idsnowdog
Imperator of Indignation
New Old Mixer Day. Earlier this week I saw a curb alert for some free audio gear on Craigslist. So, I stopped by after work and picked up a Shure M67 4-channel microphone mixer, a Behringer crossover, and a Yamaha power amp. The power amp was garbage so I scrapped it and got dozens of transistors, diodes, resistors, and capacitors from it.
The M67 worked but the more I read about it they talked about it being noisy and low-fi due to its AC transformer creating a lot of hum and hiss. I opened it up and I could see all the components were original. One of the odd features is it could be powered from a 30V DC battery for concert use like this example at Woodstock.
People who used it with DC power didn't have as many complaints because the AC transformer is out of the picture. So, I studied the schematic and replaced the 57 year old electrolytic capacitors on the DC portion of the circuit with capacitors I salvaged from the Yamaha. I cut off the AC power cord and replaced it with a 29V DC wall wart that I soldered internally to the battery terminals.
Moving the transformer away from the main board and replacing the old capacitors did the trick and I think the people who say these things are useless are FOS. I did some recoding today and I don't think it's much worse than a lot of budget gear. My Line6 Toneport seems noisier.
The M67 worked but the more I read about it they talked about it being noisy and low-fi due to its AC transformer creating a lot of hum and hiss. I opened it up and I could see all the components were original. One of the odd features is it could be powered from a 30V DC battery for concert use like this example at Woodstock.
People who used it with DC power didn't have as many complaints because the AC transformer is out of the picture. So, I studied the schematic and replaced the 57 year old electrolytic capacitors on the DC portion of the circuit with capacitors I salvaged from the Yamaha. I cut off the AC power cord and replaced it with a 29V DC wall wart that I soldered internally to the battery terminals.
Moving the transformer away from the main board and replacing the old capacitors did the trick and I think the people who say these things are useless are FOS. I did some recoding today and I don't think it's much worse than a lot of budget gear. My Line6 Toneport seems noisier.
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