Is the pop really loud? Check the DC voltage on the speaker outputs before power on, then with power on and then right after power off.
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NCORE MP Build using Ghentaudio Kit.
- Thread starter decoRyder
- Start date
No input plugged to the amp:
- before power on: 0.0mv
- power on: peak to 1.2V, then stabilized to 15.4mV (less than a second to stabilize)
- power off: peak to -1.5V then slowly(more than a minute) increase to stabilized 15.4mV
Same on left and right channel.
During power on/off, I briefly saw a .0L on my cheap multimeter (don't know what it means)
If possible I would suggest to try triggering from external 5V source to J6.9. My NC250MPs did plop sometimes using the main switch which connects J6.3 to J6.9, not loudly but it did. But for practical reasons I use external triggering from source device's USB, and it never ever ploped since then. I made a specific USB to 3.5 TRS for that purpose.
As per specs, PS Enable pin get logic high with voltage from 3.3V to 12V.
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There's a pop when the speakers are disconnected?
My bad. When XLR inputs connector are disconnected
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.0L likely means overload, and that it was trying to find the proper range. If possible, you should 'fix' the range at 2-3 volts for this test. I am surprised at the magnitude of the on/off step transient. However, even at 2 volts, with a nominally 8 ohm load, that is still only a momentary peak of about 1/4W and should not harm anything.
So if I understand correctly: if you feed the J6.9 with internal 5V (J6.3 Vout) you have the plop.
If you feed the same J6.9 with external 5V, you don't ?
Yep, I can't explain why but that's a fact. Maybe low current of USB port, I don't know. I can'ty say if J6.3 is also 5V, I didn't check.
this is how trigger is connected on my amp. Trigger input beeing a female TRS3.5 connector on the chassis (as every trigger input).
https://www.audiosciencereview.com/...ding-an-existing-amp-build-2-x-nc250mp.13094/
https://www.audiosciencereview.com/...ding-an-existing-amp-build-2-x-nc250mp.13094/
I struggled to find how to deal with pin1.
Hypex whitepapers tells to connect to chassis only, so I would expect ghent audio case kit to have only 2 wires (hold and cold) from h-box connector to XLR pins..but there are 3. (and all 3 used in every pictures on the web)
And so, what are J4.3 (GND ch1) and J4.14 (GND ch2) used for if we should connect pin 1 to chassis?
Unless they are chassis ground and not circuit ground?
Whatever It's a little bit confusing (at least with my limited audio and electronics knowledges)
I personally try wiring pin 1 to both h-box and XLR chassis lug, then to J4.3 only.
Didn't try only to chassis (and no more h-box)
If someone had the good wiring, please share
Hypex whitepapers tells to connect to chassis only, so I would expect ghent audio case kit to have only 2 wires (hold and cold) from h-box connector to XLR pins..but there are 3. (and all 3 used in every pictures on the web)
And so, what are J4.3 (GND ch1) and J4.14 (GND ch2) used for if we should connect pin 1 to chassis?
Unless they are chassis ground and not circuit ground?
Whatever It's a little bit confusing (at least with my limited audio and electronics knowledges)
I personally try wiring pin 1 to both h-box and XLR chassis lug, then to J4.3 only.
Didn't try only to chassis (and no more h-box)
If someone had the good wiring, please share
My understanding of Hypex paper is that pin 1 should connect to chassis as near as possible to XLR socket and that GND ch1 (and ch2) should also be connected to chassis near the XLR, but not at the same point of contact with chassis.
quoting section 4.3, 3rd line : "Instead, pin 1 was connected to chassis. The audio circuit was also tied to the chassis, but crucially, elsewhere."
This is also mentionned on the build below but considered "as not a real world problem" hence connecting pin 1 directly to GND ch1/2 AND to the chassis through XLR socket.
http://www.enjoythemusic.com/diy/0415/SiebeNCore_DIY_Stereo_Amplifier.htm
quoting section 4.3, 3rd line : "Instead, pin 1 was connected to chassis. The audio circuit was also tied to the chassis, but crucially, elsewhere."
