R1 is part of the CRC-filter to reduce ripple of the power supply. Do a search on CRC, a very popular method for ClassA amps.
The B1 has decent PSRR since the jfet is fed by a (jfet) current source, so using a regulator probably brings little benefit. Of course feel free to experiment 😀
Have fun, Hannes
The B1 has decent PSRR since the jfet is fed by a (jfet) current source, so using a regulator probably brings little benefit. Of course feel free to experiment 😀
Have fun, Hannes
AndrewT said:
The R1 is that one wich you can see on the full schematic of the B1, just between the alim (+18V) and the C1 (15000uF).
Thanks
Compact enough, just warm, won't oscillate easily, readily available Mosfets, leftover unmatched SK170s. Iccs = (Vleds-3.4)/R1 (1W resistor). Start with 10R. Led string of 3 gives different Vdrop total depending on color and maker. Use green ones, more constant. I wanted it ''Kitsch LED Shunt'' so I used tricolore.😀
Attachments
Haven't made a negative side. My Riaa is positive only, B1 is positive only with caps, you want to make a capacitor-less one with symmetrical PSUs like I did? I can try to mirror it on the simulator if so.
Neg reg
That would be nice, if you don't mind Salas.
Instead of the B1, I use a "JC" buffer (k170, j74) like NP's, in the Lightspeed Vol Control for my F3 and headamp (DOA-T) - both have low input Z.
It's nearly totally transparent but is very dependent on the supply - using a "rough" Toole shunt reg at present, and curious to hear the sound of yours, and also in comparison to the "Teddy-reg".
That would be nice, if you don't mind Salas.
Instead of the B1, I use a "JC" buffer (k170, j74) like NP's, in the Lightspeed Vol Control for my F3 and headamp (DOA-T) - both have low input Z.
It's nearly totally transparent but is very dependent on the supply - using a "rough" Toole shunt reg at present, and curious to hear the sound of yours, and also in comparison to the "Teddy-reg".
RC filter only.
1 Ohm times 15000uF times 6.28 ~ 0.0942
1/0.0942~10.5 Hz, an RC filter drops voltage ripple by 20dB/decade.
Means something like 19.5dB ripple suppression in the EC (50Hz mains) and ~1.5dB more in the US(60Hz).
1 Ohm times 15000uF times 6.28 ~ 0.0942
1/0.0942~10.5 Hz, an RC filter drops voltage ripple by 20dB/decade.
Means something like 19.5dB ripple suppression in the EC (50Hz mains) and ~1.5dB more in the US(60Hz).
I've got a couple of quick questions. I'm got a few more parts to order, but I've got some 'spare' parts I could try.
I've got 100k Stereo pot, and a 100k stepped attenuator from a previous project. I guess I could substitute them in for a while.
What's the best way to scope and test this buffer?
I've got an oscilloscope I haven't used in years, hopefully it still works.
I've got 100k Stereo pot, and a 100k stepped attenuator from a previous project. I guess I could substitute them in for a while.
What's the best way to scope and test this buffer?
I've got an oscilloscope I haven't used in years, hopefully it still works.
I found this on ebay.
It measures 200mm x 145mm x 70mm (8" x 5.7" x 2.8")
I was hoping I could fit the B1 (sideways) in a case like that and mount the jacks and controls on the front/back.
Aluminum Case
It measures 200mm x 145mm x 70mm (8" x 5.7" x 2.8")
I was hoping I could fit the B1 (sideways) in a case like that and mount the jacks and controls on the front/back.
Aluminum Case
Just put your pot in and try it. It wont hurt anything and if it sounds good to you then you have a winner.
Uriah
Uriah