Soundtechguy
Active member
I just finished some extensive repair work on a pair of Quest speakers and wanted to share some info in case it helps others.
If you noticed some loss in volume to the electrostatic panel, you may want to take a good look at the wiring between the panel and internal amplifier/crossover module (including the terminal blocks) before suspecting the panel itself. This may also be a good preventive maintenance measure as well. It seems that the terminal block originally used in this application is problematic in the sense that they tend to loosen, tarnish and in one way or another become resistive. The resistance at this point will generate heat and further damage the connector creating more resistance and heat until the connector burns under hard use. Besides the connector burning, the circuit board it mounts to will suffer worse than the connector itself. I have talked with Martin Logan technician who is familiar with this occurrence.
Although it looked good from the outside, I found the wiring was in need of replacement as well. Stripping it back indicated that the wire was black and tarnished from one end to the other. This condition (even not as extreme as this) will greatly affect the performance and operating efficiency of the panel.
My remedy was to remove the panel connector and replace it with an in-line 3 pole phoenix block connector. At the amplifier end, I removed the existing terminal block (identical to the one pictured here) from the amplifier circuit board and soldered a 5 inch long 3 conductor wire to create a pig tale. I then put another in-line 3 pole phoenix connector in place so that the amplifier/crossover module can be disconnected easily for removal as initially designed.
In my case, this was all that was needed to bring the panels back to life 100%. Luckily when all this interconnect failure occurs, the panels are spared since they are basically loosing connectivity. I believe these same connectors were used in other models in and around the same time period as the Quest. It may be worth a look.
If you noticed some loss in volume to the electrostatic panel, you may want to take a good look at the wiring between the panel and internal amplifier/crossover module (including the terminal blocks) before suspecting the panel itself. This may also be a good preventive maintenance measure as well. It seems that the terminal block originally used in this application is problematic in the sense that they tend to loosen, tarnish and in one way or another become resistive. The resistance at this point will generate heat and further damage the connector creating more resistance and heat until the connector burns under hard use. Besides the connector burning, the circuit board it mounts to will suffer worse than the connector itself. I have talked with Martin Logan technician who is familiar with this occurrence.
Although it looked good from the outside, I found the wiring was in need of replacement as well. Stripping it back indicated that the wire was black and tarnished from one end to the other. This condition (even not as extreme as this) will greatly affect the performance and operating efficiency of the panel.
My remedy was to remove the panel connector and replace it with an in-line 3 pole phoenix block connector. At the amplifier end, I removed the existing terminal block (identical to the one pictured here) from the amplifier circuit board and soldered a 5 inch long 3 conductor wire to create a pig tale. I then put another in-line 3 pole phoenix connector in place so that the amplifier/crossover module can be disconnected easily for removal as initially designed.
In my case, this was all that was needed to bring the panels back to life 100%. Luckily when all this interconnect failure occurs, the panels are spared since they are basically loosing connectivity. I believe these same connectors were used in other models in and around the same time period as the Quest. It may be worth a look.
Last edited:
