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Paul's Posts — 05 June 2012

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The preamp conundrum

One of our customers was upset because he loved the sound of our phono preamplifier directly into his power amplifier but then not so much when he inserted his preamp between the phono stage and his amp.

His question, naturally, was this: if my preamp sounds great by itself and the phono stage sounds great by itself why do the two not work so well together?

It’s easy to ignore the cumulative degradation of equipment where each piece in the chain adds a bit of flavor not natural to the source – but preamps may be the worst of the lot.

A preamp consists of three elements: an input switch that selects the desired input, a volume control that provides its namesake and an output amplification stage that provides the gain to drive the power amplifier.  Problem is, while the first two elements in the chain are needed the third is not and usually gets in the way.

The vast majority of sources you connect to a preamp have enough output to drive your power amplifier directly, in fact, many have more than enough.  Preamps reduce that volume level of the source only to re-amplify it back up to match what the amp wants.  This process can only cause harm to the purity of the signal.

It’s natural to want a preamplifier in the mix because we all have multiple inputs we need to select from and, at a minimum, we all need to turn down the volume.  If every manufacturer built power amps with multiple inputs and a volume control there’s be no need for any of this but we don’t.

‘Tis a shame.

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About Author

Paul McGowan is the CEO and co-founder of PS Audio Inc. a Boulder Colorado design and manufacturing company of high-end audio products and services. McGowan has been designing and building high-end products for nearly 40 years. Hobbies include skiing, music, hiking, artisan bread baking, kick boxing and cooking. He lives in Boulder Colorado with his wife Terri and his 4 sons.

(9) Readers Comments

  1. Another reason I love my PWD – multiple inputs and volume control!
    And yes, there’s a difference. And I have a good preamp (largely bypassed for my listening sessions now).

  2. Gee what you are describing is called an integrated amp and seems to have been relegated to back ground status by high end audio being defined as SEPERATES. With phono stages, the only special low level input, not needed by many users it’s surprising we don’t see its return(except for huge amps, etc.). I suspect it’s a form of tradition in the way. And, of course, the audiophile desire to mix and match multiple components.

    • Yes indeed but most integrateds represent compromise – not perfection – so they don’t count.

      • But that’s because the designs were aimed at a lower end of the market. It’s not inherent in an integrated design, especially if the phono stage is not in the amp as it probably wouldn’t be in today’s market. There’s no reason why there can’t be a high end integrated as long as you’re not looking for huge wattage.

  3. Hugeness is definitely a factor. You want your volume control and selector switch up where you can reach them, not down where people put today’s huge power amps (far bigger than even the biggest tube amps were).

    • Good point Ivan – maybe some clever folks have to get around that issue – but a move away from separates is still something I support.

  4. I’d love to take Paul’s suggestion and drive my amps directly with the PWD it would certainly clean up the cable mess! But then I’d have to reconnect the preamp for my turntable/vinyl. What a shame there’s no analog input into the PWD’s analog board. How about a mod?

  5. Paul, while you are designing a state of the art analogue section for the PWD, having a phase reversal option would just be the icing on the cake.

  6. The rain…..in Spain…..falls mainly…….in the preamplifier! :-)

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