I had a strange experience when making the final DC offset adjustments on M2X mono blocks. The L-channel was easy to adjust and was very stable. The R-channel fluctuated and jumped suddenly 20-30 mV and never got really stable. I had scope on power supply and output to see if voltage was ok and if I had an oscillation at output. Then I worked the spade connectors to the M2X PCB and after that R-channel was as stable as L-channel. Strange......maybe this also was the reason why I had more 50 Hz noise on R-channel than L-channel in above measurements. Maybe I check later but first I think I will see if the amps can play some music.......but as I use high quality connectors I don't like this.......
They were crimped on using a prof. Knipex crimper tool.
I think the bad connection was not in the crimping but in the connection.
I pulled connectors half off and on again which seems to work. I don't know which was bad. I think very little contact resistance can cause unstable DC offset. The resistance will probably not be stable but change a bit all the time. I will keep an eye on it and measure DC offset regularly.
I heard some music and they played extremely well. It was hard to switch off for the night.......
.....very crisp and detailed with good bas control....and no noise.....
I think the bad connection was not in the crimping but in the connection.
I pulled connectors half off and on again which seems to work. I don't know which was bad. I think very little contact resistance can cause unstable DC offset. The resistance will probably not be stable but change a bit all the time. I will keep an eye on it and measure DC offset regularly.
I heard some music and they played extremely well. It was hard to switch off for the night.......
.....very crisp and detailed with good bas control....and no noise.....
I also have a couple of those which are good if you need more DMMs for e.g. combined bias/offset adjust. I got my in Lidl. 0.1 mV resolution is quite normal if you pay around 100 - 150 USD
I have considered a bench model which goes lower......but they are more expensive.
I used to have HP with 5 zeros precision, alas that's no more.
I ordered a bunch of those connectors, from Germany, as well. I guess more people did than talk here. It took them several weeks to “source” them. The thingees are roughly 1 euro a piece. Shipping was about $15 Germany-Alabama.
I will probably stick with the nuts (switching to bolt on top shortly) until I make a few more daughter cards, and decide which ones I will want swap in from time to time. Keep in mind, each set of daughter cards will use 8 euro of connectors.
I will probably stick with the nuts (switching to bolt on top shortly) until I make a few more daughter cards, and decide which ones I will want swap in from time to time. Keep in mind, each set of daughter cards will use 8 euro of connectors.
131A12049X CONEC | Mouser
Pins are a little harder to find than the sockets.
Spendy, but worth it to me and that is all that matters
Pins are a little harder to find than the sockets.
Spendy, but worth it to me and that is all that matters
I also have a couple of those which are good if you need more DMMs for e.g. combined bias/offset adjust. I got my in Lidl. 0.1 mV resolution is quite normal if you pay around 100 - 150 USD
I have considered a bench model which goes lower......but they are more expensive.
A compact Fluke 101 is about $70 and is pretty good for ascertaining if your amp output is low enough noise. I noticed that 0.1mV ms reading is usually pretty quiet and 0.0mV is basically inaudible with my ear pressed to the speaker cone. Meaning you can use it for a headphone amp. A headphone amp should not measure higher than 0.0mV on the Fluke or you will hear noise with typical 96dB/mW 32ohm cans.
what do you have going on here?
It looks like an great way to hot swap the input boards. I want to do it too!
So the code 706-131A12049X you linked is for the 3.18mm diameter. Does it fit fine in the M3 holes on the board?
From the pic one of the sides is gold plated but I can tell about the other. Can both sides be soldered? Is it sold as a male-female unit, right? It is a little pricy but whatever.
thanks
I prefer Mouser in the US.
If others are interested the numbers are:
706-132C12049X socket 3.18mm class 1 $3.2 each
706-131A12049X pin 3.18mm class 3 $1.7 each
The class 1 is rated at 500 cycles of plug/unplug vs 50 for class 3. Class 1 pin is special order.
Given the cost, I will put to the sockets on the main boards and the pins on the daughter boards.
If others are interested the numbers are:
706-132C12049X socket 3.18mm class 1 $3.2 each
706-131A12049X pin 3.18mm class 3 $1.7 each
The class 1 is rated at 500 cycles of plug/unplug vs 50 for class 3. Class 1 pin is special order.
Given the cost, I will put to the sockets on the main boards and the pins on the daughter boards.