16-09-2015, 03:14 PM
By the way, I have diagnosed the problem with the balance control. It was my error. I failed to specify the pot fully. The pot as delivered from Blore-Ed had the antilog section at the rear. But the anti-log section was meant to be for the Right-hand channel. As laid out by Mullard, the front pot sections control the Right-Hand channel. I have re-wired the balance pot so the rear section controls the right channel.
By the way, the symptom of a back-to front log/antilog control is a distinctly low-level mid position, with each channel increasing significantly in volume if the control is rotated in that direction.
This cobbled-together diagram illustrates the problem. A properly-wired standard log/antilog balance control gives about 75% volume on both channels at mid-point. A mis-wired control gives 25% at mid-position.
Of course, the purists will say that you don't need tone or balance controls, but Mullard specified them in about 1962 and who am I to quibble!
Jeremy
By the way, the symptom of a back-to front log/antilog control is a distinctly low-level mid position, with each channel increasing significantly in volume if the control is rotated in that direction.
This cobbled-together diagram illustrates the problem. A properly-wired standard log/antilog balance control gives about 75% volume on both channels at mid-point. A mis-wired control gives 25% at mid-position.
Of course, the purists will say that you don't need tone or balance controls, but Mullard specified them in about 1962 and who am I to quibble!
Jeremy
Jeremy. G8MLK. BVWS Chairman. British Vintage Wireless and TV Museum Friend.
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