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Re: was HYPEX amps cheap surround system

Posted: Tue Apr 16, 2019 5:02 am
by mediatechnology
I have some Hypex nCore modues on my bench right now that are in a client's bass amp.

Do you see about 1V P-P of residual carrier on the output?

Re: was HYPEX amps cheap surround system

Posted: Tue Apr 16, 2019 7:20 am
by billshurv
Sounds about right if its at a few hundred kHz

https://www.stereophile.com/content/aud ... asurements for example.

Re: was HYPEX amps cheap surround system

Posted: Tue Apr 16, 2019 9:56 am
by JR.
mediatechnology wrote:
Tue Apr 16, 2019 5:02 am
I have some Hypex nCore modues on my bench right now that are in a client's bass amp.

Do you see about 1V P-P of residual carrier on the output?
Hypex FAQ wrote: 2 Q: I hooked up my UcD to an oscilloscope and I see some HF sine wave at about 400 kHz. Is this normal?

A: Yes. The 400kHz signal you see at the output of the amplifier is the residue of the switching nature of class D amplifiers. This is completely normal and does no harm. For more information please refer to our EMI application note.
Sorry no I have not put scope to the output, but the HYPEX class D is different from typical class d amps. Bruno connects NF to the very output and uses the natural lag of the switching stages and simple LPF to cause it to alternate, most class D amps take feedback from the nominal output before running through a big honking LP output filter that can introduce impedance changes and other stuff in the audio band.

https://www.hypex.nl/img/upload/doc/an_ ... nd_EMI.pdf Here is the emi note written by Bruno himself.
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I am getting closer to final assembly on my new surround sound system, but taking my time (measure three times cut once).

I am adding 10k attenuator trim pots to each input for balance trim while the different Hypex modules in Ucd series use a fixed 26dB gain.

The hypex amp modules have a 5V DC output so I could actually power my digital decoder from one of the amp modules but choose not to, since I will continue looking to upgrade that... Note: The new cheap chinese 5.1 decoder is significantly different from the first one. If I leave the TV monitor speaker on with the surround playing I used to get a short combing between center speaker and TV speakers (less than 2 feet away). Now there is clearly a few tens of mSec more delay inside the decoder, not sure what this means if anything, but seems to work better than the old (cheap) one.

I still need to strip the relays off the output board and sort out the wiring.

JR

PS: I had a little drama trying to grok the pinning on the 22pin audio input connector, and figured it out from following the traces on the PCB... today looking at the data sheet I notice they label both pins 1 and pin 2... duh.

Re: was HYPEX amps cheap surround system

Posted: Sun May 12, 2019 7:31 pm
by JR.
Ran out of things to double check, and guessed right on a couple.... fired it up and now making good sounds and no smoke.

I will check it out further tomorrow for now I'm watching movies.

JR

PS: I miss the meters on my old cheap amps.

Re: was HYPEX amps cheap surround system

Posted: Sun May 12, 2019 8:16 pm
by mediatechnology
Nice!

So what kind of meters did the old amp have?

Re: was HYPEX amps cheap surround system

Posted: Sun May 12, 2019 11:39 pm
by JR.
mediatechnology wrote:
Sun May 12, 2019 8:16 pm
Nice!

So what kind of meters did the old amp have?
three separate stereo amps,,, lots of LED meters.

I need to see what I end up with for a front end.. the new (cheap) decoder is way better than the old one but still can get stupid and lose sync requiring a power down/up reset.

New amp sounds different but I haven't put my finger on it yet... nothing wrong, so maybe good for a change. :lol:

JR

[edit- using a variant on the multiplex LEDs in my drum tuner (3x12) I could make a 6x10 LED meters with that one 16 line latch/driver and 6 high side mosfets. That would be a lot of LEDs but not much of anything else. The hypex has a 5V@ 100mA supply available so I can easily power the meter and maybe even a few opamps.. or just use it as is. :roll: /edit]

[edit2] after a second night of watching movies without meters, I miss them less and less. :lol: I was going to dig in and check some more, but sounds too good to mess with for now, maybe next weekend. [/edit]