Input/Output Impedance Matching

jbreezy5
jbreezy5 Posts: 1,141
in 2 Channel Audio
I’ve been perusing S’phile’s measurements section on PrimaLuna preamps (e.g. Prologue Three, Prologue Premium, and Evo 400) and noticed that there is great variation on the output impedance relative to each preamp’s individual frequency response, as well as, the frequency responses of the preamps when compared to each other.

Since the Prologue Three is no longer available it doesn’t matter; but the other two pre’s are still available and still have significant variation between them (I’m only considering the unbalanced measurements, not the balanced ones for the Evo 400).

Does anyone know the rule of thumb for how high the input impedance should be on the partnering amplifier when the output impedance of the preamp is also high?

S’phile only shows a 100kohm input impedance, or 600 ohm (torture test), but nothing in between to show the effects on frequency response.
CD Players: Sony CDP-211; Sony DVP-S9000ES; Sony UDP-X800M2 (x2); Cambridge Audio CXC

DACs: Jolida Glass FX Tube DAC III (x2); Denafrips Ares II (x2)

Streamers: ROKU (x3); Bluesound Node 2i and Node N130 w/LHY LPS // Receivers: Yamaha RX-V775BT; Yamaha RX-V777

Preamps: B&K Ref 50; B&K Ref 5 S2; Classe CP-800 MkII; Audio Research SP16L (soon)

Amps: Niles SI-275; B&K ST125.7; B&K ST125.2; Classe CA-2300; Butler Audio TDB-5150

Speakers: Boston Acoustics CR55; Focal Chorus 705v; Wharfedale Diamond 10.2; Monitor Audio Silver-1; Def Tech Mythos One (x4)/Mythos Three Center (x2)/Mythos Two pr.; Martin Logan Electromotion ESL; Legacy Audio Victoria/Silverscreen Center; Gallo Acoustics Reference 3.1; SVS SB-1000 Pro; REL HT-1003; B&W ASW610; HifiMan HE400i

Turntable: Dual 721 Direct-Drive w/Audio Technica AT-VM95e cart

Cables: Tripp-lite 14ga. PCs, Blue Jeans Cable ICs, Philips PXT1000 ICs; Kimber Kable DV30 coaxial ICs; Canare L-4E6S XLR ICs; Kimber Kable 8PR & 8TC speaker cables.
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Comments

  • mhardy6647
    mhardy6647 Posts: 33,801
    edited January 2020
    The ol' rule of thumb: input impedance of the load (e.g., amplifier) should be at least 10x the output impedance of the source (e.g., preamp).
    The goal, as I understand it, is so that the load doesn't load the source; i.e., the source is delivering voltage but is not asked to deliver any significant amount of current to the load.

    we were just kind of talking about this yesterday :)

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  • jbreezy5
    jbreezy5 Posts: 1,141
    Thanks for the explanation!

    I just joined the forum tonight, so I guess I’m tardy for the party. 😁
    CD Players: Sony CDP-211; Sony DVP-S9000ES; Sony UDP-X800M2 (x2); Cambridge Audio CXC

    DACs: Jolida Glass FX Tube DAC III (x2); Denafrips Ares II (x2)

    Streamers: ROKU (x3); Bluesound Node 2i and Node N130 w/LHY LPS // Receivers: Yamaha RX-V775BT; Yamaha RX-V777

    Preamps: B&K Ref 50; B&K Ref 5 S2; Classe CP-800 MkII; Audio Research SP16L (soon)

    Amps: Niles SI-275; B&K ST125.7; B&K ST125.2; Classe CA-2300; Butler Audio TDB-5150

    Speakers: Boston Acoustics CR55; Focal Chorus 705v; Wharfedale Diamond 10.2; Monitor Audio Silver-1; Def Tech Mythos One (x4)/Mythos Three Center (x2)/Mythos Two pr.; Martin Logan Electromotion ESL; Legacy Audio Victoria/Silverscreen Center; Gallo Acoustics Reference 3.1; SVS SB-1000 Pro; REL HT-1003; B&W ASW610; HifiMan HE400i

