I recently purchased a used Keces DA-131 DAC from my favourite on-line retailer. I am still getting familiar with the open and transparent sound of this great DAC in my system. However, I could never get used to the clearly audible toroid transformer mains buzz that I could hear during music gaps and quiet passages. Something the seller "forgot" to mention and no doubt the real reason he got rid of this absolute gem of a DAC.
The good news is I fixed it and it was really easy🙂. I unscrewed the toroid bolt and metal clamp, noticed the buzz was greatly reduced with the toroid just sitting on its rubber washer on the base. I re-assembled using a piece of "closed cell" packing material as a base washer and a used solder wick spool as a top clamp, though any piece of plastic would do. I tightened the whole assembly just enough to prevent the toroid moving freely. The mains buzz has now completely disappeared. This method could be applied to troublesome toroids in other DAC's or pre-amps though the effect might lessen as the toroid size increases. IMHO it also has had some benefit to the DAC sound quality though as I am still "breaking in" the new DAC, this might just be "listener expectation". Try it and hear!😉
The good news is I fixed it and it was really easy🙂. I unscrewed the toroid bolt and metal clamp, noticed the buzz was greatly reduced with the toroid just sitting on its rubber washer on the base. I re-assembled using a piece of "closed cell" packing material as a base washer and a used solder wick spool as a top clamp, though any piece of plastic would do. I tightened the whole assembly just enough to prevent the toroid moving freely. The mains buzz has now completely disappeared. This method could be applied to troublesome toroids in other DAC's or pre-amps though the effect might lessen as the toroid size increases. IMHO it also has had some benefit to the DAC sound quality though as I am still "breaking in" the new DAC, this might just be "listener expectation". Try it and hear!😉
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