um.. connect power supplys V- and GND together. Also, use short, hi quality cables between source and amp.
Have you seen the schematic? This should already be the case, otherwise the amp would not work at all.
I hope you don't mean the PS GND by the way, because that should really not be connected to the amplifier anywhere....
Sorry if this is a stupid question, but what does the "power down" output on the T4 do? Is it to connect a switch and put it in standby mode?
Also a more general question, where would I put a power switch, before or after the power supply? I see a lot of cool push button switches, but I can't find any rated for 120v.
Also a more general question, where would I put a power switch, before or after the power supply? I see a lot of cool push button switches, but I can't find any rated for 120v.
Okay, an almost 50mV ripple at almost 60Khz, that's just not right! I wonder what he chose as voltage reference for the probe ground of the scope??
If that means you have to earth the output V- this is a poorly designed power supply!! Or not designed for audio....
The problem is when you earth the output you will definitely run in to ground loop problems with earthed sources..... Not very desirable.... Not really a 'solution'.....
If that means you have to earth the output V- this is a poorly designed power supply!! Or not designed for audio....
The problem is when you earth the output you will definitely run in to ground loop problems with earthed sources..... Not very desirable.... Not really a 'solution'.....
Guys, I finally started working on my amp, based on ver1.2 with the 510A and the Alps pot. Using the Meanwell PSU at 28V.
I've got a problem that I don't yet know how to solve. I started testing with one speaker output, and I've got a loud buzz that kind of sounds like a ground loop buzz, but isn't because the source and the amp are running off the same outlet. Also, the music is very quiet, not only relative to the buzz but overall.
The buzz appears as I plug in the input wires from the source, and is present _occasionally_ even when I use a battery-powered source like the iPod. I've reset the DC offset (it wasn't that either, that's would just result in a hiss).
When I connect the input's ground to the power supply's ground, the buzz gets quieter--currently, the input's ground is isolated from the PSU's ground and is simply connected to the "input/ground" terminal on the amp.
How do I diagnose something like this? Thanks in advance.
I've got a problem that I don't yet know how to solve. I started testing with one speaker output, and I've got a loud buzz that kind of sounds like a ground loop buzz, but isn't because the source and the amp are running off the same outlet. Also, the music is very quiet, not only relative to the buzz but overall.
The buzz appears as I plug in the input wires from the source, and is present _occasionally_ even when I use a battery-powered source like the iPod. I've reset the DC offset (it wasn't that either, that's would just result in a hiss).
When I connect the input's ground to the power supply's ground, the buzz gets quieter--currently, the input's ground is isolated from the PSU's ground and is simply connected to the "input/ground" terminal on the amp.
How do I diagnose something like this? Thanks in advance.
Last edited:
Actually, I hear the buzz with an iPod too, but it's a lot quieter.
Do you think this is a grounding issue? Does anybody know why the power terminals of the T1 amp are labeled V+ and GND (instead of V+ and V-)? I tried connecting the GND of the power terminal to the GND on the PSU and that did not work...
Do you think this is a grounding issue? Does anybody know why the power terminals of the T1 amp are labeled V+ and GND (instead of V+ and V-)? I tried connecting the GND of the power terminal to the GND on the PSU and that did not work...
This is probably because ground is made on more than one point to the AGND of the amplifier board.
To diagnose this you have to find the one and only point where AGND and PGND are connected. With a god design this is a ferrite choke, cheaper designs use either a zero ohms resistor or just a PCB trace. You can remove this connection and then measure if the grounds are floating with regards to the casing or each other. They should not connect when the single connection is removed.
Very common with hum problems is also poor/poorly assembled input wiring.
To diagnose this you have to find the one and only point where AGND and PGND are connected. With a god design this is a ferrite choke, cheaper designs use either a zero ohms resistor or just a PCB trace. You can remove this connection and then measure if the grounds are floating with regards to the casing or each other. They should not connect when the single connection is removed.
Very common with hum problems is also poor/poorly assembled input wiring.
These amps do not have noise issues. They are totally silent, even with highly sensitive speakers.
second v-bro with that: most of the noise issues in my experience came from input wiring/soldering issues. Usually easy to fix.
In rare cases, it helped to connect amp power ground to chassis with meanwell earth also connected to chassis.
second v-bro with that: most of the noise issues in my experience came from input wiring/soldering issues. Usually easy to fix.
In rare cases, it helped to connect amp power ground to chassis with meanwell earth also connected to chassis.
Surely this can help, but it usually indicates another problem. These problems are best solved at the cause, and not patched by compromising safety and risk of ground loops.
And then if the connection needs to be made, use a breaker circuit such as described here:
Earthing (Grounding) Your Hi-Fi - Tricks and Techniques
I want to thank Nick Steinar for helping me narrow down the cause... Well, it turns out that white 3-post input connector is supremely wonky; jiggling it around revealed that it wasn't making good contact on any of the three posts, actually.
Out went the connector and the input wire was soldered through the holes on the board. Thanks to all replying, it was a grounding issue after all.
Out went the connector and the input wire was soldered through the holes on the board. Thanks to all replying, it was a grounding issue after all.
Last edited:
this is my main suspicious in my case ! I checked up T4 recently and have noticed a very slight hum and an intensive noise. I try to solder them tightly on the board and fix the cinch outputs in better way.
You seem to be right - I find this white plastic plug as a real weak point of the board.
I NEED HELP !! Today arrived my T4...I connected it to the meanwell, signal input, and output to 8ohm speakers; I turned PSU on but T4 amp did not turned on! Any ideas? I connected AC and ground to the meanwell, DC to T4 amp, as shown on the board( side connectors DC, center empty). There is tension at DC input on the T4 board, because I've measured it.... Could someone help me??
Got my new amp (I just ordered a new one minus the pot), replacement coming soon too to replace the one that went south. Great service from Steinar.
Soldered in the old alps pot from the damaged one. I removed the heatsink on the new one and wet sanded the paint off the bottom with 400 then 1000 wet or dry and cleaned up the chip and applied some fresh heatsink compound. Amp sounds great, she's running on 36v........The heatsink seems to be getting hotter than the last one I had. Maybe the heatsink mod making it transfer more heat? So far so good !!
Soldered in the old alps pot from the damaged one. I removed the heatsink on the new one and wet sanded the paint off the bottom with 400 then 1000 wet or dry and cleaned up the chip and applied some fresh heatsink compound. Amp sounds great, she's running on 36v........The heatsink seems to be getting hotter than the last one I had. Maybe the heatsink mod making it transfer more heat? So far so good !!
Heatsink temperature
Yeah, great service from Steinar
About the temperature...I made this thought: if you look at the datasheet of these DDX amps, efficiency increases up to about 90% after 5-6W; if you use lower power (=lower volume) probably the chip gets hotter...I've noticed this yesterday night listening to T4 at very low volume: the heatsink became hotter than the day before, at higher volume...
just my 2c
Yeah, great service from Steinar
About the temperature...I made this thought: if you look at the datasheet of these DDX amps, efficiency increases up to about 90% after 5-6W; if you use lower power (=lower volume) probably the chip gets hotter...I've noticed this yesterday night listening to T4 at very low volume: the heatsink became hotter than the day before, at higher volume...
just my 2c
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.