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The era of the preamp is over

Paul's Posts — 01 August 2012

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The era of the preamp is over

As you probably are aware TAS (the magazine) is publishing a major review on the PerfectWave system in their September issue that starts mailing out today.  Since part of the core idea behind the PerfectWave system is using the DAC as a preamp connected directly to your power amplifier, I thought it might be instructive to start another mini series of posts on DACS as preamps.

We’re all interested in music and its reproduction and the preamplifier has been central to most of us for most of the music we enjoy.  The day of the preamp is over and I want to explain how we got to where we are and why.

Perhaps in today’s post we’ll cover something very basic: what is a preamp?  Yeah, I know, that sounds stupid because YOU already know what a preamp is, so I am talking to the OTHER guy who isn’t completely sure exactly what’s inside.

Let’s start with the name: preamp.  As the name implies, it’s “pre” meaning something that comes before the amplifier.  But other than the order of the signal chain it also means it is amplifying or conditioning and controlling before the amplifier.  So, depending on what our preamp is it can be both a pre-amplification device or it can be a controller or both.  For example, a passive preamp has no amplifier inside and it is only a control device: selecting the input and controlling the volume level.

Most preamplifiers we are familiar with are both: a controller and a first stage of amplification before the power amplifier.  Which brings us to the insides of a preamplifier.  What’s inside?

Actually preamplifiers are quite simple having only 3 elements to them: an input select switch, a volume control and a voltage amplifier.  Here’s the signal flow: of the multiple sources plugged into your preamplifier’s inputs, one is selected and  fed into the volume control.  The level is adjusted (as well as channel to channel volume or balance between the two channels) and then fed into the amplification stage.  This stage amplifies the signal between 5 and 10 times larger and then provides enough drive capability to get the signal properly transferred to your amplifier through an interconnecting cable.  Note: many preamplifiers also have a phono stage built in to amplify the output of a turntable but that’s not really a part of the definition of preamplifier as it is concerned only with making a source come up to the level of all other sources.  The phono preamplifier is more appropriately placed inside the turntable but that’s another story.

So, the preamp selects what we want to listen to, turns the volume up and down and then amplifies the signal to a level acceptable to a power amplifier.

Preamps are nearly always analog and made a lot of sense for many decades when nearly all sources were also analog – tuners, turntables, tape decks etc.

When the digital era began in the early 1980′s CD player manufacturers naturally built analog preamplified outputs into their players so they would be compatible with the analog preamplifiers of the day.  In other words, CD players were originally designed as just another analog input for one reason only: to be compatible with existing analog preamplifiers (and receivers which consist of an analog preamp, amp and tuner in one box).

But, today, most sources are digital and not analog anymore so the notion of adding an analog output to every digital source just to be compatible with analog preamplifiers doesn’t make any sense anymore.  So the day of the preamp has long passed and it’s time to rethink the entire genre.

Tomorrow we’ll work through more of this.

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About Author

Paul McGowan

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.

(16) Readers Comments

  1. Ladderman

    August 1, 2012 at 3:57 am

    If we are heading towards digital only inputs, what’s the chance of a high quality digital RIAA phono stage. Or is this to much for my analogue friends to cope with.

    • August 1, 2012 at 5:34 am

      No, actually it’s not easy to make a perfect RIAA digital phono stage but certainly a better solution in the long run and there are several excellent ones out there that actually seem to sound better than an analog. You can alos mix and match which is what we’ll be doing along the way.

  2. robertawillisjr

    August 1, 2012 at 5:23 am

    There is a problem for those of us with large LP and SACD collections. We need analog inputs. If you decide to have analog inputs and do ADC conversion, it will need to be transparent. Alternatively, you can include an analog preamp with limited inputs.

    This “pesky” problem of analog inputs may go away over time but it exists for many of us. What is your solution :-) ?

    • August 1, 2012 at 5:35 am

      SACD’s are easy because they’re digital – but LP’s can be handled in many ways – digital or analog in a hybrid sense. We’ll cover all that.

