SDA question/problem

vmaxer

I have a set of SDA SRS 1.2tl's...and am looking for help to correct an issue:

If I hook the speakers up without the interconnect and set the levels using the preamp's calibration function, the speakers outputs are the same on my SPL meter. I then connect the interconnect and the right one runs about 3db louder than the left one?? I can't seem to figure this one out. I swapped the crossovers between the speakers and it had no effect??

Any ideas??

kcoc321

Did you follow the "SDA balancing" procedure? I think it is posted in the Vintage speaker/ SDA thread.

I seem to remember several ppl reporting that the "balanced" location turned out to be 11oc or so..I don't remember exactly...So I think you have no worries...but check it out.

http://www.polkaudio.com/forums/showthread.php?t=85837

vmaxer

kcoc321 wrote: »

Did you follow the "SDA balancing" procedure? I think it is posted in the Vintage speaker/ SDA thread.

I seem to remember several ppl reporting that the "balanced" location turned out to be 11oc or so..I don't remember exactly...So I think you have no worries...but check it out.

http://www.polkaudio.com/forums/showthread.php?t=85837

Thanks,

I can do some of these tests, but not the ones that require a balance knob....don't have one:(

Additionally, if I unhook the interconnect cable, all eight drivers still function I just talked to Ken at Polk Audio and have some things to test out... But welcome all the advise I can get as these have about whipped me!!

nooshinjohn

If all 8 are functioning with the interconnect removed, someone may have bypassed the SDA functions... I would begin by looking at both crossovers and the terminal plates to make certain no mods have been done.

vmaxer

I have completed a couple quick tests...had to take a time out and mow the yard...

If I remove the neg cables from both speakers and plug the interconnect in all eight drivers work, the volume is very low, but they all work??

vmaxer

Lasareath wrote: »

Are you sure all 8 drivers functioning per speaker or are 4 playing and you just think sound is coming from the other 4?

No doubt, I have pulled all drivers out and know which ones are being powered..

DarqueKnight

With the interconnect cable disconnected, the dimensional drivers will still move due to two reasons:

1. Air coupling within the cabinet (which is also how motion is transferred to the passive radiator).

2. There will still be a small amount of signal reaching the dimensional drivers, even if you remove the 7 other drivers, passive radiator, and tweeters so that there is no air coupling.

If you look at the crossover schematic, you will see that the dimensional drivers are not electrically disconnected from the crossover, and therefore the input signal, when the interconnect cable is disconnected. However, the dimensional drivers should never play as loud as the stereo drivers.

Bear in mind that speaker crossover circuits are more like traffic conductors rather than "brick wall" barriers. Even with the interconnect cable removed, there are certain frequencies that will make both the stereo and dimensional drivers move, just as there are certain frequencies that will make both the bass and midrange drivers move and again, the same with the tweeter and midrange drivers.

With my preamp's balance control set on "0", my right 1.2TL plays a 1 kHz test signal 1 dB louder (dB-C) than the left. With a 60 Hz test signal, the right 1.2TL is 1.5 dB louder than the left. I don't know how much of the disparity is due to electronics and how much is due to room interaction. The left speaker is 3 feet from a side wall and the right speaker is 15 feet from a side wall.

vmaxer wrote: »

I swapped the crossovers between the speakers and it had no effect??

This seems to indicate a channel imbalance in either your amp or preamp. Do you have another amp and preamp that you can swap out?

vmaxer

DarqueKnight,

Thanks a lot for your reply, I do feel a lot better. I have had a long day at work and just don't feel like testing tonight. Hopefully tomorrow will be better and I will try a few things.

Over the weekend I did connect an old Onkyo TX-SV535 receiver, that has a balance control!!! First, it suprised me, the sound wasn't half bad.... Anyway, the speakers did function as they should per the quick tests - SDA functions procedure. The best balance was with the knob set to just before 11 o'clock.

I do have one question, when you state:

"With my preamp's balance control set on "0", my right 1.2TL plays a 1 kHz test signal 1 dB louder (dB-C) than the left. With a 60 Hz test signal, the right 1.2TL is 1.5 dB louder than the left. I don't know how much of the disparity is due to electronics and how much is due to room interaction. The left speaker is 3 feet from a side wall and the right speaker is 15 feet from a side wall."

Are you unhooking one speaker or moving in front of each one to test them...since you say your balance knob is on 0??

Thanks again!!

DarqueKnight

I left both speakers connected. Measurements were taken standing 2 feet in front of each speaker.

nooshinjohn

"With my preamp's balance control set on "0", my right 1.2TL plays a 1 kHz test signal 1 dB louder (dB-C) than the left. With a 60 Hz test signal, the right 1.2TL is 1.5 dB louder than the left. I don't know how much of the disparity is due to electronics and how much is due to room interaction. The left speaker is 3 feet from a side wall and the right speaker is 15 feet from a side wall."



room acoustics would play a big factor in that result...

vmaxer

Well, I've not been to do much lately, bot my daughter and I have bee sick a couple of times, she's just getting over the flu....

