This is an Audiophile LDR volume control. If you want to know more about this technology please check the linke below. https://tortugaaudio.com/evolution-of-ldr-volume-control/ I have assembled it an old TOA amplifier medal case. This thing requires 12V via jack connector shown in back of box (Pre Amp Out) I also have brand know DM1 display module (to show % volume and other info). It is currently not connect to volume control but can be connected as additional feature. Without this display module, volume control still works. Everything is expensive but selling cheap to clear out my closet. Local pickup in Chicago area is welcomed and contact me on 630 446 0165 Some DIY info can be found here: https://tortugaaudio.com/docs/v25-7segment-display/#display-assemblyhttps://tortugaaudio.com/docs/v25-7segment-display/https://tortugaaudio.com/docs/ Local Chicago pickup welcomed. Contact me on 630 446 0165 LDR Volume Control There’s growing recognition within the community of audio enthusiasts (a.k.a. audiophiles) that LDRs (light dependent resistors) deliver the best sounding volume control technology available today. Over the past 5 years, Tortuga Audio has been leading the charge to evolve and perfect LDR based volume control.In Q2 2017 Tortuga Audio released its fourth generation LDR technology which is included in all of our current passive preamp products.Tortuga Audio’s LDR technology moves beyond the old challenges of integrating LDRs into audio volume control. For those who like to look under the hood, here is a brief review of the evolution of LDR volume control.How LDR Volume Control WorksTo understand LDR volume control let’s first review volume control with a conventional potentiometer or “pot”.Potentiometers used for volume control will have a fixed resistance rating that is typically between 10k and 100k ohms. The audio input signal connects at one end of this fixed resistance and the other end is connected to ground. The output signal from the pot is a third connection to what’s referred to as the “wiper” which slides along the pot’s fixed resistor. The output signal of the pot comes from the wiper.The resistance above the wiper is the series resistance (Rseries) and the resistance below the wiper is the shunt resistance (Rshunt). The resistance Ratio is defined by the formula: Ratio = Rshunt/(Rshunt + Rseries). This Ratio also happens to be the voltage ratio of Vout divided by Vin such that Vout = Vin x Ratio. Putting all this math together the resulting attenuation expressed in decibels is defined as: dB = 20 x log(Ratio) or if you like dB = 20 x log (Vout/Vin) where Ratio = Vout/Vin = Rshunt/(Rseries + Rshunt).Thus, when Rseries is zero the volume is maximum (no attenuation) and when Rshunt is zero the volume is minimum (maximum attenuation).Volume control with an LDR is conceptually similar to a potentiometer.With LDRs, attenuation is achieved by varying the resistance levels of 2 separate series and shunt LDRs to achieve specific resistance ratios that correspond to specific dB attenuation levels. With a pot all this is done mechanically whereas with LDRs it’s done electronically and thus can be manipulated in ways that you can’t with a pot.

This preamp has been tested and is in working order. **No remote included** Includes standard 12 volt power supply Shows some light cosmetic wear. Please see photos. Shipping in the U.S. Lower 48 only.