Well, we had these leftover Manley Reference Preamplifier chassis that we brought with us from the VTL move... shame to see them go to waste so David laid up a PCB for a stereo EL34-based integrated amplifier to be crammed into this chassis. New aluminum tops were made to accommodate the hole needed for the output tubes to poke through.
As we see from the gutz picture above, each of the four inputs were hand-loomed up to the selector switch and stepped volume control at the front panel using good ol' Mogami wire. The circuitry here is nothing new, same ol' same ol'. The output tubes' heaters run off of AC which is then rectified and fed to the input and driver tube heaters. The input stage is the tried and true basic paralled-double triode 12AT7 feeding the 6414 long tailed pair phase splitter into a push-pull pair of EL34's strapped in triode with a separate regulated screen supply producing around 50 watts into 5 Ohms. The plates were running 560VDC.
Output transformers were the Mercury Magnetics VTO-50's, wound for maximum power transfer into a 5 Ohm load, and the power tranny was also built by Mercury. This amplifier uses an adjustable Fixed Bias system. Bias trimpots are located inside the amplifier. The readout points are on the front center section of the faceplate. Instructions for biasing can be found in the Owner's Manual.
On the silk-screened front panel were two small toggle switches, one on the left side for MUTE and the other one on the right side for POWER. Handy LED's below each switch declared the status of that switch. The rear quartet of RCA jack pairs fed the input selector and then the volume control. There is also an unbuffered Record Output that is run off the selected input.
There were only 19 of these amplifiers manufactured. They were built in 1994 and 1995.
The Serial Numbers were: MANRS50001 - 019
- Output tubes: 4 x EL34G Sovtek
- Driver tubes: 2 x 6414 USA
- Input tubes: 2 x 12AT7 Ei Yugoslav large plate
- Input sensitivity: 375mV
- Input Impedance: 100 kOhms
- Output load impedance: 5 Ohms
- Freq. Response ±0.5 dB: 10 Hz-20 KHz at 50% rated power
- S/N ratio: 80 dB
- Power consumption: 220W Quiescent, 360W at full power
- Max. power @ 1.5% THD: 51.2 watts into 5 Ohms; 36 watts into 4 Ohms; 45 watts into 8 Ohms
- Supersonic rolloff via feedback capacitor begins at 30KHz
- Factory set for 100V, 120V or 220-240VAC operation for original destination country's mains voltage.
- Operating Mains Voltage changeable with power transformer re-wiring and fuse value change.
- Mains Voltage Frequency:
- Mains Fuse 100-120V operation: 5Amp SLO-BLO 1/4"; x 1 1/4"; MDA or MDL5
- Mains Fuse 220-240V operation: 3Amp SLO-BLO 1/4" x 1 1/4"; MDA or MDL3
- Dimensions: W=19", D=10", H=7.5"
- Shipping weight: 41 lbs.
Specifications subject to change because they just might.