I received my new BHK250 from Underwood HiFi on Wednesday, 12/28/2016.
I previously was using an Anthem P2 for all my 2 channel listening; now traded in to allow the BHK250 purchase. All equipment and cables are identical to what I was using with the Anthem amp; the only difference being now the BHK250 is in the mix!
Power is from a dedicated 20amp outlet to which a PSA Powerplant P3 is connected. I have front-end digital equipment (PSA Directstream, Auralic Aries, DirecTV Genie box, Anthem D2 pre/pro, Opportunity BDP-83) connected to the regenerated circuits and the BHK250 and a Richard Gray Power Conditioner to the HC circuits. The RGPC houses additional inputs of my 5.1 equipment in the same room, and network switches power.
This was the setup with the Anthem in place as well and speakers were dead silent with all 2 channel equipment on!
I immediately noticed a harsh buzz from both speakers when I fired up the BHKs from the get-go. After much reading and numerous permutations of isolating the suspected equipment (PSA DirectStream and its interaction with the BHK250), I have the following setup observations:
20amp line to which the PSA PP3 is connected; PSA BHK 250 into the HC circuit: silent with PP3 switched on and amp off; obviously harsh buzz with amp’s main back switch on, worsened in magnitude when front switch also turned on. Only connection here with amp is with PP3 and speakers
to see the effect on music, I first connected the Directstream to one of the PP3’s regenerated circuits; connection to amp via XLRs. Initially, without any input into the Directstream, I turned on the Directstream and once it cycled through there was a faint buzz through the speakers (amp is off presently); I turned on the back switch of the amp with a slight increase in intensity of the buzz noted; with the front switch engaged on the BHK250’s, marked increase in the magnitude of the buzz (audible five feet or so from the speakers’ front). Powered everything down and changed the fire-up sequence: amp on first with slight buzz with back switch on, magnitude increased with front switch on, even higher magnitude once power up to DirectStream completed. I powered everything down and connected the Aries to the Directstream via USB using Jitterbug; power to Aries fed from PP3 regenerated circuit plug immediately below the Directstream (same outlet). Aries on first no buzz; Directstream on next with same previous observations and same again with turning on the amp. The buzz clearly audible at listening position. Music played streaming via Aries from my NAS and it was glorious! Clearly audible buzz continues between tracks…annoying!
Attempts at remedy: it seemed to me that the interactions between the DirectStream and BHK250 were the culprits and everything pointed to a ground loop issue.
Current setup: 20amp line to which the PSA PP3 is connected; PSA DirectStream into same regenerated circuit via a HUM X; PSA BHK250 into the HC circuit via a second HUMX. All other connections are the same as per previously cited observations. Dead silence with firing up in sequence: PP3, the Aries, the DirectStream after full cycle (dead silence!), BHK250 back switch on (dead silence!). When the tube input is switched on via the front switch on the BHK250 and full cycling completed, an same, obvious buzz from both speakers is heard, however markedly lower in intensity from previous…audible faintly to about 1 foot from both speakers (from all three drivers of the Focal Scala Utopias)
The music is gorgeous indeed…significantly improved low-end, marked improvement in soundstage and just overall more engaging in both soft and complex passages. Cannot hear the buzz from my listening position any longer!
As this is my first foray into tubes, is this normal tubes behavior. If not, I am open to suggestions from the community.
Thanks is advance for dissecting through my observations and any assistance…