I think something's gone wrong with my SDA crossovers
nadams
Posts: 5,877
So, after my one SDA got knocked over (see thread about cats in offtopic), I was checkign the drivers to see if they were operating. What I came to find out is confusing me.
I have original SDA 2's, which have a stereo and SDA tweeter, two stereo 6.5's, and one dimensional 6.5. What I've found, is that the SDA drivers never stop producing sound when the balance knob is turned. It was my understanding that if you turned the balance 100% to the RIGHT, the stereo drivers in the RIGHT speaker will be active, but the SDA drivers will be dead... the SDA drivers in the LEFT speaker will be active, and the stereo drivers will be dead. Then, if you turn the balance to the LEFT, the opposite is true.
What I've found is this. If I turn the balance to the RIGHT, the right speaker will be completely active - stereo and SDA drivers producing sound. However, the left side speaker will be SDA drivers only. Now, if I turn the balance to the LEFT, all drivers in the left speaker will be active - stereo and dimensional, and in the right speaker only the SDA drivers will be active.
Is this the way it's supposed to work? With SDA drivers in both channels active all the time? Or is something messed up with my crossovers, from when the previous owner rebuilt them? The amp I'm driving them with is a GFA-535, which should be compatible with these as it is common-ground.
I have original SDA 2's, which have a stereo and SDA tweeter, two stereo 6.5's, and one dimensional 6.5. What I've found, is that the SDA drivers never stop producing sound when the balance knob is turned. It was my understanding that if you turned the balance 100% to the RIGHT, the stereo drivers in the RIGHT speaker will be active, but the SDA drivers will be dead... the SDA drivers in the LEFT speaker will be active, and the stereo drivers will be dead. Then, if you turn the balance to the LEFT, the opposite is true.
What I've found is this. If I turn the balance to the RIGHT, the right speaker will be completely active - stereo and SDA drivers producing sound. However, the left side speaker will be SDA drivers only. Now, if I turn the balance to the LEFT, all drivers in the left speaker will be active - stereo and dimensional, and in the right speaker only the SDA drivers will be active.
Is this the way it's supposed to work? With SDA drivers in both channels active all the time? Or is something messed up with my crossovers, from when the previous owner rebuilt them? The amp I'm driving them with is a GFA-535, which should be compatible with these as it is common-ground.
Ludicrous gibs!
Post edited by nadams on
Comments
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Yes, that's correct assuming I'm reading your post right. The SDA drivers produce an out-of-phase canceling signal generated by the opposite non-SDA drivers. So if the volume is turned to the right (non-SDA drivers active) then the left SDA drivers will be active. I'm sure someone can explain it better but basically that's it.
edit: I believe the SDA drivers on the volume side are always active for certain frequencies but it will require someone more knowledgeable to explain.Sony 60'' SXRD 1080p
Amp = Carver AV-705THX 5-Channel
Processor = NAD T747
Panasonic BD35 Blu-Ray
Main = SDA-1C Studio with RD0s, spikes, XO rebuild, rings, I/C upgrade
Center=Polk CS10, Surround = Athena Dipoles, Sub= Boston 12HO
Music/Video Streaming = Netgear NEO550
TT = Audio Technica -
I guess what I'm getting at is that with the balance directly centered, the SDA drivers are outputting both channels of audio. I thought they were only supposed to put out the opposite channel?Ludicrous gibs!
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I just did that test with my 2Bs.When I turn the balance to the right all the drivers produce in right ch and the left ch only the 6511 produces.The opposite is true when I turn balance to the left.SDA-2BTL with custom IC
Adcom 565 monoblocks--Monarchy Audio M-10 preamp
Theta Data Basic Transport--Stello DA100 Signature DAC--Camelot Dragon Pro2 MK III
Harman Kardon T-55c TT
DH Labs Q-10 Signature Speaker Cables With Furez silver plated copper bananas
Revelation Audio Labs Prophecy Cryo-Silver Reference AES/EBU
Revelation Audio Labs Prophecy Cryo-Silver i2s digital cable
4 Furutech FP-314Ag with FI-11cu Plugs/FI-11AG IECs--- Power Cords
DH LABS REVELATIONS ICs-amps
Revelation Audio Labs Paradise cryo-silver ICs-Source to pre -
Okay, so apparently the SDA drivers are supposed to produce both channels.Ludicrous gibs!
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They are working perfectly....no worries.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 -
that's the way mine work too...PolkFest 2012, who's going>?
Vancouver, Canada Sept 30th, 2012 - Madonna concert :cheesygrin: -
I just picked up a pair of SDA-2's today and that is how they sound with the interconnect cable hooked up. With out the interconnect they sound like average speakers.HT Theater
SRS-SDA 2.3tl RDO's
Custom Center made out of a RTA15tl
Pioneer Elite SC-25 Receiver
CineNova Grande 5 channel Amp
Klipsch KA-1000-THX Sub Amp
(2)Klipsch KW-120-THX Subs
Basement System
SRS-SDA 1.2 upgraded Xover
Pioneer Elite SC-25 Receiver
ADCOM GFA 5500
ADCOM GFA 5503
Yahama P7000S Pro Audio Amp
dbx 120x-ds Sub-harmonic Synthesizer
2-JBL 4645C Subs
1-Paradigm SW2200 Sub
Klipsch Reference in wall's -
Yes, that's correct assuming I'm reading your post right. The SDA drivers produce an out-of-phase canceling signal generated by the opposite non-SDA drivers. So if the volume is turned to the right (non-SDA drivers active) then the left SDA drivers will be active. I'm sure someone can explain it better but basically that's it.
edit: I believe the SDA drivers on the volume side are always active for certain frequencies but it will require someone more knowledgeable to explain.
You're right. If you push the balance all the way toward the right speaker, you will observe that BOTH the dimensional and stereo drivers will produce the right channel information. The dimensional driver(s) gets the full bass signal from that side, but the frequencies above 100-150Hz are attenuated. On the SDA 2.3TL, it's roughly 6dB attenuated at the crossover point. The large inductor on the dimensional low pass section of the crossover accomplishes this feat.
From a stereo signal perspective, this inductor looks like a series inductor, attenuating higher frequencies. From an SDA signal perspective it looks like a shunt inductor attenuating the bass signal.
This was done to maximize the bass producing potential of both the dimensional and stereo drivers, without a bass canceling affect from the SDA signal from the opposite speaker.
There are some differences in implementation if you have dimensional tweeters too like the early SDA's, but the basic principle is the same.
DFS
