Hi BGRoberts,
My LD amp sits with three aluminum cones on a MDF shelf on an equipment rack. The rack itself sits with spikes on a hardwood floor. Each shelf sits on four tabs within a metal frame. Each tab has a round marble between the tab and the shelf. All this is supposed to eliminate unwanted vibrations. Don't know what works best individually or in combination, but I do not have any problems with microphonics. What my set up is lacking in looks is made up by practicality.
Here is the equipment rack with various contents. The blue, yellow and white plastic ties hold the two fans in place. On the top left is a temperature probe whose tip touches the transformer housing. On the shelf underneath is the Little Dot MKIII standing on three footers. On the transformer housing an 15A voltage regulator is attached with two rubber bands. The two white pieces behind it are wooden chopsticks to make a space between the voltage regulator mounting plate and the transformer housing to allow for better air circulation and cooling.
To the left of the amp on the shelf is a mounting board for two voltage regulators that supply power to one of the fans and the driver tube, seen on the bottom suspended by wires to the two Vector adapters (less hum).
Here the shelf is lifted up to show the arrangement with a marble to cancel out vibrations.
Here are the 80's aluminum cones attached with generic bluetack to the bottom of the LD amp.
This is the 12V 4" fan mounted above the amp.
Here is a close up of the temperature probe. Actual temperature of the transformer housing today with the amp in operation is 78F. Room temperature is 67F. On a hot day with a room temperature of around 76F with A/C on the temperature may go up to 89F.
Here is the second fan, also mounted above the amp. It is a 12V 3" computer fan from a busted power supply. It was chosen because it is quiet. Rather than blowing air on the amp, both fans draw the hot air away from the amp. Under the fan are seen two 6080WA Sylvania 2.5A power tubes. How do these octal tubes fit into the 9pin sockets on the LD?
Since the octal to 9pin adapters are too wide to fit inside the decorative rings on the LD MKIII, a 9pin socket extender is needed. The little red strip marks the orientation of the adapter for easy insertion. The octal adapter goes into the extender, and the tube - you guessed it - goes into the octal adapter.
Since the 6080 tubes use much more current than the amp can provide, an external 15A voltage regulator is connected to the heaters of the tubes. On the left of the extender you can see a wire coming out. A hole was drilled in the bakelite of the extender. The heater pins were desoldered and removed (the extender comes apart easily with one screw) and the wires soldered onto the pin tabs inside the extender. If you use 6SN7/6SL7 octal tubes as power tubes no external power supply is necessary.
The 15A voltage regulator is powered by a 430W computer power supply. I found that that a beefier power supply resulted in better sound.
This is the15A voltage regulator. The smaller voltage regulators can be bought with voltage readouts, but for some reason these come without - you will need a simple voltage meter to set the voltage to 6.3V using a little set screw on the voltage regulator. For some reason the voltage reading taken at the tube pins always is lower than at the voltage regulator itself, but may differ a little between different tubes. Usually, with the 6080s, I have to set the voltage to around 7V to get 6.3V at the tube itself. The large heat sinks never get warm in use.
What else is there to describe? The fans run on 12V, and I used whatever I had on hand. One is powered by a 12V wall wart from an old portable phone, the other shares the 12V PC power supply with the heaters for the power tubes. The 12V driver tube uses an old laptop 19.8V power supply via a voltage regulator.
This set up is very flexible, and I can use all kinds of driver/power tubes that use different voltages - 6V, 7V, 8V, 12V - no problem.
It's been a long journey, littered with tubes relegated to the dust pile, but very rewarding.....
