I never got mine to work
I build a final using the ECC85 + ECC88 (PSU+CCS) + EL84s and used it for 1 year without any problem, this 'normal' hours say 8 hours a week. Than this amplifier passed to one of collegues and he used it over the last say 8-10 years without any problems (in fact he is still suing using it now), he changed some years ago the tubes, not because they failed working, but just because he wanted some new tubes. So design seems very reliable.
Wim, author of the orginal EW+WW article
I build a final using the ECC85 + ECC88 (PSU+CCS) + EL84s and used it for 1 year without any problem, this 'normal' hours say 8 hours a week. Than this amplifier passed to one of collegues and he used it over the last say 8-10 years without any problems (in fact he is still suing using it now), he changed some years ago the tubes, not because they failed working, but just because he wanted some new tubes. So design seems very reliable.
Wim, author of the orginal EW+WW article
Just wondering, did the TS finish that amp?
I never got mine to work, -it's been over a year- but I remember the ecc88 (6922) in the PS glowing bright purple, then I turned it off...
That sounds just like what happens to an ECC88 when the heater-to-cathode voltage is exceeded for too long... I remember bright purple-white sparks inside the tube.
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HV delay DC coupled designs
These DC coupled circuits will only work with a delay of the High Voltage, so first the heaters, than after 30 sec. the High Voltage
In the article it is mentioned that de HV supply should have a delay of at least 30 seconds. I made a little timer circuit with a delay of 1 minute. But 2 switches by hand works as well of course.
Normally I use floating heaters, this with two 100 resistors connected together with say a 1 uF capacitor to ground, works very well.
These DC coupled circuits will only work with a delay of the High Voltage, so first the heaters, than after 30 sec. the High Voltage
In the article it is mentioned that de HV supply should have a delay of at least 30 seconds. I made a little timer circuit with a delay of 1 minute. But 2 switches by hand works as well of course.
Normally I use floating heaters, this with two 100 resistors connected together with say a 1 uF capacitor to ground, works very well.
Strong performers indeed
An externally hosted image should be here but it was not working when we last tested it.
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