    Turntable: Dual 721 Direct-Drive w/Audio Technica AT-VM95e cart

    Cables: Tripp-lite 14ga. PCs, Blue Jeans Cable ICs, Philips PXT1000 ICs; Kimber Kable DV30 coaxial ICs; Canare L-4E6S XLR ICs; Kimber Kable 8PR & 8TC speaker cables.
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  • BlueFox
    BlueFox Posts: 15,251
    What is ‘S’phile’?
    Lumin X1 file player, Westminster Labs interconnect cable
    Sony XA-5400ES SACD; Pass XP-22 pre; X600.5 amps
    Magico S5 MKII Mcast Rose speakers; SPOD spikes

    Shunyata Triton v3/Typhon QR on source, Denali 2000 (2) on amps
    Shunyata Sigma XLR analog ICs, Sigma speaker cables
    Shunyata Sigma HC (2), Sigma Analog, Sigma Digital, Z Anaconda (3) power cables

    Mapleshade Samson V.3 four shelf solid maple rack, Micropoint brass footers
    Three 20 amp circuits.
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  • jbreezy5
    jbreezy5 Posts: 1,141
    :D
    CD Players: Sony CDP-211; Sony DVP-S9000ES; Sony UDP-X800M2 (x2); Cambridge Audio CXC

    DACs: Jolida Glass FX Tube DAC III (x2); Denafrips Ares II (x2)

    Streamers: ROKU (x3); Bluesound Node 2i and Node N130 w/LHY LPS // Receivers: Yamaha RX-V775BT; Yamaha RX-V777

    Preamps: B&K Ref 50; B&K Ref 5 S2; Classe CP-800 MkII; Audio Research SP16L (soon)

    Amps: Niles SI-275; B&K ST125.7; B&K ST125.2; Classe CA-2300; Butler Audio TDB-5150

    Speakers: Boston Acoustics CR55; Focal Chorus 705v; Wharfedale Diamond 10.2; Monitor Audio Silver-1; Def Tech Mythos One (x4)/Mythos Three Center (x2)/Mythos Two pr.; Martin Logan Electromotion ESL; Legacy Audio Victoria/Silverscreen Center; Gallo Acoustics Reference 3.1; SVS SB-1000 Pro; REL HT-1003; B&W ASW610; HifiMan HE400i

    Turntable: Dual 721 Direct-Drive w/Audio Technica AT-VM95e cart

    Cables: Tripp-lite 14ga. PCs, Blue Jeans Cable ICs, Philips PXT1000 ICs; Kimber Kable DV30 coaxial ICs; Canare L-4E6S XLR ICs; Kimber Kable 8PR & 8TC speaker cables.
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  • mhardy6647
    mhardy6647 Posts: 33,801
    BlueFox wrote: »
    What is ‘S’phile’?

    On the off chance that this post wasn't meant facetiously:
    https://www.stereophile.com/
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  • BlueFox
    BlueFox Posts: 15,251
    He should have written that instead of making up a nonsensical contraction.
    Lumin X1 file player, Westminster Labs interconnect cable
    Sony XA-5400ES SACD; Pass XP-22 pre; X600.5 amps
    Magico S5 MKII Mcast Rose speakers; SPOD spikes

    Shunyata Triton v3/Typhon QR on source, Denali 2000 (2) on amps
    Shunyata Sigma XLR analog ICs, Sigma speaker cables
    Shunyata Sigma HC (2), Sigma Analog, Sigma Digital, Z Anaconda (3) power cables

    Mapleshade Samson V.3 four shelf solid maple rack, Micropoint brass footers
    Three 20 amp circuits.
    · Share on FacebookShare on Twitter
  • steveinaz
    steveinaz Posts: 19,538
    Welcome!
    Source: Bluesound Node 2i - Preamp/DAC: Benchmark DAC2 DX - Amp: Parasound Halo A21 - Speakers: MartinLogan Motion 60XTi - Shop Rig: Yamaha A-S501 Integrated - Shop Spkrs: Elac Debut 2.0 B5.2
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  • joecoulson
    joecoulson Posts: 4,943
    Welcome to the forum, don't mind the dementia patient.
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