Hi all,
I have a Defy 7 from 1992 with the large power trafo, which should make it a mark lll. Though upon asking Jadis, they as such do not regard the the Defy as been produced in series, only in small steps of continuous improvement 😉
Now - I am aware, that the Defy 7 along with other Jadis designs is not to everyone’s liking on here, but I should mention, that I have had no trouble at all during all these years of ownership. It has been rock solid and just a continuous joy to listen to.
Tubes are Telefunken for input stage and Svetlana “winged C” 6550C in matched sextets from Ruby Tubes. Even though the Defy 7 is with fixed bias and has this crazy layout with a variable resistor to adjust each row of three tubes, I am very impressed by how tightly I can adjust bias between all four rows and have all tubes to perform very closely to each other. A testimonial to the matching from Ruby Tubes.
Not long ago I started to observe a small anomaly upon powering up. The bass units started to move in the right channel only. Very low frequency as you can follow the movement with your eyes. Three or four cycles. Then followed by a small snare of electronic buzz. This whole phenomena in total last fewer than 8 seconds and then all is good. No sound compromise, no noise what so ever.
I’m in need of some knowledge and insight on we’re to start searching for the root cause for this anomaly. Is it as simple as an output tube on its way to heaven? The bias is not drifting on any of the 12 output tubes.
The basic design is quite simple, but instead of starting in upper right corner and measure all components in the right channel, I am hoping for some guidance on where to strategically start my search.
I have a Defy 7 from 1992 with the large power trafo, which should make it a mark lll. Though upon asking Jadis, they as such do not regard the the Defy as been produced in series, only in small steps of continuous improvement 😉
Now - I am aware, that the Defy 7 along with other Jadis designs is not to everyone’s liking on here, but I should mention, that I have had no trouble at all during all these years of ownership. It has been rock solid and just a continuous joy to listen to.
Tubes are Telefunken for input stage and Svetlana “winged C” 6550C in matched sextets from Ruby Tubes. Even though the Defy 7 is with fixed bias and has this crazy layout with a variable resistor to adjust each row of three tubes, I am very impressed by how tightly I can adjust bias between all four rows and have all tubes to perform very closely to each other. A testimonial to the matching from Ruby Tubes.
Not long ago I started to observe a small anomaly upon powering up. The bass units started to move in the right channel only. Very low frequency as you can follow the movement with your eyes. Three or four cycles. Then followed by a small snare of electronic buzz. This whole phenomena in total last fewer than 8 seconds and then all is good. No sound compromise, no noise what so ever.
I’m in need of some knowledge and insight on we’re to start searching for the root cause for this anomaly. Is it as simple as an output tube on its way to heaven? The bias is not drifting on any of the 12 output tubes.
The basic design is quite simple, but instead of starting in upper right corner and measure all components in the right channel, I am hoping for some guidance on where to strategically start my search.
Allright - do you mean setting tubes in a tube tester or measure in circuit?
As stated in first post bias is not drifting, so I should look for other irregularities.
Any suggestions to which part in particular or is that trivial?
As stated in first post bias is not drifting, so I should look for other irregularities.
Any suggestions to which part in particular or is that trivial?
I would switch tubes one by one to the other channel and listen. Soon as the same problem shows up on other channel, you found your culprit tube. Easiest and cheapest solution.
Or you can pull each tube to test individually, but I have many tubes that seem to test well in my tester (Knight 600) but give firework display when in an amp.
Or you can pull each tube to test individually, but I have many tubes that seem to test well in my tester (Knight 600) but give firework display when in an amp.
Hi John65b,
Super logical answer. Wish I had thought that up myself. It's obvious. I wasn't zoomed in on the output tubes, even if I had a comment once or twice before...
I will jump into action in the weekend if time permits..
Thank you so much...
Super logical answer. Wish I had thought that up myself. It's obvious. I wasn't zoomed in on the output tubes, even if I had a comment once or twice before...
I will jump into action in the weekend if time permits..
Thank you so much...
Might not even be a tube issue at all. Smells to me like a marginal low frequency stability issue which can be caused by other things besides the tubes. 8 seconds is a little long for a settling time (ask anyone in rodeo). Could even be feedback between output stages and front end, due to power supply cap aging. If you pull the input tubes and it goes away, you can exonerate your output tubes (if the amp topology permits this without damage).
So - inspired by the latest post I did som trials this afternoon.
First a brief description:
Defy 7 has one ECC82 per channel which then hands signal over to two ECC83 again per channel (where only one half of each ECC83 is used). The ECC83 sits physically next to each other. These driver tubes then drive a sextet of (in my case) 6550C.
I started by switching the ECC82 right and left. Same picture.
Then I switched the left side ECC83. Same picture.
Then I switched the right side ECC83. Sound moved to left channel.
Voila! Case solved (for the time being). One faulty ECC83.
All tubes in the input and driver stage are Telefunken (made in February 1966]. They are rumored to outlive most others, but I guess, that after 28 years of continuous musical enjoyment it is fair, that one of them goes to tube heaven..
Not long ago all capacitors were inspected for leakage and other physicals signs of aging, but all looked pristine. No discoloration, no swollen and no material on pcb.
Thanks a lot to all for your simple and effective suggestions on how to attack this problem without complete disassembly and hunt for faulty components involved.
First a brief description:
Defy 7 has one ECC82 per channel which then hands signal over to two ECC83 again per channel (where only one half of each ECC83 is used). The ECC83 sits physically next to each other. These driver tubes then drive a sextet of (in my case) 6550C.
I started by switching the ECC82 right and left. Same picture.
Then I switched the left side ECC83. Same picture.
Then I switched the right side ECC83. Sound moved to left channel.
Voila! Case solved (for the time being). One faulty ECC83.
All tubes in the input and driver stage are Telefunken (made in February 1966]. They are rumored to outlive most others, but I guess, that after 28 years of continuous musical enjoyment it is fair, that one of them goes to tube heaven..
Not long ago all capacitors were inspected for leakage and other physicals signs of aging, but all looked pristine. No discoloration, no swollen and no material on pcb.
Thanks a lot to all for your simple and effective suggestions on how to attack this problem without complete disassembly and hunt for faulty components involved.
Is the same side of each ECC83 used on each channel? If not, then you cannot really be 100% sure about your conclusion since the other side of the swapped tube is being used after being moved.
If diferent sides of the twin triodes are not being used, then you hasve a possible route to maximse the bang for bunk of your Telefunkens.
If diferent sides of the twin triodes are not being used, then you hasve a possible route to maximse the bang for bunk of your Telefunkens.
My blunder - my memory must have been in the wrong place, since my comment regarding only one half of the ECC83 being used is wrong 
Attached is a circuit diagram floating on the web; circuit is more or less correct, values are not. But it gives you an insight on, how the two ECC83 are set up driven by the single ECC82.
Hopes this helps forum members in understanding and explaining my findings.
Attached is a circuit diagram floating on the web; circuit is more or less correct, values are not. But it gives you an insight on, how the two ECC83 are set up driven by the single ECC82.
Hopes this helps forum members in understanding and explaining my findings.