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Cattle Driver - low output volume

MattG

New member
I just built the Cattle Driver. It works, except the output volume seems way too low to me. Unity gain is just past 3:00 on the level control (i.e. a little past 75%). I'm thinking it's probably not supposed to be like that. I think it's working as-expected otherwise, though I can't be 100% sure, since I'm just going off online videos of the Cattle Driver and the Buffalo TD-X (of which the CD is supposed to be a clone). Other than the volume issue, there's no other obvious problems.

Does anyone else happen to have a Cattle Driver that's willing to take voltage readings for me to compare with, particularly around the op-amps? Otherwise, what's the most likely culprit to start with for debugging this?

Thanks!
 

twebb6778

Active member
Take a close look to see if you've got any cold solder joints and verify all resistor values are correct. Can you post some pics of our board?
 

MattG

New member
Thank you for the quick reply! I'll go through and double-check the resistor values.

Here are my voltages:

At power input: 9.37 V

TL072:
pin 1: 4.24
pin 2: 4.24
pin 3: 3.85
pin 4: 0
pin 5: 3.86
pin 6: 4.24
pin 7: 4.24
pin 8: 8.46

LM301:
pin 1: 1.44
pin 2: 4.21
pin 3: 3.83
pin 4: 0
pin 5: 1.36
pin 6: 4.21
pin 7: 8.46
pin 8: 3.61

Edit: Resistor values check out. I also swapped in different op-amps, and re-measured pin voltages - only negligible differences compared to those I listed above. Looks like I'll have to pull it out of the case.

Here's a pic of one side of the board, in the enclosure. If all the resistor values check out, and I don't see any other obvious problems, I'll remove it from the case and post more pics of the other side of the PCB.

Thanks again!

guts_in_case.jpg
 
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MattG

New member
No particularly compelling reason for using film caps over electrolytics. But I spent a long time over at diyAudio doing audio electronics (though with a focus on music reproduction/playback, as opposed to guitar-specific), and developed a neurosis for avoiding electrolytics in the signal path. In theory, film caps ought to last longer than electrolytics (though I know that's not really a legitimate concern in this application). A minor practical benefit: I don't have to worry about polarity!

If nothing else, they look cool. :)
 

MattG

New member
I removed the board from the case. I won't have time until tomorrow to un-solder the two lower pots that block the view on some of the board. But from what I can see, I don't see any obvious issues. Before I took the pictures, I thought there may have been some tiny solder bridges, but I cleaned all those up, yet the problem remains. I'm using this fancy Cardas Soldering Wire Quad Eutectic Silver Solder, which is supposed to greatly reduce the chances of a cold solder joint.

Let me know if you see anything I missed. If no one here notices anything, when I remove those pots, I'll probably re-touch all the existing solder joints.

Sorry, these pics aren't the greatest - it was hard to get the camera to focus properly and have everything well lit. If the problem persists, I'll have to get out the DSLR and tripod. :)

Thanks again!
 

Attachments

Do you have an audio probe? I recently made one for my simulcast build and it helped me super fast. After you have it built you will have to follow the schematic through the audio path to track down where the signal dramatically decreases. If you need more info, check out my simulcast build in the troubleshooting section.
 
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