Completed Beepre with polyurethane finish

[denteom]

The basic Beepre 2 is singing nicely, works well even with my Class D DIY Purifi power amp. The last problem I encountered was the right speaker on channel 1 was not working, fixed it after simple trouble shooting.  I just have two questions left for the basic Beepre 2.
1. The knobs for changing the channels, balance control is kinda slipping. turning the control without the black colored knobs is easier, I've tightened the screws but it some how does not have a bite to it. Do I just have to tighten it more?  I'm worried might break it, also will be working with the upgrades by December which would require me to unscrew it again.  Is there an easy work around to this?
2. I already have the two upgrades with me.  But looking at the 2nd upgrade kit, it comes with 6CM7 tubes.  I think it is a rare tube (I'm in Asia).  Are there any compatible tubes with different numbering on it?  Russian, Japanese or Chinese tubes are easier to come by here.
I really enjoyed the product!
Kudos to the Bottlehead Team!  I'll promote you guys to the my audiophile friends here.  They just have to overcome the fear of using the soldering station.  But after my experience of a resistor going up in smokes and able to finish the kit, will encourage them on taking the path I took.  I'll audition my kit with them once I finish all the upgrades.  Hope they will  be impress, they have really expensive gear, but I'm confident my Beepre 2 can go toe to toe with their gear.

[Paul Birkeland]

Yes, just crank the knob set screws down harder.  If you want a little extra tension, you can take the knobs off and see where the divot is that the set screw made in each shaft, then drill with a 2mm drill bit about 1mm deep to provide a detent for the set screw.

The 6CM7 is an uncommon tube but it's completely worthless since we are the only ones using them.   
https://www.ebay.com/itm/225119630376?hash=item346a2cf428:g:ByQAAOSwBIxi77e9&amdata=enc%3AAQAHAAAA0NFfoIINgQXXpV9wZ7SOP33aH2ETmhQ4pF%2Fvq8HwmNoCVz4Qh9Qi65mPMa9kIvm0sPG6p9qzBSjxkx3HDeikIJYnVIV9csa55UlpISXx09BF2mqURnUyqUa2HngacGfN1AtefqpMnGpukyiaJ8UltDun7hPbz7lF681Z%2Ftsci%2BOXiOwHSzXurcVAmqlVVZAwtKeUSBIUv3u3Ys%2F8XtFYwwTdOLvIAxfgsR8tZ87UQXEWEyPr2AjqfthBOOscFLwpuXYSKVo3kFmvBL3mXqOp13s%3D%7Ctkp%3ABk9SR7yVxIP3YA
Something like that would be a lifetime of spares.

[denteom]

Thanks for the tip on the knob set screw, I'll do the drilling once the build is already final.

With regards to 6CM7, isn't a matched pair required? The one selling at ebay says some are good others strong.  How long does a 6CM7 last? Still have to ask a friend to buy it from US. I should have harvested the tubes from the old TV sets that we had before throwing those out.  But a time machine would be a better way to go, hahah....  Thanks for the tip. Hope I can find a stockpile new old stock. 
Can rewiring the pin connectors fit new tubes with 9 pins?  Just in case some looney buys all the stock in the world.

[Paul Birkeland]

The tubes should be matched in terms of the internal construction.  Electrical matching is absolutely not necessary.

I would expect the 6CM7 tubes we provide to last 10-20 years or so.

No, I am not aware of any other tube tube that can be used easily.  These are extremely inexpensive tubes that are available NOS for prices well below what you would pay for a new production 9 pin tube. If you have someone in the US who can buy them for you, lots of tube dealers online have these new in box for about $4 each.  A US postal small flat rate box is $30 to ship internationally, and I'd bet you could easily fit 10-15 6CM7s inside with some padding, so you would still be able to get 10 for $8 or so per tube.  The most similar new production 9 pin tube I can find (which wouldn't recommend using and won't name) is over $20 each, so the economics here don't make a ton of sense. 

[johnsonad]

That finish is shiny! Congrats!

Don’t stress over the 6cm7 tube. It’s more likely you’ll move on to a new version of the preamp before that tube gives out.

[denteom]

Thanks for the complement, working on the wood is harder than the electronics.
Ok will explore that route of treasure hunting for 6CM7. In the meantime enjoying my Beepre 2!

[ccmccull]

I completely agree. It's taken me 4 builds to feel even marginally comfortable on the wood finishing. I use water based polycrylic. Unforgiving stuff!