This circuit is based on the classic Mullard amplifier design of the 1950's and holds with our philosophy of keeping things simple and allowing the tubes to work their magic. Even though we use factory matched KT88's, they are still different enough that individual tube bias adjustment is required. To that end, we now use the excellent AB-Q auto bias module. Bias is pre set by us and from then on will never require adjustment again. The Auto Bias module will compensate for aging tubes as well as the slight difference bewteen each KT88 power tube to keep the bias for each tube at the pre set optimum operating level for the best sound and longevity of each KT88 output tube.
Once a tube does get to a point, due to wear or a fault, where the auto bias module can no longer hold the pre set bias, the corresponding LED indicator light, which is located on the top plate next to each power tube, will go out which indicates that the tube will need to be replaced.
Power is supplied by our custom designed power transformer that is manufactured for us by Heyboer Transformers. It is a solid state rectified and choke input power supply followed by a CRC circuit to arrive at the various levels of the high voltage B+ required by Elvis.
To limit inrush current when first powered up, we use an NTC (Negative Temperature Coefficient) thermistor.
Only high quality components are used in the construction of Elvis. All power supply electrolytic capacitors are Nichicon high voltage snap in caps. Film capacitors are WIMA, and coupling capacitors are Russian PIO (Paper In Oil), hand picked and matched by us from our very own collection. Resistors in the signal paths are Vishay CMF and RN low-noise military spec film resistors. RCA sockets are gold plated, and speaker posts are Rhodium.
The printed circuit boards are designed in house and manufactured to FR4-TG standards. They are double layer with full ground planes on both sides to ensure complete screening of the circuits.
The power transformer is our own design and custom made for us by Heyboer Transformers. The output transformers are either Edcor units, or the first class Lundahl LL1679PP.
Power output with 4x Gold Lion KT88 power tubes: 60Watts/channel from 15Hz to 35KHz at less than 1% THD in ultra linear mode.
IMD: < 0.38% (18Khz and 21Khz) at rated power
Frequency response: 10Hz to 40Khz +/- 0.1dB at 60Watts
Power bandwidth: 16Hz to 39Khz +/- 0.3dB at 60Watts
Sensitivity: 1.5 volt in for 60Watts/channel
Damping Factor: 14
Input impedance: 270,000 ohms
Hum & noise: > 90dB below 60Watts output
Power requirement: 120VAC 60Hz or can be wired for 220/240VAC 50Hz
Dimensions: 15"W x 13"D x 9"H