That's what I thought. I have a similar full family of MyRefs and only the RC build has had any hum problems. It has to be a build error or a faulty part on the board. I'm not going to pursue it now but will after this build.
Sorry Will, I honestly wish there was an easy fix for you and me. It's not what you want to hear, but the Mini2496 kit is very inexpensive and a quick build. Maybe that combination will give you the same great results I'm getting.
Sorry Will, I honestly wish there was an easy fix for you and me. It's not what you want to hear, but the Mini2496 kit is very inexpensive and a quick build. Maybe that combination will give you the same great results I'm getting.
Bob, not to worry, all is not lost. I really dont think anything is wrong with the circuit, I think it is somthing I changed. Anyways I had the opportunity to try a few different "tests" today and here are the results.
The first ones were done while I still had the cheater in place or no safety earth.
I removed the caps and rcas from the chassis and connected everything outside of the case (as seen in the photo). The hum was still present.
I then removed the rods that support the caps. The hum became very faint and could only be heard with an ear to the speaker.
I noticed that if i touched the plate that the rca is mounted on it was audible through the speakers. (I should note that there is no continuity between the rca and the plate. I checked) I then re-installed the rca into the chassis again with no rods. The hum was like before, barely audible, but present.
I then removed the cheater and powered on the amp. The hum was present, louder than without the cheater but less than with the rods.
I then removed the rcas again and ran the caps outside the chassis. Same hum. When I touched the plates it was audible in both channels even though I was only touching one plate, and they were isolated from each other.
The most interesting fact is when I touched the body of the cap with my finger, the hum volume increased significantly. I really was not expecting this. Has anyone had any experience with these caps, and noticed anything like this? Is this normal for these and other caps? I was carefull not to over heat these while soldering and they still test right (they are still 1uf) Dario, or any others using these caps, did you notice any of this behaviour while these were mounted on the pcb?
Thanks....
The first ones were done while I still had the cheater in place or no safety earth.
I removed the caps and rcas from the chassis and connected everything outside of the case (as seen in the photo). The hum was still present.
I then removed the rods that support the caps. The hum became very faint and could only be heard with an ear to the speaker.
I noticed that if i touched the plate that the rca is mounted on it was audible through the speakers. (I should note that there is no continuity between the rca and the plate. I checked) I then re-installed the rca into the chassis again with no rods. The hum was like before, barely audible, but present.
I then removed the cheater and powered on the amp. The hum was present, louder than without the cheater but less than with the rods.
I then removed the rcas again and ran the caps outside the chassis. Same hum. When I touched the plates it was audible in both channels even though I was only touching one plate, and they were isolated from each other.
The most interesting fact is when I touched the body of the cap with my finger, the hum volume increased significantly. I really was not expecting this. Has anyone had any experience with these caps, and noticed anything like this? Is this normal for these and other caps? I was carefull not to over heat these while soldering and they still test right (they are still 1uf) Dario, or any others using these caps, did you notice any of this behaviour while these were mounted on the pcb?
Thanks....
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It seem an interesting progress and seem to hint to some interaction between caps and environment.
It's passed a lot of time and I can't remember for sure if touching them produced hum but I think that I would have noted it.
BTW I remember of one post on one of the My_Ref C threads on Obbligatos having noise pickup problems (they have copper body).
I've mounted K71s directly on PCB's pads bending leads and using a dense foam as support:
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Will - I'm too lazy to go back and read, but have you ever had other caps in that position and if so, was the hum present?
Bob, these are the only caps I have tried in this position. I will do some "shopping" tonite on partsconnexion etc. And see what's available. I am considering mounting these to the board to see if there is a difference.
Is there somthing about the pcb that would cancel the effect these have?
Iirc the new true coppers are much larger and would need to be mounted off board . If the k71s are unusual and my c13 mounting system can be salvaged for other caps that would be great, if not oh well.😀
Is there somthing about the pcb that would cancel the effect these have?
Iirc the new true coppers are much larger and would need to be mounted off board . If the k71s are unusual and my c13 mounting system can be salvaged for other caps that would be great, if not oh well.😀
You'r welcomed to try my spare Audyn Plus and a set of Mundorf ZNs if you are interested. Probably just three or four bucks for postage - round trip.
PM me if you want to give it a go....
PM me if you want to give it a go....
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This is not specific to the FE, but I've noticed that NOS Siemens MKL input caps, which have a similar ungrounded/floating metal shield around the film/foil bundle, also pick up some hum from a finger or probe nearby. This happens mainly when the board is outside the cabinet for testing - when it's inside the aluminium cabinet, there's no trace of hum, probably due to Faraday shielding.
How can you be measuring Hum with your ear?
Measure the output voltage of the amplifier. Correlate this to what you can hear, if you prefer.
Measure the output voltage of the amplifier. Correlate this to what you can hear, if you prefer.
Listening?
Dario,
I don't want to rush you, but I am curious. It has been at least a week since you got the new TCs. Any additional impressions?
Of course, "I'm not ready yet" is an acceptable answer.
Jac
Dario,
I don't want to rush you, but I am curious. It has been at least a week since you got the new TCs. Any additional impressions?
Of course, "I'm not ready yet" is an acceptable answer.
Jac
As it can be noted my 'on the bench' setup have my Plasma TV on the back.
When the TV is powered on there is some hum picked up by wires.
The interesting thing is that it started with my new Panasonic TV, the old LG (also Plasma), had no audible emissions.
I have received 1,2uF Audyn Copper caps from recent production yesterday. Size is 50 x 50 mm. To avoid them mounting offboard I have send them back and ordered tin foil caps instead. They are available for lower voltage ratings and have therefore smaller dimensions.
Br,
1543
BC639-16 and BC639G question
Hi,
I made a mistake in my mouser order and forgot to buy the BC639G for Q1
I know that Vbr and Hfe are different, but can I use BC639-16 instead for Q1 ?
Thanks,
Hi,
I made a mistake in my mouser order and forgot to buy the BC639G for Q1
I know that Vbr and Hfe are different, but can I use BC639-16 instead for Q1 ?
Thanks,
I'm not an expert (the DC protection circuit has been designed by Penasa) but I expect it to work also with the -16 version.
Bob,
Try reversing your input wires. I had mine hooked up wrong and the system would go dead silent when i grounded PGND. The pin closest to the mounting hole is -.
Hopefully we will see a + - on the new boards. 😉
Try reversing your input wires. I had mine hooked up wrong and the system would go dead silent when i grounded PGND. The pin closest to the mounting hole is -.
Hopefully we will see a + - on the new boards. 😉
