Tube Bias Adjusted Automatically



The Rhythm 1.1 is the first preamplifier to adjust tube bias, ensuring that it runs at the correct bias for your tubes at all times.  Adjustment is automatic, requiring no action on the user’s part.

Why is this important?  Each pair of tubes requires slightly different bias.  The result of our automatic bias adjustment:  a circuit that brings out the very best from every tube you insert.

Why Does Bias Matter?

If your tubes are not biased correctly, your amp or preamp will run at a voltage and current  that are different from what the designer intended.  These incorrect operating parameters can affect sound quality.

How Do Other Manufacturers Handle Tube Bias in Preamps?

Tubed power amplifiers always allow for tube bias adjustment.  In fact, they require it.  But preamplifier manufacturers assume that any tube of the correct type will allow the unit to run at voltage and current “close enough” to what the designer intended.  So they use one fixed bias.  To test this, we got a typical preamp that doesn’t adjust bias, and replaced a pair of modern Chinese 12au7 tubes with a pair of JJ’s.  The circuit voltage went from 130V to 111V.  That’s more than enough to affect sound quality.  It wasn’t the tubes’ fault — they just required different bias.

However, when we tested these tubes in the Rhythm 1.1, both pairs caused the unit to run at the exact same voltage (the voltage specified by designer Bob Backert).  That’s our automatic bias adjustment in action.

The Best From Every Tube

Some tube brands sound better than others.  And clearly, some really are better.  But something else is happening.  As our test showed, inserting different tubes in a typical preamp will change the voltage and current that were intended by the designer.  So in a typical preamp, a great pair of tubes might sound merely “OK”, because bias isn’t adjusted correctly for them.

Because the Rhythm 1.1 automatically adjusts bias, a newly inserted tube will never sound worse merely because it throws off the unit’s operating parameters.  With the Rhythm 1.1’s automatically customized bias, you will hear each tube perform at its very best.