This is also mentionned on the build below but considered "as not a real world problem" hence connecting pin 1 directly to GND ch1/2 AND to the chassis through XLR socket.
http://www.enjoythemusic.com/diy/0415/SiebeNCore_DIY_Stereo_Amplifier.htm
To summarize:
EDIT: I made a continuity test between IEC ground and XLR chassis lug (as well as all bottom case screws and board screws), and it's ok.
No need to sand in my case
- sand the case under the XLR chassis connectors: remove anodization so that xlr chassis lug (pin 4) is connected to chassis
- connect XLR connector pin 1 to pin 4
- connect h-box GND ch 1/2 to chassis
- ideally elsewhere than pin1/pin4
- but pin1/pin4 should be fine
EDIT: I made a continuity test between IEC ground and XLR chassis lug (as well as all bottom case screws and board screws), and it's ok.
No need to sand in my case
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So I managed to pick up some NC400's second hand (but looks like they glued on the front of the original Hypex case because I cannot remove it). Using my E30 for now with a converter to connect RCA cables to the NC400. There are some small pops when turning stuff on and off (switch on the back of the amp, or shutting off the DAC), but nothing crazy. But I think I'm not hitting the max amplification with the max output from the E30 (a little over 2v), because I can go to -10 dB on the E30 without any issue and -5dB is uncomfortably loud but not distorting or louder than my 2x90W Marantz could do. Doesn't feel like I can go up to 200W like this. That is due to me using RCA right?
dkinric
Addicted to Fun and Learning
The pops are a widespread issue. I also have it on power up and power down on my Hypex/Ghent amp. However, it is not that loud at all, so no real concern there for me.
The volume adjustments are a function of the preamp (e30 in your case). I tried a DX7PRO as a preamp, and also noticed you have to go pretty high on the volume scale to get into the power. I no longer use this as a preamp, though.
When you say a "converter" do you mean rca to xlr converter box? This may be fine, but usually cables designed for this purpose are recommended (easily available on amazon, etc), with xlr on one end and rca on the other. For shorter runs in home use, rca should be fine if you have no ground loop issues. My understanding is you will still be using the full power of the amp, but feeding it 2v instead of 4v requires more amp gain for a certain volume, so yes it can affect the max SPL, all else being equal.
The volume adjustments are a function of the preamp (e30 in your case). I tried a DX7PRO as a preamp, and also noticed you have to go pretty high on the volume scale to get into the power. I no longer use this as a preamp, though.
When you say a "converter" do you mean rca to xlr converter box? This may be fine, but usually cables designed for this purpose are recommended (easily available on amazon, etc), with xlr on one end and rca on the other. For shorter runs in home use, rca should be fine if you have no ground loop issues. My understanding is you will still be using the full power of the amp, but feeding it 2v instead of 4v requires more amp gain for a certain volume, so yes it can affect the max SPL, all else being equal.
So yes, the amplification is the same, but the signal level it has to amplify is not as high, so the resulting output isn't either.
What "converter" are you using? There is no actual conversion needed, just an adaptor plug or cable.
What "converter" are you using? There is no actual conversion needed, just an adaptor plug or cable.
Top of my head I have to be at -50dB before I start hearing anything, I could be 10dB of.
I just use a passive converter like this, maybe I'm using the wrong word:
The leads are only 75 cm, and I plan to move to XLR in due time (when I find a DAC that suits my needs). Don't have a ground loop issue right now. But I also have to say it depends on what I listen to because for other things I can't turn it up that high. But on my old Marantz amplifier I would never go higher than -20dB, there is no way I'd get to -10dB there. And that one is "only" 90W@8hm according to the specs (measures near a 110w). I mean don't get me wrong, it gets plenty loud regardless but I was just wondering.
And before anyone asks if I hear a difference between this and the Marantz: nope. I just got them because I wanted something a lot smaller.
