Category 5
Well-known member
So silly me, I hooked the output of the channel a to the input of the channel a. in closed ear headphones I wondered why no output from the mic. As I proceeded to crank the gain I heard a ringing sound. i removed my headphones and noticed my error.
It was the transformers ringing...audibly! I immediately pulled the cables off and proceeded to test the preamp... Whew, the mic worked and sound came through.
Tonight I had a stereo pair hooked up (matched mind you) and noticed the output of channel 2 seemed noticably brighter than 1. I swapped cables, channels, pans, mics...always channel 2 was brighter.
Now I am worried! Did I fry my op-amp? Did I fry my transformers? (is that possible?).
Are my 1973 2520s just "different" and I never noticed it before?
Also, on preamp one the voltage pots and dc offset pot are a little twitchy compared to the pots on module 2. Could this be because I had heat on them too long while soldering? Channel 1 was my first and I may have done this. Also, could a less accurate +/- ratio or DC offset setting cause the effects I hear? I'd rather replace the pots than the op-amp, or transformers.
If it's the Op-Amps, at least I can get A-P-eye to replace them, can't I? Anyone know what this costs?
Thanks!
Shane
It was the transformers ringing...audibly! I immediately pulled the cables off and proceeded to test the preamp... Whew, the mic worked and sound came through.
Tonight I had a stereo pair hooked up (matched mind you) and noticed the output of channel 2 seemed noticably brighter than 1. I swapped cables, channels, pans, mics...always channel 2 was brighter.
Now I am worried! Did I fry my op-amp? Did I fry my transformers? (is that possible?).
Are my 1973 2520s just "different" and I never noticed it before?
Also, on preamp one the voltage pots and dc offset pot are a little twitchy compared to the pots on module 2. Could this be because I had heat on them too long while soldering? Channel 1 was my first and I may have done this. Also, could a less accurate +/- ratio or DC offset setting cause the effects I hear? I'd rather replace the pots than the op-amp, or transformers.
If it's the Op-Amps, at least I can get A-P-eye to replace them, can't I? Anyone know what this costs?
Thanks!
Shane