Preamps are, first and foremost, devices for controlling volume. 99%+ of all preamps do this by throttling the audio signal through some type of mechanical device made with resistive materials. Devices like a potentiometer (worst) or stepped attenuator (better). The unfortunate reality is the materials in these devices, together with their mechanical interface points, alter the audio signal in ways that are not benign. Let’s speak more plainly – they suck at conducting music.
Tortuga Audio uses light dependent resistors (LDRs) to control volume. The conductive material in LDRs is amazingly kind to the audio signal. The difference is undeniably audible. LDRs are more articulate. LDRs are more open. LDRs are more neutral.
Simply put, LDRs are better conductors of music.
2 – Lower Noise Floor
A passive preamp has an inherently lower noise floor compared to most any active preamp. A lower noise floor means a quieter darker background between notes. This adds more dynamic range to the music and creates a more interesting and engaging listening experience.
Passive preamps have a lower noise floor because they don’t use a power supply to actively alter (amplify and/or buffer) the audio signal. All power supplies impart noise on an audio signal.
Why add noise if you don’t need to?
3 – Lack of Coloration
Every component in the audio signal chain imparts its own coloration to the sound; passive preamps much less so than active preamps.
LDR passive preamps are THE most neutral sounding preamp available and are essentially without coloration.
The question comes down to: Do you want to listen to your music or to your hardware?
4 – You Don’t Need The Gain
Long ago and far away there was a time and place when most audio sources had weak outputs and amps were mostly low powered. To make up for this preamplifiers were designed to actively boost the voltage level of the audio signal to achieve sufficient loudness. This boost is referred to as “gain”.
Today, it’s rare that you need to actually pre-amplify the audio signal. Adding a gain stage when you don’t need one inevitably degrades the audio signal and puts greater distance between the true sound of the recording and what you hear coming out of your stereo.
Why pre-amplify before your amplify? Think about it.
5 – Costs Less
Active preamps require quite a bit of hardware? What hardware? Capacitors, resistors, diodes, op amps, tubes, transformers the list goes on. Your music has to get through all of that…stuff. And all that stuff costs manufacturers more money to both procure and to assemble.
Thus, not surprisingly, most high performance active preamps cost thousands of dollars more and yet don’t out-perform LDR passive preamps.
With LDR passive preamps, less is indeed more.
6 – BONUS REASON!
Are you an iconoclast? Do you enjoy overturning the apple cart with new found information that challenges existing assumptions? If so, then you’re in for a treat.
Ask most any informed audiophile and chances are quite good they will tell you that passive preamps simply do not measure up to high end performance standards and that you’d better stick with a conventional active preamp.
Once you have your Tortuga passive running and broken in, go ahead and invite your audiophile friends over for a listen. Make sure to tell them it’s “just a passive”. And then watch their faces as they listen to how good your system sounds. Priceless!
[FYI, no pigs were harmed in authoring this article. 🙂 ]
As a follow-up to our original post below, we wanted to share some unsolicited feedback from a recent LDR3x customer. Note that the LDR3x board is our second generation LDR preamp board design that builds on the success of the original LDR1/LDR6 passive preamps. A pair of LDR3x boards will be the twin beating hearts…
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Tortuga Audio plans to release its new LDR300.V25 Buffered Preamp on August 28. The LDR300 is a remote controlled, singled-ended, active preamplifier that combines Tortuga Audio’s popular LDR (photoresistor) attenuation technology together with a powerful JFET output buffer to deliver robust sonics that will satisfy the most discerning audio enthusiast.
What Is Volume Control? Whether you own $10k+ of high end gear or a humble $200 receiver from Best Buy, chances are about 100% that every note of recorded music played through your system is funneled through a volume control device (a.k.a. an attenuator) before it reaches your ears. In the analog signal world volume…
Summary As 2014 rolls to a close, we are pleased to announce the following expanded product offerings including the LDR3.V2 Passive Preamp plus year end specials and price changes. New V2.1 Version of our DIY LDR3x Passive Preamp Controller board is available for for pre-order @ $199 through Jan 5th ($259 thereafter). Reintroducing the LDR3 in…