Anyway, curious... ten tubes from the same week, possibly had some prescreening since they were installed somewhere/sometime. My question is how many are low noise and also have tight triode to triode matching. Since CCa's are selected standard production 6922s, I'm curious to know how many "waiting to be discovered CCa's" you scored in this heist.
It's actually a useful statistic since you would rarely see ten or more of these at any given time.
Tride matching is actually super tight:
| | Ia1 | Ia2 | | | Gm1 | Gm2 | | | Mu1 | Mu2 | Ra1 | Ra2 | Ra % delta |
| Valvo 7L4 '59 E88CC D-Getter #1 | ~11 | ~11 | | | 8,63 | 8,68 | | | 32,6 | 33,4 | 3,77752 | 3,847926 | 1,846606 |
| Valvo 7L4 '59 E88CC D-Getter #2 | ~11 | ~11 | | | 8,42 | 8,35 | | | 33,6 | 32,8 | 3,990499 | 3,928144 | 1,574894 |
| Valvo 7L4 '59 E88CC D-Getter #3 | ~11 | ~11 | | | 8,49 | 8,28 | | | 33,2 | 33,6 | 3,910483 | 4,057971 | 3,701799 |
| Valvo 7L4 '59 E88CC D-Getter #4 | ~11 | ~11 | | | 7,8 | 7,98 | | | 31,2 | 31,4 | 4 | 3,934837 | 1,642451 |
| Valvo 7L4 '59 E88CC D-Getter #5 | ~11 | ~11 | | | 7,95 | 7,13 | | | 33,8 | 30,3 | 4,251572 | 4,249649 | 0,04524 |
| Valvo 7L4 '59 E88CC D-Getter #6 | ~11 | ~11 | | | 8,42 | 8,1 | | | 31,8 | 31,6 | 3,776722 | 3,901235 | 3,243375 |
| Valvo 7L4 '59 E88CC D-Getter #7 | ~11 | ~11 | | | 8,17 | 8,3 | | | 32,9 | 32,6 | 4,026928 | 3,927711 | 2,494568 |
| Valvo 7L4 '59 E88CC D-Getter #8 | ~11 | ~11 | | | 8,18 | 8,23 | | | 32,5 | 31,9 | 3,973105 | 3,876063 | 2,472668 |
| Valvo 7L4 '59 E88CC D-Getter #9 | ~11 | ~11 | | | 8,13 | 7,74 | | | 32,4 | 31,6 | 3,98524 | 4,082687 | 2,415676 |
| Valvo 7L4 '59 E88CC D-Getter #10 | ~11 | ~11 | | | 7,87 | 8,02 | | | 34 | 33,2 | 4,320203 | 4,139651 | 4,268453 |
This is taken at 100V Ua, and somewhere between -1.5V and -2V (I'm using the autobias method for matching for the Lyr 2 on my Tube Imp - meaning I vary the grid voltage until each triode stabilizes at 11mA, then I write down Gm and Mu, calculate the plate resistance (Rp or Ra) and then I have a formula to calculate the percentage different of Ra on each triode. Less than 10% is really good matching, < 5% is perfect matching. Then I match out pairs aiming for close Gm, Mu and Ra values.
So out of these results I have pairs - (ordered from best to worst in strength):
(1, 6) (2,3) (7,8) (4,9) (5,10).
I've currently only listened to (1,6) and (2,3), there is 0 noise that can be heard at high gain on the lyr and the volume control past 13/14 o'clock. I'm currently listening to pair (2,3) as rest of pairs finished soaking in isopropyl alcohol and I just applied deoxit gold to them
. I love the fact that deoxit gold makes the glass on the bottom of the tubes clear again
any of you guys deal with a seller called wedge high fidelity or similar name. do not remember exactly? Is there some kind of formula you need to apply to his test readings like a -6 or thereabouts to get a true test reading, he got some really nice stuff but all his tubes seem to be on HGH or steroids or his tester is borked or maybe he don`t know how to use it or whatever? Even a relative tube newbie like myself is pretty leery about his readings. My gut is telling me to stay away.
Guy is boosting the measurements by picking a bias point where 100% is higher, now this doesn't necessarily mean that his tubes are bad, but I asked him about the real measurements at a standard bias point and he was being a smart schiit arguing about the definition of NOS/NIB and did not give me any measurements. I pasted our conversation a few posts back. I assume his tubes are still good - as they really do look unused and new in box, and they seem to be matched at the higher voltages, but I decided not to buy from him just because I did not like his attitude
