Hypex SMPS a minor Tweak

[Ianmac]

I have Hypex Ucd 400 amps with Hypex SMPS power supplies. They perform extremely well. Driving ATC SCM40 speakers and fed balanced from a Benchmark HDR DAC.
I was recently investigating the effect of using screened mains cable on parts of my system and noticed that when I used screened mains cable on my Hypex amps there was a slight improvement to the sonics.The cable used was 6A, 3 core mains + insulation +screen + outer insulation. Investigating further I concluded (correctly or incorrectly) that the Hypex SMPS supplies were outputting unwanted signals into the mains supply which were colouring the audio output of the amps.ie each was contaminating the other. I again concluded that the screened cable was acting as a form of filter and removing some of these unwanteds. I remade the mains cable,( 2 runs of app 4.5 M from each amp to the mains supply socket) using 10A screened instrumentation cable of the correct voltage rating. This cable was 3 core + screen + outer insulation so a higher capacitance /Metre than my earlier screened mains. I could not get a full tech spec on the cable, Capacitance was indicated at 100pf/M. So in theory a better filter.
The results were indeed noticeable a smoother treble and a little more detail, probably equivalent to about a 1.5 db improvement in sig/noise.
I have had another Hypex owner run totally independant tests with the same cable type and identical results were experienced.

I am now looking at a alternative to cable and experimenting with professional mains filters built into the IEC connectors I use as mains input connectors on my amps.
I have no experience of specifying these types of filters and the manufacturers data sheets do not show the filter response below 10Khz, where most of them are at 0db. The lower the current rating of the filter the better the bottom end response I presume due to the higher inductance value used. I am also assuming that the unwanted shash emanating from the Hypex SMPS is in the audio band + harmonics say up to 150Khz.
(I dont have a spectrum analyser)

Anyone give me advice on filter selection and am I progressing correctly

I am running fully balanced and my Hypex chassis is connected to mains earth.

The end result with my system was to identify the real culprit - the SMPS supplied with the Logitech Touch Streamer. I have now built a linear supply
which my DAC really appreciates and the end result is a well worthwhile improvement in my total system.

When I built my first Hypex I did email them regarding input filters and was told I didnt need them- anyway Ive learned a little more about mains contamination from both SMPS and Linear supplies.

Again can anyone keep my right on Filter Selection.

Ianmac

[dublin78]

This is interesting.

I am planning a new "music centre" build. See my last efforts here: DIYPARADISE CD63 based "music centre"

The new one will have a Transport > Tentlabs Clock > Monica 3 DAC > Nelson Pass B1 Buffer > 2x Hypex 180HG all in one box, served with one power cable.

The amps will be powered by the Hypex SMPS180.
The tranport (Marantz CD5000) will be powered by its original suppy.
The clock, DAC, and Buffer will be powered by a single 24vdc Meanwell SMPS, feeding each via individual Super Regs (Burson??? or similar) at appropriate voltages.

Ianmac: From your findings, do you think that there would there be excessive noise in the system from the Hypex SMPS? I do not have room for a linear supply, and I do not want external components.

[Ianmac]

No there would not be excessive noise. If you filter the mains in to the SMPS.it will improve things
Filters are readily available from Farnell or CPC farnell that are built into the IEC mains input socket. If you need details let me know.
I have e mailed Hypex re this issue and await their reply.
Ianmac

[Jan-Peter]

Originally Posted by Ianmac

I have Hypex Ucd 400 amps with Hypex SMPS power supplies. They perform extremely well. Driving ATC SCM40 speakers and fed balanced from a Benchmark HDR DAC.
I was recently investigating the effect of using screened mains cable on parts of my system and noticed that when I used screened mains cable on my Hypex amps there was a slight improvement to the sonics.The cable used was 6A, 3 core mains + insulation +screen + outer insulation. Investigating further I concluded (correctly or incorrectly) that the Hypex SMPS supplies were outputting unwanted signals into the mains supply which were colouring the audio output of the amps.ie each was contaminating the other. I again concluded that the screened cable was acting as a form of filter and removing some of these unwanteds. I remade the mains cable,( 2 runs of app 4.5 M from each amp to the mains supply socket) using 10A screened instrumentation cable of the correct voltage rating. This cable was 3 core + screen + outer insulation so a higher capacitance /Metre than my earlier screened mains. I could not get a full tech spec on the cable, Capacitance was indicated at 100pf/M. So in theory a better filter.
The results were indeed noticeable a smoother treble and a little more detail, probably equivalent to about a 1.5 db improvement in sig/noise.
I have had another Hypex owner run totally independant tests with the same cable type and identical results were experienced.

I am now looking at a alternative to cable and experimenting with professional mains filters built into the IEC connectors I use as mains input connectors on my amps.
I have no experience of specifying these types of filters and the manufacturers data sheets do not show the filter response below 10Khz, where most of them are at 0db. The lower the current rating of the filter the better the bottom end response I presume due to the higher inductance value used. I am also assuming that the unwanted shash emanating from the Hypex SMPS is in the audio band + harmonics say up to 150Khz.
(I dont have a spectrum analyser)

Anyone give me advice on filter selection and am I progressing correctly

I am running fully balanced and my Hypex chassis is connected to mains earth.

The end result with my system was to identify the real culprit - the SMPS supplied with the Logitech Touch Streamer. I have now built a linear supply
which my DAC really appreciates and the end result is a well worthwhile improvement in my total system.

When I built my first Hypex I did email them regarding input filters and was told I didnt need them- anyway Ive learned a little more about mains contamination from both SMPS and Linear supplies.

Again can anyone keep my right on Filter Selection.

Ianmac

Hi Ian,

Can you post us some pictures from your actual setup? We have designed the SMPS400 to have as low as possible EMI, so I'm really surprised you have this kind of difference with or without a screened cable.

Regards,

Jan-Peter

[Ianmac]

Jan-Peter

I will be pleased to provide what you want.
It will be much easier for me to send pictures over to your address at Hypex. If you dont mind I will do that.
I have built 3 pairs of Hypex Ucd /SMPS monoblocs. 2 are here in use on my two systems. The third is in London being used by an audio enthusiast who carried out the independant test
All 3 systems perform well but the above tweak does make a noticeable improvement

Ianmac

[Jan-Peter]

Ianmac,

please send it to; info (at) hypex (dot) nl

Thanks!

Jan-Peter