  3. bondmanp

    August 1, 2012 at 7:04 am

    Paul – I get your points, but I beg to differ in several aspects. First, minimalist design may work for some audiophiles, but not all. For example, I must have a quality balance control on my preamp. I simply cannot enjoy listening if I feel the soundstage is skewed to one side. TAS’s Anthony Cordesman is as passionate about this as I am. Some of us need tape loops, mute switches, remote controls, and even analog inputs for legacy source components. Not everything is better digitized. My preamp has tone controls with a bypass switch. I rarely use them, but like ABS brakes, I like knowing they’re there. Of course, all of these things can be built into a combo preamp/DAC, and some newer full feature preamps are inclulding high quality DAC sections, but we consumers want choices. Perhaps we like the DAC capabilities of one manufacturer, and the preamp designs of another. This is why we all don’t own Meridian or Arcam all-in-one systems. They might work in some applications, but most of us want to select individual components based on their unique strengths and features.

    • August 1, 2012 at 7:50 am

      We can certainly agree on the balance controls. One of the things that pushed Cordesman over the edge in favor of the PWD in his upcoming review was the addition, in the MarkII version, of a precision balance control. he (and I) use it almost every time to get the soundstage just right. One of the cool features you can do with digital that you cannot with analog is something I’ve always wanted to implement is a memory for that balance control on a per track basis. How cool would that be?

      Certainly there remains many use cases for analog only preamps or analog centric preamps but that doesn’t obviate the point I am making that the era of the analog preamp is over – yes the remnants are all around us, but they’re going to be history soon enough.

      • bondmanp

        August 1, 2012 at 10:52 am

        Cool, Paul. I am about 16 months behind in my TAS reading, so I haven’t gotten to that review yet. But kudos to PS Audio for the balance control. And, yes, the memory for each track would be cool. I guess, what I was trying to say, was that DAC/preamp combos can replace separate units, but designers still need to take consumer preferences into account. I was intrigued by a new preamp on the market that not only included a DAC section, but also full DSP capabilities, and, when auditioned, sounded really great.

        And, obviously, care must be taken to avoid noise contamiination from digital signals into the analog signal. Ultimately, we will always be listening to an analog signal coming out of our loudspeakers, no matter how long it stayed in the digital domain.

  4. erich.j.henkel

    August 1, 2012 at 7:24 am

    Paul,

    for me the future will look like the following:
    Digital Source will be a PC (I use a MacBook with Amarra from Sonic Studio) – digital connection to the active speaker – speaker with integrated DAC aand Class D amp and room controll etc.

    But what will I do with my 10 K$ Turntable and hundreds of Vinyl Records. I will need a Phono Preamp with a 32 Bit /192 kHz A/D- Converter to interface with the speakers.

    What will I do with my SAT reciever and with my Blueray Player and my old Cassette Recorder and…

    Question for me is: Do we need a digital Pre-Amp with analog Inputs and active speakers?

    Erich Henkel
    Germany

    • August 1, 2012 at 7:51 am

      Erich, yes that’s exactly what we need as a crossover piece before the final everything digital.

  5. Jah

    August 1, 2012 at 9:04 am

    I can see creating a digital equivalent of the preamp, but I think this debate goes back to the receiver versus separates debate. The preamp offered the flexibility to update various parts of the audio input chain without replacing what I call the power chain (preamp-amp-speakers). I can also see building turntables with A/D converters in them.

    My vision of an ideal setup?

    * 2 ch Power amplifiers with a built in DAC/digital switcher/volume control
    Available front end components:
    * DVD/BluRay players with PCM channels out (2+2+1)
    * Internet radio/video tuners with PCM channels out
    * Turntables with built-in A/D conversion (or just an outboard A/D converter with multiple analog inputs)

    This setup would reduce/eliminate analog cabling.

