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Post by Leonard on Jan 28, 2018 12:16:15 GMT -5
I'm looking into acquiring a pair of XPA-1 Gen 2 monoblocks and I have some questions about its absolute polarity. First, if I use its RCA input, does the amp invert polarity? Second, if I use its balanced XLR input, does the amp invert polarity? Thanks!  |
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Post by Gary Cook on Jan 28, 2018 15:33:52 GMT -5
No and No
Cheers
Gary
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Post by Leonard on Jan 30, 2018 12:54:12 GMT -5
Thanks for the info. Appreciate it. |
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Post by doc1963 on Jan 30, 2018 14:52:28 GMT -5
Thanks for the info. Appreciate it. Actually, I believe the answers to your questions are (1) no and (2) yes. The unbalanced input maintains absolute signal polarity (phase), but the balanced input does not. The modern standard XLR pin configuration is 1 = Ground, 2 = Hot, 3 = Cold. Most electronics manufactures adhere to this standard. However, I believe Emotiva, instead, seems to use the old "legacy" configuration where pins 2 (Hot) and 3 (Cold) are reversed. I also believe this to be true of all Emotiva products all the way back to Gen 1. The recent Stereophile measurements of the XPA-2 Gen 3 (found HERE) confirms this. In addition, here's a quote of Keith L's response to a member over at AVS (found in post #820 of THIS thread)... " AUG 24, 2017 | 05:25PM CDT
Keith Levkoff replied:
Tom,
I checked with engineering and there seems to be some slight confusion about wiring and circuit conventions (and what they mean by how things are connected).
In short, overall, from input to output, the XPA Gen3 amp preserves absolute phase when using the unbalanced inputs and inverts absolute phase when using the balanced inputs......
Keith" To be fair... In a "stereo" setup being driven by a pair of XPA-1's, this likely will not matter because both speakers are "in-phase" to each other. However, if you are using multiple amps (in addition to the XPA-1's) driving multiple speakers in a "multi-channel" system, then you should compensate for any discrepancies. The easiest solution for this would be just to simply swap "positive" and "negative" at the affected speaker terminals. |
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Post by Leonard on Jan 31, 2018 12:54:59 GMT -5
Thanks for the info. Appreciate it. Actually, I believe the answers to your questions are (1) no and (2) yes. The unbalanced input maintains absolute signal polarity (phase), but the balanced input does not. The modern standard XLR pin configuration is 1 = Ground, 2 = Hot, 3 = Cold. Most electronics manufactures adhere to this standard. However, I believe Emotiva, instead, seems to use the old "legacy" configuration where pins 2 (Hot) and 3 (Cold) are reversed. I also believe this to be true of all Emotiva products all the way back to Gen 1. The recent Stereophile measurements of the XPA-2 Gen 3 (found HERE) confirms this. In addition, here's a quote of Keith L's response to a member over at AVS (found in post #820 of THIS thread)... " AUG 24, 2017 | 05:25PM CDT
Keith Levkoff replied:
Tom,
I checked with engineering and there seems to be some slight confusion about wiring and circuit conventions (and what they mean by how things are connected).
In short, overall, from input to output, the XPA Gen3 amp preserves absolute phase when using the unbalanced inputs and inverts absolute phase when using the balanced inputs......
