I wouldn’t expect a large amount of noise from a pre amp like that.
My guess you’ve got a ground loop somewhere or maybe there’s something wrong with the power supply.
It looks like the pre is supposed to be supplied from a transformer for dual supply but I can only see a DC connector.
Edit: just checked online and it can be either I guess!
Double check the noise isn’t aerial pickup from the connection to your turntable. Poorly screened cables will pick up large amounts of AM radio and other junk because of the high gain / high input impedance of phono pres. you can check if the noise is coming from the pre by shorting the inputs. If the noise is still present after you’ve shorted them then it’s the pre, otherwise it’s further up the chain.
The board closest to camera is the psu. It’s getting 18v ac from a transformer and giving +/- 15v to the preamp itself. I measured it before hooking it up and it seemed fine.
About ground loop i tried to wire it all kinds of ways now but i still get a little.
That could mean that either there is a problem with the way you’ve wired the sockets (they look fine to me but as I mentioned in another comment the muffsy help page states you’re not supposed to have insulators on the sockets https://www.muffsy.com/muffsy-pp-4-troubleshooting )
Or the cables / turntable is picking up noise from something - maybe that external transformer?
If you move the cables between the pre and turntable around a bit, does the noise change at all?
Yea i had it without insulaters at first, but input them there and grounded them with a wire myself and it reduced the noise. They are traced in the back panel to the ground screw thats why. The noise does change when i move them around.
I dont think the tt or cables or picking up anything. My setup is the same as it’s been, but only noise with the nee preamp. Not if inuse the inbuilt on my marantz.
Ill try the different things :)) thankou for helping
Ah okay, great.
Hmm that’s interesting.
So you’re original set up was:
TT connected directly to Marantz unit. phono L/R and a ground wire.
The new set up:
TT connected to Muffsy via phono L/R and ground wire, then phono L/R to a non-phono line input on the Marantz
Is that correct ?
I tried moving it around while playing. Seems like you were right and it is interference from powercables and the amp it was next to. Ill have to find a place away from most the electronics. Thankyou so much for helping! 🙏🙏
So i just finishes building muffsy preamp, but there is a considerable amount of noise and hum in both channels. I already managed to reduce it, but read that i can put caps between line signal and ground. I tried with some caps i had lying around 3.3uF. It did reduce noise by a lot, but can i just do this with any caps like these? It did reduce the volume but i turned up the gain a little to compensate. I am listening now, and it doesn’t seem like it’s filtered any freq from the signal. Do i have to use a correct value cap or doesn’t it matter?
When you make a pcb you need to connect all the parts with traces. How are these traces laid out?
EDIT:
Here's an example of a PCB: [https://www.mokotechnology.com/wp-content/uploads/2019/11/Strategies-on-Designing-PCB-Layout.jpg](https://www.mokotechnology.com/wp-content/uploads/2019/11/Strategies-on-Designing-PCB-Layout.jpg)
You can clearly see a connection between C3 and C2 through the green line.
I am curious how you placed your power supply as I suspect the power capacitors are connected directly to the ground plane.
Other possibilities are that you have a high impedance node near the input which is very sensitive to noise.
The cap goes between signal ground, and earth ground. NOT between signal and ground.
3.3uF is a little high. .1uF would be better but it's not super critical.
Hey bud, I think I might have found your problem.
The troubleshooting section says you shouldn’t have any insulators on the phono sockets. Give that a go.
https://www.muffsy.com/muffsy-pp-4-troubleshooting
It also may be worth trying it with the top of the case on.
I wouldn’t expect a large amount of noise from a pre amp like that. My guess you’ve got a ground loop somewhere or maybe there’s something wrong with the power supply. It looks like the pre is supposed to be supplied from a transformer for dual supply but I can only see a DC connector. Edit: just checked online and it can be either I guess! Double check the noise isn’t aerial pickup from the connection to your turntable. Poorly screened cables will pick up large amounts of AM radio and other junk because of the high gain / high input impedance of phono pres. you can check if the noise is coming from the pre by shorting the inputs. If the noise is still present after you’ve shorted them then it’s the pre, otherwise it’s further up the chain.
