atomicbob's SMPS Noise Nuke for HP amps with external SMPS

I don't intend to take the simulations as the final performance. They provide some guidance / insight. I am waiting on a metal box in which to enclose the filter components. If it achieves even 80 dB of reduction, the residual noise is likely to be in the single digit microvolt range for a typical SMPS input. Not going to measure that reliably without the whole system including cables shielded appropriately.

thank-you for those measurement insights. The final system will have bypass caps and a small output inductor to limit downstream component inrush current at component power up and possibly a few other components. The above simulations are mostly a teaser, not meant to be taken as the final performance.

 

Just a simple MOV will do this!

Don’t forget to add the capacitors. It’s not just the inductor. It’s the combined filter of the inductor and capacitors.

 

It would be cool to see how supercapacitor banks help with DC in measurements.

not telling anyone what to do, but merely a suggestion, since there is more attention now and supercapacitors around for DC

@atomicbob , have you done any measurements around supercapacitors and noise? Both common mode and differential ?

 

Nichicon UKW1J682MRD capacitors used in the original design are now obsolete. As of the date of this post there 2333 are available at mouser.com:
https://www.mouser.com/ProductDetail/Nichicon/UKW1J682MRD?qs=kArNe9LFxXkIEiFBJFI9JA==

Design criteria for the capacitor or capcitors:
1) 63V - want at least 24% margin when using at 48V. Greater margin when used at lower voltages
2) 13000 ~ 14000 uF to achieve desired noise reduction at 60 Hz with choke shown on BOM
3) low ESR

Parallel combinations of 4 qty 3300 uF or 2 qty 6800 uF capacitors are logical choices.
Here are some currently available reasonable 6800 uF options on digikey.com:


Personally I might seriously consider the Kemet ALS30A682DB063 on the list above due to the low ESR spec and very long life at 105°C.

 

Has anyone used Noise Nuke for iCAN Pro?
I understand the limitation is:

iCAN Pro is 15VDC 4A.
It may be a silly question but I do not understand if 4A is the hard limit, no matter what VDC, to 95VA is the limit.

 

I would be very wary of using a choke rated for less than the power supply, even if it is only for small transients.

Looking at the datasheet, you could switch up the specified 155B to a 157E to maintain the same inductance, or jump to the monstrous 159ZG for a big jump in inductance. Obviously these higher current options will be larger, heavier, and more expensive.

 

Volts x Amps = Watts

You can't go over 48V and you can't go over 96 watts.

Noise Nuke: 48V x 2A = 96W

iCAN: 15V x 4A = 60W​

Looks like you are totally safe.

 

The original design uses a Hammond 155B 6mH 2A choke. That is a hard limit for current. As mentioned above to achieve 4A requires a larger choke such as the 157E or 159ZG. Both will have larger physical size so a larger enclosure should also be considered.


155B is 2.38 x 1.38 inches
157E is 3.25 x 1.75 inches
159ZG is 4.03 x 2.25 inches

 

So I misunderstood. Thanks for clarifying @atomicbob.

The 48V is a hard limit AND 2A is a hard limit. Meaning that the 2A is a limit regardless of voltage input. Unless you go with one of the other inductors listed above.

 

I don't think the iCan Pro actually consumes that much power itself, but it does also daisychain power out so it probably accounts for that.

 

You bring up some good points.
The current rating of the choke used limits the maximum current regardless of voltage.
The voltage rating of the capacitors used limits the maximum voltage regardless of current.
In practical designs a margin should be allowed for electrolytic capacitors. Thus 48V is 76% of the 63V rating for the capacitors specified leaving a 24% margin. Typical design margins are at least 20% and frequently 40%.

 

Would the Massdrop THX AAA 789 benefit from this, or is the story with that one similar to the Cavalli amps?. It's 24V 1.8A DC.

 

Well I guess I get to answer my own question. I went ahead and built one of these and over the last week and a half I've been using it on and off with the THX AAA 789. There is MAYBE a hint better blackness and engagement. Sometimes I think I hear it, other times I don't.

My overall impression is that it's probably not worth it for this amp.