RCA 6SN7 grey bottles

Brent Jesse is a good source. A few months ago I purchased a pair of Tekefunken 12AX7’s curve matched @ $318 delivered. They look great but didn’t offer a sonic improvement over the other two brands I had. That was my fault as I’m a Tekefunken fan boy. I didn’t consider returning them as my new ( to me ) pre amp lacks a phono stage. So I’ll just save em for future use. My tube drawer has about $3-4k in tubes that cost less than now. Most barely used. I saved all the original packaging and invoices. I keep track of the hours and can always get my money back. I lack a pre that takes large signal tubes which is sad because I’ve read they sound better. Regards , Mike B. Some years back I purchased quite a few tubes on EBay from sellers that had huge volume and basically searched and cleared out old warehouses. One was a radio supply that moved from SoCal to Las Vegas. I’m leery of individual sellers especially foreign. Other reputable dealers like Vintage Tube, Antique Radio Supply in Arizona and Tube Museum I’ve had good luck with. Prices are crazy and most people aren’t offering anything below market. Regards , Mike B. 

Thanks for your input 

How expensive is the equipment the Tubes are to be used as part of the Circuit.

Matching Glass Colours on a Valve, is very very far removed from matching Valves. 

@billpete 

If you have a visually mismatched pair of RCA Grey/Tinted glass tubes and you want a visually matching pair, send me a photo of the two tubes you have and indicate if you have a preference for one over the other) and I’ll even swap you a tube that looks (and tests) like the one you want in exchange for the one you don’t want. No problem.

@chickenoregg I missed this somehow. Anyway, it isn't the RCA's that I have a mismatch in, it's the NOS pair of KR Black Glass. I bought them on Ebay from MIller Tubes, in Oregon, if I remember right. At any rare, they match perfectly by test and that is far more important to me than appearance. They match in codes as well, have to be the same lot, just one is more black than the other. I have a couple others that I bought used, one out of The Ukraine and one out of Kansas. The Ukraine find is the weakest but still plenty good, if I find a good even match for it. The one out of Kansas tested "almost new", and well balanced but has a crack in the base and started making noise so it is now on the shelf. I don't know if the crack in the base affects it but it was fine for a few hours, then started making noise. I'll keep it no matter what as I like it's story. Made in 1944 and taken from a WWII B17 bomber radio salvage. I just think that's cool, true or not, it's the story I was given and I'll stick with it. 

I have a good number of the RCA's, mostly the civilian version but the VT231's seem better in my limited tests. The pair I'm using in buffer position, are a pair that I made up from separate finds. One came with the Ukraine KR and the other somewhere in the US, I'd have to look up where. According to Brent Jessee, many of the civilian versions are the exact same as the military version, just got numbered differently. I don't know if that was the case with the RCA's or not but I found the VT's to sound better..........or so I thought. I have tried a lot of combinations. It's just fun stuff to me.