If I may add a suggestion, I would put in two gnd tabs on the amp board to connect speaker and PSU gnd sor SMPS use. Regular PSU usually have multiple gnd tabs and is the ideal way of connecting but I'm dealing with SMPS and there's a single gnd tab on the SMPS and a single gnd tab on the amp PCB. Not the best setup splitting cables.
Thanks
Do
Thanks
Do
So, I'm going back to the drawing board with my PSU... Whatever I tried with the dual SMPS would always end up having some gnd loop noise. I will have to either get a single Cresnet 1200W SMPS to power both modules or a linear PSU. I'll have to see the costs. It's too bad I'm getting this noise with the dual 600W SMPS setup. I've had this issue with many amp setup with dual SMPS but only one I was ever able to have zero hum. Single SMPS or single/dual-mono linear PSU is never an issue though.
I'll be testing a few things in PSU in the coming weeks. I really like this amplifier and want to have it completed shortly.
Do
I'll be testing a few things in PSU in the coming weeks. I really like this amplifier and want to have it completed shortly.
Do
Simpelstark v1.3 does not use laterals, although v1.1 still uses them in its driver stage. We can check if Jeff ordered some v1.1 boards earlier.
What kind of noise are you getting? Can you figure out what frequency it is? I'm chasing a strange noise in a different build right now that moves around in the low hundreds Hz range. I think it might be a harmonic of the SMPS and changes with the regulation in the supply. Tough to cure!
Hi Do,
Jeff has been struggling the hum from a single SMPS lately in one of our prototypes (the other design, never mind). It seems to be EMF - it runs nicely on the table, but as soon as the boards are mounted in the chassis (close proximity to SMPS - the hum appears. Jeff is trying to rearrange the chassis space, adding some shielding across SMPS. Let's keep in touch on this 😉
Cheers,
Valery
Huh! Same time 😀
ok.. In the meantime, I will add the 10000uF low ESR caps on each rail at the output of the SMPS. This was how I got it totally silent on the FirstOne amp years ago. It could potentially work in this scenario. However, you need to modify the SMPS for this to work due to protection.
Do
Do
Just added those... Let's see if it works... Highly experimental setup... Kids, do not try this at home! LOL
@Pinnocchio
What kind of noise you have?
after connecting those big capacitors, the noise disappeared?
What about the 24V unregulated output? did you try to feed that from an external source, not from the SMPS? just a try.
What kind of noise you have?
after connecting those big capacitors, the noise disappeared?
What about the 24V unregulated output? did you try to feed that from an external source, not from the SMPS? just a try.
Hi Cresnet,
The 24V has just recently been used and did not impact/change the sound I’m hearing. I don’t know what frequency it is but much higher than 60Hz I would say.
The big caps is what had fixed the issue on the FirstOne amplifier but I have not yet tested with the big caps on this amp. Just connected and took a picture. I will test tomorrow if I can.
Thanks
Do
Hi Do,
Have you tried a ground loop breaker circuit ?
Connect the PS ground to earth through 10ohm resistor//diodes.
With dual mono PS you need two of these circuits.
In my amps it removes the 50/100Hz hum to complete silence, I've also added a switch to this circuit.
Have you tried a ground loop breaker circuit ?
Connect the PS ground to earth through 10ohm resistor//diodes.
With dual mono PS you need two of these circuits.
In my amps it removes the 50/100Hz hum to complete silence, I've also added a switch to this circuit.
I’ve tried the setup with extra caps on it made things worst... right now I’m just using a CL-60 per psu to ground but will try full ground loop breaker shortly.
I believe it disappears when using a single channel but I will need to double check this again. Can’t fully remember. I’ll let you know
With the multimeter set to Hz and probing the speaker terminals with nothing playing, I’m getting a frequency of between 400Hz to 500Hz. Don’t know if this test is even valid though... Single RCA connected (the other one just shorted), still getting the gnd loop or high frequency switching noise on both channels but less on the shorted one.
Do
Do
Do,
If this is any help to you I found that smps is not a good way to drive linear audio amps. You can quieten them, and I am sure you are using a very good one, but to do it well you need some [expensive] series inductance and there are limitations in the capacitance you can connect to an smps.
X and I find that Antek toroids with active rectification using the LT4320 is the best way to do it and there are absolutely no issues with earthing either. With a toroid you can actually float the supply - uni or bipolar - and this is where most of the earth loops appear with smps.
I am deeply impressed with Valery's Simplestark and since the amp has such levels of nuance I feel the best for it is to use a linear suppy........
A suggestion, just my 2c.
Hugh
If this is any help to you I found that smps is not a good way to drive linear audio amps. You can quieten them, and I am sure you are using a very good one, but to do it well you need some [expensive] series inductance and there are limitations in the capacitance you can connect to an smps.
X and I find that Antek toroids with active rectification using the LT4320 is the best way to do it and there are absolutely no issues with earthing either. With a toroid you can actually float the supply - uni or bipolar - and this is where most of the earth loops appear with smps.
I am deeply impressed with Valery's Simplestark and since the amp has such levels of nuance I feel the best for it is to use a linear suppy........
A suggestion, just my 2c.
Hugh
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I'm getting around the same frequency. In my case it seems to be
mostly radiated noise. I'm adding a bunch of shielding around my supply to hopefully help with that. The noise is radiated from the supply wiring as well, in my case the digital control wiring. As Hugh suggests some large inductors in the rail feeds will help with that.
One concern I'm having with the SMPS is that there is much more noise being generated well beyond the audio range so it's very likely the noise is much louder, we just can't hear it. The Zobel network on the output of the amp should help minimize the output of this but your poor tweeters must be seeing some awful abuse from it.