That’s just freakin gorgeous!!
Thank you so much. I wish I had a better picture of the face. the lighting is not good in the rack.
Here is one from during the restoration process.
It wasn't too shabby. But it had clearly been sitting for a long time. I just took the time to replace all the caps, many of the resistors, built a rectifier, re-flowed almost all the solder joints, and polished the chassis.
I am still in the process of tuning the phono stage. I am adjusting the resistor values on the input to match my MC Cartridge.
I am also going to be replacing the volume pot with a 23-step attenuatior.
Sorry for over sharing. lol
Oh yeah, and matched up with my restored Thorens TD160.
I am still in the process of tuning the phono stage. I am adjusting the resistor values on the input to match my MC Cartridge.
I am also going to be replacing the volume pot with a 23-step attenuatior.
Sorry for over sharing. lol
Oh yeah, and matched up with my restored Thorens TD160.
Maybe they are Uniodes - an amplifying tube with just one element ...
... and heater of course.
to my knowledge, these directly heated monodes been manufacturing for long time
Well; and they were called Barretters, or Ballast Tubes.
An externally hosted image should be here but it was not working when we last tested it.
What does a ballast do ?
Kind of CCS. Resistance of the filament depends on it's temperature, so the higher is the voltage drop, the higher is the resistance.
My self restored HH Scott LK-72
Wow that is very very nice!
50W Williamson
Here are a couple of 50W Williamson monoblocks I built 18 months ago. Based on My KT88 Williamson Amp Build but with modifications to accommodate 6GU7s and 6550s and an LC power supply. I believe this was originally a GEC design.
There's 12.5dB of feedback.
For stabilisation I tried 47pF across the feedback resistor and various RC combinations across the V1A anode resistor but settled on 4k7 in series with 470pF across the V1A anode resistor.
In addition to the pictures of the units and circuit diagrams there are 5kHz scope shots of no added stabilisation and with the stabilisation (resistive load and 2uF load).
They sound great!
Thoroughly enjoyed the whole process of simulation using LTSpice, ordering parts, designing the physical layout, having the chassis' laser cut, bent, welded and painted, assembly and testing.
I learned a lot. Like if I ever build more, don't put the bias test points so close to the hot output valves!
The only major problem I had was electromechanical hum induced into the chassis' by the mains transformers (another thread) reduced to an acceptable level by putting sliced rubber grommets under the feet of the mains transformers.
Here are a couple of 50W Williamson monoblocks I built 18 months ago. Based on My KT88 Williamson Amp Build but with modifications to accommodate 6GU7s and 6550s and an LC power supply. I believe this was originally a GEC design.
There's 12.5dB of feedback.
For stabilisation I tried 47pF across the feedback resistor and various RC combinations across the V1A anode resistor but settled on 4k7 in series with 470pF across the V1A anode resistor.
In addition to the pictures of the units and circuit diagrams there are 5kHz scope shots of no added stabilisation and with the stabilisation (resistive load and 2uF load).
They sound great!
Thoroughly enjoyed the whole process of simulation using LTSpice, ordering parts, designing the physical layout, having the chassis' laser cut, bent, welded and painted, assembly and testing.
I learned a lot. Like if I ever build more, don't put the bias test points so close to the hot output valves!
The only major problem I had was electromechanical hum induced into the chassis' by the mains transformers (another thread) reduced to an acceptable level by putting sliced rubber grommets under the feet of the mains transformers.
Attachments
Here are a couple of 50W Williamson monoblocks
Nicely done! I like how you placed a particular attention to placement of parts and crossing wires at 90deg. Must sound good.
Here are a couple of 50W Williamson monoblocks I built 18 months ago.....
Nice! Build looks good and I bet they sound great. It sucks having to wait so long for the Edcors but they're worth it.
Nicely done! I like how you placed a particular attention to placement of parts and crossing wires at 90deg.
I wish I could take credit for that but it was purely accidental.
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