A WORD ABOUT 45 TUBES

The Silver 45-SE is a limited production series in which the designer pays homage to a vintage era of tube manufacturing and amplifier circuit design. As such, the circuit is optimized and the amplifier voiced around the electrical specifications, as well as, internal physical characteristics of the 45 tube as originally designed by RCA and manufactured by several vendors beginning in the late 1920’s through the late 1950’s (in addition to RCA, Cunningham and National Union are a couple others that come to mind). Using these tube types (both the ST and globe versions) ensures the most appropriate match within the circuit yielding the lowest distortion and highest power measurements, as well as, best sonic characteristics.

The concept of tube rolling is understandable. Each brand of tube may sound different in a particular high-resolution circuit. This is because no two manufacturers make a tube type in quite the same way, and the central tendencies of the performance parameters will differ slightly with each manufacturer. Such is the case with new production 45 tubes versus their vintage counterparts. While some new production 45 tubes are designed to the same original electrical specifications, others are not. In addition, a visual comparison can sometimes indicate differences in physical characteristics such as spacing, geometry, size, plate design, and materials used.

Therefore, while we appreciate that the owner of a tube amplifier can generally select those tubes that provide sound characteristics that match their preferences, in a circuit like the Silver 45-SE that is designed around the electrical specifications and internal physical characteristics of a specific genre of 45 tube, we would encourage caution. When another tube labeled as a 45 or designated a 45 equivalent with a different geometry is installed, it is anyone’s guess as to what may happen. It is possible one might hear pleasing sonic enhancements. On the other hand it is also possible distortion may increase, power may decrease, the loading may be incorrect, etc.

If you have any questions regarding tube rolling and which 45 tubes are acceptable replacements for the ones supplied with your amplifier, please contact us and we will be happy to discuss options with you.

A WORD ABOUT 6SN7 TUBES

As for 6SN7 tubes the circuit of the Silver 45-SE offers more flexibility, but again, some of the 6SN7 variants (especially those not designated with 6SN7 markings) may not work ideally in the circuit as it was originally designed. However, in our own testing and analysis we have found that for our preferences and best sound characteristics the Raytheon VT-231 with black flat plates (or alternately Raytheon 6SN7GTB, either short glass envelope with side getter or tall glass envelope with top getter) is the tube of choice. Next would be the Sylvania VT-231 with black plates (or alternately Sylvania 6SN7GT with medium glass envelope, black plates, and bottom silver getter, a.k.a. "Bad Boy"). Lastly the Tungsol 6SN7GT with black glass and round mica, a.k.a. "Mouse Ear", work well in the circuit.

Recently one of our customers did extensive testing of different 6SN7 tubes in the Silver 45-SE. Click HERE to view the 6SN7 tube analysis. So as you can see, many different sound characteristics are possible, all due to the different electrical and, perhaps more precisely, distortion characteristics of the tube.

As with the 45 tube types, if you have any questions regarding tube rolling and which 6SN7 tubes are acceptable replacements for the ones supplied with your amplifier, please contact us and we will be happy to discuss options with you.

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