Hello All
My set up is as follows;
- PC as source ( music converted using apple lossless) =>
- Audio Alchemy DAC =>
- Rose RV-23S Valve/Transistor Pre-amplifier =>
- NAIM NAP90 Power Amp (Chrome Bumper model) =>
- Speaker cable Audioquest FLX -SLiP 14/4 ( 2.5M) =>
- B&W DM 602 speakers
I've been using this "Frankenstein" set up for years and it sounds amazing.
However it all started going horribly wrong, I would be listening and one channel would suddenly generate a hum.
when I mean hum, it was a large buzz (not background noise) which forced me to switch it all off.
I decided to get the amps serviced, since the pre-amp in particular was still on the original tubes and assumed it was possibly this that was causing the hum.
- Got the amps back from the chap that serviced them hum still present, the person that serviced them said did not experience any such issue in his setup. - only difference was he did not have the speaker cables
- I switched on the amps and put my pre-amp on mute - no buzz
- As soon as I "un-mute" the pre-amp - loud buzz in one channel only
- Power amp on only - no buzz
- Is this what they call ultrasonic instability? If so why is it only buzzing in the one channel?
- I did change my speaker cable as the insulation from the chord cable I had was falling apart , I see reading the forums that Naim power amps are fussy about cables - could this cause the buzzing but why would it only happen in one channel?
Any recommendation or pointers would be welcomed !!
Thanks
Hazi Mistry (Nottingham)
Posted on: 18 April 2017 by james n
I'd try and find the source of this issue Hazi.
Try swapping L&R inputs to the Preamp. Does the buzz move ?
Try swapping L&R outputs from the Pre (i presume you are using an RCA to 4 Pin DIN to the 90). Does the buzz move ?
Posted on: 18 April 2017 by Potato_Head
I am using the DIN to phono cable made by flashback and thinking it was the interconnect bought another interconnect from Heavenly sounds - still get the dreaded buzz.
In answer to your question James I swapped the phono on the pre-amp ...buzz moved to the other channel.
I am using JPW minims so as not to destroy the B&Ws
- Could something as simple as a loop in the the interconnect cause issues?
- Would changing speaker cables affect the channel in this way ?
- Is one of the frequency channels on the tube output too high and causing instability in the NAP90
Thanks again for those that have taken the time to respond.... any ideas and thoughts welcomed !!
Thanks
Hazi
Posted on: 18 April 2017 by james n
Hazi - i'm not sure if you swapped input or output. If you swapped the preamp input phonos (from the DAC) and the buzz moved to the other channel then this points to a problem with the cable or DAC. If you swapped the output phonos (to the 90) and the buzz moved then this would indicate a problem with the preamp or pre-amp to 90 cable (although you seem to have another cable which looks like the cable is not an issue here).
Check these first as i would say it's more of a problem with a intermittent connection or component than anything related to speaker cables or any amp instability. Working your way logically down the chain from source should help you find the problem.
Posted on: 18 April 2017 by james n
Ok good - you've eliminated the 90 as being a problem so don't worry about this or the speaker cables.
Still worth swapping the input channels around to see if the buzz moves channels (if you've not done this already) just to eliminate the source and source to pre-amp cable having any issues. If the buzz does not move then it sounds like the pre-amp has an issue that will need further investigation. It could be something simple like a failing valve or something more that needs attention.
James
