slipperyflax
Active member
- Joined
- Oct 2, 2016
- Messages
- 27
First post and a newbie in the DIY-world. Like it so far though Anyhow, put together a MP 573 as a first build (have soldering experience since before though) and when it came to the setup I got these results:
Setup step:
1. Short circuit check: No problem, it was value greater than 1k ohm. However, it kept rising steadily, and didn’t really set at any value. Is this normal?
2. -
3. General power check: I have a Fredenstein Bento 6, The DMM read 25.2V both with the output transformer connected and without. Bad sign I guess?
4. Bias adjust: I had no problem here.
5. Sound check: I had no problem here really. However, between gain steps 20-30, 30-40, 40-50 and 50-60 there’s a popping sound.
6. DI Check: No problem.
Also, when having a guitar (humbucker) plugged in the DI, I feel that it’s kind of hard to get the unit to "distort/clip" before my interface does (Saffire Pro 40, with input pad engaged). When I have the MP573 set to LINE, I can have the GAIN knob all the way up but and the trim-knob all the way down, but the LED won’t turn red. I can make the LED turn red at other settings, and with a condenser/dynamic microphone, but I found it kind of baffling. I'm not necessarily implying that anything is wrong with the lack of distortion/clipping at LINE input, just want to confirm this is the way it should be. My main concern is that the voltage didn't drop with the output transformer plugged in. I do realize that when designing a micpreamp like this back in the day you'd like to avoid distortion/clipping :
I’ve tried to check solder joints but I can’t find anything that seems wrong. Nice and shiny joints but I guess I have a fault somewhere. What do you guys think? It doesn't seem to be anything that gets particular hot either. Could there be faulty resistors somewhere? or is everything fine?
EDIT
Schematics: http://www.soundskulptor.com/docs/mp573-schematic-02.pdf
Setup guide: http://www.soundskulptor.com/docs/mp573-setup-guide-02.pdf
Setup step:
1. Short circuit check: No problem, it was value greater than 1k ohm. However, it kept rising steadily, and didn’t really set at any value. Is this normal?
2. -
3. General power check: I have a Fredenstein Bento 6, The DMM read 25.2V both with the output transformer connected and without. Bad sign I guess?
4. Bias adjust: I had no problem here.
5. Sound check: I had no problem here really. However, between gain steps 20-30, 30-40, 40-50 and 50-60 there’s a popping sound.
6. DI Check: No problem.
Also, when having a guitar (humbucker) plugged in the DI, I feel that it’s kind of hard to get the unit to "distort/clip" before my interface does (Saffire Pro 40, with input pad engaged). When I have the MP573 set to LINE, I can have the GAIN knob all the way up but and the trim-knob all the way down, but the LED won’t turn red. I can make the LED turn red at other settings, and with a condenser/dynamic microphone, but I found it kind of baffling. I'm not necessarily implying that anything is wrong with the lack of distortion/clipping at LINE input, just want to confirm this is the way it should be. My main concern is that the voltage didn't drop with the output transformer plugged in. I do realize that when designing a micpreamp like this back in the day you'd like to avoid distortion/clipping :
I’ve tried to check solder joints but I can’t find anything that seems wrong. Nice and shiny joints but I guess I have a fault somewhere. What do you guys think? It doesn't seem to be anything that gets particular hot either. Could there be faulty resistors somewhere? or is everything fine?
EDIT
Schematics: http://www.soundskulptor.com/docs/mp573-schematic-02.pdf
Setup guide: http://www.soundskulptor.com/docs/mp573-setup-guide-02.pdf