Those voltage drops indicate 125mA & 129mA output stage bias if with 10R R10s or 104 & 107.5mA if with 12R R10s. Very close bias matching considering Mosfets and resistors tolerances. Offset behavior looks good.
Not with output shorted, with input shorted I believe you meant for offset adj. Check offset again when the volume pot will be installed. At 12 o' clock position on open input for a final pass/adj with the op-amp in place.
Not with output shorted, with input shorted I believe you meant for offset adj. Check offset again when the volume pot will be installed. At 12 o' clock position on open input for a final pass/adj with the op-amp in place.
Such champion measuring amps achieve fantastic SNR figures by exploiting low own voltage gain as well. This can be a subdued dynamics trap when on medium sensitivity speakers if not with high output XLR connected (doubling the signal voltage) digital sources. I suggest around 20dB power amp voltage gain for single ended signal if digital source only or around 25dB for phonographic source in your case with the Totem Hawk loudspeakers. That's on top of your DCG3 9.54dB line gain (x3). A well proportioned system voltage gain structure is key. Not too sleepy not too noisy.
Great. Put some thermal paste between plate and chassis when you will finalize it though. For good thermal travel to the main metal mass. Helps when the top lid will be closed. Especially in summertime when class A living isn't easy. 😉
Looks good except the wrong red and black colors on the input RCAs vs your L,R designations (trivial). They are basically channels 1,2 and you call them anything you like as long as they do not get mixed up.
Thanks. Can I check output resistance as an indicator of attenuation? Or something else to know I am not putting out max volume and see if pot wired and working as intended?
You can put say 400Hz 1V RMS sinewave in the pot from a computer gen app if you don't have a bench generator and see it attenuating at the pot's output with a DMM on ACV mode or on a scope if you got one.
There was a humming noise in both channels, increasing as I turn volume up. Will check on thursday evening all wiring again.
Try also connecting the two input RCA barrel pins together to see if that helps. Remember about grounding the pot's body too especially if the bracket isolates it (asterisk note in post #7,074).
I have a problem on the negative rail of my DCSTB which worked fine until now.
Could anyone help me determine which component I need to change?
My measurements (positive rail OK, negative rail NOK) :
+Vi: 28 V
+V0: 13,8 V
+Dref: 14,4 V
-Vi: 27,2 V
-V0: 27,8 V
-DRef: -28V
Is the bar graph out of service?
In the photo you can see that the LEDs are highlighted.
Thank you.
Could anyone help me determine which component I need to change?
My measurements (positive rail OK, negative rail NOK) :
+Vi: 28 V
+V0: 13,8 V
+Dref: 14,4 V
-Vi: 27,2 V
-V0: 27,8 V
-DRef: -28V
Is the bar graph out of service?
In the photo you can see that the LEDs are highlighted.
Thank you.
Attachments
Too much current runs in the top bar graph. Maybe permanently compromised or not. Test/replace Q4 first.
Thanks Salas.
I replaced Q4 and -V0 went down to -14.3V.
One LED on the LED bars remains off (see photo) which must explain the 0.5V difference.
Would it be possible to decrease by 0.5V without changing the LED bars?
Because with Ry = 1 ohm, I don't see how.
I replaced Q4 and -V0 went down to -14.3V.
One LED on the LED bars remains off (see photo) which must explain the 0.5V difference.
Would it be possible to decrease by 0.5V without changing the LED bars?
Because with Ry = 1 ohm, I don't see how.
I see two right side segments off in each bar in your photo #7,116. Are those bypassed on purpose to have Vout <15V?
You mean the central segment is off also on the top bar?
You mean the central segment is off also on the top bar?
Yes, 2 segments are bypassed to have a voltage around 13.8 V.
Indeed a central segment is off.
Indeed a central segment is off.