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Thread: What's the purpose of a preamp?

  1. #1
    Join Date: May 2015

    Location: Greece

    Posts: 249
    I'm Panos.

    Default What's the purpose of a preamp?

    Since most -if not all- sources (e.g. DAC, CD player, phono stage) have an output voltage, that's capable of driving a power amp, then what's the purpose of an active preamp?

    Doesn't a passive attenuator seem like a simpler, less intrusive and 'cleaner' solution of controlling volume, instead of an active preamp?

    In my particular case, I have a Croft Micro 25RSLS (line stage only preamp), a pair of Croft Series7R monoblocks and Harbeth speakers. Should I consider replacing my preamp with a passive attenuator, such as the Goldpoint SA4M?

    Thanks,
    Panos
    System1: Lenco L75 with custom plinth, SLAT, sph bearing, SG4 external power supply + Alfred Bokrand AB-309 tonearm + Denon DL103R (aluminum body) + Well Tempered 12" tonearm clone + Denon DL103R (wooden body), ASR Mini Basis Exclusive HV, Marantz CD6005, LAB12 DAC1 SE+, Hattor BIG passive + active pre, Lab12 Suono power amp, Falcon LS3/5a Gold Badge, LAB12 Gordian, Belden 8428, Black Cat Red Level Triode, LAB12 Knack MkII

    System 2: Roksan Xerxes original (HiFi Inspire plinth) with Maxon ReMax motor + Audiomods Series6 + Ortofon Cadenza Black microridge retipped, ASR Mini Basis Exclusive, Marantz CD6003, Croft Micro25R + Series7R monoblocks (110W/ea), Harbeth SHL5 Plus 40th Anniv.

    System 3: Marantz CD6003, Croft SuperMicroII ('R' spec by Croft, Tesla E83CC in phono)+ Series7, Snell Type EII (with bypass caps, new internal wiring, WBT nextgen 0703Cu), Mark Grant HDX1, Atlas Hyper 3.0

  2. #2
    Join Date: Oct 2012

    Location: The Black Country

    Posts: 6,088
    I'm Alan.

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    As well as providing some gain (not always necessary as you have pointed out), an active pre will usually provide better drive conditions to the power amp and an easier load to the source components.
    I have specifically avoided using the word matching as that isn't accurate. As source components give only a voltage output, not a power output, the best loading is a reasonably high impedance, for my mind 50 kohms or above.

    For the output a low impedance is better to drive whatever capacitance is presented by the interconnects and/or power amp.
    An active pre can be considered as an impedance changing device, high on input and low on output.

    A passive pre is always limited in how high and how low the impedance transform is.

  3. #3
    Join Date: May 2015

    Location: Greece

    Posts: 249
    I'm Panos.

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    My idea is to use just a passive attenuator, the least intrusive device in the signal path. Apologies for my lack of technical knowledge, but isn’t the passive attenuator different from a passive preamp?
    System1: Lenco L75 with custom plinth, SLAT, sph bearing, SG4 external power supply + Alfred Bokrand AB-309 tonearm + Denon DL103R (aluminum body) + Well Tempered 12" tonearm clone + Denon DL103R (wooden body), ASR Mini Basis Exclusive HV, Marantz CD6005, LAB12 DAC1 SE+, Hattor BIG passive + active pre, Lab12 Suono power amp, Falcon LS3/5a Gold Badge, LAB12 Gordian, Belden 8428, Black Cat Red Level Triode, LAB12 Knack MkII

    System 2: Roksan Xerxes original (HiFi Inspire plinth) with Maxon ReMax motor + Audiomods Series6 + Ortofon Cadenza Black microridge retipped, ASR Mini Basis Exclusive, Marantz CD6003, Croft Micro25R + Series7R monoblocks (110W/ea), Harbeth SHL5 Plus 40th Anniv.

    System 3: Marantz CD6003, Croft SuperMicroII ('R' spec by Croft, Tesla E83CC in phono)+ Series7, Snell Type EII (with bypass caps, new internal wiring, WBT nextgen 0703Cu), Mark Grant HDX1, Atlas Hyper 3.0

  4. #4
    Join Date: May 2016

    Location: Much Wenlock

    Posts: 1,520
    I'm Gary.

