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- May 15, 2020
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Dear all,
I wondered whether anyone could give me some pointers on the following "design". I have been trying to muddle through "Basic Electronics for Absolute Beginners"-type books along side various posts here and on the wider internet, but have no idea how well I am actually comprehending things. My sincere apologies for the technically illiterate diagramme: "resistor", "battery" and "switch" were the only symbols I recall from school (25+ years ago). The XLR In/Out circle mid-left of the diagramme is just a placeholder to remind me what I'm doing.
The aim is to have a single switch to change between two "modes". Mode A takes a mono phono input, and sends that same input to three mono phono outputs. Mode B takes Left and Right XLR inputs, and sends the Left XLR to one phono output, the Right XLR to one phono output, and the Left+Right mono sum to the third phono output.
The three outputs would be the phono inputs of three active sub-woofers. The stereo XLR inputs would be from a D/A converter, and the mono input would be from an A/V receiver.
The main questions I had were:
* if I actually connected this (including errors), what damage would I risk? I'm guessing that line-level signals are not going to be hazardous to my health provided I take reasonable care.
* I found the stereo to mono summation circuit on the internet (from Rane). I understand the concept (I think), but I have absolutely no idea how the actual designer would have calculated the resistor values
* I'm assuming that because there are lots of y-splitters available for both domestic/phono recording/XLR cables from audio shops, the current drop from the splittings (the circles with the crosses) is not an issue so long as the potential differences remain the same - how wrong is my assumption?
* I'm assuming that because you can buy XLR-phono adaptors, there's no need for a step-down transformer from 4V RMS XLR to 2V RMS phono?
* What are the search terms I need to find the contraption which allows a single mechanical toggle to change the 6 electronic switches?
The background, for those who are curious, is that I'm finally in a position to get a pair of powered sub-woofers, which have both speaker-level (1xSpeakOn socket) and line-level (2x phono sockets, so they sum to mono) connexions, as well as picking up a speaker+AV receiver package with its own powered sub-woofer, which has a single line-level connexion ("LFE", which I gather is just a single standard phono).
My D/A converter has both balanced XLR and phono outputs, the latter of which I use to connect to my power amplifier. From reading (mostly on this site), it seems like speaker-level connexions are to be avoided. It also seems like multiple mono sub-woofers are recommended. However, I would like to *try* stereo subwoofers based on a friend's recommendation. It occurred to me I could have my cake and eat it if I managed to build (a proper version of) the above design. If the low-pass content was mono, then I'd have 3 mono subwoofers, and if the low-pass content was left or right channel, I'd have 2 subwoofers.
Now, it could be that is the most foolish idea ever, but I'm also keen to try it as part of teaching myself a bit of basic electronics; if it sounds awful, I can always just use the two subwoofers in mono from the high-level connexion for music and the other from the AV receiver for films.
Many thanks to all the people who make this site so enjoyable,
Sasha.
I wondered whether anyone could give me some pointers on the following "design". I have been trying to muddle through "Basic Electronics for Absolute Beginners"-type books along side various posts here and on the wider internet, but have no idea how well I am actually comprehending things. My sincere apologies for the technically illiterate diagramme: "resistor", "battery" and "switch" were the only symbols I recall from school (25+ years ago). The XLR In/Out circle mid-left of the diagramme is just a placeholder to remind me what I'm doing.
The aim is to have a single switch to change between two "modes". Mode A takes a mono phono input, and sends that same input to three mono phono outputs. Mode B takes Left and Right XLR inputs, and sends the Left XLR to one phono output, the Right XLR to one phono output, and the Left+Right mono sum to the third phono output.
The three outputs would be the phono inputs of three active sub-woofers. The stereo XLR inputs would be from a D/A converter, and the mono input would be from an A/V receiver.
The main questions I had were:
* if I actually connected this (including errors), what damage would I risk? I'm guessing that line-level signals are not going to be hazardous to my health provided I take reasonable care.
* I found the stereo to mono summation circuit on the internet (from Rane). I understand the concept (I think), but I have absolutely no idea how the actual designer would have calculated the resistor values
* I'm assuming that because there are lots of y-splitters available for both domestic/phono recording/XLR cables from audio shops, the current drop from the splittings (the circles with the crosses) is not an issue so long as the potential differences remain the same - how wrong is my assumption?
* I'm assuming that because you can buy XLR-phono adaptors, there's no need for a step-down transformer from 4V RMS XLR to 2V RMS phono?
* What are the search terms I need to find the contraption which allows a single mechanical toggle to change the 6 electronic switches?
The background, for those who are curious, is that I'm finally in a position to get a pair of powered sub-woofers, which have both speaker-level (1xSpeakOn socket) and line-level (2x phono sockets, so they sum to mono) connexions, as well as picking up a speaker+AV receiver package with its own powered sub-woofer, which has a single line-level connexion ("LFE", which I gather is just a single standard phono).
My D/A converter has both balanced XLR and phono outputs, the latter of which I use to connect to my power amplifier. From reading (mostly on this site), it seems like speaker-level connexions are to be avoided. It also seems like multiple mono sub-woofers are recommended. However, I would like to *try* stereo subwoofers based on a friend's recommendation. It occurred to me I could have my cake and eat it if I managed to build (a proper version of) the above design. If the low-pass content was mono, then I'd have 3 mono subwoofers, and if the low-pass content was left or right channel, I'd have 2 subwoofers.
Now, it could be that is the most foolish idea ever, but I'm also keen to try it as part of teaching myself a bit of basic electronics; if it sounds awful, I can always just use the two subwoofers in mono from the high-level connexion for music and the other from the AV receiver for films.
Many thanks to all the people who make this site so enjoyable,
Sasha.
