re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System
Hello Wayne,
It's great of you to write this article on such an interesting subject.
You might want to add to this what the impact is of using an AVR with a built-in equalization system such as Audyssey. I've thought about this a little in terms of my Denon, even though I use external amplification only for the powered sub. It strikes me that the effects come from two areas that affect the point at which clipping might occur: the AVR may have different level settings for each speaker, and the static equalization may boost certain frequencies up to 9dB.
In Part 7, where you discuss measuring the maximum voltage from the AVR, the setting of the speaker trim might matter, especially if it was very negative. For purposes of the experiment, it might be best to set it to at least 0dB, or perhaps to its maximum positive value.
In Part 9, where you discuss how much headroom to allow, it would be nice to allow enough headroom for the maximum boost that the equalization system might introduce, e.g., 9dB for Audyssey. This would ensure that no clipping would occur from the voltage peak. The speaker trim might come into play here, too. Obviously if one has verified that clipping does not occur with the trims set to 0dB, and if the AVRs calibration sets a higher trim to achieve reference levels, clipping might now appear. Related to this, adjusting the amplifier's gain to the highest level that avoids clipping at maximum signal affects how the AVRs volume setting is calibrated for reference levels. At this highest possible amplifier gain, you might have a situation where the AVR cannot set the speaker trim low enough to correctly calibrate the volume level.
I don't think a system like Audyssey's DynEQ affects the discussion significantly. As you are recommending doing these procedures with the AVR's volume set to maximum, DynEQ should be providing no boost to the signal. As it might even be providing a reduction in the sub range, if it thinks the levels are above reference, it would probably be best that it be disabled.
I also think any source level adjustment in the AVR does not affect the discussion. Assuming the user calibrates the analog source inputs to give the same volume as the digital inputs, one would hope that these will not drive the levels past the 0dBFS that was used when adjusting the gain.
I think that exhausts my suggestions.
Thanks for writing this,
Bill
Hello Wayne,
It's great of you to write this article on such an interesting subject.
You might want to add to this what the impact is of using an AVR with a built-in equalization system such as Audyssey. I've thought about this a little in terms of my Denon, even though I use external amplification only for the powered sub. It strikes me that the effects come from two areas that affect the point at which clipping might occur: the AVR may have different level settings for each speaker, and the static equalization may boost certain frequencies up to 9dB.
In Part 7, where you discuss measuring the maximum voltage from the AVR, the setting of the speaker trim might matter, especially if it was very negative. For purposes of the experiment, it might be best to set it to at least 0dB, or perhaps to its maximum positive value.
In Part 9, where you discuss how much headroom to allow, it would be nice to allow enough headroom for the maximum boost that the equalization system might introduce, e.g., 9dB for Audyssey. This would ensure that no clipping would occur from the voltage peak. The speaker trim might come into play here, too. Obviously if one has verified that clipping does not occur with the trims set to 0dB, and if the AVRs calibration sets a higher trim to achieve reference levels, clipping might now appear. Related to this, adjusting the amplifier's gain to the highest level that avoids clipping at maximum signal affects how the AVRs volume setting is calibrated for reference levels. At this highest possible amplifier gain, you might have a situation where the AVR cannot set the speaker trim low enough to correctly calibrate the volume level.
I don't think a system like Audyssey's DynEQ affects the discussion significantly. As you are recommending doing these procedures with the AVR's volume set to maximum, DynEQ should be providing no boost to the signal. As it might even be providing a reduction in the sub range, if it thinks the levels are above reference, it would probably be best that it be disabled.
I also think any source level adjustment in the AVR does not affect the discussion. Assuming the user calibrates the analog source inputs to give the same volume as the digital inputs, one would hope that these will not drive the levels past the 0dBFS that was used when adjusting the gain.
I think that exhausts my suggestions.
Thanks for writing this,
Bill
