terryforsythe
Major Contributor
This is Audio Science Review. Many of us are engineers, and we discuss measurments. That is what engineers do. If you think engineering is a cult, so be it.
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Hypex Nilai500DIY Amplifier Review
- Thread starter amirm
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This is Audio Science Review. Many of us are engineers, and we discuss measurments. That is what engineers do. If you think engineering is a cult, so be it.
antcollinet
Grand Contributor
My question was about shielding of this particular Nilai build, not about Purifi versus Nilai.
D
Deleted member 58670
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The internal mains power cables should probably have been twisted. Apart from that, it looks fine to me.
The internal layout of the Audiophonics is very similar to the Nilai DIY, so I'd expect little difference in the measured response.
SMPS don't have the magnetic spray issues at 50/60 and 100/120 Hz that LPS exhibit, and the switching frequency is normally way out of the audio band at several hundred kHz, so shielding generally isn't necessary.
On Amir's bench test of the Nilai, there's a ~10 dB bump at 60Hz, but it's still at -136 dB, so completely inaudible:
Shielding would seem an unnecessary expense for no audible gain.
That's not a shield, that's a decoration preventing proper cooling.
Those look like they're machined from aluminium too. Magnetic shields are normally constructed from mu-metal.
AFAIK, when it comes to shielding EMI, aluminum is almost like air (distance). See the table below. Regular carbon steel, or better iron, or even better permalloy would be a lot better for that application.
en.wikipedia.org
Permeability (electromagnetism) - Wikipedia
Digital_Thor
Addicted to Fun and Learning
What are people actually afraid of? Shielding from something from the outside? Shielding from the components themselves? Or shielding from the AC-line - maybe both ways?
If build properly - then often, it's not a practical issue.
I often hear a "sizzle", buzz or high pitch sound, directly/physically from switching amplifiers - also with the Hypex 502. It is low, and you need to be within 30-40cm of it - with no music - but it's there.
I guess it is the lower harmonics of the components "singing" along with the higher switching frequency.
I would say it sound a bit like the coil wine from motherboards, graphic cards and power supplies, that is so normal in PC's, during load.
Old amplifiers hum - and new amplifiers wine. There's always something something
If build properly - then often, it's not a practical issue.
I often hear a "sizzle", buzz or high pitch sound, directly/physically from switching amplifiers - also with the Hypex 502. It is low, and you need to be within 30-40cm of it - with no music - but it's there.
I guess it is the lower harmonics of the components "singing" along with the higher switching frequency.
I would say it sound a bit like the coil wine from motherboards, graphic cards and power supplies, that is so normal in PC's, during load.
Old amplifiers hum - and new amplifiers wine. There's always something something
antcollinet
Grand Contributor
Do you mean from the speakers, of from the device itself? @Digital_Thor was (I think) talking about noise from the device itself - like coil whine.
Digital_Thor
Addicted to Fun and Learning
Absolutely. Hypex made them easy to use, build and like. I only kept my current amps, because they still work, can't really hear a difference in direct comparison, quite a big price to upgrade the 6 channels I need for my active setup, and no matter how great something is - then I'm actually still very happy with what I got
Digital_Thor
Addicted to Fun and Learning
Actually a bit of both. I borrowed them from a friend, who use them with Mini-dsp. Which has way less output than my pre-amp. So the 4dB higher gain on the Hypex, seemed to amplify some noise, that I never hear with my normal amplifiers - like a slight "growling" - actually from the speaker drivers.
My Groundsound setup, is build with the logic, that if you have a higher output from the pre-amp, and less gain on the power amplifiers - then you have less noise overall.
My power amplifiers have 22dB of gain, and my pre-amp has 10Vrms - if I remember correctly. I have a little hiss with my ear 5cm from the tweeter - but that's it.
There's definitely a lot of gain lost with passive speakers, which can make quite a difference with perceived noise from active speakers, where you connect the amplifiers directly to the speaker units.
Both, but anyway protect the audio signal from interference.
antcollinet
Grand Contributor
We'll ignore the fact that RFI is part (subset) of EMI
If the designer sees any artefacts from EMI in measurements of the output of the amp, they might implement shielding (or more likely other measures such as separation, and/or twisting of wiring) to fix it. If there are no such artefacts, then shielding is not needed. A typical example of such interference would be mains hum.
When amps using these modules - or similar ones - are measured here, we normally don't see any such interference (at least not at audble levels) - whether shielding is employed or not.
Also bear in mind - even when PSU interference is seen on the output (at any level) it is as likely to be conducted along the power wires, as radiated. Shielding can do nothing for conducted interference.
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antcollinet
Grand Contributor
Because if it is left out, and there is no interference, it is not needed. As in nearly all of this type of module based amp.
For example, take the hypex NCxxxMP series of modules. They have PSU and amp built onto the same PCB right next to one another. No shielding. No radiated interference that has any impact on the sound.
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