Well, I'd prefer to think of it as a simple case of leaving the bench with the cause as yet undetermined.
It'll be interesting if the noise comes back in "the usual location".
BTW, Do you keep notes?
Getting more and more convinced, that the problem lies with one of the 4 diodes
in the cathode string of the 5687. Cambridge Audio used some green ones in the old days
in their amplifiers. Nothing bult trouble. Can´t count, how many I´ve replaced back then 😉
in the cathode string of the 5687. Cambridge Audio used some green ones in the old days
in their amplifiers. Nothing bult trouble. Can´t count, how many I´ve replaced back then 😉
I use old 5mm diameter green LEDs in my phono (and other equipments green and red too) for more than a decade without any problem.
Looking back at my notes from a year ago, it looks like I found the noise was in the second stage and I replaced the 300 ohm Rinken CC grid stopper and the 330K grid leak resistor just in that channel and stage.
Those connections, the ones in the offending channel, have been reflowed twice last year but I'll try again.
Yes, but my point is really about redoing everything while there is no problem in hopes that something you do hits the source and the hiss doesn't come back , in which case you will never know exactly what the problem was.
On the other hand , if you just enjoy til it comes back, then you'll have a symptom that you can work with one step at a time until you're certain of the cause.
On the other hand , if you just enjoy til it comes back, then you'll have a symptom that you can work with one step at a time until you're certain of the cause.
Exactly. I'm going to gather some parts, take some measurements, build another set of CCS units and put it back in the system for now. I'll be back as this is the third time it has done this.
I had some 2W metal film resistors that were noisy once. It can happen. Since then I bite the bullet and try to get decent quality metal films.
Carbon film can be good too, but sometimes they drift in their value, which is not so great if you are building phono amplifiers.
Carbon film can be good too, but sometimes they drift in their value, which is not so great if you are building phono amplifiers.
I was going to say the Rinken was a likely source, having replaced it I understood the problem was resolved. So is it back now?
Perhaps an amplified probe and small speaker would allow you to determine the issue with a high degree of certainty. (A new project to build, o r a kit?) Freeze spray component by component can be revealing. Do not spray components with high voltage across them. 🙂
Perhaps an amplified probe and small speaker would allow you to determine the issue with a high degree of certainty. (A new project to build, o r a kit?) Freeze spray component by component can be revealing. Do not spray components with high voltage across them. 🙂