This preamplifier is designed to provide the finest and most transparent acoustic performance available while increasing the value to our customers. It is the control centre of your system.
Specifically, the new Sanders Preamplifier combines the performance and features of our previous Line Stage and Phono preamps into one.
Our previous preamps (line stage and phono) were $4,000 each, for a total cost of $8,000 for our customers who needed a phono preamp. Since both preamps are now combined, customers who need a full-function preamp can now save several thousand dollars as the new preamp sells for almost half the price of the previous two.
Additionally, more modern circuit design technology has reduced distortion and noise figures from those in the earlier preamps. The styling has been redesigned to better match our amplifiers. A video processor pass through also is included in the new preamp. All the previous ergonomic and performance features of the earlier preamps have been retained.
The goal of a true audiophile grade preamplifier is to offer gain, switching, and other conveniences, while at the same time passing the original signal downstream without adding distortion, noise, or a sonic signature of its own. The Sanders Preamp does exactly that but includes many ergonomic features for convenience and ease of use that are not available on even far more expensive preamps.
The levels of each individual input can be adjusted to get them all matched so that you don't get "blasted" or have to turn up the main level each time you switch sources. A stereo/mono switch remains standard equipment. The overall gain, individual gain between devices, and channel balance can be adjusted in precise, 1 dB increments. Muting by remote control is standard. A video readout makes it easy to monitor the levels.
Controls are available both by remote control and on the front panel. Front panel controls are done through micro-touch electronic switches. Internal switching is done by miniature, sealed, gold relays. Conventional rotary volume controls have channel matching error of around 20%, which causes the left/right balance to shift as you change the level. To solve this problem, some preamp manufacturers use discrete, precision resistors on a multi-step switch.
While this solves the channel tracking problem, they introduce new ones. Specifically, they have very limited resolution due to too few steps (typically 31 steps of 2 dB each). These "stepped attenuators" produce very annoying switching transients at each step.
The Sanders Preamp solves these problems by using the "volume control" knob to drive an optical comparator circuit. The optical circuit operates a microprocessor that controls an electronic gain system. This controls the level using one hundred, one dB steps, with precision of greater than 0.1% between channels.
The microprocessor monitors the signal voltage and waits for it to cross the zero voltage point between waves before switching to the next level. This prevents any switching transients.
There is a digital display with beautiful, blue, light emitting diodes (LEDs). The display continually shows the output level of the unit and switches automatically to show level differences between channels, when you adjust the balance, or when you adjust the input levels. You no longer have to guess at the levels or try to see fine gradations on a knob to know the levels, since you can see them from several feet away.
Five unbalanced inputs at line level using RCA connectors.
One balanced input using XLR connectors.
One unbalanced, RCA phono input with switchable gain, adjustable input loading, and RIAA equalization.
One unbalanced video processor input with fixed level at unity gain for "pass-through" use.
Two pair of adjustable, unbalanced, outputs at line level using RCA connectors
One pair of adjustable, balanced, outputs using XLR connectors (Pin 2 "hot")
One unbalanced, fixed level output at unity gain for recording using RCA connectors
All outputs may be used simultaneously
-3 dB at 5 Hz and 200 kHz
Greater than 100 dB below 1 volt reference
Less than 0.002% from 10 Hz to 40 KHz @ 5 volts peak into 600 ohms or higher, shunted by 1,000 pF or less
50 ohms, non-reactive, balanced or single-ended
Phono Input Impedance
User adjustable between 47,000 and 100 ohms. Default setting is 47,000 ohms
Phono Input Capacitance
User adjustable between 50 pf and 1,200 pF. Default setting is 50 pF.
47 kohms, balanced or single-ended
User adjustable up to 18 dB. Default setting is +8 dB
10 volts peak
Greater than 70 dB from 20 Hz to 20 KHz
Independently regulated with shielded toroidal transformer and 20,000 uF of capacitance
Voltage is user selectable for use world-wide
Net Weight: 8 pounds (3.6 KG)
Shipping Weight: 13 pounds (5.9 KG)
17" wide x 2.5" tall x 10.5" deep (43cm x 6.35cm x 27cm)
dagogo.com by Phillip Holmes
"The Sanders Preamplifier is rather unassuming. It doesn’t have a separate power supply chassis or fancy knobs. The finish is good, but not flashy. The price is downright “cheap” compared to many competing products. When sitting next to one of Sanders’ big amps, it may look like an afterthought, but you would be wrong. Roger, the engineer, made the unit big enough to get the job done, but no bigger. Fancy enough to match the other electronics, but no fancier. This is a preamp, not a status symbol.
Considering the price and performance, I doubt you’ll find anything better without spending significantly more. Considering you can leave it on all the time, and it comes with a lifetime warranty, it’s an easy recommendation."
Roger Sanders has been at this for 40 years. His first published article on Electrostatic Speakers was in 1974, followed by another on amplifiers to drive ESL's in 1976.
His contribution to audio include the invention of the curved, free-standing, electrostatic loudspeaker driver (click on image to right to view the published article); the development of extremely compact transmission line woofer systems; integration of electrostatic speakers and transmission line woofer systems; and, several "how to" construction articles in "The Audio Amateur" and "Speaker Builder" magazines.
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