Hi All,
I am new to the hobby, but with a couple successful builds under my belt so far. I have been working away at this project but I've encountered a difficulty I cannot seem to troubleshoot, or find an instance of in the thread so far so here goes nothing.
For reference I am running the Signal out of my Motu M2 usb i/o device into the H2, then using a NAD 2140 to power a pair of Paradigm cinema micro bookshelf speakers. Just using this system to test so I don't damage anything on my main system.
When the H2 is plugged in, it produces a high-pitched whine that I can't seem to eliminate. I have double checked all the solder connections and off-board wiring. I thought perhaps it was being caused by the mediocre quality power supply I was using so I added in a SMPS DC filter board but it made no discernable difference at all. The whine is volume-agnostic. I tried to use a couple other power supplies but the frequency of the whine just got higher rather than it going away. I also tried to use both positive and negative phase with my speaker connections but it didn't make a difference either.
I took a few voltage readings to help the diagnostic process:
T2: 10.22V / 10.22V (as prescribed on the JFET bag)
T1: 4.22V / 4.22V
Q1: 4.22V/0V/0V
Q2: 4.22V/0V/0V
All of these measurements were taken using ground as reference.
Thanks for any help you all might be able to offer. In spite of the high pitched whine, my partner who is by no means an audiophile was able to blindly identify the H2 as offering more "air" and "space" between instruments, even on my $200 speakers and hand-me-down NAD. I'd love to try it on my main system and see what the 2nd harmonic distortion character adds or takes away from the experience.
Go easy 'cause I'm just a beginner and loving every minute of it.
Cheers
Edit: I have used different values for R1 and R2 based on a post by Nelson early in the H2 Build thread concerning unity gain. The values are as follows:
R1: 22k
R2: 10k
Hope that helps
I am new to the hobby, but with a couple successful builds under my belt so far. I have been working away at this project but I've encountered a difficulty I cannot seem to troubleshoot, or find an instance of in the thread so far so here goes nothing.
For reference I am running the Signal out of my Motu M2 usb i/o device into the H2, then using a NAD 2140 to power a pair of Paradigm cinema micro bookshelf speakers. Just using this system to test so I don't damage anything on my main system.
When the H2 is plugged in, it produces a high-pitched whine that I can't seem to eliminate. I have double checked all the solder connections and off-board wiring. I thought perhaps it was being caused by the mediocre quality power supply I was using so I added in a SMPS DC filter board but it made no discernable difference at all. The whine is volume-agnostic. I tried to use a couple other power supplies but the frequency of the whine just got higher rather than it going away. I also tried to use both positive and negative phase with my speaker connections but it didn't make a difference either.
I took a few voltage readings to help the diagnostic process:
T2: 10.22V / 10.22V (as prescribed on the JFET bag)
T1: 4.22V / 4.22V
Q1: 4.22V/0V/0V
Q2: 4.22V/0V/0V
All of these measurements were taken using ground as reference.
Thanks for any help you all might be able to offer. In spite of the high pitched whine, my partner who is by no means an audiophile was able to blindly identify the H2 as offering more "air" and "space" between instruments, even on my $200 speakers and hand-me-down NAD. I'd love to try it on my main system and see what the 2nd harmonic distortion character adds or takes away from the experience.
Go easy 'cause I'm just a beginner and loving every minute of it.
Cheers
Edit: I have used different values for R1 and R2 based on a post by Nelson early in the H2 Build thread concerning unity gain. The values are as follows:
R1: 22k
R2: 10k
Hope that helps
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The whine is unrelated to the board with the JFETs (the preamp itself.) There is nothing on there that can cause that.
Can you try it with a 12v battery (or something around that?) A 9v battery should do too, for testing whether the noise is your PSU, or something else in your system that's upset about the low impedance.
Can you try it with a 12v battery (or something around that?) A 9v battery should do too, for testing whether the noise is your PSU, or something else in your system that's upset about the low impedance.
Thanks for the response. Just tried with a 9V Battery and the whining doesn't seem to be there. So I suppose my luck was such that all three power supplies I tried had different faults of their own. What would you recommend I do to remedy that? Is it advisable to make a PSU for the H2 board or would that be overkill?