Quick question, when I am installing the crossover back onto the mount does it matter how the inductor is connected?? 2 wires, both black, same size connectors??

Thanks!!

thsmith

vmaxer wrote: »

Well, I've not been to do much lately, bot my daughter and I have bee sick a couple of times, she's just getting over the flu....

Quick question, when I am installing the crossover back onto the mount does it matter how the inductor is connected?? 2 wires, both black, same size connectors??

Thanks!!

Not sure about your SDAs but my 1Cs have the wire labed P on circuit board going to left connector and one labled R going to the right.

Hopefully someone with more experience and knowledge will comment.

vmaxer

My boards are also labeled with a P and R, when you say right and left, what perspective, from top looking down with the connections at the top??

ben62670

I think the P and R connectors go to the large inductor.

vmaxer

ben62670 wrote: »

I think the P and R connectors go to the large inductor.

They do, but does it matter which way they are connected??

thsmith

vmaxer wrote: »

My boards are also labeled with a P and R, when you say right and left, what perspective, from top looking down with the connections at the top??

yes, thats the way my 1Cs are

DarqueKnight

vmaxer wrote: »

They do, but does it matter which way they are connected??

No. The inductor is just a plain coil of wire.

vmaxer

DarqueKnight wrote: »

No. The inductor is just a plain coil of wire.

Many thanks DarqueKnight...Care to look at thie thread as it has a few of us puzzled???

http://www.polkaudio.com/forums/showthread.php?t=89204


I need to know if my speakers are wired correctly or not...Is the thin or wide terminal on the tweeters positive??

DarqueKnight

The wide terminal is negative and should have the white wire connected to it.

In some 1.2TL's, both wires going to the tweeters are white, but the positive terminal wire will have a colored band near the ends.

vmaxer

DarqueKnight wrote: »

The wide terminal is negative and should have the white wire connected to it.

In some 1.2TL's, both wires going to the tweeters are white, but the positive terminal wire will have a colored band near the ends.

Thanks again, but I am getting a bit confused...Is the wiring connector correct?? Doesn't make sense to me....See photo, all white wires are on positive??

DarqueKnight

I don't think Polk meant for their customers to ever look inside their speakers. One can easily get confused if all the "family secrets" aren't known.:)

If you compare the crossover schematics for the 1.2 and 1.2TL, you will see a lot of circuit layout similarities. One big difference is the polarity arrangement for the tweeter array.

The polarity markings in your picture are the same as those of the 1.2, so I suspect that you have a 1.2 board with 1.2TL parts. Polk had a practice of using up old parts from a previous model.

vmaxer

I sometimes wish I hadn't "looked inside"...But then, I have learned a lot, and upgraded my crossovers and binding posts!

DarqueKnight

I sometimes wish I had never gotten into audio...but it's too late to turn back now.:)

vmaxer

DarqueKnight wrote: »

I sometimes wish I had never gotten into audio...but it's too late to turn back now.:)

If you ever decide you want out, I will come and pick up your equipment and care for it for as long as you want:o

I have very reasonable fees........ :eek:

RichCanDo

vmaxer wrote: »

I have a set of SDA SRS 1.2tl's...and am looking for help to correct an issue:

If I hook the speakers up without the interconnect and set the levels using the preamp's calibration function, the speakers outputs are the same on my SPL meter. I then connect the interconnect and the right one runs about 3db louder than the left one?? I can't seem to figure this one out. I swapped the crossovers between the speakers and it had no effect??

Any ideas??

In reply to your original question, my right channel also is louder than the left. I have my balance control just below the 12 o'clock position. This seems inherent with the model as others have noted the same thing. I thought it may be room acoustics, but have had my TL's in 2 different homes with same result. I now have both speakers 6'-8" from the side walls and 6'-8" apart on the long wall of a rectangular room. Still, right speaker plays louder than the left, hence the balance control setting not dead on at 12 o'clock. I set the balance by ear and not yet used my sound level meter.

F1nut

All 3 sets of my SDA's are perfectly balanced. The likely cause, if not room related, is your pre amp.

RichCanDo

F1nut wrote: »

All 3 sets of my SDA's are perfectly balanced. The likely cause, if not room related, is your pre amp.

I have measured my pre amp outputs in the past and they are equal to 4 digits on a voltmeter. I have also swapped the right and left preamp outputs and the right speaker was still louder than the left. Maybe it has something to do with different values of xover components due to age or tolerance of the parts. I'll see what the volume levels are like after I upgrade my xovers with matched parts.

F1nut

Hmmmm, have you tried swapping the crossovers and/or the drivers?

RichCanDo

No, I have not tried swapping xovers or drivers. I just had my drivers out and I weighed each one. A +/- .4 ounce difference in the weight of 4 drivers from the same cabinet, same model # drivers. (almost a 1/2 ounce difference) Weight difference can be several things such as magnet weights, etc. But if higher weight is from more coils of wire used on a driver, this could make one louder than another. Normally speakers or motors would be wound with the same number of turns of wire. Possibly more turns were used on a speaker to keep the impedance within specs.

Less turns of wire would make one speaker louder than another due to less resistance and a lower impedance.