SDA difference signal test
Bubinga99
Posts: 283
Many of you probably know about this test already, so this is for those that don't. While I'm the original owner of my 2.3TL's I never did this test in the same way described in a paper I found in this forum.
You set up the test like this:
1) With the SDA cable plugged into both speakers, disconnect the black(-) lead at both speakers. (this assumes all your other wiring is correct)
2) Set your preamp in mono mode.
3) Use a noise source (the paper recommends empty FM stations but my tuner won't tune to empty stations so I dusted off my old Stereophile Test CD #2, and used track 15 (pink noise).
With the balance control in the 12 o'clock position, "in theory" you have perfect balance, and since this is a difference signal test, you should hear no output.
Come to find out, I need to set my balance control slightly off the 12 o'clock position, not quite to 1 o'clock, to get zero output. This is a really touchy setting and you *barely* move it a tiny bit either way and you get very audible output. So that's where I'll leave my balance control from here on out. I'm guessing this probably has a subtle improvement for music with heavy stereo effects, making the location of a sound to one side or the other a bit crisper.
As you move the balance full left or full right (and only the dimensional drivers are active for this test), just as the paper describes, the noise has an odd spacey quality to it, and from the listening position you can't place where the noise is coming from.
Anyway, maybe I'm easily amused, but I thought this was a very worthwhile test, if you've never done it before.
Maybe it's not all that surprising that the center detent of a balance control isn't perfectly in the center, to a fraction of a percent. It's such a touchy setting that I'd bet it's audible (for this difference test and SDA speakers anyway) even if the center detent is off by 1% (but I didn't actually open the preamp and measure it).
You set up the test like this:
1) With the SDA cable plugged into both speakers, disconnect the black(-) lead at both speakers. (this assumes all your other wiring is correct)
2) Set your preamp in mono mode.
3) Use a noise source (the paper recommends empty FM stations but my tuner won't tune to empty stations so I dusted off my old Stereophile Test CD #2, and used track 15 (pink noise).
With the balance control in the 12 o'clock position, "in theory" you have perfect balance, and since this is a difference signal test, you should hear no output.
Come to find out, I need to set my balance control slightly off the 12 o'clock position, not quite to 1 o'clock, to get zero output. This is a really touchy setting and you *barely* move it a tiny bit either way and you get very audible output. So that's where I'll leave my balance control from here on out. I'm guessing this probably has a subtle improvement for music with heavy stereo effects, making the location of a sound to one side or the other a bit crisper.
As you move the balance full left or full right (and only the dimensional drivers are active for this test), just as the paper describes, the noise has an odd spacey quality to it, and from the listening position you can't place where the noise is coming from.
Anyway, maybe I'm easily amused, but I thought this was a very worthwhile test, if you've never done it before.
Maybe it's not all that surprising that the center detent of a balance control isn't perfectly in the center, to a fraction of a percent. It's such a touchy setting that I'd bet it's audible (for this difference test and SDA speakers anyway) even if the center detent is off by 1% (but I didn't actually open the preamp and measure it).
Post edited by Bubinga99 on
Comments
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I have done this test, too, and my balance point (minimal noise) was also at 1 o'clock. I should go further and try with a different amp and also try switching left and right output to eliminate the amp and preamp.
Jim5.1 System:
TCL R613 55" 4K
Front: SRS-3.1TL
Center: CS400i
Surround: Monitor 10B
PSW10 subwoofer
Onkyo PR-SC886P Pre/Pro
NAD T955 5 channel power amplifier
Technics SL-1710 MK2 turntable
Audio-Technica AT14Sa cartridge
Parasound P3 pre-amp
Oppo BDP-103 Blu-Ray
2014 MacBook Pro 2.8 GHz
2.0 Office System:
Monitor 10A (Peerless)
Outlaw 1050 receiver
Parasound HCA-1000A power amp
MacPro -
I'd imagine your room layout, speaker positioning and room/wall reflections play a lot into that. Are either your left or right walls closer or farther than the other wall?____________________
This post is a natural product. The slight variations in spelling and grammar enhance its individual character and beauty and in no way are to be considered flaws or defects.
HT:Onkyo 805, Emotiva XPA-5, Mitsu 52" 1080p DLP / polkaudio RTi12, CSIa6, FXi3, uPro4K
2-chnl : Pio DV-46AV (SACD), Dodd ELP, Emotiva XPA-1s, XPA-2, Odyssey Khartago, LSi9, SDA-SRS 2 :cool:, SB Duet, MSB & Monarchy DACs, Yamaha PX3 TT, SAE Tuner...
Pool: Atrium 60's/45's -
What's a balance control?Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
JC approves....he told me so. (F-1 nut)
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I don't have a balance control either...been a few years......I really wish I still had it!!Pio Elete Pro 520
Panamax 5400-EX
Sunfire TGP 5
Micro Seiki DD-40 - Lyra-Dorian and Denon DL-160
PS Audio GCPH phono pre
Sunfire CG 200 X 5
Sunfire CG Sig 405 X 5
OPPO BDP-83 SE
SDA SRS 1.2TL Sonicaps and Mills
Ctr CS1000p
Sur - FX1000 x 4
SUB - SVS PB2-Plus
Workkout room:
Sony Bravia XBR- 32-Inch 1080p
Onkyo TX-DS898
GFA 555
Yamaha DVD-S1800BL/SACD
Ft - SDA 1C
Not being used:
RTi 38's -4
RT55i's - 2
RT25i's -2, using other 2 in shop
LSI 15's
CSi40
PSW 404 -
~ In search of accurate reproduction of music. Real sound is my reference and while perfection may not be attainable? If I chase it, I might just catch excellence. ~
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I was about to go through the exercise when I realized I don't have a balance control. And I didn't have a tuner hooked up either. :eek:
So I hooked up a Tuna and after figuring out how to override the auto digital tuning so that I could get static, I realized the balance controls on the Integrated weren't working. Well, not that they weren't working but that I was using the preouts on tuner to an integrated, and again preouts to my Dodd ELP. So the Balance controls on the Integrated were bypassed. I guess I'll have to hook up the integrated speaker outputs to run the test with Balance.
