[bregez]

I am still enjoying the Clarinet.  A great preamp by any standards.  The last couple months I have rolled many tubes through the preamp (Telefunken, RCA clear tops, Amperex, JJ, EH to name a few).  Some of the tubes are sensitive to the Grayhill selector switch when turned will produce a "ping".  Has anybody else noticed this?  Also, does anyone have opinions regarding tube recommendations on the Clarinet?  My favorite thus far is the RCA 5Y3 and RCA 12AU7A's

Brad

[hagtech]

Yes!  That is microphonics you are experiencing.  Some tubes worse than others.  It is typically caused by mechanical vibration of the tube electrodes, grids, mica, etc. 

jh

[Tone Deaf]

Some dampers on the tubes should sort out the microphonics quite easily.  I've got some pearl coolers that do the trick for me.

I currently use 2 mullard ECC82s in my clarinet which sound great.  I accidentally used a ECC81 (12AT7 ?) in the front socket at one point and didn't notice for a month or two!  Obviously I don't have audiophile ears because it still sounded fine to me