Keith" To be fair... In a "stereo" setup being driven by a pair of XPA-1's, this likely will not matter because both speakers are "in-phase" to each other. However, if you are using multiple amps (in addition to the XPA-1's) driving multiple speakers in a "multi-channel" system, then you should compensate for any discrepancies. The easiest solution for this would be just to simply swap "positive" and "negative" at the affected speaker terminals. Thanks for the detailed info, doc1963 . It is much appreciated. I was recently at a friend's home theater. His preamp-processor is balanced and he's got XLR cables running to his amps. An XPA-3 Gen 2 powers the front L, C, R speakers and an XPA-5 Gen 2 powers the side L & R, rear L, C & R speakers. That day, he swapped the XPA-3 for a Gen 3 model he borrowed from his dealer. The Bluray of Terminator 2 was played and immediately all midbass tones were gone. It sounded as if there was a big chunk of frequencies missing between the subwoofer and the floorstanders. All his speakers are wired with banana plugs, so he simply reversed the phase of the front L, C, R speakers and problem solved. The Gen 3 sounds awesome. A few movies later, he removed it and put back his Gen 2. Of course, he didn't forget to restore the phase of the three speakers he had earlier reversed. Since this is firsthand experience that the Gen 3's XLR inputs invert absolute phase, it stands to reason that the Gen 2's XLR inputs don't - at least for the XPA-3 model. Do you suppose this goes for all Gen 2 models? Including the XPA-1 I am asking about? |
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Post by doc1963 on Jan 31, 2018 14:44:38 GMT -5
Thanks for the detailed info, doc1963 . It is much appreciated. I was recently at a friend's home theater. His preamp-processor is balanced and he's got XLR cables running to his amps. An XPA-3 Gen 2 powers the front L, C, R speakers and an XPA-5 Gen 2 powers the side L & R, rear L, C & R speakers. That day, he swapped the XPA-3 for a Gen 3 model he borrowed from his dealer. The Bluray of Terminator 2 was played and immediately all midbass tones were gone. It sounded as if there was a big chunk of frequencies missing between the subwoofer and the floorstanders. All his speakers are wired with banana plugs, so he simply reversed the phase of the front L, C, R speakers and problem solved. The Gen 3 sounds awesome. A few movies later, he removed it and put back his Gen 2. Of course, he didn't forget to restore the phase of the three speakers he had earlier reversed. Since this is firsthand experience that the Gen 3's XLR inputs invert absolute phase, it stands to reason that the Gen 2's XLR inputs don't - at least for the XPA-3 model. Do you suppose this goes for all Gen 2 models? Including the XPA-1 I am asking about? Since Emotiva uses balanced inputs/outputs throughout all of their "X Series" and "Reference" products, I would assume that it's a safe bet that their choice of XLR pinout configuration has remained consistent over their various "legacy" generations in order to maintain coherency between their own products. I have seen your question asked many times over the years, but I've seen no definitive " direct" answer from Emotiva (other than what I posted above). The general consensus derived from those older questions, and resulting answers, has most often been that pins 2 & 3 are apparently reversed. However, there's no doubt that what you've described above would be a direct result of the mains being "out of phase" with the subwoofer. I'm just not so sure that Emotiva would have intentionally made a change in the XLR pinouts only between Gen2 and Gen3. The results you've heard seems obvious, but it wouldn't make much sense for Emotiva to have done this... |
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Post by leonski on Mar 3, 2018 21:48:09 GMT -5
Good troubleshooting:
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Post by lhracing on Mar 3, 2018 22:47:42 GMT -5
This is interesting information. When using the balanced inputs of multiple Emotiva amps is the resulting phase at the speaker terminals all the same? (I don't care if they are inverted or not as long as they are all the same) The reason that I ask is because I have a 2 channel system using 2 Gen2 XPA-1's and a Gen3 XPA-4 in a Tri-amped configuration using an active crossover. The XPA-1's drive the woofers and the XPA-4 drives the mids and tweeters.
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Post by leonski on Mar 4, 2018 14:11:11 GMT -5
What active crossover do you use?
Something like Marchand which is $$$ but very good isn't as flexible, IMO, as some of the products from MiniDSP.
In the Mini System, you can change ANY drivers polarity and even, depending on plug-in used, have as many as 10 Parametric EQ setting per INPUT and the same for EACH output.
With choices from 6db/octave to 48db/octave, this would be enough to drive me Nuts.
The current sweet-spot might be the 2x4HD which has adjustible sensitivity and will work with FIR filters and have all the other features you'd like.
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