I would like to generate line level outputs, for driving active speakers, from speaker level outputs. I have the added complication of the active speaker input being balanced. I think a 20dB attenuator might be about right normally but going from unbalanced to balanced (by grounding the -ve balanced speaker input) will also affect the attenuation. Can anyone throw some light on this for me? And also suggest some suitable resistor values for the potential divider?
How much money and time must be spent?
I put your thread topic in Google, Images, and hit reasonable looking plan. It uses a transformer, which is a universal solution to unusual problems; I would not start there for a home system (opposed to a radio network or a 13 storey studio complex). A good "balanced" input eats unbalanced fine. 10k in each leg ensures no ground-short power faults even with bridge output. The "200r" can be adjusted on test to get the required attenuation (20dB is a good guess but probably not the final answer; and as you say, details of "balanced" give 6dB uncertainty best cured by test).
I put your thread topic in Google, Images, and hit reasonable looking plan. It uses a transformer, which is a universal solution to unusual problems; I would not start there for a home system (opposed to a radio network or a 13 storey studio complex). A good "balanced" input eats unbalanced fine. 10k in each leg ensures no ground-short power faults even with bridge output. The "200r" can be adjusted on test to get the required attenuation (20dB is a good guess but probably not the final answer; and as you say, details of "balanced" give 6dB uncertainty best cured by test).
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Thanks for your help. This does seem like a good idea but is a suitable Tx easily available. I did have in mind a simple potential divider, is there much to be gained by adding the Tx? Maybe just trying a variable pot to get the correct ratio would be a good idea?
I have found that there are pro audio DI boxes which can take high impedance inputs from instruments and also loudspeaker outputs before changing them to balanced XLR connections. At least one has switchable attenuation 0, 20 or 40 dB. It could probably be easily modified for other attenuations. The drawback is that it needs a 9V battery but a power supply would be easy to wire in. That might do the job.
Thanks for the suggestion, it looks like a very good one. The 20dB steps are quite large but I might be able to trim it enough with the volume controls on the channels.
This amp has no preamp outputs, the only other possibility is HDMI from its Zone 2 output but most HDMI to analog converters only have L/R audio AFAIK. I'm trying to avoid buying a much more expensive amp just to get preamp outputs.
Something else was brought to my attention on this subject. It appears that most modern AV amps have Class D power amps, and that these amps usually work in bridge mode - in a way they are already differential outputs (the negative is not connected to ground).
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It's not hard to find one with 5.1/7.1, but they are not meant to be a preamp, so no volume controls.
Amazon.com: SKSL LPCM 7.1CH HDMI Audio Converter HDMI Digital Audio Converter Support 3 Modes for Audio Output Blue-Ray Player LPCM 4k Video: Home Audio & Theater
You've got a project either way.
Thanks for that, I'll see what is available here but I don't know if an HDMI output from an amp is fixed level or alters with the amp's settings. I'll take a look, it's a possibility for sure.
HDMI includes the original bitstream. No volume control. That has to happen after HDMI is de-multiplexed.
HDMI
Thanks for the info, it looks as though HDMI is off the list of possibilities then.
Thanks for the info, it looks as though HDMI is off the list of possibilities then.