Weird/ confused!!!

[lonergan2468]

Yes..The op of the audiolab is 2.5..I have 2 attenuators..will try that. I love the detailed sound of the Emille......

[anthonyTD]

Thanks paul,
Yes, if you follow the signal path [shown on last pick] you will see that there is just a grid resistor to ground[normal] and nothing else in the signal path to pin two on the valve base, which is the grid of the first gain stage!
Hope this helps.
A...

[Reffc]

Thanks paul,
Yes, if you follow the signal path [shown on last pick] you will see that there is just a grid resistor to ground[normal] and nothing else in the signal path to pin two on the valve base, which is the grid of the first gain stage!
Hope this helps.
A...

Thanks Anthony, so a simple fix would be to add a DC blocking cap at the input and connect the input to one leg of the cap and the other leg to the signal input track on the PCB? What value would you recommend (presumably a poly bipolar axial cap, 400V rated?)

[anthonyTD]

Yes,
Just lift the white wire out of the printed circuit board, and put the cap between the white wire, and the board connection.
Try a 100nf, [doesent have to be a high voltage one, something at least 25v working] that should be fine for starters.
A...

Thanks Anthony, so a simple fix would be to add a DC blocking cap at the input and connect the input to one leg of the cap and the other leg to the signal input track on the PCB? What value would you recommend (presumably a poly bipolar axial cap, 400V rated?)

[Reffc]

Yes,
Just lift the white wire out of the printed circuit board, and put the cap between the white wire, and the board connection.
Try a 100nf, [doesent have to be a high voltage one, something at least 25v working] that should be fine for starters.
A...

Thanks Anthony, very helpful. I'm sure that Tim could try this mod or have someone do it for him locally and (hopefully) job done. RE rating, yes of course, it's not on the Hv side of the circuit. Cost = a few pounds Well spotted. Presumably a similar cap on the output stage of the CDP would work equally as well?

[anthonyTD]

No worries,
Some source equipment, like CD players etc have directly coupled output stages, ie; they have no cap on the output to block and isolate the output, so if there is any significant level of DC offset coming out of the player's output, they can upset the front end of amplifiers with no input capacitors fitted.
Hope it fixes the issue.
A.

Thanks Anthony, very helpful. I'm sure that Tim could try this mod or have someone do it for him locally and (hopefully) job done. RE rating, yes of course, it's not on the Hv side of the circuit. Cost = a few pounds Well spotted. Presumably a similar cap on the output stage of the CDP would work equally as well?

[Firebottle]

You would need a larger capacitor value, so more expense, at the CDP output as you would be driving into the impedance of the volume control on the Emille.

The impedance of the first grid is a lot higher so 100nF is OK there,


Good shout Anthony about possible DC offset

Alan

[anthonyTD]

You would need a larger capacitor value, so more expense, at the CDP output as you would be driving into the impedance of the volume control on the Emille.

The impedance of the first grid is a lot higher so 100nF is OK there,


Good shout Anthony about possible DC offset

Alan

[Audio Advent]

But the thing that people are forgetting is that the Audiolab worked absolutely fine with the Emile amp for a whole 20 minutes before starting to distort..

That would suggest the Audiolab was at fault (e.g. a sudden DC offset caused by a dry joint which kicks in after 20 minutes warm-up) and adding a cap on it's output (if it doesn't have one) wouldn't fix the fault it would only be a work around.

Need to check if it is indeed the Audiolab and to see if the fault always kicks in after 20 minutes from cold consistantly.

[Firebottle]

A very quick check of the Audiolab with a voltmeter on the output (when the fault is showing) will confirm or discount the Audiolab at fault.