Tavishdad, I find the ECC99 to be very useful in a variety of applications, partly or mostly because it has the same pin-out as do the 12AX7/AT7/AU7, etc, family, whilst having a much lower Rp and higher Gm than any of those do. I use it as a CCS and as a follower in some cases in gear that was previously wired for a 12AT7 or 12AU7. However, in my phono stage, I use ECC99 as the top tube in a hybrid dual-differential cascode topology at the input to my phono stage, a very critical application, as you point out. Because of the very very high Gm of the bottom transistor, the gain at the input is enormous and the S/N is very good, enabling me to run just about any very low output MC cartridge with room to spare.
List of Audio Tube Measured Noise Performance
I have begun to post and maintain a list of the measured noise performance of the types of vacuum tubes typically used in phono stages and other low-noise audio equipment. It might be of interest to any audiophile replacing or upgrading tubes in a phono stage.
So far the list is modest, with samples of twelve different brands and/or types, and a total of 58 tubes measured, but it is updated regularly. It includes tubes such as the 12AX7, 12AT7, 5751, 6922 / 6DJ8 / E88CC, and 6SL7GT. And it includes a sampling of tubes from all three major current production tube factories, as well as some new, old-stock (NOS) tubes.
I don’t sell tubes (or own stock in any tube factories), and the list is strictly measurement-based, so I believe it is completely objective. And I explain in detail how the measurements are made, for anyone who would like to repeat them.
You can see the list at:
http://tavishdesign.com/pages/downloads
I’d be interested in hearing about other tubes or brands you think should be included.
Scott
So far the list is modest, with samples of twelve different brands and/or types, and a total of 58 tubes measured, but it is updated regularly. It includes tubes such as the 12AX7, 12AT7, 5751, 6922 / 6DJ8 / E88CC, and 6SL7GT. And it includes a sampling of tubes from all three major current production tube factories, as well as some new, old-stock (NOS) tubes.
I don’t sell tubes (or own stock in any tube factories), and the list is strictly measurement-based, so I believe it is completely objective. And I explain in detail how the measurements are made, for anyone who would like to repeat them.
You can see the list at:
http://tavishdesign.com/pages/downloads
I’d be interested in hearing about other tubes or brands you think should be included.
Scott
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- 20 posts total
- 20 posts total