Put a lid on it (or not?)

Well!

’George said’..."Could be your just exciting tube microphonics and adding false euphonics.
A simple good test to see if any tubes are microphonic in tube preamps or amps, is to turn the volume up to normal, have someone listen close at each speaker, and for you to gently flick each tube with your finger nail. The person listening at the speaker will tell you if they can hear that flick, bad ones will really stand out."


George. I would rather think Kevin Deal has the true skinny on tube microphony...


From Kevin’s website...

Microphony, tube dampers, and tapping on tubes -

Okay...listen closely class, because I will say this only once: DO NOT TAP ON TUBES! You can permanently damage them! Repeatedly tapping on a tube’s glass can cause a perfectly good tube to become too microphonic for use.

ALL tubes are microphonic to a greater or lesser degree. Whether or not that microphonics is audible will depend more on the tube’s function in the product, rather than the microphony of the tube itself. In some positions, you will never hear anything, even with the worst tube. In other positions you will hear something even with the best tubes. At that point you make a judgement call: does this level of microphony interfere with my listening enjoyment?

Tubes are supposed to make noise when tap you tap on them! If a tube is truly microphonic, and in a position where it is critical, you will know it. It will feedback as you play music and be so objectionable you’ll turn it off.

For those interested in a more in-depth discussion on microphony, click here.

not necessary to tap on tubes it’s enough to tap on amp/preamp chassis to hear tube microphony. also if you softly touch with palm of your finger you may hear either hum or noise.

My LP12 has a dust cover. I like it. Keeps platter and Tonearm cleaner than Kuzma Stabi even w/ a cloth cover on it. But I am a proponent of the long ICs / short speaker cables school. Only amps and speakers in the listening room! At low volume no problem with eguipment and TT in room; but at normal to Rock Out volumes IT IS a problem!! Even wth all the racks, spikes, footers, isolation platforms, that I have tried in last 28yrs out of 45yrs; I prefer the long IC/ short speaker cable and TTs and other eguipment OUT of the room! 
Sure it is a compromise; but so is the short ICs and all equipment stacked between the speakers school. 
Yes, I am one of the lucky guys. Dedicated Room, no kids, no pets, great WAF. 
I bought better ICs than tons of $ on racks, platforms, spikes, you name it !!! It is easier to clean, change out a piece of eguipment for audition, more pleasing to the eyes, and sounds better to these ears. 
Listen, Trust your Ears,
Best to all on this Journey!

I've been doing this with my Rogue Ares phono preamp. The lid+sides is one piece of sheet metal of relatively low gauge; any disturbance and it rings like a bell -- not a good thing for a tube phono stage. Plus the weird tube cage thingy is ugly. So, off with the lid.

Meanwhile my Rogue Hera preamp chassis is machined aluminum, and works quite well to isolate the components/tubes inside, so the thick/heavy lid stays on.

And as has been said before -- DON'T tap your running, hot tubes with a fingernail, etc. Tap around them, or at most use a light touch with the soft part of finger (depending on how hot).