Up for sale is a ONE pair of Empirical Audio Final Drive Analog Isolators (original listing had two pairs for sale, pictures are from the original listing).
I recently purchased a DAC with balanced transformer outputs which make these redundant. Product description is below and I can verify the manufacturer's description that when the Final Drives are inserted in a system, the noise floor drops significantly, more details are heard and they made my previous DAC sound more like analog.
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From Empirical Audio's website:
The Final Drive is a pair of passive transformer buffers/selectors, one for the left channel and one for the right channel. The Final Drives can be inserted between DAC and amps or between preamp and amps. The Final Drive can be beneficial in virtually any system. (The Final Drive is not a variable Volume Control)
The purposes and benefits of the Final Drive are numerous:
1 Improves audio quality
2 When driving direct from DAC to amps, it provides a method to select other analog sources such as SS preamp (HT) or Vinyl preamp
3 Provides a method for conversion of balanced to single-ended
4 Provides a method for conversion of single-ended to balanced
5 Eliminates DC offset in balanced signals
6 Eliminates positive-negative signal amplitude differences in SS generated balanced signals
7 Breaks the ground connection between DAC and amps or preamp and amps
#6 is an interesting problem and not obvious. Most modern balanced outputs from preamps and DACs are generated using solid-state circuits and no transformer. Because of these designs, it is impossible for the positive output and the negative output to be exactly the same amplitude. One is always a bit higher in level than the other. It is also impossible for these to have zero DC offset (#5) unless they are capacitively coupled. The impact of these things is that the amplifiers don't sound as good as they could if the signal was truly balanced. The ONLY way to get a truly balanced signal is using a transformer.
The benefits of #7 should be obvious. The ground-loop created by a stereo amp or monoblocks and the DAC or preamp driving them has to be the most problematic in most systems. If it does not create hum, there is a lot of RF pickup of the big loop antennas of the ground-loops. Many systems have dedicated power runs to the amplifiers, which is good for the amps, but bad for the system because it creates very large ground-loops with different circuits. The Final Drive eliminates these ground-loops.
Some will claim that inserting yet another component in the signal chain is a negative thing, but in this case they are dead wrong. The transformers used in the Final Drive pair are simply the best on the planet. These use the Finemet core and winding technology from Japan. These are some of the most expensive signal transformers available which have been customized specifically for this application. The wiring inside the Final Drive uses cotton-insulated continuous-cast silver from Japan. Only the best ELMA and C&K switches with the optimum contact plating are used for the selectors. Neutrik XLR and Vampirewire solid-copper direct-gold plated RCAs are used. Only the very best and the sound quality improvement reflects this.
When the Final Drives are inserted in a system, the noise floor will drop significantly. Low-level high-frequency information in the music will not be masked by ground-loop noise anymore. Amplifiers will behave more ideally. More detail will be heard. DACs will sound more analog. Analog will sound more lifelike. The stereo image will be more 3-D. Even movies will sound more live.
If you are driving balanced from your DAC to your amps, the Final Drive is a no-brainer.
If you are driving balanced from your DAC to tube amps with RCA inputs, the Final Drive is a no-brainer.
Typical usage is:
DAC XLR output -> Final Drive XLR1 input
SS Proc RCA output -> Final Drive RCA input
Final Drive XLR output -> amplifier
This would be a typical system with DAC for music and SS Proc. for movies. A flip of the rotary switch and you select movies or 2-channel music. (only XLR or RCA output can be selected, not both at the same time)
Each of the inputs can be boosted +6dB with toggle switches. This allows for differences in level from different sources, such as SS proc and DAC or RCA versus XLR. (The RCA path automatically adjusts for RCA/XLR amplitude difference)
Specifications (Each Final Drive)
InputsRCA
XLR1
XLR2
OutputsRCA
XLR
RCA-XLR1-XLR2 input select rotary switch
RCA-XLR output select toggle switch
0 or +6dB RCA input select
0 or +6dB XLR1 input select
0 or +6dB XLR2 input select
