I have a 99% done F5 that hums in both channels. Is there anyone that would help fix it? I would be willing to pay and even ship the amp.
I am in eastern MA.
I am in eastern MA.
Does it hum even with nothing connected to its inputs ?
Try disconnecting all leads to the inputs of the amp and see if that improves matters.
You need to ascertain wether this is supply or signal generated.
Try disconnecting all leads to the inputs of the amp and see if that improves matters.
You need to ascertain wether this is supply or signal generated.
Try taking one amp in isolation and just connect supplies and the speaker.
The 0V from the amp MUST be connected to a single point close to the centre point of the two power supply capacitors.
0V or GROUND hum can often be caused if the 0V wire gauge is not heavy enough.
If you look at the multitude of photos of successful amps you will generally notice that the CENTRAL point between the power supply caps is a huge area of copper and that the 0V from the amp is connected to that mass of copper.
Also try disconnecting 0V from Mains Earth. LEAVE MAINS EARTH CONNECTED TO CHASSIS FOR SAFETY.
Have a look at these exampes.
The 0V from the amp MUST be connected to a single point close to the centre point of the two power supply capacitors.
0V or GROUND hum can often be caused if the 0V wire gauge is not heavy enough.
If you look at the multitude of photos of successful amps you will generally notice that the CENTRAL point between the power supply caps is a huge area of copper and that the 0V from the amp is connected to that mass of copper.
Also try disconnecting 0V from Mains Earth. LEAVE MAINS EARTH CONNECTED TO CHASSIS FOR SAFETY.
Have a look at these exampes.
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I know this is not the correct location for this thread. I am looking for someone who is will to help in person or via shipping. I am tapped.
Here is what they would be dealing with.
https://picasaweb.google.com/lh/photo/weFCP9Yqjb2P_YPA6eMKjj9JjZv_LowwRcCW6VDsar8?feat=directlink
Here is what they would be dealing with.
https://picasaweb.google.com/lh/photo/weFCP9Yqjb2P_YPA6eMKjj9JjZv_LowwRcCW6VDsar8?feat=directlink
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I can't impress enough the importance of the STAR 0V.
DO NOT connect 0V to mains Earth until the 0V is working correctly.
Make ABSOLUTELY SURE that the RCA input GND is NOT connected to the CHASSIS.
The 0V connections must also be VERY HEAVY cable.
Do not underestimate the problems that can occur with thin 0V leads.
DO NOT connect 0V to mains Earth until the 0V is working correctly.
Make ABSOLUTELY SURE that the RCA input GND is NOT connected to the CHASSIS.
The 0V connections must also be VERY HEAVY cable.
Do not underestimate the problems that can occur with thin 0V leads.
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Moved to Pass Labs
Hi Stefan, just take picture from top and place here...be sure, someone will help you..😉
I would really just start by taking everything back to building block stages. I would then dress the leads for each of those blocks. I would trim excess, twist the power leads, and lay out wiring paths that would be easy to follow.
This would clear up wiring so it can be better diagnosed. The current layout could be the problem.
Did you test it laid out before you mounted it in the chassis? I always build it in raw form and test with alligator clips, etc. If the unit worked then and now it is humming in the chassis that can be part of the problem.
Steve.
This would clear up wiring so it can be better diagnosed. The current layout could be the problem.
Did you test it laid out before you mounted it in the chassis? I always build it in raw form and test with alligator clips, etc. If the unit worked then and now it is humming in the chassis that can be part of the problem.
Steve.
STS9FAN may have solved his problem.
He thinks he's found the problem with too many routes to 0V - ie a poor STAR 0V.
He thinks he's found the problem with too many routes to 0V - ie a poor STAR 0V.
You've indicated it hums with no input....
But does it hum when the inputs are shorted (inner connector of the RCA jack connected to the outter braid)?
But does it hum when the inputs are shorted (inner connector of the RCA jack connected to the outter braid)?
I see advice to locate the Main Audio Ground (star ground) on the PSU Zero Volts.
Please don't. Keep the Main Audio Ground separate from the PSU Zero Volts.
Short the input RCA hot to return.
Measure the output noise. Both in mVdc and mVac.
Please don't. Keep the Main Audio Ground separate from the PSU Zero Volts.
Short the input RCA hot to return.
Measure the output noise. Both in mVdc and mVac.
And, then there is me. When I'm done with the Rs for the EUVL F5X project. But, I'm in Southern R.I. And I really need a road trip North!!!
Andrew- I'm doing as you suggest with the monoblocks I'm about to fire up, well the power supply anyway. I have 4 Rifa's connected together with a copper plate, but Main Audio Ground is NOT connected there, but rather to an isolated post nearby with some short fat wires taken directly from the last pair of caps. This avoids all heavy charge current, correct?
Yes Wil,
trace out the charging pulse route and the audio signal route via speaker. They must not share a trace. Just one connection between the routes.
trace out the charging pulse route and the audio signal route via speaker. They must not share a trace. Just one connection between the routes.
Thanks guys, I solved my hum problem but I may have another. The amp sounds great but is very low power. Like less then half of my Zv9. I think it must be my bias.
flg and labjr:
I would love to have a DIY G2G in the Northeast. Or even a bit of a lesson.
My set up and projects are modest but I love to listen.
Zv9, Pearl and Geddlee Nathans.
flg and labjr:
I would love to have a DIY G2G in the Northeast. Or even a bit of a lesson.
My set up and projects are modest but I love to listen.
Zv9, Pearl and Geddlee Nathans.
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