I recently purchased a used Threshold FET 10HL preamp, it has a sticker on the top panel indicating it has been factory upgraded to e/STASIS topology. I assume this upgrade was performed by Threshold in Houston, TX, after Nelson Pass left long ago to start PASS LABS. The preamp did not have a power supply with it, however, I have an E power supply for my FET 10Pe phono stage.
The problem I have is the HL uses a circular power connector for the umbilical cable from power supply to preamp, and the Pe phono has the umbilical cable hard wired to the phono section and a Tajima 3 pin connector to the power supply. I need the 8mm 3 pin female connector for the HL section, does anyone know who the manufacturer/supplier is for the connector?
The problem I have is the HL uses a circular power connector for the umbilical cable from power supply to preamp, and the Pe phono has the umbilical cable hard wired to the phono section and a Tajima 3 pin connector to the power supply. I need the 8mm 3 pin female connector for the HL section, does anyone know who the manufacturer/supplier is for the connector?
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search for Lemo connector
regular 3pin, find datasheet and compare that one you have on preamp
for starters, you can make quickie , using some solid copper wire and hot glue
regular 3pin, find datasheet and compare that one you have on preamp
for starters, you can make quickie , using some solid copper wire and hot glue
This was an unloved FET 10HL, I bought it from a wholesaler who buys and sells lost/damaged shipping goods.
Using Ivory soap and water, a sponge and toothbrush it cleaned up very nicely. I then used DEOXIT on the rear panel RCA connectors and the XLR connectors, they cleaned and polished to an acceptable level. It also did a great job removing the corrosion from the front panel logo plate. Besides a couple of paint chips on the top panel, the preamp looks great for being 30+ years old.
I contacted Threshold in Houston TX to see if they had any old e Power Supplies and maybe just the rear panel power connector and information regarding the e upgrade. They responded in one day and advised me that the e upgrade would have been done sometime in the early 90's and that their records only went back 20 years. The factory sticker does state that the upgrade to the e STASIS topology is "equivalent" circuit design. I was curious as to how old the electrolytic capacitors were, there are 8 470uF 35v filter caps and a single 2200uF 10v cap. The 470uF caps are filters for the regulated rails and the 2200uF cap is in the relay circuit. All were ELNA caps from Threshold, so I found and purchased ELNA caps from Mouser, except the 2200uF which I used a Nichicon cap.
I removed the old and installed the new caps, hooked up my e power supply and was very happy to see and hear a working preamp! It shows just how good the quality of design and build really was/is. I must admit, the original solder connections on the PCB are tiny and beautiful where my new solder connections look huge and clunky in comparison.
I searched LEMO's website and datasheets with no luck finding a corresponding connector, I was able to find mini-XLR connectors which have the panel mount connection very close to the hole size in the preamp rear panel, so I will replace the preamp power supply connection and finish the umbilical cable from the power supply to the preamp.
Using Ivory soap and water, a sponge and toothbrush it cleaned up very nicely. I then used DEOXIT on the rear panel RCA connectors and the XLR connectors, they cleaned and polished to an acceptable level. It also did a great job removing the corrosion from the front panel logo plate. Besides a couple of paint chips on the top panel, the preamp looks great for being 30+ years old.
I contacted Threshold in Houston TX to see if they had any old e Power Supplies and maybe just the rear panel power connector and information regarding the e upgrade. They responded in one day and advised me that the e upgrade would have been done sometime in the early 90's and that their records only went back 20 years. The factory sticker does state that the upgrade to the e STASIS topology is "equivalent" circuit design. I was curious as to how old the electrolytic capacitors were, there are 8 470uF 35v filter caps and a single 2200uF 10v cap. The 470uF caps are filters for the regulated rails and the 2200uF cap is in the relay circuit. All were ELNA caps from Threshold, so I found and purchased ELNA caps from Mouser, except the 2200uF which I used a Nichicon cap.
I removed the old and installed the new caps, hooked up my e power supply and was very happy to see and hear a working preamp! It shows just how good the quality of design and build really was/is. I must admit, the original solder connections on the PCB are tiny and beautiful where my new solder connections look huge and clunky in comparison.
I searched LEMO's website and datasheets with no luck finding a corresponding connector, I was able to find mini-XLR connectors which have the panel mount connection very close to the hole size in the preamp rear panel, so I will replace the preamp power supply connection and finish the umbilical cable from the power supply to the preamp.
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The FET 10HL is finally finished, Threshold in Houston, TX found a power supply cable with the correct connector for the preamp. The FET 10 HL has the cable hard wired to the power supply and the FET 10 HLe version has the cable hard wired to the preamp.
Since mine is an updated FET 10HL to "e" equivalent topology, I made a cable with connectors on both ends so I can use the "e" power supply.
This preamp has 20dB of gain, I have a P channel VFET lottery amp, an N channel OS2 VFET and a Singing Bush with THF51s to use with this preamp driving a pair of Lowther PM2A drivers in Medallion 2 cabinets.
I used REW to check the distortion of the preamp with a 10K load on the outputs with 1.0v out.
Since mine is an updated FET 10HL to "e" equivalent topology, I made a cable with connectors on both ends so I can use the "e" power supply.
This preamp has 20dB of gain, I have a P channel VFET lottery amp, an N channel OS2 VFET and a Singing Bush with THF51s to use with this preamp driving a pair of Lowther PM2A drivers in Medallion 2 cabinets.
I used REW to check the distortion of the preamp with a 10K load on the outputs with 1.0v out.
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