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#1
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Preserving zero feedback
Would a passive high-pass filter between a preamp and amp preserve zero feedback, e.g., a fully balanced Marchand passive high-pass filter between an Ayre KX-5/20 and VX-5/20? Obviously the balanced cables that run between the preamp and amp preserve zero feedback.
I was up until 6 this morning reading about the virtues of Ayre's zero feedback design and reviews of the VX-5/20. I'd like to high-pass my KEF Ref 1s at 80 Hz, but not at the expense of the Ayre sound I so enjoy. |
#2
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Filters
I am not familiar with the Marchand filter, but a filter has no feedback per se.
I do think that active filters (like a Bryston or JL Audio crossover) can often out-perform passive designs. Are you certain of the high-pass frequency (80 Hz)?
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Main - Roon on Synology/Sonos Port/SoTM Neo endpoints; Chord Qutest, Bryston BP-17 cubed with phono option; EAT C-sharp with Ortofon Bronze MM, Bryston cubed Amplifier; Revel F126Be on custom Atocha stands; interconnects by WireWorld, furniture by Atocha Design 'Phones Audeze LCD-3, Bryston BHA-1; Office: Sonos/Roon; OPPO HA-1, Naim NAP100 and PSB Mini-C. Media Room:, Samsung QLED QN90 series, Sonos, OPPO 205, ATI N-core driving KEF LS-50's with REL subs; furniture by Glassisimo; Kids - U-turn for vinyl, Sonos Play5; Summer Shack - Sonos, vintage Pioneer, Dynaudio Special 40's. |
#3
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The use of feedback or in your case zero feedback is accomplished within each individual component and is not related to the interaction of amp, preamp and speakers.
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System: ML:5206,5302 Serafino's Nordost Lumin U1 RM15 |
#4
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Yes it would.
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Main System: Amati Futura Mains Amati Homage VOX Center, Proac Response 1sc Rears, Three MC2301's for L,C,R MC 602 for the rears C 1100, MX 151, MCD 1100, MR 80 Nottingham Dais with Wave Mechanic Sumiko Palo Santos Presentation SurfacePro 3, RPi 4, ROON, WW Starlight Platinum USB, Schiit Yggdrasil, Benchmark DAC3 HGC MX 151, OppO BDP-95, JVC RS-500 DILA projector, 106" diagonal Stewart Luxus Screenwall Deluxe with Studiotek 130 G3 material. Lake House: Ohm F, MC 275V, C2300, MR 77, Rega P3 OnDeck: McIntosh MAC 4300v |
#5
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I've now talked with Gary at Ayre and Phil Marchand, both of whom think a Marchand fully balanced passive high-pass filter could be inserted between the Ayre KX-5/20 preamp and VX-5/20 amp with no harm to the Ayre sound. So I've ordered the building of a 80 Hz 24 dB/octave filter. Its arrival is probably some weeks away at which time I'll reset the low-pass to the subs to match the high-pass crossover and slope.
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#6
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Usually, zero feedback refers to zero global negative feedback, so there's typically local or nested feedback networks in a ZNF amplifier. Use of negative feedback in a preamp is far less problematic, because the preamp will have its output impedance fixed by a resistor, and thus will never be exposed to a load impedance that creates hf stability problems. That said, use of op-amp based filter networks really isn't desirable in a high-end system, so a passive filter is probably the best choice.
Last edited by Art Vandelay; 04-03-2019 at 07:27 AM. |
#7
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I hope so. I received a notice this morning that the Marchand fully balanced passive filter I ordered is being shipped. It's a fixed 80 Hz with 24 dB/octave slope filter I plan to insert it between my KX-5/20 and VX-5/20. I'll adjust the Velodyne SMS-1 bass manager to low-pass to the subs at 80 Hz rather than the 40 Hz I'm currently using and rerun its acoustic room correction with the new configuration.
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#8
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Quote:
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Industry Affiliation - Ayre CEO |
#9
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For the uninitiated, there is definitely merit in the approach, particularly in terms of transient behavior, slew rate, and unconditional stability. This adds up to an amplifier that gets you closer to a live listening experience. |
#10
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Thanks for the encouragement, Ryan.
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