Post by boomzilla on Nov 9, 2019 20:06:52 GMT -5
I went to visit my audio amigo, Russell, today. While there I commented on the excellent integration between his satellite speakers and his two subs. Asking Russell his secrets on why the subs blended so well, he offered the following:
1. "Never run the satellites full-range and then try to "blend in" the subs beneath them." This creates inevitable phase issues at the crossover point because the natural roll-off of the speakers is almost never matched to the roll-off of the subwoofers. In other words, the slopes for roll-off on speakers and subs must be slope-matched. Either a symmetrical even-order or odd-order slope must be used, or at least even-even or odd-odd slope matches between the speakers and subs. Russell's choice, for example, is to use a 18 dB / octave roll-off for the subs and a 6 dB / octave for the main speakers. Other acceptable slope matches would be:
6/6 - 12/12 - 18/18 - 24/24 or matched, yet non-symmetrical pairs such as 6/18 - 18/6 - 12/24 -24/12
The 6/6 - 6/18 - 18/6 and 18/18 slopes are preferable to the others because the phase of the sub and satellites can be matched. With any of the 12 and 24 combinations, the polarities of the sub and satellites must be reversed in order to achieve smooth response in the crossover region.
2. "Never use any current commercial subwoofer." Russell contends that ALL commercial subwoofers are designed with over-damped cabinets. This provides "thump" for home theater applications, but the uneven, highly-peaked frequency response is anathema to natural-sounding music. A bigger box is needed than is supplied by any mass-market vendor.
3. "Never use any self-powered subwoofer." Russell contends that the plate amplifiers used on commercial subs are serious junk. They have high distortion, poor control, and cheap power supplies. Russell prefers a "passive" subwoofer in a large box powered by either an Electron-Kinetics Eagle 7a amplifier, a Crown DC-300a amplifier, or a big Krell amplifier. He contends that the quality and control of a high-quality amplifier is clearly audible when compared to a plate amp.
4. "Never use standard "speaker wire" for a subwoofer." Russell contends that multi-strand wires are appropriate for main speakers (in fact, the more strands, the better), but that better subwoofer results are always available by wiring with single-conductor "Romex."
5. "Never use a line-level electronic crossover." Russell contends that active electronics are never the way to go for crossovers. He prefers a "passive" crossover utilizing capacitors, coils, and resistors only rather than any unit with active amplification. Russell uses a modified Dahlquist DQ-1LP passive crossover from the '80s that goes between the preamplifier output and the power amplifiers' inputs. Russell is particularly dismissive of audio-video processors and receivers that he claims are stuffed with multi-function op-amp chips (a guarantor of poor quality sound).
6. "Never use summed monophonic bass." Summed bass, says Russell, is an abomination foisted on consumers by the THX movie standard, and will never sound as natural as stereo bass for music listening.
7. (one I almost forgot) - "Never use too low a crossover frequency." Russell uses 100 Hz. for ALL his different satellite speakers. He chose that frequency because it is at least 2x the -3dB point for the satellite speakers. If you move the crossover frequency lower, several bad things happen - the satellites don't receive the benefit of lower IM distortion because they still have too much woofer-cone movement. Also, the "natural" roll-off of the satellite speakers will alter the intended crossover slope, and there will be a "hole in the bass" because of the mismatched frequency slopes. Finally, the phasing (time alignment) of the satellites and subwoofers will cause blur.
8. (another I almost forgot) - "Never use too large a subwoofer driver." Doing so, Russell contends, will prevent the speed necessary (on some drivers) and add to the "cone cry" of the subs, making them easier to locate with the ears. If you need greater volume, use more drivers. Russell uses two (LARGE) boxes, each with two 10" drivers. I'd guess that Russell's sub boxes are 24" tall by 36" wide by about 18" deep (just eyeballing the things). They are placed close to the back wall (behind the speakers) and are raised from the floor by about 15" tall, open-steel stands.
