R2 measures 47K both channels.
Junction of R1 and R2 8mV each channel.
Is the JFET's current close to 8ma? Using P3 I balanced the two JFets to have max. 6mA.
I don't know what's the wiper position of P1 & P2.
Are P1 and P2 shrting the C1 and C2 caps? I guess yes because I adjusted the mosfet bias to 1V.
Junction of R1 and R2 8mV each channel.
Is the JFET's current close to 8ma? Using P3 I balanced the two JFets to have max. 6mA.
I don't know what's the wiper position of P1 & P2.
Are P1 and P2 shrting the C1 and C2 caps? I guess yes because I adjusted the mosfet bias to 1V.
I don't know if this information matter but I let you know: the source impedance of noDac connected to the input of BA-3 is 50 ohms.
I'd keep that R1 in place, especially with that low noDAc output impedance.
I am not sure why this is happening....
The amp seems to be working correctly, as you stated here:
I am thinking about this statement:
How do you measure the voltage drop? Do you place the oscilloscope probe on SG output, and then connect the SG to the amp input, at which point you see the voltage drop on the oscilloscope screen?
On a side note, make sure the shunt regs can supply the required current... without collapsing.
I am not sure why this is happening....
The amp seems to be working correctly, as you stated here:
I am thinking about this statement:
How do you measure the voltage drop? Do you place the oscilloscope probe on SG output, and then connect the SG to the amp input, at which point you see the voltage drop on the oscilloscope screen?
On a side note, make sure the shunt regs can supply the required current... without collapsing.
Last edited:
The noDac it's an USB I2S output filtered with a 4th LPF, attached schematic, there isn't the output coupling capacitor that the value depend of input impedance that for BA-3 47K is 1,69uF but I installed 4,7uF that's the value that I have on hand..
Attachments
Measured with my true RMS voltimeter, yes probes direct to SG one measurement without nothing connected to set 1kHz 0,190Vrms, second measurement with BA-3 connected to Input + and GND probes connected also to to Input + and GND of BA-3 lowered to voltage to 0,009Vrms
Measured each reg is giving 200mA or a little more.
What happens with the voltage reading of 0.009Vrms if you remove the power to BA3?? Recovers to 0.190Vrms?
Try what Boky is suggesting above, though it seems the BA-3 is working fine.
What is the DC V at the 50 ohm resistor?
What is the DC V at the 50 ohm resistor?
Not recovers 190mVrms, increase but only till 18mVrms but in place of 1kHz like connected to SG measures 0Hz.
If you disconnect the BA-3 and play a sine wave through the JLSounds, do you get a sine wave at the 50R resistor? You would either need an oscilloscope for this or an RMS meter that can measure the frequency. 60 Hz is best. Trying to make sure that you are getting signal that you want from the JLSounds. If this works, then it is likely a question of loading.
Yes, otherwise didn't listen music. I listened several years only with Amanero USB-I2S + LPF + step-up 1:7 ratio without any problem but not reach the standard output of 2Vrms so when recordings are low level doesn't enjoy the same.
Last edited:
Hey looking for some more Jfets I have a couple of 2SK170V, one 11,66mA and the other 11,77mA so surely reach the 10mA with BA-3, also I have a couple of SJ74BL not so strong but can be good: one 10,73mA & the other 10,75mA, worth the change to increase the SQ?