Several months ago, I got an F5, built with correct boards and parts, from a builder that had completed his F5 Turbo. A few days ago, the volume ramped down to a lower level while listening, than returned to previous volume after 20 seconds or so. Seemed to happen in both channels at the same time, so I'm thinking it's a power supply issue. This happened several times over several days, and I figured I shouldn't torture it any more. I do not listen at high volume, and the amp has never been more than warm when I check. A Museatex mosfet amp is now back into my system - it's a nice amp, but not up to the sound quality of the F5.
I am not technically savvy, and a multimeter is my only piece of test equipment.
Pretty sure I can get a local, qualified repair tech to deal with this. Does anyone have any advice that I can relay to him? How 'bout a link to a schematic and board layouts to help him?
I am not technically savvy, and a multimeter is my only piece of test equipment.
Pretty sure I can get a local, qualified repair tech to deal with this. Does anyone have any advice that I can relay to him? How 'bout a link to a schematic and board layouts to help him?
There's a chance it's from an upstream component like the preamp, so try running it from a different one first.
It could be a bad power supply connection in the amp, though.
F-5 – diyAudio Store
https://cdn.shopify.com/s/files/1/1006/5046/files/F5_Schematic_w-P3.jpg
Universal PSU – diyAudio Store
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Thanks! The seller did say he'd put quick-connectors between power supply and the amp boards, so he could switch between Aleph J boards (which I also have) and F5 boards. I'll have a look. Will also change power cords, just in case.
The volume issue happened playing my turntable, and also playing music from my PC/DAC. And, with the Museatex amp in the system, there's been no issue. I have a spare preamp (Nikko Beta 30), so will give it a try with the F5.
Seems it's not the F5 that's at fault. I got another amp, a Sears dual-mono MOSFET made by Inkel, and have been listening to it for the last five days. All OK, until a few hours ago when the volume again ramped down then back up, several times over an hour or so.
My preamp is the Meitner PA6i with corded remote. It may be the culprit, time to put a vintage Nikko Beta 30 back into the system
My preamp is the Meitner PA6i with corded remote. It may be the culprit, time to put a vintage Nikko Beta 30 back into the system
I've learned that the volume level of the Meitner preamp is voltage controlled (no pots or stepped attenuators), and apparently this type of setup can develop the wandering volume that I experienced. Whatever the cause, it decided to correct itself and I had the Meitner in-system for several more months without any issue.
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