In modern high-gain amplifiers, the first tube stage may be extremely sensitive to tube microphonics which is caused by elements inside the tube moving (with respect to each other) due to physical shock or vibrations. The way to stop microphonics from occurring is to stop the tube elements from vibrating. One way this happens is through modern design.

Tubes today have to be built with very high precision. If the higher gain tubes of today were similar in microphonics and signal-to-noise specs to the good quality but lower-gain tubes of yesterday, they would be unacceptable to the user!

Many old amplifiers, including all 50's Fenders, Gibsons and most Ampegs used rubber "shock-mounting" to cope with the microphonics inherent in the available tubes. Shock-mounting isolates the tubes from the bulk of the amplifier which leaves the tubes "floating" in much the same way as a rubber duck in a tub of water. Any jolt to the amplifier will still move the tube, but to a lesser degree, just as any sudden churning of the water will move the duck, but not as much as the water moves.

Mechanical Shock Mounting to Quell Microphonics

In the case of sockets held in place by screws (modern Fender and others) a rubber or neoprene washer may be placed under the screw head and another under the socket itself (four washers per tube). If the two screw holes are drilled our, neoprene rubber grommets may be used. This is the 50's method, but it does require new screws to hold the sockets in. This decouples the socket from the chassis and damps any vibrations that would otherwise reach the tube.

This issue's Tube Talk is courtesy of Bruce Zinky. Bruce was the head of the Fender Custom Amp shop for many years. He is a great source of information on amps and rubber duckies.

Many of you might not be aware of the excellant warranty that RUBYTM tubes has always had on their tubes.

All RUBYTM TUBES come with a 6-month warranty, one of the best in the industry. They are so careful about selecting and testing their tubes that they have no problem making this kind of offer. If one of their premium RUBYTM TUBES fails during the 6-month warranty period, we will replace it at no charge. This is a great point to remember when discussing tubes with your customers.

Greg Zaccaria, Owner Zack Engineering and Vibroworld.com

RUBYTM Pre-Amp Tubes
All of these RUBYTM pre-amp tubes are carefully tested and selected by skilled technicians for low microphonics and hum. This insures that even the highest gain tubes will be quiet and dependable. They come with a 6-month warranty, one of the best in the industry.

ALL RUBYTM TUBES HAVE A 6 MONTH WARRANTY

These tubes are made in Russia and tested by Sovtek and are silk screened with the Sovtek label. They are packaged in Red, White and Blue boxes. We Retest these Tubes before shipping them to you.