Gee Arian, so you work for a company that makes teflon caps aye? Old buddy old pal! Just kidding, but thanks for that info. That may be the first time I've ever seen an explanation of why any cap would improve with use.
In the spirit of full disclosure, I guess I should list the things that I've found along the road that have improved the sound of my rig and some of the things that I've yet to explore.
I started out by building a Seduction (dead stock) and adding the tape head conversion (actually I started by pestering Doc about upgrades he made to his tube 900 series Ampex but that's a different story). It came with Phillips JAN 6922's and having had a good bit of experience with that type tube, I had a box of "also rans" that I keep around just in case other changes in my systems lend themselves to their particular flavor of sonics. One pair that, as I recall, weren't that bad (for the price of admission) were some NOS Russian 6h23n 1980's production. They have a lively, slightly forward sound and are pretty clear. They aren't as refined and smooth as my favorites but I think I paid a whopping $12 ea for them about 10 years ago and they may have gone up a couple since then. One thing I'd like to mention regarding tube choices in the Seduction. Another thing that the 6h23's had going for them is that they're quiet. If you've ever tube rolled a phono stage for use with a MC cartridge, than you know how important that can be. The tape hiss on the TP tapes is pretty far down there. In fact, when I've had former reel to reel guys listen to them at the demos I've done, that's one of the things that really surprises them. Most of us have plenty of records that have much more tape hiss than the TP tapes have (there are some whose masters obviously had more though). So getting the tube rush below or at that level has always been a consideration for me. Luckily, most of the tube stock that I have was purchased back when tube noise grading actually meant something. So, if you have a choice, go for the phono stage grade (or MC cartridge grade if available).
Another tube that is nice is a Tungsram 6922/E88CC. These were made in Hungary and while they aren't cheap anymore, they're available from lots of offshore sellers for reasonable prices. I find them a little veiled but unless I'm A/B-ing them, my ears/brain loses track of the veil and it become a non issue. They have a pleasing tube sound from top to bottom and while I wouldn't say that they have great extension, it isn't bad either.
Folks who know my tube preferences would have asked "which Amperex 7308?" right off the bat. Well, I went back a forth between the white labeled PQ and the green globe JAN. I find the white to have better bass but the green is quieter. The white label has skyrocketed in price in the last few years but there's a few things that can help you find a "relative" bargain. First off, some tubes were made to a higher standard. This doesn't mean that they sound better but man, do they last! The Amperex 7308 and Seimens and Halske Cca are a couple. They were manufactured with a harder vacuum and more refined materials (supposedly) and were touted as 10,000 hour tubes. That's more than 3 times the life of a normal tube. So, when I buy one that is twice the price of a comparable tube, I'm saving money in the long run (and I never ever rationalize damn it!). So, if you have a trusted tube seller with some nice used Amperex 7308's for cheap, go for it. I have some used ones in the phono stage of my preamp that have been in there for 6 years!
There are differing opinions on which Amperex tubes are best and IMHO, that's how it should be. For example, Doc likes the orange label and some folks say "you've gotta get the Holland production".
I think it's a real testament to the sound quality of these tapes that it is pretty easy to identify problems or characteristics in the sound. It's just as easy to stop tweaking and just get lost in the music.
Oh, "what about the S&H Cca's?" you ask. Well, they just weren't for me and I sold off the last 4 I had 3 or 4 years ago for $70 each,.. sob sob.
For those of you who have a Repro amp, I'll refer you to a previous book I wrote on that subject in this forum.
http://www.tapeproject.com/smf/index.php/topic,164.0.htmlHey,.. btw Welcome to the forum Myles (if you made it down this far!)