Thanks for merging the threads. Sorry for the double posting. Rewired all the input, output and ground wiring. The rca’s are the ones in the kit with isolation washers.
Also checked all joint solders. Also moved the unit and dac to another shelf position. It looks like if I take the case in my hands while the “beep-whisle” is going on, it stops. Is the pcb board connected to the case, ground wise?
Also checked all joint solders. Also moved the unit and dac to another shelf position. It looks like if I take the case in my hands while the “beep-whisle” is going on, it stops. Is the pcb board connected to the case, ground wise?
I believe the perimeter trace on the board is connected to gnd of all inputs/outputs including the (-) input of power supply. In my build that is also connected to the 1U chassis (if memory serves) I have mine installed in. Possible ground issue?
What power supply are you using? Is it grounded?
I had issues with my build and had to provide a chassis ground via another device (the SMPS earth pin was not connected internally to anything).
Try run a line from your chassis (any screw) to a properly grounded equipment.
The PCB should (ideally) mount to the metal chassis with star washers and metal screws / standoffs to connect it to the perimeter gnd plane. (Look at the top right corner of the picture you posted to see the connection)
I had issues with my build and had to provide a chassis ground via another device (the SMPS earth pin was not connected internally to anything).
Try run a line from your chassis (any screw) to a properly grounded equipment.
The PCB should (ideally) mount to the metal chassis with star washers and metal screws / standoffs to connect it to the perimeter gnd plane. (Look at the top right corner of the picture you posted to see the connection)
It should be, but perhaps yours is not. Try making a direct connection
between circuit and chassis.
I'm having similar problems. Here's what I've determined.
1. Nutube is microphonic and needs dampening material under it. I can tap on it and it will ring in the speakers - interestingly tapping will also cause the osculating to start.
2. There is a definite oscillation. Seems to not be related to input, I can have the input turned all the way down and it will still start osculating just sitting on a shelf. It comes and goes at various times - can be 1 min or 10 mins. If I lift the preamp off the shelf it's sitting on the oscillation will eventually stop or I can turn it off and back on and it will stop.
I shield the output from the board to the output jacks, which helped lower the occurrence of the oscillation.
All test measurements check out and I have T7, T8 set to 9.5.
When it works the preamp sounds very good.
Any ideas how to stop the oscillation?
1. Nutube is microphonic and needs dampening material under it. I can tap on it and it will ring in the speakers - interestingly tapping will also cause the osculating to start.
2. There is a definite oscillation. Seems to not be related to input, I can have the input turned all the way down and it will still start osculating just sitting on a shelf. It comes and goes at various times - can be 1 min or 10 mins. If I lift the preamp off the shelf it's sitting on the oscillation will eventually stop or I can turn it off and back on and it will stop.
I shield the output from the board to the output jacks, which helped lower the occurrence of the oscillation.
All test measurements check out and I have T7, T8 set to 9.5.
When it works the preamp sounds very good.
Any ideas how to stop the oscillation?
A heavy chassis dampened inside with bitumen. If chassis also is closed (air tight) there will be not feedback from moving air. I can knock on my chassis without any audible trigger of ringing in speakers. However if I have FocusRite with Arta or REW software to measure distortion and I knock…..I can see "something". I used that as a tool to see what happened without damping of chassis and with damping. A huge difference.
Regarding the ground connection between chassis and board trace, there is no actual connection. It seems that the case and bolts anodizing prevent actual contact. So, I will make sure there is a connection. I did the connection of board ground to another chassis properly grounded as suggested here but still got the beep. I shall report.
It looks like it is fixed!
As mentioned, there was no actual connection between the board ground and chassis. Why? Because the whole case and bolts were anodized. That includes the chassis chamfered holes and bolts, well, not the bolts that come with the kit to attach the pcb stands to the chassis, but as mentioned, these chamfered holes were anodized completely, offering no contact with the bolts.
