To Danoroo (and ArnettPartners): I have been a longtime lurker on these forums and never posted until now. I thought I was going to be the only one who had ever had this anomaly (since the HK 990 seems to be somewhat rare). You're two posts confirm my suspicion on what was causing this scary phenomena.
I had the error with the volume happen 3 times, and I finally narrowed it down and can probably reproduce it (not that I would want to). I guess since it is a real issue I will call it the HK 990 runaway volume issue. If you can point me to the european forum that describes this, please do as I have not ever seen this pop up before publicly.
Let me explain how this happened to me:
In my normal listening setup, I primarily listen to a Dual 721 TT connected to the HK 990 via the MM inputs and ground wire connected there too. I also have a media comp. connected via toslink-1 and cable box connected via toslink-2. I have used the amp with no issues, only immense satisfaction at how awesome it sounds connected to these devices and outputting to KEF LS50 speakers and Klipsch 12 sub. Amazing sound. Maybe more on that later.
However, I have several other TT's that I like to rotate in to my living room from time to time. To keep from having to disconnect the main Dual, I purchased an Emotiva XPS-1 phono preamp and would connect that device to one of the other HK 990 RCA inputs (such as CD or tuner). I then connect whatever TT I desire to the Emotiva (along with ground wire to Emotiva). Note that the separate phono pre has a power supply connected to same wall outlet.
One afternoon I decided to connect a Sony TT to the XPS-1 and do some listening (I had a new stylus I wanted to hear). After listening a bit I was changing volume with the remote and all of the sudden the volume rapidly started getting louder and louder (the number in display was not changing). It quickly rose to deafening sound and I rushed across the room to turn it down as the remote was not helping. I visible was horrified at the head-busting distorted sound and the noticed the drivers on my KEF's were going to maximum displacement.I hit the power button and started to cringe as I thought the worst had happened to my system and fairly newly purchase KEFs.
I monitored things closely as I powered it back on and tried to listen to the Sony TT again. After a few minutes the volume started to runaway again but I shut it down before it got out of hand.
I disconnected the Emotiva amp (thus the Sony TT too). I was able to safely listen to the other inputs (inlcuding Dual TT) just fine from then on. Luckily my system was unharmed and the KEFs are fine :).
After a few days I decided to troubleshoot this and I removed the Dual from the system. I then connected the Sony T to the primary MM inputs on the HK 990. No problem, I never had the runaway volume issue. Weeks went by and I wanted to try the 2 turntable setup again and I redid the same configuration as before (Dual on primary inputs, Sony on Emotiva). The volume got wacky once again after some time and I decided I simply cannot have the Emotiva plugged into the other inputs, there is something electrical that is causing the HK 990's computer or outputs to go nuts.
After seeing your comments. It does seem possbly related to the ground loop. Let me know the european forum link... I would like to compare notes.
I don't want to change to a different amp as it does everything I need (I just have to be careful with the 2 tt setup) and I love the sound too much. It is an incredible combination with the KEF's which ar3 4-6 ohm speakers and the HK is perfect for them as it can push 300 watts to 4 ohms!
However, I am going to audition a Schiit Uber DAC this weekend with the HK 990 to see how external DAC compares with the included one.
I had the error with the volume happen 3 times, and I finally narrowed it down and can probably reproduce it (not that I would want to). I guess since it is a real issue I will call it the HK 990 runaway volume issue. If you can point me to the european forum that describes this, please do as I have not ever seen this pop up before publicly.
Let me explain how this happened to me:
In my normal listening setup, I primarily listen to a Dual 721 TT connected to the HK 990 via the MM inputs and ground wire connected there too. I also have a media comp. connected via toslink-1 and cable box connected via toslink-2. I have used the amp with no issues, only immense satisfaction at how awesome it sounds connected to these devices and outputting to KEF LS50 speakers and Klipsch 12 sub. Amazing sound. Maybe more on that later.
However, I have several other TT's that I like to rotate in to my living room from time to time. To keep from having to disconnect the main Dual, I purchased an Emotiva XPS-1 phono preamp and would connect that device to one of the other HK 990 RCA inputs (such as CD or tuner). I then connect whatever TT I desire to the Emotiva (along with ground wire to Emotiva). Note that the separate phono pre has a power supply connected to same wall outlet.
One afternoon I decided to connect a Sony TT to the XPS-1 and do some listening (I had a new stylus I wanted to hear). After listening a bit I was changing volume with the remote and all of the sudden the volume rapidly started getting louder and louder (the number in display was not changing). It quickly rose to deafening sound and I rushed across the room to turn it down as the remote was not helping. I visible was horrified at the head-busting distorted sound and the noticed the drivers on my KEF's were going to maximum displacement.I hit the power button and started to cringe as I thought the worst had happened to my system and fairly newly purchase KEFs.
I monitored things closely as I powered it back on and tried to listen to the Sony TT again. After a few minutes the volume started to runaway again but I shut it down before it got out of hand.
I disconnected the Emotiva amp (thus the Sony TT too). I was able to safely listen to the other inputs (inlcuding Dual TT) just fine from then on. Luckily my system was unharmed and the KEFs are fine :).
After a few days I decided to troubleshoot this and I removed the Dual from the system. I then connected the Sony T to the primary MM inputs on the HK 990. No problem, I never had the runaway volume issue. Weeks went by and I wanted to try the 2 turntable setup again and I redid the same configuration as before (Dual on primary inputs, Sony on Emotiva). The volume got wacky once again after some time and I decided I simply cannot have the Emotiva plugged into the other inputs, there is something electrical that is causing the HK 990's computer or outputs to go nuts.
After seeing your comments. It does seem possbly related to the ground loop. Let me know the european forum link... I would like to compare notes.
I don't want to change to a different amp as it does everything I need (I just have to be careful with the 2 tt setup) and I love the sound too much. It is an incredible combination with the KEF's which ar3 4-6 ohm speakers and the HK is perfect for them as it can push 300 watts to 4 ohms!
However, I am going to audition a Schiit Uber DAC this weekend with the HK 990 to see how external DAC compares with the included one.