Just begun building my SSE amplifier.
Using 360-0-360 @0.4amps, 2x6.3v @ 4a, 1x5v @ 4amps transformer from 230v at 50hz.
Here we have a steady 240v AC supply here rather than 230v so I guess that'll increase the output a bit to 375-0-375
SSE OPTs (not push pull) at 5k with taps @ 1.5k/3.5k so hopefully I can utilise UL
100uf run capacitor
5h choke impedance somewhere between 50-100 ohms - not arrived yet so unsure. Does the impedance matter?
Planning on having independent volume controls for each channel to allow balancing of tubed if they are not matched well.
EL34's for output valves, just cheapies from China initially.
Using 360-0-360 @0.4amps, 2x6.3v @ 4a, 1x5v @ 4amps transformer from 230v at 50hz.
Here we have a steady 240v AC supply here rather than 230v so I guess that'll increase the output a bit to 375-0-375
SSE OPTs (not push pull) at 5k with taps @ 1.5k/3.5k so hopefully I can utilise UL
100uf run capacitor
5h choke impedance somewhere between 50-100 ohms - not arrived yet so unsure. Does the impedance matter?
Planning on having independent volume controls for each channel to allow balancing of tubed if they are not matched well.
EL34's for output valves, just cheapies from China initially.
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Cheers
I am looking at bias adjustment via a rotary switch and resistors in parallel with a 680 resistor.
What was the switchable voltage you did? Or was it just bias resistor changes like I am thinking?
First build I put a DPDT switch with 275 & 300. I get 310, 340 & 360v with either SS or tube rectifier.
Second build has 300 & 350. I get 340, 360, 390 & 410v with either SS or tube rectifier.
- The higher voltages work with Russian 6P3S-e & EL34 at 560R.
Please try UL /Triode switching. Earlier I didn't like Triode, but with 560R it sounds great. I'm running Altec speakers but can't say if that makes the difference.
- 340v for 6V6 | Vk ~23.4v | 680R
- 360v for 807, 6L6GC, 5933 | Vk ~27-30v | 680R /560R (560 sounds superb)
Second build has 300 & 350. I get 340, 360, 390 & 410v with either SS or tube rectifier.
- The higher voltages work with Russian 6P3S-e & EL34 at 560R.
Please try UL /Triode switching. Earlier I didn't like Triode, but with 560R it sounds great. I'm running Altec speakers but can't say if that makes the difference.
Cheers, yes getting there. Waiting on chassis punches at the moment. Once they arrive hopefully I can make some more progress.
When you get it up, could you let us know how the 120R thermistor is working. I tried 10 & 50R and couldn't control the B+ startup 
. If the 120R works I'll try that.
With 50R and SS supply, the B+ ramps up within 3-5secs. The cathode V takes a few secs later to climb up. With tube rectifier, they both rise slowly in about 10-15 secs. Its scary.
. If the 120R works I'll try that.With 50R and SS supply, the B+ ramps up within 3-5secs. The cathode V takes a few secs later to climb up. With tube rectifier, they both rise slowly in about 10-15 secs. Its scary.
I've actually got 2 120D's one on the centre tap input on the board, and another inline with the 240vac before the power transformer (not 100% sure I need the second one, but it should slow down the heater warm up).
I removed tr1 substituted a wire link because I am using 120D on centre tap.
You say scary, what do you mean by scary?
I removed tr1 substituted a wire link because I am using 120D on centre tap.
You say scary, what do you mean by scary?
Maybe 'scary' is being dramatic, but I don't know better and happy to be educated.
At 300v secondary and a tube rectifier, I never see the digital meters go higher than 345 on the B+ and this is over 10 secs. The B+ and cathode voltage come up together and settle around 340v.
With SS, the B+ jumps to ~ 400v almost as soon as it is switched on. The cathode V takes a few seconds and then the B+ starts dropping to ~ 360v. That is what is scary.
The 120R thermistor on the primary has almost no effect. I read somewhere two could be used in series to get a delay. If someone could help understand how that is and values, it would be great.
Sorry, I didn't mean to hijack your thread.
At 300v secondary and a tube rectifier, I never see the digital meters go higher than 345 on the B+ and this is over 10 secs. The B+ and cathode voltage come up together and settle around 340v.
With SS, the B+ jumps to ~ 400v almost as soon as it is switched on. The cathode V takes a few seconds and then the B+ starts dropping to ~ 360v. That is what is scary.
The 120R thermistor on the primary has almost no effect. I read somewhere two could be used in series to get a delay. If someone could help understand how that is and values, it would be great.
Sorry, I didn't mean to hijack your thread.
You are not hijacking my thread. It's helpful to hear about your experiences. Cheers Ian