Cathode bias caps

[20to20]

In reality i’m missing out on a lot of high and low notes anyway. But in saying that, it must be the combination of valve amp and speakers that makes it worth listening to.

How are you patching the music into the console? Via the microphone jack?

 

[ausdrt]

Yes. They came with a left and right jack in and out. At one stage I tried soldering direct into that area of the amp, but during breaks in the notes I could hear interference. So I went back to standard.

 

[20to20]

How well does the impedance requirements of your music source device match what the microphone specs for impedance and signal levels expected by those inputs? Any paperwork still available for the original mic specs?

 

[ausdrt]

I know there is a web site that has the wiring diagrams for the stereograms, but I have never seen any info on the microphone. I now just use an IPod with a split cord. My son likes playing the modern big bass electronic music on it, and it handles it well.

 

[20to20]

I know there is a web site that has the wiring diagrams for the stereograms, but I have never seen any info on the microphone. I now just use an IPod with a split cord. My son likes playing the modern big bass electronic music on it, and it handles it well.

6!

 

[Zung]

... what is wrong with using a balancing potentiometer between two tubes with a low value resistance between each output of the potentiometer?...

This is a perfectly valid solution: assuming the original Rk is 360R, you can use a 330R from a cathode to a 50R WW pot, wiper to ground, and repeat for the other half of the PP. It lets you catch about 10% of DC unbalance between tubes.

One day I'll implement this in my Leak TL60 that a friend had kindly blown.