Directstream Mk 2 observations

@DennyD Are you using a MK2 without a preamp? If so, then attenuators between the DAC and the amp might be in order. I used Rothwell -20dB units with an NAD Purifi unit before. The NAD had a gain reducing dial. But I am not usually keen on dials. I now have a Benchmark AHB2 amp. It is set on the middle gain and the noise floor issue is not noticeable between tracks as my head is more than six inches away from the tweeters.

This audible noise that some are reporting in between tracks is something that I haven’t experienced with 228 until this past weekend. I normally use the MK2 in my main system connected to a Hegel H590, and before that an H390. I experience no noise with those two amps running 228. Over the weekend however, I decided to insert the MK2 into my desktop system, which comprises a Hegel H190 connected to a Mac mini. With the MK2 connected to the H190 I get noise at the beginning and ends of every track I play, which are AIFF CD rips. It is certainly a very annoying experience, which on a few quiet tracks I can even hear the noise throughout the song. I even connected the H190 to my main system with the MK2 and the noise was still present. As soon as I swap back in either the H590 or H390 the noise problem disappears. So it would seem that the noise is prevalent only on certain equipment. If I roll the firmware back to say 179 I get no noise with any of my Hegel integrated amps connected to the MK2. It is a very strange problem indeed.

I assume the volume setting on your MK2 is the same no matter which system it is hooked up to?

I have run the mk2 directly into the BHK 250 amp at 35 level without any noise issues. I tried your experiment with my BHK preamp in the chain. When the mk2 is set to 35 and the preamp set to 90 I still cannot duplicate your noise issue.

I run my MK2 at volume level 100, which is where it’s been coming up on a year now. I experimented with different volume settings at the beginning, but settled on 100 fairly early on.

Thanks for doing the experiment.
I go directly into BHK 300s and get the noise.

I replaced the BHKs with an Ayre AX-7 integrated amplifier and get similar results.
With the MK2 set at 100 and controlling the listening volume on the Ayre there is no noise.
I then set the Ayre to it’s fixed gain power amplifier mode.
I then control the listing volume from the MK2 and I get noise.

Very interesting problem.
I wonder if your MK2 would be clean in my system and mine would be noisy in yours.

With Massive 228 to BHK pre, then to BHK 300s, with MKII at 100, l don’t get the noise, but at 35 I do get the noise.

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In light of what I have read here, I may try the experiment sooner than I planned.

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As I have posted my system info a few weeks ago, I do not use a preamp. Roon>AirLens>MKII>JL CR-1 electronic crossover> Benchmark AHB2 amps set on monoblock with on medium gain>Maggie 3.7i speakers. Therefore I really need to use the MKII for volume control. I listen anywhere between 40 - 85 on the control and the noise is there at all volumes. I was a beta tester for the MKII and I have one of the early units so I don’t know if that matters. The noise issue with Massive is the only problem I have had with the unit. Besides the noise the MKII is fantastic.

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Did PSA support get back to you at all after Paul referred you to them in August? Reading above, in January, you were happy with no noise issues using USB from your Nucleus to the MK2. Unless you had a beta test version like 182 from Ted, you would have been on FPGA 179 then. If nothing changed downstream of the MK2, then the variables are the addition of the AirLens and the upgrading of the FPGA to 228 Massive, right? Have you tested USB from the Nucleus without the AirLens but with Massive again? Had you tried any of the interim FPGAs like the April 208 that PSA put out with firmware 2.5.1? My beta build MK2 has always been problematic for noise floor issues. Any set up that allows MK2 volume control to start from a higher level helps. But this has been a constant for me, not something that got worse.

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Yes, I have been in touch with tech and they suggested setting the volume to 100 while they are working on the fix for Massive. Once I received the AirLens I moved my nucleus to an equipment closet behind my audio system, so that would be a real pain to hook it back up via USB. As I recall the noise began once I updated to Massive. I have not tried going back to a previous FPGA which I should try as I was just waiting for the final version of Massive. By the way, thank you for taking the time with your suggestions, I really appreciate it.

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Just confirmed the noise for me is there at 35 volume with Massive 228, but when I reverted back to Antero 208, still at 35 volume, noise is not there.

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I will try to see if I have the noise at Mk2 Massive at 35. Hopefully, Ted can fix this in the final release of Massive.

As I have posted previously, on my MKII direct to BHK300’s I could not use massive, since my MKII volume is between 35 and 70.

My suggestion to fix the issues quickly is to have one version for full volume users and another for low volume users.

That sounds like something that would be very unlikely. Ted has enough work to deal with one code never mind having to customize it.

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@tonyplachy I tried going back to FPGS 208 as well. It did not change the noise floor characteristics for me… no better no worse. But I do not have bad sound at 35 on Massive either. Got lucky this time I guess.

@DennyD You gave me the idea to go with two Benchmark AHB2 amps in mono. Killer idea. I have them in low gain though, not the middle. This pushes the noise floor way down. Very nice sounds resulting. The volume settings on the PSA MK2 DAC are pretty much the same as when I used one amp in stereo at the middle gain setting.

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Small update. Had to shuffle gear around a bit today to fit the second Benchmark AHB2 amp into the cabinet. Each one is 28cm wide and the space is 56.5cm wide. Noticed in the process that I mis-wired the speakers originally when testing. I have twin REL subs and the high-level wiring is different than for the speakers with twin AHB2’s and I got them confused. Anyway, all fixed now. Still sounds great.

I took the opportunity to get the MK2 out of another cabinet so I can see the (small) screen better with no glass door in front. Had to put the MK2 on rails though so that I could plug in the USB cable by going through a hole in a metal support that was 3cm higher up.

One more item, I decided to add a Topping HS02 USB Isolator instead of getting a Holo Red. I do not expect the HS02 to make a difference for sound. But what it does do is allow me to take USB outs from two devices (BACCH4Mac and HQPlayer) and send them into the one MK2 USB input transparently (it seems). No power supply is needed. Adding in an isolated power supply driven by an LPS is optional if the downstream device needs power.

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The swirling noise on Massive is now worse than ever. It is constant during all music and so loud that I can no longer use Massive. I even tried pausing the music and turning the volume on the MKII up to 100 to see if there was any difference, just constant hiss but no swirling. I sure hope they get the fix done soon.

There must be a strange thing in the synery of your system that is exaserbating the issue. Sounds like you have extremely high gain following the output of the mk2. The fact that you have high hiss and the strange noises that not everyone is getting leads me to believe that.

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Of course, unless the dac can only be used in PSA-exclusive systems, the fact that users are complaining of noise issues is newsworthy, regardless of whether it sounds fine in PSA-only systems.

With bugs and errors, the repeated suggestions of “everything good here in a PSA-only system, must be you” is not a good way to get the problems fixed (again, unless this is only for PSA-exclusive systems).

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