Hi guys, i am very stoked about my new sum2 but i ran into some unknowns while calibrating the levels.
-First i noticed when i send in a perfect square wave it comes out scewed/slewed. i have learnt this could be caused by low pass filtering or ac coupling. would love to know for sure.
-i now have calibrated each individual channel around 9v peak to peak so it doesnt come out clipped with gain and master out potentiometers opened fully. i noticed that channel 3 cant get upto that level and has minor distortion. what can i do to check/fix this section?
-about the send channels... ive noticed my effects sometimes send back over 20v peak to peak levels. what would be an acceptable level to tune these to?
-in general what would be a wise calibration procedure? opening gain and master fully/ halfway or something else entirely?
thanks in andvance, yoeri
Hey Yoeri, Thank you for reaching out, and apologies for the delayed response. Your thread was caught in the internal spam validation system (for whatever reaeson?), so I hadn’t seen it earlier.
Regarding the waves, they’re affected by the internal EQ, which is why the square appears slewed. You should be able to achieve a less slewed wave by adjusting the EQ settings.
All channels use the same components and should be capable of being calibrated to the same gain settings. What’s the maximum setting you can achieve with channel 3? If you adjust the gain trimmer on the front, are you unable to match the settings with the other channels?
The sends only have attenuation and gain control at the send output, which you can adjust using the Send potentiometer and the small send gain trimmers. On the return side, SUM2 processes whatever signal the effect is returning. If the return signal is too hot, you can lower the gain on the send channels.
In general, you can calibrate the gain to suit your specific needs. A good approach is to set the level potentiometers to a preferred maximum position—say, around noon. In this position, adjust the gain trimmers just below the point of distortion or clipping. This setup gives you maximum loudness at 12 o’clock with some headroom for oversaturation below that point. The same principle applies to the send pots. Thanks,
Stefan