David Bugbee

Item: Valve Amplifier Seaford, Victoria Extra Info: Dared VP-845 INTEGRATED VALVE AMPLIFIER DESCRIPTION Model: VP-845 INTEGRATED AMPLIFIER (SINGLE-END CLASS A) TECHNICAL SPECIFICATIONS: MAX OUTPUT POWER: 18Wx2 FREQUENCY RESPONSE: 20-20KHz (±1.5dB) DISTORTION: =1% SIGNAL TO NOISE RATIO: =84dB INPUT SENSITIVITY: 250mV INPUT IMPEDANCE: 100K ohm OUTPUT IMPEDANCE: 4 ohm/8 ohm SIZE: L540 x W300 x H240 MM WEIGHT: 40.0Kgs approx including packaging THE TUBE USED: 845Bx2, 6N8Px2, 12AX7x2 Location: Seaford, Victoria This amp has been used with quad ESL 57s and Tannoy Saturn S10. Performance on both was excellent. The 845B tubes are quite new and have only had a few hours use. I have the original box for the Amp. Weight is 40 kgs including packaging. Demonstration by appointment. Includes display cabinet. Price: $1,950 will consider reasonable offer Item Condition: Very Good Reason for selling: New speakers are less efficient. Payment Method: Pickup – Cash Buyer to collect. Pictures:

Thanks to everyone who has contributed their ideas. Andy's minidsp unit sounds interesting and I would like to learn more about it. I have not used Siegfried Linkwitz's bass boost circuit and have thought this would be a good idea. The active crossover I am using is based on the Dahlquist DQ-LP1 which has an adjustable crossover point for the 18db active filter to the bass. The high pass is a series capacitor and resistor network which is adjusted by substituting components depending on the input impedance of the amplifier. Thanks again Dave

Thanks for the warm welcome and the interesting feedback on integration of a conventional sub-woofer with an electrostatic speaker. I am careful not to allow the bass to dominate. Seamless integration is difficult to achieve. If you are allowing the full range speaker to operate without a crossover or filter there are likely to be integration problems.

Thanks for your interest. The filter I have built is active to the bass driver has a boost to the bottom end to compensate for the dipole cancellation due to the lack of a cabinet. Still experimenting with the amount of boost required to the bass driver. The bass drivers are rolled off at 18db per octave above 100 cycles. The feed to the quads above 100 cycles is passive to avoid degrading the signal and is a 6db per octave roll off below 100 cycles.

Hi I have been interest in audio since my teenage years and have mainly stereo equipment in my main system. I particularly like the the smooth musical sound of quad electrostatic speakers and have both ESL 57s and ESL 63s. The amplifiers are Dynaco MK111 valve amps in triode mode. Currently I am experimenting with dipole sub-woofers to enhance the bottom end performance and have built an active filter. Other members of the Melbourne Audio Club have been very helpful over the many years I have been a member. David