Pre-Amplifiers
An analog voltage amplifier for adjusting the volume and selecting of inputs and outputs to the power amplifier(s). In some cases, shaping the sound scape.
C310
User switchable paper in oil and high slew rate capacitor line stage preamp
3 line level inputs, one of the inputs is a SE/BAL combo. With optional balanced and up to 5 inputs
Headphone jack, SP Capacitor jack for user "plug and play" future upgrade
Click here for additional pictures of C310 Line Stage Preamplifier and its variations
C310 TSV
The Tandem Stepped Volume Control (TSV) is an optional feature for the C310. It features a 121-position dual-knob stepped attenuator with a coarse control on the left and a fine control on the right. The coarse control adjusts attenuation in 10 dB steps, and the fine control provides 1 dB of attenuation per step. Since each control has 11 steps, this results in a total of 121 possible volume steps.
However, when the coarse control is set to the infinity attenuation (∞) position, the fine knob's position becomes irrelevant, and the overall result remains at infinity attenuation. This means there are 111 usable attenuation combinations, including the ∞ position.
The C310 TSV includes a remote control feature as standard. The user can choose between using the manual stepped volume control or the internal remote volume control by flipping a locking toggle switch. This locking feature prevents accidental selection between the two modes.
When the manual stepped volume is fully engaged (remote bypass mode), the remote is completely out of the circuit.
When the remote is in circuit, the manual stepped volume is used to set the maximum allowable volume, and the user can then remotely control the internal volume setting.
Since this is an RF remote control, the user can operate the system remotely, even from another room or out of sight. Using the TSV to set the maximum volume will prevent the system from playing too loud and causing potential damage.
George Taylor of Entracte Audio (our Toronto, Ontario dealer) explains the features on C310 pre-amplifier
C312
Tube Simulator and Solid-State all in the signal path
User selectable and variable for each signal path
3SE and 2 SE/BAL inputs
Standard remote for Master Volume only.
Optional remote to control all four adjustment dials. Including Warm, Tube S, SS and Master Volume.
SP Capacitor jack for "plug and play" future upgrade
Click here for additional pictures of C312 Preamp with GC312 Power supply
Shown standard configuration with one pair of balanced output.
George Taylor of Entracte Audio (our Toronto, Ontario dealer) explains the unique features on C312 pre-amplifier.
This video explains how to use the three adjustable knobs. The Warm, Tube S and SS.
The above image was from the video How to use C312 preamp seasoning knobs. Someone has asked what's the logic behind the tube sound if it doesn't have tube inside. George Taylor of Entracte Audio answer with a brief history of the C312 and how it came about. Here is his reply to the question on June 18, 2025.
@EntracteAudio To answer that, we have to go back a few years... about a decade ago (give or take) Angela-Gilbert came up with preamp called the BC307. That was an all tube preamp that allowed the ability to mix two tube gain stages and a solid state gain stage. the latest iteration of that preamp is called the BC318. However, tube preamps can be fussy and noisy, and their power supplies can be complex and expensive to build, so Angela-Gilbert built an integrated amplifier (NFS238) that had an adjustable simulated tube stage, and an adjustable solid state gain stage. The tube simulation circuit in the NFS238 worked really well. The C312 is essentially the preamp section of the NFS238, with adjustable Warm, Tube, and Solid State gain stages.
The "logic" as you put it is in the ability to adjust these gain stages so that the use can control how much tube sound they want, what flavour of tube sound they want, and how much solid state sound that they want. It's an effective way dial in a specific tone profile that works best for a system. The added bonus is that you don't have to worry about tube longevity and tube consistency.
C318
With 6SN7, 6922 and Solid-State all in the signal path
User selectable and variable for each signal path
3SE and 2 SE/BAL inputs
SP Capacitor jack and FCF 200V B+ jack for "plug and play" future upgrade
Separate tube and solid-state power switch to save tube life
Click here for additional pictures of C318 User adjustable hybrid parallel line stage preamplifier
Mike Woodcock of Absolute Sound (our Chatham, Ontario dealer) explains the unique features on C318 pre-amplifier.