Now available, the 66-001b Balanced Line Stage
The 66-001b balanced line stage has the same excellent sound quality and performance that won the 66-001p so much praise, as it should; the line stage topology is identical to the unbalanced preamp. But the 66-001b features balanced inputs using high-quality transformers. The input transformer is a 2:1 step-down unit wired in 'balanced to ground' configuration, which is the absolute best way to cancel common mode noise (induced AC hum and spuria, RF, etc) coming in from the interconnects. Additionally, all unbalanced inputs are routed through the same transformers, but at a 1:1 ratio. This will allow switching between balanced and unbalanced sources without the usual 6dB increase in gain from balanced sources. It also ensures that all signals have the same path through the circuit.
The line stage is two sections. First a medium gain amplifier that has a low output impedance for driving the volume and balance controls. This isolates the sources from fluctuating input impedance and frequency response relative to the volume control setting. The second stage amplifier is also medium gain and drives an output transformer that knocks the overall gain down to a reasonable level for driving an amplifier for an overall gain of 14dB. This is the same output transformer used in the 66-001 except that it has two secondaries; one for the balanced output and the other for the unbalanced headphone output and second unbalanced output.
Many preamps will output up to 20 volts peak to peak which is way more than most amplifiers need for full output. But vacuum tubes are high-gain devices and need to breath. The 66-001b lets the tubes live their at high-gain operating points while the output transformer lowers the output gain via the turns ratio from primary to secondary. This gives the advantage of lower noise floor, lower gain and lower output impedance for rock-solid drive; the output impedance is less than 10 ohms- it will drive any power amp, tube or solid state, over long interconnects with no high frequency losses. For those with low sensitivity speakers the output can be wired for 20dB of gain.
For the home theater buffs out there, we now offer an optional HT bypass function that will route any signal present on the 'video' jacks to the second output whenever the power is off so that the signal from your surround system is "passed through" the preamp to your power amp and speakers. This enables you to use your two channel system as part of your multi-channel theater setup.
Additionally, the sweet sounding MM phono stage offered on the 66-001p is available as an option for an added cost of $500.00
**Click here to see specifications and performance data**
Features and Specifications:
*2 Balanced and 4 unbalanced inputs / balanced outputs
*Input transformer configured in true 'balanced to ground' mode
*Input impedance = 50K balanced, 20K unbalanced
*Fully point to point construction with high temp wiring and silver solder
*Hand-matched high quality parts used throughout
*Line stage gain = 14dB (can be wired for 20dB on request)
-S/N ratio: 100dB, reference 1V p-p out, no weighting
*2 ea. ECC99 - line stage
*High-quality Alps Blue volume pot
*Balance control out of direct signal path
*Volume and balance controls nested between amplifier stages providing constant load on line inputs for consistent frequency response
*Mono (true summing) and Mute switches for added convenience
*Record output jacks
*Dual main output jacks, 1 balanced XLR 1 unbalanced RCA
*Optional HT bypass function
*Transformer coupled output - headphones and main outs
*8 ohm output impedance - will drive 8 ohm speaker to 1 watt!
*Fully regulated external solid state power supply for low noise
*35lb shipping weight
All units are hand built personally by me, burned in and auditioned in my reference system for 1 week before shipping. All units ship with frequency response and distortion plots. Ships in sturdy carton with custom foam inserts.
$4350.00* w/ MM phono stage
*Washington State residents pay 9.5% sales tax.