A few months ago, I decided to bypass my preamp and feed the output of my Eversolo DMP-A8 streamer straight into my VTA ST-70. The DMP has a built-in preamp and since I was only listening to streaming music, I figured it would be a "purer" sound. I recently hooked up my turntable and fed it into the DMP. When I switch the source on the DMP between the streamer and the turntable, I get a loud "POP" coming out of the speakers. I also get a quieter "POP" when the DMP powers on and off. I contacted Eversolo and after some troubleshooting, we figured out that the ST-70 doesn't like the way the output of the DMP is switched (like the relays are break-before-make and the output floats briefly). Is there a way of modifying the input circuit of the ST-70 so it isn't affected by the switching? Thanks!
3 posters
VTA ST-70 sensitive to switching input source
medphys- Posts : 5
Join date : 2020-04-05
Brap- Posts : 234
Join date : 2013-11-28
Age : 69
Location : Plainfield, illinois
Why not just mute the input signal prior switching?
markeby- Posts : 33
Join date : 2019-02-13
Age : 66
Location : Near Austin, Texas
The "pop" you hear is quite common when connecting a power amplifier the way you did. I have trained my wife and my children to turn the volume all the way down before turning off or on the power amp. Since I have a tube preamp as well, I have a power sequencer I designed to turn the power amp on last and off first so that any other devices do not cause the pop. This pop can damage the speakers as well.
medphys- Posts : 5
Join date : 2020-04-05
markeby wrote:The "pop" you hear is quite common when connecting a power amplifier the way you did. I have trained my wife and my children to turn the volume all the way down before turning off or on the power amp. Since I have a tube preamp as well, I have a power sequencer I designed to turn the power amp on last and off first so that any other devices do not cause the pop. This pop can damage the speakers as well.
The problem isn't because there's music playing that gets switched off mid-signal. The DMP-A8 mutes the signal before switching off and if I switch between inputs with nothing playing, it still creates the pop. In jact, it's much louder switching between input than when switching off. There's something about how it switches that's weird. I've put a scope on the output and I don't see any voltage spikes so maybe it's something like switching a ground connection in and out?
In the meantime, when I power down, I switch the VTA off first and wait a few seconds before switching off the DMP-A8 but I have to listen to the sound slowly decay into distortion, which isn't pleasant either.