I have a BHK Pre and BHK 250 combination.
Since the beginning I find that the pre has a noticable “electical” sounding “click” whenever changing the volume.
When increasing the volume it “clicks” each numerical volume increase. When decreasing, it only clicks every second numercial.
Is this normal or could there be an issue?
Strange that the volume control/increment isn’t completely silent.
Thanks in advance.
That is normal and to be expected. The BHK volume control is the heart of this preamplifier. Unlike a standard volume control or stepped attenuator, the BHK instead changes gain of the vacuum tube stage in small 1/2dB steps and this is what you are hearing.
It is this unique volume control that helps the BHK be as good as it is.
This issue has come up before. Paul explained that designing a volume control that doesn’t negatively affect sound quality is a difficult job. The system that Bascom King devised does exhibit the clicks; I can’t explain all the details, but the clicks seem to be the price to preserve the SQ.
That said, I noticed:
a) the clicks became much softer when I switched from an RCA to an XLR interconnect between the preamp and amp (I also have a BHK 250). I now hardly hear them unless I listen for them.
b) there was inconsistency; as you said, clicks did not behave the same way going down as going up. Even going up I occasionally got a “skip” in the clicks.
So I don’t think your unit is faulty.
Edit: Paul posted his reply while I was typing.
Thanks for both replies! Glad to hear it is normal. Certainly having some clicks and maintaining the sound quality is the best outcome!!
I am using RCA interconnects at the moment, but will change to XLR in the next few weeks. Will be interesting to compare.
Only had the units for a few weeks now and loving them.
(Also have a P10)
I’ve noticed that it varies with type of valve in place , I’m trying out some NOS RCA black plates and the clicking became so pronounced that I had to replace them with Genalex Gold Lions .
Tubes will affect that. When you use triode matched, matched paired tubes you can have a quiet volume control. I am currently running NOS Conn Sylvania 12AU7’s. They are dead quiet.
Thanks for that , I replaced the Genalex with the RCA NOS and as I pushed the valves in I rocked them in a circular fashion to get a bit of contact and that seems to have cured the clicking problem . Are you using the Sylvania in conjunction with the BHK 250 as I have a pair and I did think they’d work well in that combo , but right now I’m trying out the Purifi class D amp which needs a bit of warmth as it’s quite characterless particularly with my speakers which are a bit clinical
Yes, I have a 250 and so far prefer the stock Genalex tubes to the Tungsrams, and the matushita’s that I have tried. The Conn’s in the preamp give me a huge wide deed enveloping soundstage.