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HOLO Audio MAY DAC


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1 minute ago, ETWok said:

Have you tried pausing the music from source then crank the volume on the amp to 99? I get the noise then.
But no noise that way when I unstack the May. 
We might say at normal listening level the noise are not noticeable but that is besides the point, if you know what I mean. 

i'm going to give it a go tonight

 

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I actually measured the May on the APx555 when stacked and when separated and there was no difference at all

Most likely issue is either some interconnect near the power cord maybe? Or perhaps a poor contact on one of the pins on the interlink cable (try wiggling the interlink cable to see if it alters the noise, also try unplugging may, flipping the interlink cable and then plugging back in).

It's very unlikely you're getting interference through two thick metal chassis. Especially when this is not normal behaviour.

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Roon -> HQPlayer -> SMS200 Ultra/SPS500 -> Holo Audio May (Wildism Edition) -> Holo Audio Serene (Wildism Edition) -> Benchmark AHB2 -> Hifiman Susvara

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Note to anyone doing these kinds of tests: many DACs mute their outputs when no signal is present, so one cannot test the noise floor accurately with no signal.  Make sure to be giving the DAC a signal to be sure the output is not muted.  Of course if you are going to be testing this at full gain of your system, be absolutely sure that your signal is digital silence!

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2 hours ago, ETWok said:

Have my Holo May DAC for 4 days now.

 

Just found out that when they are stacked, static noise can be heard (with ear fairly close to the speaker) from the speakers when volume of the Hegel H190 is turned to max. Once they are not stacked, the noise is totally gone.

 

The noise level is fairly high. As a comparison, the internal DAC of the Hegel's noise is about one twentieth of that of the May when stacked. Unstacked, totally silent.

 

How are they stacked? Hegel at the bottom, then MAY power supply, and then MAY DAC at the top?
Or, Hegel at the top?

 

There's a WiFi module inside Hegel that could potentially cause interference.... especially with that ribbon cable being exposed well above the DAC PCB ground fill/ground plane. Ideally, those ribbon cable' signals should be sandwiched between DAC PCB ground planes (multi-layered PCB design)

 

Anyway, it would be interesting to know how you stacked the units. 

Capture.JPG

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The other path would be via mains cabling; Hegel decided to ground the IEC mains right next to the WiFi module.... there's probably a reason for that.... the noise.

 

 In addition, Hegel does not have a mains RF filter (it's supposed to protect noise/rubbish being fed from Hegel, BACK to mains). Maybe when you unstacked the stack, you also plugged MAY PS to a different outlet??

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28 minutes ago, barrows said:

Note to anyone doing these kinds of tests: many DACs mute their outputs when no signal is present, so one cannot test the noise floor accurately with no signal.  Make sure to be giving the DAC a signal to be sure the output is not muted.  Of course if you are going to be testing this at full gain of your system, be absolutely sure that your signal is digital silence!


All the DACs I have had, they are only done for the USB input and the muting logic is implemented in the USB receiver board itself. This is also primarily done to avoid pop with sample rate change. All non-USB inputs have fairly high signal to noise ratio and I suspect if the USB wasn’t muted when signal is present, it would behave the same. 

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27 minutes ago, Extreme_Boky said:

 

How are they stacked? Hegel at the bottom, then MAY power supply, and then MAY DAC at the top?
Or, Hegel at the top?

 

There's a WiFi module inside Hegel that could potentially cause interference.... especially with that ribbon cable being exposed well above the DAC PCB ground fill/ground plane. Ideally, those ribbon cable' signals should be sandwiched between DAC PCB ground planes (multi-layered PCB design)

 

Anyway, it would be interesting to know how you stacked the units. 

Capture.JPG

Hegel at the bottom.

The Hegel does not have wifi, it relies on ethernet for Airplay.

Even if I move the May stack away from the Hegel, the noise was still there.

But now I have the May PSU stacked on top of the Hegel, and then the May main unit is not stacked at all, and the noise is totally non-existent. 

BTW, I had tried May main unit on top of Hegel with the May PSU not stacked on the side, there was a bit of noise too.

Wildism just got back to me saying that it could be cross-talk from my AC Cable and the interconnects(?), but he also said that unstacking them makes the sound more open.

 

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28 minutes ago, Extreme_Boky said:

The other path would be via mains cabling; Hegel decided to ground the IEC mains right next to the WiFi module.... there's probably a reason for that.... the noise.

 

 In addition, Hegel does not have a mains RF filter (it's supposed to protect noise/rubbish being fed from Hegel, BACK to mains). Maybe when you unstacked the stack, you also plugged MAY PS to a different outlet??

No, same outlet.

 

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1 hour ago, mr. Fancypants said:

I did this exact test on my system (using a Technics SU-G30 integrated amp) and there is some static noise when volume is near maximum, but when I turn the May off, the noise is still there.  So from what I can tell, the May is silent and the noise is coming from the integrated amp.

When I switched the integrated amp's input from analogue (May DAC) to USB (Hegel's own internal DAC), the noise level dropped a lot. Unstacking the May and then input through USB gives no noise at all.

