Matt_J
04-08-2019, 10:54
Due to an impending change around I have this cracking pre amp for sale.
Some comments from the builder:
The balanced output transformers are from Sowter.
Yes, a single gain stage using a 76 direct coupled to a cathode follower using a 7193/2C22 single triode. The cathode followers could also be 6J5’s as the valve sockets are wired to accommodate either the 7193 with the anode and grids on the top caps, or 6J5’s with all connections at the valve sockets.
There is provision inside the case to store and insulate the anode and grid top caps if 6J5’s are used"
The input selector switch is made by Elma in Switzerland. Gold plated contacts. I believe Goldpoint use a similar switch body, but they use a small PCB to mount the contacts.
The 10uf Solen capacitors are decoupling capacitors for the B+ power supply. The gain stage is direct coupled to the cathode follower.
Gain controlled by 50k ohm stereo stepped attenuator with 24 steps. The output impedence is approximately 365 ohms and will drive long cable runs and difficult loads. Input impedence is 50K ohms.
There are 5 valves used: 2 x Type 76 and 2 x Type 7193 for the preamp stage and 1 x 6AX4GT for the soft start on the HT supply. The signal valves are vintage (1930/40s). The builder has a plentiful supply of spare valves should you need them.
Comes with a comprehensive manual/design guide which details some of the alternative valves that could be used such as Type 37 which will give slightly lower gain (13dB) compared to the Type 76 (15dB).
As you can see, the workmanship and quality of components/build are very impressive, I shudder to think what this would cost built by one of the well known manufacturers inside a fancy case.
£725 Collection only from Nottingham as I don't have a sturdy enough box to ship, or could meet up somewhere around east mids.
https://i.ibb.co/hZq3Y08/IMG-20190804-112100.jpg ('https://ibb.co/QC5yD0m')
https://i.ibb.co/bPC2qsh/IMG-20190804-112130.jpg ('https://ibb.co/jTQWByK')
https://i.ibb.co/92ZkHNt/IMG-20190804-112138.jpg ('https://ibb.co/vmX64HY')
https://i.ibb.co/n0F1P9j/IMG-20190804-112146.jpg ('https://ibb.co/8BHxYq9')
https://i.ibb.co/VpGqQqR/IMG-20190804-112200.jpg ('https://ibb.co/BKJCrCb')
https://i.ibb.co/k8b3MPj/IMG-20190804-112208.jpg ('https://ibb.co/YknDbVm')
https://i.ibb.co/h7L9Lpn/IMG-20190804-112559.jpg ('https://ibb.co/bWQmQpy')
https://i.ibb.co/8dbWZ69/IMG-20190804-112608.jpg ('https://ibb.co/Tb1V3mt')
https://i.ibb.co/dp1F7cM/IMG-20190804-112640.jpg ('https://ibb.co/QHzLXcQ')
Some comments from the builder:
The balanced output transformers are from Sowter.
Yes, a single gain stage using a 76 direct coupled to a cathode follower using a 7193/2C22 single triode. The cathode followers could also be 6J5’s as the valve sockets are wired to accommodate either the 7193 with the anode and grids on the top caps, or 6J5’s with all connections at the valve sockets.
There is provision inside the case to store and insulate the anode and grid top caps if 6J5’s are used"
The input selector switch is made by Elma in Switzerland. Gold plated contacts. I believe Goldpoint use a similar switch body, but they use a small PCB to mount the contacts.
The 10uf Solen capacitors are decoupling capacitors for the B+ power supply. The gain stage is direct coupled to the cathode follower.
Gain controlled by 50k ohm stereo stepped attenuator with 24 steps. The output impedence is approximately 365 ohms and will drive long cable runs and difficult loads. Input impedence is 50K ohms.
There are 5 valves used: 2 x Type 76 and 2 x Type 7193 for the preamp stage and 1 x 6AX4GT for the soft start on the HT supply. The signal valves are vintage (1930/40s). The builder has a plentiful supply of spare valves should you need them.
Comes with a comprehensive manual/design guide which details some of the alternative valves that could be used such as Type 37 which will give slightly lower gain (13dB) compared to the Type 76 (15dB).
As you can see, the workmanship and quality of components/build are very impressive, I shudder to think what this would cost built by one of the well known manufacturers inside a fancy case.
£725 Collection only from Nottingham as I don't have a sturdy enough box to ship, or could meet up somewhere around east mids.
https://i.ibb.co/hZq3Y08/IMG-20190804-112100.jpg ('https://ibb.co/QC5yD0m')
https://i.ibb.co/bPC2qsh/IMG-20190804-112130.jpg ('https://ibb.co/jTQWByK')
https://i.ibb.co/92ZkHNt/IMG-20190804-112138.jpg ('https://ibb.co/vmX64HY')
https://i.ibb.co/n0F1P9j/IMG-20190804-112146.jpg ('https://ibb.co/8BHxYq9')
https://i.ibb.co/VpGqQqR/IMG-20190804-112200.jpg ('https://ibb.co/BKJCrCb')
https://i.ibb.co/k8b3MPj/IMG-20190804-112208.jpg ('https://ibb.co/YknDbVm')
https://i.ibb.co/h7L9Lpn/IMG-20190804-112559.jpg ('https://ibb.co/bWQmQpy')
https://i.ibb.co/8dbWZ69/IMG-20190804-112608.jpg ('https://ibb.co/Tb1V3mt')
https://i.ibb.co/dp1F7cM/IMG-20190804-112640.jpg ('https://ibb.co/QHzLXcQ')