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    Quote Originally Posted by pankon View Post
    My idea is to use just a passive attenuator, the least intrusive device in the signal path. Apologies for my lack of technical knowledge, but isn’t the passive attenuator different from a passive preamp?
    A passive pre-amp is an attenuator.

    Gary
    It is easier to seek forgiveness than to ask permission

    Rules are meant for the obedience of fools and the guidance of wise men

  5. #5
    Join Date: Aug 2009

    Location: Staffordshire, England

    Posts: 37,737
    I'm Martin.

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    Quote Originally Posted by pankon View Post
    Since most -if not all- sources (e.g. DAC, CD player, phono stage) have an output voltage, that's capable of driving a power amp, then what's the purpose of an active preamp?

    Doesn't a passive attenuator seem like a simpler, less intrusive and 'cleaner' solution of controlling volume, instead of an active preamp?

    In my particular case, I have a Croft Micro 25RSLS (line stage only preamp), a pair of Croft Series7R monoblocks and Harbeth speakers. Should I consider replacing my preamp with a passive attenuator, such as the Goldpoint SA4M?

    Thanks,
    Panos
    I'd avoid the Goldpoint, it's expensive and not that good.
    Current Lash Up:

    TEAC VRDS 701T > Sony TAE1000ESD > Krell KSA50S > JM Labs Focal Electra 926.

  6. #6
    Join Date: Jun 2014

    Location: Chorley Lancs

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    I'm Steve.

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    As my power amp has a volume control, I manage with just this. Changing interconnects from phono amp to cd player is a bit of a faff though. Would having a pre amp be a good thing sonically, or would it just be more 'stuff' in the audio chain?
    I just dropped in, to see what condition my condition was in

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  7. #7
    Join Date: Apr 2012

    Location: Southall, West London

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    I'm Geoff.

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    No point adding more gear if you don't need to as long as you're happy using your system that way.

    If there's room in the power amp case, you could even investigate fitting a remote control pot.

  8. #8
    Join Date: Apr 2012

    Location: London

    Posts: 685
    I'm James.

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    This is an old chestnut. Firebottle has explained the electronic purpose admirably which shows the limitations of the more usual passive attenuators, the fact remains that many audio buffs never the less like the presentation an active pre gives. The reasons for this are divisive and inconclusive and deeply system dependent.

    I can only suggest you try and hear for yourself. If ever system synergy played a part it is in how this component interfaces with the rest of your system.

    Me? I'm on the fence. Currently my pre is lying idle, but with many of my other amps in the system it goes straight back in!

    Sent from my BLA-L09 using Tapatalk

  9. #9
    Join Date: May 2015

    Location: Greece

    Posts: 249
    I'm Panos.

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    Martin,
    Someone suggested the Goldpoint as a very good dual mono passive attenuator. Obviously you do not agree, which is fine. Can you, or anybody else, recommend any better dual mono alternatives, that do not create any artifacts on the sound?
    Thanks
    System1: Lenco L75 with custom plinth, SLAT, sph bearing, SG4 external power supply + Alfred Bokrand AB-309 tonearm + Denon DL103R (aluminum body) + Well Tempered 12" tonearm clone + Denon DL103R (wooden body), ASR Mini Basis Exclusive HV, Marantz CD6005, LAB12 DAC1 SE+, Hattor BIG passive + active pre, Lab12 Suono power amp, Falcon LS3/5a Gold Badge, LAB12 Gordian, Belden 8428, Black Cat Red Level Triode, LAB12 Knack MkII

    System 2: Roksan Xerxes original (HiFi Inspire plinth) with Maxon ReMax motor + Audiomods Series6 + Ortofon Cadenza Black microridge retipped, ASR Mini Basis Exclusive, Marantz CD6003, Croft Micro25R + Series7R monoblocks (110W/ea), Harbeth SHL5 Plus 40th Anniv.

    System 3: Marantz CD6003, Croft SuperMicroII ('R' spec by Croft, Tesla E83CC in phono)+ Series7, Snell Type EII (with bypass caps, new internal wiring, WBT nextgen 0703Cu), Mark Grant HDX1, Atlas Hyper 3.0

  10. #10
    Join Date: Mar 2008

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    I'm inthescottishmafia.

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