New to Tubes & BHK expectations

Audio Components Preamplifiers
#1

Making my first venture into tube-based sound, and have had my new BHK Signature preamplifier and 250 amplifier up-and-running for about a week.

Sonically, the pair are a noticeable upgrade from my previous Rotel separates. Strings, woodwinds and brass sound more natural and less abrasive—especially noticeable when the orchestra leans into a performance. Bass is firmer and more detailed at lower volumes; tympani, cello, and double bass really come alive on a quality recording.

So my question is not about solid state v. tube sound… but about what to expect in terms of tube ‘quirks’.

Either the BHK preamplifier or the amplifier (not within the signal) will periodically emit a random click (a bit like the old-fashioned thermostat turning-on). At least I perceive it as random: it may happen once every 10–15 minutes, or more—or even less—frequently. But it usually happens at least once during a listening session. And it doesn’t necessarily occur more frequently early in the session when one might expect increasing temperatures to be the culprit. It’s just loud enough that it will distract a bit from the experience. As it’s random I’ve yet to ‘catch’ the click when I am close-enough to determine which is the source. Is this just a ‘feature’ of tubes? Is additional ‘burn-in’ likely to alleviate this?

The solid state Rotel separates are virtually silent until jacking the volume up to a level that would be uncomfortable for listening. By comparison, the BHK combination emits a bit more white noise through the speakers (even with no source signal input or on an empty input selection).

[I did take PS Audio’s advice and connect the preamp and amp via Audioquest Water XLR cables. Both are powered via a PowerPlant P15 with Audioquest Monsoon AC cables. That should insulate the system from external noise.]

The white noise is nothing excessive—just a bit more noticeable. Seated across the room it’s unnoticeable—but at a few feet I can hear it. Is it just that tube pre / amps are a bit noisier than their all-solid state siblings?

Not quite certain what to expect when it comes to tube-based systems—and whether or not these are typical or atypical issues / experiences.

Thanks in advance for the help!

#2

The clicking you hear most likely is heat sink expansion in the power amp. I have rarely heard that same sound it is very rare in my system. The P 15 can also do the same. What tubes are in the preamp. My experience is 12 volt tubes are very quiet and 6 volt tubes not so much!

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#3

Hadn’t considered the heat sinks as a potential source. Makes sense, actually. Both produce sustainably more heat than any solid-state gear I’ve had in the past. Put both the preamp and amp on standby about fifteen minutes ago and have heard the click twice since (contraction instead of expansion?).

Tubes for both are the stock tubes that ship in them from PS Audio. I’m not actually sure what’s in there—but I haven’t had time to slide down the slippery slope of tube rolling.

#4

That is strange that you heard the click in standby. You will have to investigate further to get to the bottom of that. I am surprised that you are hearing hiss with the stock tubes. Are your speakers very high sensitivity? I guess you could be right about contraction when they are cooling down.

#5

As those are the stock tubes shipped in the units it might be a good idea to remove and re-seat both pair since FedEx is not known as of late for their gentle handling of audio gear.

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#6

I guess this’ll require some additional sleuthing, but good to know that this isn’t typical for the BHK series. Thanks!

My current speakers are B&W CM8 S2s (88dB sensitivity), but will soon to be replaced by a pair of Marten Oscar Trios. Not living in a major metro area, auditioning speakers has been something of an odyssey. Either the speakers I wanted to hear were completely unavailable… or it was necessary to book a trip to go hear 'em. And, with a year left in college for my youngest, just can’t quite swing a pair of FR30s.

#7

Thanks! Will give that a try, too. Gotta hand it to the PS Audio folks though… the packaging for the BHK gear is well thought-out.

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#8

No amount of packaging will help a flat drop from the back of a truck or loading dock on to concrete or asphalt.

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