Finding a bit of hash

I’m hearing a lightly audible hash from 8’ on the system below when everything is on but no music or video playing (the active speakers alone are quiet when on). Electricity starts from living room wall to PowerBase and the Furutech outlet is wired correctly, including the ground. Perhaps I should take the accept the notion of set-up expert Jim Smith, who has written that he finds systems with a little hash sound better than quiet ones, but I am curious… This is a 1970’s condo and major rewiring is not in the cards. Any thoughts?

  • Furutech outlet
  • PowerBase and P15 Regenerator -
  • AC-12 power cords to Oppo 203, DS dac, Samsung HDTV, cable box and ATC SCM19A speakers.
  • IC’s are HDMI/I2S and PAD Neptune coax from Oppo to DS, and MG Audio AG2S2 XLR’s from DS to speakers.
  • Cords are off the floor on DIY wooden spindle stands and separated by 1/2-1" or more from each other with rubber/wood blocks as well as possible, given the number involved and proximity of everything
  • Components in Salamander cabinet

Amp? Preamp? Any tubes?

I have just the faintest hash from my seated position 7’ away. BHK preamp is the primary source. Bascom stated in a video, I think, that a bit of noise is better sounding than pure silent black.

I agree.

Amps in speakers. No preamp, no tubes.

Try the attenuator in the DS?

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Too much variation in what I play and view. I wonder if the following statement in the manual is applicable here:
“DACs in particular are quite sensitive to AC power and produce a bit of line noise themselves.”

Hey Gene,

Glad to see you are back on. Have you tried unhooking the powerbase? When I first got my p20 I had some weird sound coming from the combination of p20 & powerbase. It went away when I unhooked the powerbase. Never had the issue on the p10. Worth a shot anyway.

Thanks for the suggestion, Veneet. Disconnecting the PowerBase, there’s still hash, partly from either or both the Oppo and DS, (and P15?), and partly from the TV. However, I can’t hear it from 8’ at the moment, but will have to listen at other times of the day to be sure.

Is it correct to assume that the physical isolation provided by the PowerBase is independent of its power side?

Hey Gene,

Yup, totally independent, physical isolation is separate from power. If you are still getting hash, but it isn’t less or more, I wouldn’t worry about that as being the issue, just thought it may be worth a shot.

Less or the same, tbd, but either gets one item out of the chain and saves electricity.

@highstream your speakers have an input sensitivity of 1V, and the DS full range output is by default 1.4V on RCA or double that on XLR, meaning that the speakers are amplifying the heck out of the DAC’s noise floor. You must be listening to most music at pretty low volume settings on the DS, is that right?

If you haven’t done so already, you should navigate to the settings screen on the DS and set the output level to “low” and lock it there. If this is something you haven’t done yet, you’ll enjoy the way the hash that you’ve been hearing drops by 20dB.

Thanks for those specifics. Makes sense. Depending on the source, I typically listen between 30 and 70 via the DS remote. On a quick check, invoking the filter seems to push that range up to roughly 75 to 106 (max), and there’s no audible hash ear to speaker.

Question: Does invoking the filter change the effect of the noise (hash) on sound quality or just what noise I might hear when nothing is playing? At 8’, I was hearing nothing w/o the filter after removing the PowerBase, but would expect that might fluctuate over the course of the day.

Interesting that you use the term “filter” – that’s the remote control button that’s been mapped for this feature, but what you’re turning on is an attenuator not a filter. When you engage the attenuator you cause a relay switch to close, putting a resistor in circuit between the analog output pin and ground, meaning that every part of the output signal, including the noise floor, gets lowered by 20dB.

It’s not 100.000% sonically transparent but it’s about as close as you can get in practice. I use it most of the time since like you there’s no pre-amp between my DAC and the power amp stage.

Another thing that is easy to try is to just simply shut off the DAC from the front off button and see what happens. When I tried running the DSD straight to my amp I could hear a hiss (very low, but it was there) and when you shut it off from the front button it would vanish. Now since adding a pre inbetween DAC and speakers as Dvorak said, it goes away almost completely even with the DAC on for me.

Do you mean shut it off from the screen? Since all sound goes through the dac to the ATC actives, I’m not getting the point of shutting it off.

No from the blue button on the DAC. The logo one. At least it will tell you if that is the source of the noise, but I guess you have already determined that from doing the attenuator thingy.

I know the manual says the attenuator is transparent, but to my ears it noticeably less so. Music and video took on a colder, steely quality. Taking it out is a lot more listenable (tho not completely satisfying, but that’s another matter for the time being). Perhaps that’s what Jim Smith and Bascom King had in mind.

I have the ATC50 active. Never tried it direct from the Directstream as I still have a TT… Anyhow, with my old pre (Ayre) I also had this (very quiet) hiss. It is connected to the voltage input sensitivity.
I used external attenuators to lower the signal 10dB. Worked very well, the hiss was gone. It’s the same effect as with the DAC build on in attenuator (but half the attenuation).
When I got my new pre (Pass Labs XP-22), I was able to remove the physical attenuator. The Pass is extremely quiet and has a great volume range, so now I can go from super low volumes to very loud just with the pre. The DAC is set at 100.
So - if the hiss bothers you and you don’t want an attenuator in between you might try a (good) pre-amp.

The built-in attenuator’s sonic impact is a curious topic. Your audio signal doesn’t actually pass through it, so how could it cause a change?

Ted has noted a couple of times that it can interact with cables that have high capacitance, causing a slight softening of the top end.

Still, I think I agree with you to some extent. I’ve always preferred the sound without the attenuator, provided that I’m listening loud enough to not care about the noise floor.

Been three days since I posted and disconnected the PowerBase on Veneet’s suggestion. That led to my no longer hearing the sound of the hash from my main listening seat, 8’ out, though it’s still there up close. From then on the noise floor seemed to drop a bit and the sound opened up in all directions, although I can’t fully separate that from the burning in of an iFi SPDIF iPurifier powered by a (cool, dry, off key) Kora LPS between Oppo and DS (have a Paul Hynes SR4 on order). In any case, if I listen very closely at the right time of day, the higher frequency hash seems barely audible – well, maybe. All this is with the attenuator off. So for the moment I’m happier. Thanks for the suggestions and comments.

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