I tested this amp with the computer outputs. and I hear a HUM in the 200hz region. Definatly not 60hz. The hum is clearly audible at several feet away. but not over bearing.
The hum is only present when both RCAs are connected. If I disconnect either one The sound stops.
There is no hum when I run it off of the AV preamp in the living room, nor is there any hum when there is no input connected.
Is this a faulty sound card? I have never noticed this with any other amp I had run off the computer.
It is also not a grounding problem with the amplifier. I changed the grounding scheme several times and the hum never changed.
The hum is only present when both RCAs are connected. If I disconnect either one The sound stops.
There is no hum when I run it off of the AV preamp in the living room, nor is there any hum when there is no input connected.
Is this a faulty sound card? I have never noticed this with any other amp I had run off the computer.
It is also not a grounding problem with the amplifier. I changed the grounding scheme several times and the hum never changed.
Attachments
It's 120 Hz hum -- you are using a full wave bridge rectifier.
The wall of the cabinet is not remotely adequate to conduct the amount of heat generated by a chipamp. You need a heat sink.
The transformer doesn't look adequate. The one you are using looks to be from a 10 or 15 watt stereo -- this will overheat and fail.
the diode board should have a greater clearance between itself and the bottom of the chasis. Consider putting a sheet of mylar underneath the diode board to prevent accidental contact with the chasis.
i would tackle the diode board first --you don't want to be dead before you have a chance to enjoy the music.
consider using 2 10,000 uF capacitors, with a rating about twice the transformer voltage (i.e. if the transformer is 24-0-24 V, the caps should be rated for 50V) right after the diode bridge -- this will accomodate most line voltage swings.
(edit) run the leads from the power supply along the rear of the chasis to the amplifier boards. run the input leads along the floor of the chasis. twisted pair should be OK
The wall of the cabinet is not remotely adequate to conduct the amount of heat generated by a chipamp. You need a heat sink.
The transformer doesn't look adequate. The one you are using looks to be from a 10 or 15 watt stereo -- this will overheat and fail.
the diode board should have a greater clearance between itself and the bottom of the chasis. Consider putting a sheet of mylar underneath the diode board to prevent accidental contact with the chasis.
i would tackle the diode board first --you don't want to be dead before you have a chance to enjoy the music.
consider using 2 10,000 uF capacitors, with a rating about twice the transformer voltage (i.e. if the transformer is 24-0-24 V, the caps should be rated for 50V) right after the diode bridge -- this will accomodate most line voltage swings.
(edit) run the leads from the power supply along the rear of the chasis to the amplifier boards. run the input leads along the floor of the chasis. twisted pair should be OK
well actually..........
I disagree - if you're not driving the amp hard, and your transformer voltage is fairly low, you don't need much of a heatsink at all. See pics of my Mini-Clone that runs on a 16V transformer. The case is very thin aluminium, but even then it barely feels warm, even when I play it the loudest I ever will...
Suck it and see. If the transformer doesn't get too warm, when you run the amp at your max. listening level, you don't need to change it.
I agree that this needs to be done, but would suggest that the 20V from the transformer secondary isn't very likely to kill you. -Especially if your chassis is grounded as well.
Just some opinions based upon my experiences..
Steve
I disagree - if you're not driving the amp hard, and your transformer voltage is fairly low, you don't need much of a heatsink at all. See pics of my Mini-Clone that runs on a 16V transformer. The case is very thin aluminium, but even then it barely feels warm, even when I play it the loudest I ever will...
Suck it and see. If the transformer doesn't get too warm, when you run the amp at your max. listening level, you don't need to change it.
I agree that this needs to be done, but would suggest that the 20V from the transformer secondary isn't very likely to kill you. -Especially if your chassis is grounded as well.
Just some opinions based upon my experiences..
Steve
extra windings
Hi jackinnj,
The 'bare' wires aren't quite bare. It's magnet wire, which has a thin layer of enamel insulation as it comes. The extra wires are an additional 10 ten turns of wire that powers the LED on the front panel. It produces around 2 volts if I remember right. --- Some people on here have mentioned that putting LEDs on the amp supply rails adds noise, and this was suggested as a win-win way of doing it.
Steve
Hi jackinnj,
The 'bare' wires aren't quite bare. It's magnet wire, which has a thin layer of enamel insulation as it comes. The extra wires are an additional 10 ten turns of wire that powers the LED on the front panel. It produces around 2 volts if I remember right. --- Some people on here have mentioned that putting LEDs on the amp supply rails adds noise, and this was suggested as a win-win way of doing it.
Steve
It appears that you think I am some Hack.
The diode board is fine as is. It is elevated enough and is secured by small bolts. The only way there would be contact is if the case was dropped and some how was dented in the exact plase that the bridge is.
The Xfmr is also adequate. I ran it for hours yesterday at what I consider max volume. Nothing got warm. the case was not even hot to the touch. not even directly where the chip is bolted to the side panel
The diode board is fine as is. It is elevated enough and is secured by small bolts. The only way there would be contact is if the case was dropped and some how was dented in the exact plase that the bridge is.
The Xfmr is also adequate. I ran it for hours yesterday at what I consider max volume. Nothing got warm. the case was not even hot to the touch. not even directly where the chip is bolted to the side panel
My appologies for the from the hip defensiveness.
I looked at the photo again and realize that from that angle it appears the board is right down on the metal case.
I assure you that it is about a quarter inch above and secured tightly.
Good eye I am glad that there are those that keep an eye open for others.
I looked at the photo again and realize that from that angle it appears the board is right down on the metal case.
I assure you that it is about a quarter inch above and secured tightly.
Good eye I am glad that there are those that keep an eye open for others.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.