    One of the reasons the computer is becoming a workable front end for audio (and video) is that it is flexible and modular, and relatively easy to update and reconfigure — covers almost all the components above.

    Just my 2cents — JAH

  6. Laura

    August 1, 2012 at 9:54 am

    I suppose I am part of a shrinking breed of music enthusiasts because I strongly prefer analog along with some tubes in the system. Give me a good high end TT, tone arm and cartridge paired with a great phonostage and preamp and I’m in music heaven. While the market for an analog preamp/phonostage may shrink, I don’t think it is over. It wasn’t that long ago that most folks in the music/audio industries declared the end of the vinyl record, only to see a resurgence beyond most vinyl lovers wildest dreams.

    Laura

  7. philkarlin

    August 1, 2012 at 11:57 am

    I don’t really understand why the eradication of analog from the chain is such a great goal. To eliminate cables? Why would you want to take the analog output of a turntable (which you are using because you prefer that sound to digital) then digitize it only to convert it back to analog to play through a speaker? If you are a digital only kind of person, you still need to convert the digital into analog to play it through the speaker. You want to put the DAC(s) next to the speaker instead of next to the source? Seems to me the only interesting question is whether to put the DAC before or after the amplifier. Everything else is just packaging.

    Why don’t you just combine your GCPH phono pre with your PerfectWave DAC? The remote control and variable output on the GCPH is quite clever. If it only had a digital input… I hear the PWDAC is very good. If only it had a set of analog inputs…

    • August 1, 2012 at 4:10 pm

      I think that during this time of transition the proper thing to do is add analog inputs to your DAC – instead of the opposite way around – but that’s just me.

    • Jah

      August 1, 2012 at 4:10 pm

      Don’t get me wrong. I love analog, but if the future is digital (and it is), might as well remove one of the costly and sound-sapping variables from the system, namely analog cabling.

  8. oliver T. Finch

    August 1, 2012 at 11:30 pm

    Till digital remains second best analogue sources will exist and as long these exist preamps. will remain in existence.Most high end sound lovers are analogue people except those who either cannot hear the difference or else are heavily influenced by the mistaken belief that the latest is the best. When the bit, sampling used in digital will become infinite then digital will sound like analogue but then it will cease to be digital because it will have become analogue. So to sound the death knell of preamps. seems too premature.Regards.

  9. August 2, 2012 at 4:03 am

    I think that most of Hi-End users don’t realize that this market is supported by the end-users. Can anybody imagine a future Hi-End market with all the already present technology, fooling potential new clients with 100 pieces to get a sound-system? I think that is one (another) reason why the still present Hi-End market is dying. Dying because many of those company has gone to bankruptcy. This is a very small niche. There are more manufacturers than consumers because there is no-conditions to get into this business. No one: whoever makes a weird cabinet and put some on-the-shelf speakers (obvously modified under his specifications :-) )) ) can get into this. Whoever designs a beautiful turntable chassis will get into this. Whoever selects a rare tube (valve) model will be accepted… etc, etc. Now let’s go to the unstoppable present future: digital. New potential customers have been educated with iTunes/MP3, and a pair of earphones. Their next logical step would be to listen to those recordings (stored in a pc or mac) with a pair of well set-up loudspeakers. Add now a true Hi-End touch: good DAC with new digital features, Digital Equalization, plugins, digital crossovers, active loudspeaker. My father’s generation never moved to computers: they admired but never got into that world “destinated to young next generations”. Now that generation is their 60-70 y.o. They are not potential hungry consumers anymore. You can accept that or die embracing your turntables, 1000 separate pieces, absurd expensive cables, and all that stuff: you are a minority not big enough to keep that market alive… except if manufacturers (?) of such, nowadays (almost ridiculous) accessories earn their lives with serious jobs, making such pieces a second weekend’s hobby. But, even for that, China has its own solutions… available only through Internet (ah! the virtual market). Getting years shouldn´t be a reason to get old if we are able to keep our minds up.

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