You could try making a small linear power supply, and see if that has the same issue. The remaining issues would be either a loop of some kind of external noise, or generated noise. Linear supply would be the easiest way of finding out if it's the noise generated by the PSU's.
Can you describe the other PSU's you used?
Sure thing. The main one I was using was a 12Vdc 2A wall wart that was left over in my spare cable drawer. The second was another wall wart but it was 12Vdc 2.5A. The third one was a 12Vdc 3A laptop-style power supply with an external brick and a standard AC cable on the wall side. All three connected by a barrel connector.
No unfortunately. Just what I had lying around the house. I had my reservations but I thought it would at least be worth trying what I had on hand before getting something else. I think I’ll make a small linear power supply and just use AC mains power for this board after all.
That is, mind you, unless you can recommend a reasonably-priced 12v smps that would allow me to keep everything as-is.
You'll have to use AC mains power for any power supply you make unless it's battery powered :')
If you need an SMPS, MeanWell makes some modules. As well as some bricks. Depending on what you're comfortable with, you could also buy an AC-AC transformer (not AC-DC adapter), add a couple diodes, capacitors and a regulator, and you're set 🙂
If you need an SMPS, MeanWell makes some modules. As well as some bricks. Depending on what you're comfortable with, you could also buy an AC-AC transformer (not AC-DC adapter), add a couple diodes, capacitors and a regulator, and you're set 🙂
Lol! yes of course. I'm here showing my inexperience. Thanks for the recommendations and help. I'll post back when I've had the chance to make the change and see if my issue goes away.
Cheers
Nelson recommended a Triad wall wart for H2v1, I used that on my preamp, works great with the MJ filter. I used the Triad 12v wall wart for the first H2v2 I built, once again with the filter, very quiet.
For the balanced version I built I used a Meanwell medical grade smps only because I wanted to use an iec. Haven't had any issues with these power supplies.
For the balanced version I built I used a Meanwell medical grade smps only because I wanted to use an iec. Haven't had any issues with these power supplies.
Cool! I’ll try the triad out before I get into making an LPS. I suppose I should confirm that I even want to go the distance with the h2 before investing too much more time and energy into it. Thanks for the recommendation.
Yeah you’re totally right. This also seems like a valuable dilemma that will have some crossover benefit with lots and lots of other projects in the future. Thanks again for the guidance!
Anytime. I also started like you. 🙂 Now I make my own SMPS, repair Class D amps and Class AB amps, and create things like preamps and layouts. It all comes with experimenting and time 🙂
Interesting so I tried the Triad 12V 1A wall wart and I'm now getting a lower-pitched ringing than any of the 3 power supplies before. The common factor seems to be that the frequency gets higher as the amperage of the wall wart increases. I suspected that maybe it was as HumbleDeer had initially suggested and something in this system was not dealing with the low impedance well, but the same ringing occurs when just the H2 is plugged into the amplifier with no signal. I've tried the wall wart in multiple outlets, including the switched outlet on the back of the amplifier and the ringing doesn't change.
Any ideas?
The ringing getting louder when the amps are higher is noise from the PSU, as the mosfet is being switched on for longer duty cycles.
Test your whole system's ground. Something is not working correctly here.
Test your whole system's ground. Something is not working correctly here.
Please check your solder connections for C2, C1 and P1, just reflow them. You may also want to measure DC on the outputs with an input signal. It should be as close to 0 vdc.
With the H2 inputs shorted, do you still get the ringing noise?
With the H2 inputs shorted, do you still get the ringing noise?
I double checked and re-flowed all the solder connections as a first step in troubleshooting. I know for a fact that they are all good. I just tried shorting the inputs and it didn't make a difference. I measured the voltage on the outputs with a constant input signal and I got 50mV.
I also tried it on my main system and the ringing was the exact same. That system is certainly grounded properly. Unless there is perhaps a grounding issue with my apartment's electricity on the whole (not out of the question), I'm not sure what else I can change.
May I suggest making friends? Using someone else's couch is always more fun. And you get to test your gear there, as a bonus! It's great, if you can. /S