So I removed the anodizing in the holes and established contact. My kit is the complete one that is offered for $299. But this also applies if you get the same enclosure from Italy that comes with kit. Thanks to everyone for your input and hope this helps new builders that get that enclosure.
As mentioned, there was no actual connection between the board ground and chassis. Why? Because the whole case and bolts were anodized. That includes the chassis chamfered holes and bolts, well, not the bolts that come with the kit to attach the pcb stands to the chassis, but as mentioned, these chamfered holes were anodized completely, offering no contact with the bolts.
So I removed the anodizing in the holes and established contact. My kit is the complete one that is offered for $299. But this also applies if you get the same enclosure from Italy that comes with kit. Thanks to everyone for your input and hope this helps new builders that get that enclosure.
It looks like it is fixed!
As mentioned, there was no actual connection between the board ground and chassis. Why? Because the whole case and bolts were anodized. That includes the chassis chamfered holes and bolts, well, not the bolts that come with the kit to attach the pcb stands to the chassis, but as mentioned, these chamfered holes were anodized completely, offering no contact with the bolts.
So I removed the anodizing in the holes and established contact. My kit is the complete one that is offered for $299. But this also applies if you get the same enclosure from Italy that comes with kit. Thanks to everyone for your input and hope this helps new builders that get that enclosure.
As mentioned, there was no actual connection between the board ground and chassis. Why? Because the whole case and bolts were anodized. That includes the chassis chamfered holes and bolts, well, not the bolts that come with the kit to attach the pcb stands to the chassis, but as mentioned, these chamfered holes were anodized completely, offering no contact with the bolts.
So I removed the anodizing in the holes and established contact. My kit is the complete one that is offered for $299. But this also applies if you get the same enclosure from Italy that comes with kit. Thanks to everyone for your input and hope this helps new builders that get that enclosure.
The end... Happy Ending!
As mentioned before, I assembled this linestage for a friend. So after finishing it and making sure the beep had gone, listened it for a few days in my system. It really sounds very good. Very dynamic, has a lot of bass, “soundstages” like hell, and of course smooth tube sound. Took it to my friend’s and his system never had sounded so good, a pair of Kharma 2’s loudspeakers driven by an Odyssey Kismet amplifier in Stratos case.
And how does it compare to my ba-3 linestage? Main difference is that it has a distinctive tube sound. Ba-3 has a more taut bass and both have similar soundstage properties.
As mentioned before, I assembled this linestage for a friend. So after finishing it and making sure the beep had gone, listened it for a few days in my system. It really sounds very good. Very dynamic, has a lot of bass, “soundstages” like hell, and of course smooth tube sound. Took it to my friend’s and his system never had sounded so good, a pair of Kharma 2’s loudspeakers driven by an Odyssey Kismet amplifier in Stratos case.
And how does it compare to my ba-3 linestage? Main difference is that it has a distinctive tube sound. Ba-3 has a more taut bass and both have similar soundstage properties.
The end... Happy Ending!
As mentioned before, I assembled this linestage for a friend. So after finishing it and making sure the beep had gone, listened it for a few days in my system. It really sounds very good. Very dynamic, has a lot of bass, “soundstages” like hell, and of course smooth tube sound. Took it to my friend’s and his system never had sounded so good, a pair of Kharma 2’s loudspeakers driven by an Odyssey Kismet amplifier in Stratos case.
And how does it compare to my ba-3 linestage? Main difference is that it has a distinctive tube sound. Ba-3 has a more taut bass and both have similar soundstage properties.
As mentioned before, I assembled this linestage for a friend. So after finishing it and making sure the beep had gone, listened it for a few days in my system. It really sounds very good. Very dynamic, has a lot of bass, “soundstages” like hell, and of course smooth tube sound. Took it to my friend’s and his system never had sounded so good, a pair of Kharma 2’s loudspeakers driven by an Odyssey Kismet amplifier in Stratos case.
And how does it compare to my ba-3 linestage? Main difference is that it has a distinctive tube sound. Ba-3 has a more taut bass and both have similar soundstage properties.
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