getting 6Vac from an 18Vdc supply will right at the limit of visible clipping.
But long before you get there, there is an increase in distortion. Initially it's mostly second harmonic and because it's a Follower without global feedback it can sound quite acceptable.
Because of that increasing distortion with signal level, many advise a maximum signal level of ~ half the clipping level, i.e. <3Vac from an 18Vdc supply. This fits well with most CDP and other high level sources which top out at around 2Vac to 2.5Vac.
But long before you get there, there is an increase in distortion. Initially it's mostly second harmonic and because it's a Follower without global feedback it can sound quite acceptable.
Because of that increasing distortion with signal level, many advise a maximum signal level of ~ half the clipping level, i.e. <3Vac from an 18Vdc supply. This fits well with most CDP and other high level sources which top out at around 2Vac to 2.5Vac.
Thanks Andrew, meanwhile I am also looking at possibilities to replace 2SK170 as I have exhausted all I had. I read in one of the discussions we could use BF862 as a possible replacement...can anyone on this forum guide me if this has been attempted before for B1 buffer within this forum, also if I need to make mods to the existing design from Papa Pass
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Check power dissipation.
Read Juma's Threads on using the BF862.
It may be advisable to reduce voltage slightly for the BF862. DCB1 runs @ 20Vdc, B1 runs at 18Vdc, BF862 maybe 16Vdc?
Alternatively adding a cascode to each BF862 could be a good direction to go.
Read Juma's Threads on using the BF862.
It may be advisable to reduce voltage slightly for the BF862. DCB1 runs @ 20Vdc, B1 runs at 18Vdc, BF862 maybe 16Vdc?
Alternatively adding a cascode to each BF862 could be a good direction to go.
Hi All,
I just finnished solder the PCB...
was considering to use a HP laptop power brick 18,5V 3,5A
any feedback, experience to share using that ?
thanks in advance
I just finnished solder the PCB...
was considering to use a HP laptop power brick 18,5V 3,5A
any feedback, experience to share using that ?
thanks in advance
Power Supply
That laptop supply will be plenty. Put a meter on it to see what it actually puts out. Anything in that range should be fine but I've seen some that vary widely from what is stated. I've had excellent service from an old Panasonic phone supply for a B1 I built. Rock solid.
I wouldn't worry too much about being a bit over or under. I have another B1 build using a supply that runs at 21V. Sounds fantastic. I think the B1 circuit is pretty tolerant.
DB in MN
25°f and light snow at 11am
P.S.
The B1 will run on a pair of series 9v batteries. That's a good way to test. Very low amperage means very low damage risk if something isn't quite correct.
That laptop supply will be plenty. Put a meter on it to see what it actually puts out. Anything in that range should be fine but I've seen some that vary widely from what is stated. I've had excellent service from an old Panasonic phone supply for a B1 I built. Rock solid.
I wouldn't worry too much about being a bit over or under. I have another B1 build using a supply that runs at 21V. Sounds fantastic. I think the B1 circuit is pretty tolerant.
DB in MN
25°f and light snow at 11am
P.S.
The B1 will run on a pair of series 9v batteries. That's a good way to test. Very low amperage means very low damage risk if something isn't quite correct.
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I used such a power supply for a while. It functioned, but I noticed an improvement with the simple regulated unit 6L6 used in his build thread.
Russellc
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