my room, sent amp off, couldn't correct room. It was a dimensional driver that was failing. Not noticeable through any surface detection initially, but I finally put my hand in front of it and noticed it wasn't moving near as much air. I was losing about 5 dbs on the right. Replaced the driver and all was good. Recently, I'm noticing that my right is 1-3dbs down again. I'm pretty sure that it's the seals that are leaking. thsmith did the mortite treatment and it fixed his. I'm going to do that next. Anyway, I'm guessing you've got a driver that's gone or about to go.

nooshinjohn

sounds logical... I will do the reseal on all the drivers as well

nooshinjohn

I checked the speakers travel and hold times by pressing on the passive radiator and found that the right does not stay extended as long as left, and that neither speaker seems to hold the extended position very long... also there seems to be a metalic clanking sound from the left passive

treitz3

nooshinjohn wrote: »

I checked the speakers travel and hold times by pressing on the passive radiator and found that the right does not stay extended as long as left, and that neither speaker seems to hold the extended position very long... also there seems to be a metalic clanking sound from the left passive

That right there is a big problem. Replace that driver!

dudeinaroom

if you have another set of speakers hook them up in there place. If both of the other speakers play at the same volume (left to right) then the problem is the SDAs. If not I would check interconnects between components. swap them out with another set and see if the problem remains.next step would be components( receiver, pre, amp and sources.

nooshinjohn

ok here are the readings... for the right speaker:
4ohm between the positive and negative terminals
2.5 ohm negative terminal to center pin
3.5ohm positive terminal to center pin
0 ohm center pin to shield

LEFT SPEAKER:
4ohm between positive and negative terminals
2.6 ohm negative terminal to center pin
3.5 ohm positive terminal to center pin
2.6 ohm center pin to shield

I am assuming that my trouble lies within the center pin on the right speaker or within the sda driver wiring. I will be taking apart the drivers and using mortite to seal them I will also inspect the wiring...:(:confused:

inspiredsports

Maybe, but let the experts weigh in. If an SDA effect driver is shorted, I'm not sure what that does to impedance.

dudeinaroom

your rca connection is grounding out some where in the signal path. look for a crossed wire, dripped solder, also check for a lose wire hitting the back of your passive radiator It may have came off one of the drivers

nooshinjohn

this thread has been superceded by

http://www.polkaudio.com/forums/showthread.php?t=77750

Thank you for all the help with this one... unfortunately it created a new one... receiver has been checked and it IS a common ground design...
lol
thanks for the help