Now whether or not you agree with Russell's reasoning, I can assure you that his results are among the very best I've heard, anywhere, anytime.
Boomzilla
1. "Never run the satellites full-range and then try to "blend in" the subs beneath them." This creates inevitable phase issues at the crossover point because the natural roll-off of the speakers is almost never matched to the roll-off of the subwoofers. In other words, the slopes for roll-off on speakers and subs must be slope-matched. Either a symmetrical even-order or odd-order slope must be used, or at least even-even or odd-odd slope matches between the speakers and subs. Russell's choice, for example, is to use a 18 dB / octave roll-off for the subs and a 6 dB / octave for the main speakers. Other acceptable slope matches would be:
6/6 - 12/12 - 18/18 - 24/24 or matched, yet non-symmetrical pairs such as 6/18 - 18/6 - 12/24 -24/12
The 6/6 - 6/18 - 18/6 and 18/18 slopes are preferable to the others because the phase of the sub and satellites can be matched. With any of the 12 and 24 combinations, the polarities of the sub and satellites must be reversed in order to achieve smooth response in the crossover region.
2. "Never use any current commercial subwoofer." Russell contends that ALL commercial subwoofers are designed with over-damped cabinets. This provides "thump" for home theater applications, but the uneven, highly-peaked frequency response is anathema to natural-sounding music. A bigger box is needed than is supplied by any mass-market vendor.
3. "Never use any self-powered subwoofer." Russell contends that the plate amplifiers used on commercial subs are serious junk. They have high distortion, poor control, and cheap power supplies. Russell prefers a "passive" subwoofer in a large box powered by either an Electron-Kinetics Eagle 7a amplifier, a Crown DC-300a amplifier, or a big Krell amplifier. He contends that the quality and control of a high-quality amplifier is clearly audible when compared to a plate amp.
4. "Never use standard "speaker wire" for a subwoofer." Russell contends that multi-strand wires are appropriate for main speakers (in fact, the more strands, the better), but that better subwoofer results are always available by wiring with single-conductor "Romex."
5. "Never use a line-level electronic crossover." Russell contends that active electronics are never the way to go for crossovers. He prefers a "passive" crossover utilizing capacitors, coils, and resistors only rather than any unit with active amplification. Russell uses a modified Dahlquist DQ-1LP passive crossover from the '80s that goes between the preamplifier output and the power amplifiers' inputs. Russell is particularly dismissive of audio-video processors and receivers that he claims are stuffed with multi-function op-amp chips (a guarantor of poor quality sound).
6. "Never use summed monophonic bass." Summed bass, says Russell, is an abomination foisted on consumers by the THX movie standard, and will never sound as natural as stereo bass for music listening.
7. (one I almost forgot) - "Never use too low a crossover frequency." Russell uses 100 Hz. for ALL his different satellite speakers. He chose that frequency because it is at least 2x the -3dB point for the satellite speakers. If you move the crossover frequency lower, several bad things happen - the satellites don't receive the benefit of lower IM distortion because they still have too much woofer-cone movement. Also, the "natural" roll-off of the satellite speakers will alter the intended crossover slope, and there will be a "hole in the bass" because of the mismatched frequency slopes. Finally, the phasing (time alignment) of the satellites and subwoofers will cause blur.
8. (another I almost forgot) - "Never use too large a subwoofer driver." Doing so, Russell contends, will prevent the speed necessary (on some drivers) and add to the "cone cry" of the subs, making them easier to locate with the ears. If you need greater volume, use more drivers. Russell uses two (LARGE) boxes, each with two 10" drivers. I'd guess that Russell's sub boxes are 24" tall by 36" wide by about 18" deep (just eyeballing the things). They are placed close to the back wall (behind the speakers) and are raised from the floor by about 15" tall, open-steel stands.
Now whether or not you agree with Russell's reasoning, I can assure you that his results are among the very best I've heard, anywhere, anytime.
Boomzilla