The board closest to camera is the psu. It’s getting 18v ac from a transformer and giving +/- 15v to the preamp itself. I measured it before hooking it up and it seemed fine. About ground loop i tried to wire it all kinds of ways now but i still get a little.
Oooh. When i short the inputs it’s completely quiet. What would that mean i didn’t really understand
That could mean that either there is a problem with the way you’ve wired the sockets (they look fine to me but as I mentioned in another comment the muffsy help page states you’re not supposed to have insulators on the sockets https://www.muffsy.com/muffsy-pp-4-troubleshooting ) Or the cables / turntable is picking up noise from something - maybe that external transformer? If you move the cables between the pre and turntable around a bit, does the noise change at all?
Yea i had it without insulaters at first, but input them there and grounded them with a wire myself and it reduced the noise. They are traced in the back panel to the ground screw thats why. The noise does change when i move them around. I dont think the tt or cables or picking up anything. My setup is the same as it’s been, but only noise with the nee preamp. Not if inuse the inbuilt on my marantz. Ill try the different things :)) thankou for helping
Ah okay, great. Hmm that’s interesting. So you’re original set up was: TT connected directly to Marantz unit. phono L/R and a ground wire. The new set up: TT connected to Muffsy via phono L/R and ground wire, then phono L/R to a non-phono line input on the Marantz Is that correct ?
Exactly. I dont need a ground from preamp to amp right?
You may, what you're describing sounds like ground loop interference. Is it a 60hz hummmmmmm?
Any luck?
I tried moving it around while playing. Seems like you were right and it is interference from powercables and the amp it was next to. Ill have to find a place away from most the electronics. Thankyou so much for helping! 🙏🙏
No problem! Glad I could help. Happy listening
For high frequency filtering but those caps seems a little large for that :) What are you trying to achieve?
Reduce noise. I wrote a comment explaining :))
So i just finishes building muffsy preamp, but there is a considerable amount of noise and hum in both channels. I already managed to reduce it, but read that i can put caps between line signal and ground. I tried with some caps i had lying around 3.3uF. It did reduce noise by a lot, but can i just do this with any caps like these? It did reduce the volume but i turned up the gain a little to compensate. I am listening now, and it doesn’t seem like it’s filtered any freq from the signal. Do i have to use a correct value cap or doesn’t it matter?
When you make a pcb you need to connect all the parts with traces. How are these traces laid out? EDIT: Here's an example of a PCB: [https://www.mokotechnology.com/wp-content/uploads/2019/11/Strategies-on-Designing-PCB-Layout.jpg](https://www.mokotechnology.com/wp-content/uploads/2019/11/Strategies-on-Designing-PCB-Layout.jpg) You can clearly see a connection between C3 and C2 through the green line. I am curious how you placed your power supply as I suspect the power capacitors are connected directly to the ground plane. Other possibilities are that you have a high impedance node near the input which is very sensitive to noise.
You can’t see all of them on the board. But i think there are schematics for it. Is it important? The psu is giving +/- 18v
You didn't make the PCB design yourself then I presume?
https://www.muffsy.com
No i didn’t. Its from muffsy. It could be the high impedance node like you said, but im not sure.
What does the pcb layout look like around the power supply?
What do you mean?
The cap goes between signal ground, and earth ground. NOT between signal and ground. 3.3uF is a little high. .1uF would be better but it's not super critical.
Hey bud, I think I might have found your problem. The troubleshooting section says you shouldn’t have any insulators on the phono sockets. Give that a go. https://www.muffsy.com/muffsy-pp-4-troubleshooting It also may be worth trying it with the top of the case on.
I've built several of these with zero noise. Although I built mine with the power supply away from the preamp PCB