MX-VYNL Review Update
Original MX-VYNL Power Supply
In my original review of the MX-VYNL (also updated) I commented upon the fact that I had what sounded to be hum in ONLY the left hand channel despite:
- The use of a balanced connection to the phono cartridge.
- The use of balanced line level connections to the Denon AVP-A1.
- A sophisticated and dedicated isolated technical grounding system.
- A dedicated, filtered and isolated room AC power feed.
I examined the channel noise using a dual beam oscilloscope that allowed me to compare the noise waveforms of both channels. Sure enough there appeared to be a 60 Hz ripple modulating the left hand noise. Well to cut a long time of research short and not to bore my readers to death I discovered that the problem was being caused by the original external switched mode power supply.
This cheap power supply was injecting noise into the phono stage that presented itself as what sounded and looked to be ‘hum’ on ONLY the left hand channel. This was not present with no phono cables connected nor was it audible when using the unbalanced inputs with an external Lentek headamp. This was probably because it was below the background noise of this pairing.
This was not a grounding issue as using different types/constructions and lengths of phono cables changed the noise level and interference picked up by JUST the left hand channel. I also discovered that despite the excellent solid metal case of the MX-VYNL, that placing any power cable from any switched mode supply within about 6″ of it caused RF noise pickup. I discovered this during the relocation of my turntables Phoenix external switched mode power supply that drives its motor.
Clearly the MX-VYNL has several issues:
- Its cheap external switched mode power supply needs to be replaced.
- Their may be a fundamental PCB layout or internal cabling issue that causes just the left hand channel to pickup RF.
- There must be minimal or no RF suppression on the phono inputs.
The Fix
As a temporary fix prior to replacing this cheap power supply I have added two large ferrite beads:
- One to the DC power cable where it entered the MX-VYNL and
- One to the DC power cable as it leaves the power supply.
This stopped all RF noise from entering the phono stage and completely removed all traces of what I termed ‘hum’.
My 2 Cents
This cheap cost cutting exercise by manufactures of using external switched mode supplies is just that, ITS CHEAP! As I commented in my original review it was this fact alone, and only this fact that almost caused me not to buy this phono amplifier. I would have preferred to pay a little more for an external analogue supply and not have gone through all this aggravation. (It will be interesting to see if a linear replacement PSU provides any other sonic improvements.) It is also interesting that Musical Fidelity used to sell an upgraded power supply (now discontinued) for the MX series!
Maybe I should have paid the extra and bought the Rega Aria, as I had originally intended (it has a linear PSU and more MC gain). Why didn’t I? Well the reviews of the Rega Aria and MX-VYNL were both excellent, but the MX-VYNL was smaller, more flexible and easier to use than the Rega and supported balanced I/O. Unfortunately my wallet rather than my gut feeling won out!
I DO NOT regret buying the MX-VYNL, it is an excellent phono amplifier and I can still recommend it. Just be aware of any noise issues and how you may resolve them and do not put it or any of its cabling near to ANY other switched mode supplies especially if you are using the balanced inputs.
See my original Musical Fidelity MX-VYNL review here.