What would it take to make a basic passive balance control for just such an occasion?____________________
This post is a natural product. The slight variations in spelling and grammar enhance its individual character and beauty and in no way are to be considered flaws or defects.
HT:Onkyo 805, Emotiva XPA-5, Mitsu 52" 1080p DLP / polkaudio RTi12, CSIa6, FXi3, uPro4K
2-chnl : Pio DV-46AV (SACD), Dodd ELP, Emotiva XPA-1s, XPA-2, Odyssey Khartago, LSi9, SDA-SRS 2 :cool:, SB Duet, MSB & Monarchy DACs, Yamaha PX3 TT, SAE Tuner...
Pool: Atrium 60's/45's -
I like speakers that are bigger than a small refrigerator but smaller than a big refrigerator:D
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My balance is only slightly to the left on two preamps,maybe 11:30 o'clock position on the control. The SDA-SRS speakers are sitting offset on the long wall with the right speaker being closest to that corner and firing at a double window. Drove me nuts for some time swapping preamps,amps, and cables. I just live with the balance off center. I also believed it was caused by room acoustics.
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This is good info, I wonder why they didn't include it in the literature. The testing procedures are different in my manual.
Burson HA-160D > Adcom GFA-5802 > Polk SDA-SRS 1.2tl w/ Mye Sound Spikes, Mills/Sonicap XO, Larry's Rings, Dynamat Extreme, Cardas CCGR Binding Posts and Jumpers, Custom 10ga interconnect, Custom Gaskets, RDO-198 -
I have done this test, too, and my balance point (minimal noise) was also at 1 o'clock. I should go further and try with a different amp and also try switching left and right output to eliminate the amp and preamp.
Jim
Today I hooked up my SDA-1Bs to my AVR and ran the difference test using a mono white noise track from my laptop. The minimal noise point occurred with the balance knob straight up. So the issue must be with either my preamp or power amp. I will test those this weekend.
Jim5.1 System:
TCL R613 55" 4K
Front: SRS-3.1TL
Center: CS400i
Surround: Monitor 10B
PSW10 subwoofer
Onkyo PR-SC886P Pre/Pro
NAD T955 5 channel power amplifier
Technics SL-1710 MK2 turntable
Audio-Technica AT14Sa cartridge
Parasound P3 pre-amp
Oppo BDP-103 Blu-Ray
2014 MacBook Pro 2.8 GHz
2.0 Office System:
Monitor 10A (Peerless)
Outlaw 1050 receiver
Parasound HCA-1000A power amp
MacPro -
This is good info, I wonder why they didn't include it in the literature. The testing procedures are different in my manual.
Yep, mine too. They must have just thought of it too late for the printing of the manual. It probably has just as much or more imact on the SDA effect as the other things they describe in the setup of the speakers like avoiding any toe-in or toe-out (i.e. keeping the speaker faces in the same plane) -
Today I hooked up my SDA-1Bs to my AVR and ran the difference test using a mono white noise track from my laptop. The minimal noise point occurred with the balance knob straight up. So the issue must be with either my preamp or power amp. I will test those this weekend.
Jim
My best guess would be it's the balance control itself. They just aren't manufactured for such perfect center balance, and with most of the world's speakers it isn't a factor if the center point is off a little.
I don't think this test is affected by room acoustics, which is a separate type of imbalance. This is a signal path test, and you calibrate toward zero output (which eliminates room acoustics because there are no acoustics at zero output). -
Glad I did this test the other night - found one speaker wire that was loose, and the SDA cable had fallen halfway out of one of the speakers. I thought my music had sounded a little funny recently.
Zero noise point is with the balance knob straight up. This actually surprised me, careful listening before had made me think it was a little louder on the left.
EDIT: 666 posts.... I'm evil today!
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Anybody know what is actually happening here electrically? Unless I shorted something somewhere? When I tried this I got a LOUD hum/ring... I quickly shut off my amp.
Scared the ! out of me.
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I am not sure. I have done this test, but I don't recall them saying to disconnect the negative outputs from the speakers. Mine was as connected. What this test is doing is verifying the proper output from the main and dimensional speakers. I would check again but with everything hooked up normally. I assume everything plays fine under normal conditions, and you have a common ground amp. To check for common ground, with the amp off use a continuity tester or ohm meter to verify the ground, both black terminals, are common to each other. The ohms should go to zero, or the continuity tester should beep.
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"Continuity" is not good enough. "Continuity" could include significant resistance....or the continuity tester should beep.
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Anybody know what is actually happening here electrically? Unless I shorted something somewhere? When I tried this I got a LOUD hum/ring... I quickly shut off my amp.
Scared the ! out of me.
What you did created a non- common ground. Don't do it again.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
pkquat
I'm pretty sure it's a common ground amp, as per my repair guy.
Oh, yeah that multimeter; Must buy!
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At least, then I could check some of the resistance measurements & guess-timate crossover functionality.
F1nut
I'm thinking, right about now, glad there's a short protection circuit in that amp & that it's built like a tank. Come to think of it the tweeters, too, likely were saved by the relay protection.