So Hegel internal DAC has noise but not its pre-amp nor its power amp.

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Well, if MAY DAC and PS case is aluminium... then it could be Hegel's toroidal transformer that radiates magnetic field; there's no mu-metal (magnetic) shielding of any kind around Hegel's toroidal transformer... and that's like... 300 - 400VA transformer.

 

Placing line-level HiFi equipment on top of any amplifier is just asking for trouble, unless the amp's transformer is fully shielded. Old Japanese amps had mains transformer(s) positioned in such way to minimize this magnetic field + they had magnetic shield AND copper RF shield(!!); however, those were E-transformers - not toroidal ones. 

 

I use fully shielded (electrically and magnetically) toroidal transformers. 

 

Capture.JPG

 

 

 

 

It could be wiring as well..... try to MUTE MAY DAC (this will short the analogue-out signals to the ground, and then repeat the test. Let me know the result.

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37 minutes ago, Extreme_Boky said:

Well, if MAY DAC and PS case is aluminium... then it could be Hegel's toroidal transformer that radiates magnetic field; there's no mu-metal (magnetic) shielding of any kind around Hegel's toroidal transformer... and that's like... 300 - 400VA transformer.

 

Placing line-level HiFi equipment on top of any amplifier is just asking for trouble, unless the amp's transformer is fully shielded. Old Japanese amps had mains transformer(s) positioned in such way to minimize this magnetic field + they had magnetic shield AND copper RF shield(!!); however, those were E-transformers - not toroidal ones. 

The thing is it that the noise is there when the May main unit is above the May PSU along and not on top of the Hegel. Also, I tried replacing the Hegel H190 with the PS Audio Sprout 100, and it is the same: noise when stacked, and no noise when unstacked.

 

So not the Hegel but the May main unit itself, when it is stacked above any PSU. At least in my case.

 

I will try muting May DAC and let you know.

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45 minutes ago, Extreme_Boky said:

 

It could be wiring as well..... try to MUTE MAY DAC (this will short the analogue-out signals to the ground, and then repeat the test. Let me know the result.

Ok, just tried this.

 

Stacked the two May units on top of each other and muted the May DAC, the noise is still there when volume on amp is cranked to MAX. And when I unstack the two units, the noise is gone immediately.

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I do not think it is "stacking-related".... and here's why:

 

I have May DAC stacked on top of May PS. I also have a very revealing, wide bandwidth and high input impedance, DC-coupled amplifier. No volume controls, just direct coupling from May XLR-outs to my amplifier. I use unshielded (!) XLR cables. I can not hear ANY noise whatsoever when I MUTE May, or when I pause the playback from my NUC11. NOTE: Muting the playback on NUC11 will not short the MAY's analog-out to the ground, it just sends a digital zero (which servers other purposes...), but, as I said, it does not mute MAY's analog output stage...

 

So, it must be your cabling / interconnects' interference related noise... Do you use balanced interconnects or RCA's

 

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3 minutes ago, Extreme_Boky said:

I do not think it is "stacking-related".... and here's why:

 

I have a very revealing, wide bandwidth and high input impedance, DC-coupled amplifier. No volume controls, just direct coupling from May XLR-outs to my amplifier. I use unshielded (!) XLR cables. I can not hear ANY noise whatsoever when I MUTE May, or when I pause the playback from my NUC11. NOTE: Muting the playback on NUC11 will not short the MAY's analog-out to the ground, it just sends a digital zero (which servers other purposes...), but, as I said, it does not mute MAY's analog output stage...

 

So, it must be your cabling / interconnects' interference related noise... Do you use balanced interconnects or RCA's

 

But the fact is when I unstack them, it is totally silent, even when I crank volume to the MAX.

 

Stack or unstack it is the same unbalanced RCA cables.

 

BTW, I have ordered a couple of balanced interconnects a while back and they should arrive soon and will see whether it makes any difference.

 

And in your setup, you tried to listen for noise when you crank the volume on the NUC11 to MAX? With ears close to the speakers?

 

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22 minutes ago, Extreme_Boky said:

I do not think it is "stacking-related".... and here's why:

 

I have May DAC stacked on top of May PS. I also have a very revealing, wide bandwidth and high input impedance, DC-coupled amplifier. No volume controls, just direct coupling from May XLR-outs to my amplifier. I use unshielded (!) XLR cables. I can not hear ANY noise whatsoever when I MUTE May, or when I pause the playback from my NUC11. NOTE: Muting the playback on NUC11 will not short the MAY's analog-out to the ground, it just sends a digital zero (which servers other purposes...), but, as I said, it does not mute MAY's analog output stage...

 

So, it must be your cabling / interconnects' interference related noise... Do you use balanced interconnects or RCA's

 

And if it is interconnect related, then stacked or unstacked, I would expect that there would be no difference. 

 

And I tried a couple of different power cables and USB cables as well before I tried to unstack, which works wonderfully.

