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Post by dimitryz on Jan 1, 2022 13:58:35 GMT -5
Happy New Year!
I am in the process of working with an experienced DIYer to build an external remote controlled switch. He will use it as an A/B unit and I will use it for switching phase, or polarity on the XLR output.
I used to experiment with phase reversal in the 90s and it seemed to make a difference on some vintage jazz records, if memory serves.
My question has to do with my setup that uses a pair of subs that are connected from XSP-1 RCA outs. I am not using the XSP's bass management, just the crossovers on the subs. I plan to use a pair of RCAs on the polarity switch to run from the hot pins on the XLR outputs. This would cause one side of the XLR connector to see the input of the amp only (XPA-2 in mono strap) and other to see the amp and the sub (10KOhm) leading to an impedance imbalance.
Perhaps those who know can comment if this XLR imbalance is anything to be concerned with and if I need to add a buffer for the RCAs. Hopefully, KeithL can advise.
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Post by 405x5 on Jan 1, 2022 16:20:27 GMT -5
Happy New Year! I am in the process of working with an experienced DIYer to build an external remote controlled switch. He will use it as an A/B unit and I will use it for switching phase, or polarity on the XLR output. I used to experiment with phase reversal in the 90s and it seemed to make a difference on some vintage jazz records, if memory serves. My question has to do with my setup that uses a pair of subs that are connected from XSP-1 RCA outs. I am not using the XSP's bass management, just the crossovers on the subs. I plan to use a pair of RCAs on the polarity switch to run from the hot pins on the XLR outputs. This would cause one side of the XLR connector to see the input of the amp only (XPA-2 in mono strap) and other to see the amp and the sub (10KOhm) leading to an impedance imbalance. Perhaps those who know can comment if this XLR imbalance is anything to be concerned with and if I need to add a buffer for the RCAs. Hopefully, @keithl can advise. I’ll keep you in my prayers while enjoying my DEAD QUIET RCA connections……A prime example of overthinking gone haywire |
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Post by dimitryz on Jan 1, 2022 17:24:13 GMT -5
Thank you for ^^your^^ prayers!
XLR connections are great for a polarity switching, since only a passive relay is needed and can easily be made remote controlled.
Since balanced connections generally see equal input impedance for both phases, I am not sure if a 33K/7K difference will be detrimental.
Do you know the answer?
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Post by donh50 on Jan 2, 2022 19:36:21 GMT -5
A look at the XSP-1 manual on the website did not show a spec for output impedance. Assuming a typical 100 ohms or so, you should be fine, though will lose some common-mode rejection (a don't-care since you are going single-ended anyway). You will have to match gains, natch, if that matters in this usage.
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Post by dimitryz on Jan 2, 2022 22:51:26 GMT -5
A look at the XSP-1 manual on the website did not show a spec for output impedance. Assuming a typical 100 ohms or so, you should be fine, though will lose some common-mode rejection (a don't-care since you are going single-ended anyway). You will have to match gains, natch, if that matters in this usage. Thank you for your response. I am going to adjust the subs for sure. However, they currently run from XSP's own RCAs, so maybe small adjustments. I was mostly concerned with balanced connection performance with the amps themselves. And it seems to be minor to none. |
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KeithL
Administrator 
Posts: 10,274
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Post by KeithL on Jan 3, 2022 10:26:34 GMT -5
The output impedance of the XSP-1 is actually around 1k Ohms... and it can cheerfully drive loads as low as a few kOhms. (The difference between a 10k load and a 20k load would cause a very slight difference in output level - of a small fraction of a dB - but won't affect anything else.)
I would also note something else - since you may end up experimenting with various devices. On all of our products that have balanced inputs and outputs they are in fact true balanced connections - with both lines driven. However, with other products, you might occasionally find gear where only one of the two input or output lines in the balanced connector is active.
A look at the XSP-1 manual on the website did not show a spec for output impedance. Assuming a typical 100 ohms or so, you should be fine, though will lose some common-mode rejection (a don't-care since you are going single-ended anyway). You will have to match gains, natch, if that matters in this usage. Thank you for your response. I am going to adjust the subs for sure. However, they currently run from XSP's own RCAs, so maybe small adjustments. I was mostly concerned with balanced connection performance with the amps themselves. And it seems to be minor to none. |
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Post by dimitryz on Jan 3, 2022 14:37:16 GMT -5
Thank you, Keith!
Can you also clarify if RCA outs are buffered separately from the corresponding XLR outs or are they are wired in parallel with the hot pin?
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Post by dimitryz on Jan 7, 2022 18:47:06 GMT -5
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