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May casing is aluminium, so it may be toroidal transformers' related... (inside the May PS; the toroidal transformers are not magnetically shielded), but I have May DAC stacked on top of May PS and I can't hear any noise whatsoever...

 

I mute NUC11 HQ Player, which sends a digital zero signal to May. What's left in this case, is May's analogue circuitry with its un-shorted (to ground) analog output. And, yes, I have my ears right next to the speakers.

 

The RCA cables are not ideal because any interference induced when you move equipment around will propagate to the first stage of amplification and will be amplified with a full gain that's available. You must use balanced cabling, which ensures that the induced noise will cancel-out (same amount of noise induced on Hot and on Cold, of the same polarity/direction, which gets cancelled due to the high common-mode rejection ratio of the first amplification stage).

 

Short the RCA hot to ground, at Hegel's RCA input sockets, and then crank the volume up... do you hear any noise? You should! You should hear the white noise.... the broad-spectrum noise. Then, bring the May PS case on top of Hegel and see if the noise increases. 

 

... just make sure you are drawing some current from those transformers, i.e. have May DAC connected to PS...

 

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I have the Holo Spring 3 level 2 here. Previous Dac was the Spring2Lv2.
Windows 10 PC with a internal JCat USB Femto v2 card to Singxer SU-6 then i2S to Holo Spring 3.

Majority of listening is 44.1K Nos using JRiver, Foobar etc.

 

I have noticed the Spring 3 sometimes has a slight sibilance (especially female vocals), that I did not get with the Spring 2.
The overall sound is not up to what I had before. The Spring 2 was amazing in my system and have not had that with the Spring 3.
Spring 2 was over 2 years young.

Also with the Spring 3 now, there seems to be a slight emphasis on the upper midrange?. A very slight type of sharpness especially when turning up the volume a bit.

 

Reading the forums here on the May Dac, I see there is PLL locking.

So I just disabled the PLL and just started listening. 
I don't notice the sibilance anymore or the emphasis on the upper midrange. Will have to try it over the next few days.

Could it be something to do with using the Singxer SU-6 and the PLL locking is having some sort of slight detrimental effect? 
Is it possible this could be some sort of clocking issue maybe or clashing in some way with the SU-6? 

Not cluey of this stuff myself, just throwing it out there.

 

I have only started listening with PLL off but thought I might post this in case others might shed some light or notice something like this with the May when using say an external DDC.

This Spring 3 has around 280 hours so far.

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hey guys

 

is it not advisable to use both xlr and rca output from the May at the same time? i have the KTE May, XLR out to a Wells Audio Milo Reference headamp (and sometimes swapped for an integrated amp) and RCA out to a Singxer SA-1 headamp. 

 

when both the xlr and rca outputs are connected, i get this faint distortion/static/buzz audible with vocals of higher pitch and volume, eg female vocals at the peak of a crescendo. if i disconnect the rca cables from the Singxer headamp, the distortion/static/buzz goes away.

 

i have tried changing out cables, swapping out power cords, moving the power cord from the same block (an AQ Niagara 1200) to separate blocks and also directly to the wall outlet. but seemingly the only solution is to not use both rca/xlr together. the same issue also occurs if i swap connections ie RCA to integrated/Milo headamp and XLR to Singxer headamp, and resolved by removing the XLR connection.

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44 minutes ago, Roasty said:

hey guys

 

is it not advisable to use both xlr and rca output from the May at the same time? i have the KTE May, XLR out to a Wells Audio Milo Reference headamp (and sometimes swapped for an integrated amp) and RCA out to a Singxer SA-1 headamp. 

 

when both the xlr and rca outputs are connected, i get this faint distortion/static/buzz audible with vocals of higher pitch and volume, eg female vocals at the peak of a crescendo. if i disconnect the rca cables from the Singxer headamp, the distortion/static/buzz goes away.

 

i have tried changing out cables, swapping out power cords, moving the power cord from the same block (an AQ Niagara 1200) to separate blocks and also directly to the wall outlet. but seemingly the only solution is to not use both rca/xlr together. the same issue also occurs if i swap connections ie RCA to integrated/Milo headamp and XLR to Singxer headamp, and resolved by removing the XLR connection.

 

looks like by connecting the two, you're creating a ground loop -- when you disconnect, you're breaking the loop.  would be interesting to connect another amp of some sort and see what happens.

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You missed this paragraph... it seems:

 

The RCA cables are not ideal because any interference induced when you move equipment around will propagate to the first stage of amplification and will be amplified with a full gain that's available. You must use balanced cabling, which ensures that the induced noise will cancel-out (same amount of noise induced on Hot and on Cold, of the same polarity/direction, which gets cancelled due to the high common-mode rejection ratio of the first amplification stage).

 

In addition.... google single-ended vs. balanced... The shield is not required with XLR's; whereas with RCA's -> shield carries the same amount of current as the RCA's middle pin (or hot). Also, the volume control can not attenuate the noise that comes via RCA's shield... And, look at CMRR of a typical differential input pair (in amplifiers)

 

 

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