Re: [SlimDevices: Audiophiles] High Frequency tone in the noise floor on SB3 R channel
*Isaac*;227367 Wrote: > To try and reduce this I made a quick and dirty shield from aluminium > foil, insulated with mylar tape. I fitted this between the back of the > neon display and the PCB, then soldered a wire to the incoming power > ground. Nice work Isaac. I will add a link to your article to the wiki page. -- Eric Carroll Transporter-Bryston 3B SST-Paradigm Reference Studio 60 v.4 SB3-Rotel RB890-B&W Matrix 805 SB3-Pioneer VSX-49TXi-Mirage OM7+C2+R2 ReadyNAS NV+ Eric Carroll's Profile: http://forums.slimdevices.com/member.php?userid=9293 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] High Frequency tone in the noise floor on SB3 R channel
NewBuyer;227722 Wrote: > Does anybody know, if the Transporter has any similar issue? It does not. -- Eric Carroll Transporter-Bryston 3B SST-Paradigm Reference Studio 60 v.4 SB3-Rotel RB890-B&W Matrix 805 SB3-Pioneer VSX-49TXi-Mirage OM7+C2+R2 ReadyNAS NV+ Eric Carroll's Profile: http://forums.slimdevices.com/member.php?userid=9293 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] High Frequency tone in the noise floor on SB3 R channel
Does anybody know, if the Transporter has any similar issue? -- NewBuyer NewBuyer's Profile: http://forums.slimdevices.com/member.php?userid=7862 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] High Frequency tone in the noise floor on SB3 R channel
The next version of the SB should be a box with no display and a remote control with a big display. Of course, the big display will be a power hog, so the remote will need to sit in a nice display stand/charging dock. You could do this yourself now by modifying the heck out of the SB - get rid of the display and put in an analog supply for the audio stages that are normally powered by dc-dc converter in the power supply. Use N800 type device as the remote control/display. TD -- tyler_durden tyler_durden's Profile: http://forums.slimdevices.com/member.php?userid=2701 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] High Frequency tone in the noise floor on SB3 R channel
Very good - well done. So basically you've physically inserted a grounded screen between the VFD and the main circuit board...and the noise is gone or greatly reduced. I agree that SD/Logitech should improve the screening of the VFD in future hardware. Hopefully they will notice this - they may already be aware of it. -- Phil Leigh You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal... ...SB3+TACT+Altmann+MF DACXV3/Linn tri-amped Aktiv 5.1 system and some very expensive cables ;o) Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] High Frequency tone in the noise floor on SB3 R channel
If this doesn't bother you, or you have an external DAC, great. I like to see a circuit perform as well as it can be made to; for me the problem is that this noise limits the s/n ratio of the whole system, at it's worst it is 27dB above the thermal noise floor. The fact that it only affects one channel led me to believe that the issue was one of board layout, and close inspection seems to confirm this: As you can see, the inverting input node, which is usually the node most sensitive to interference (dotted yellow) of the left channel is much smaller than the Rch one. Further, the right channel trace is directly behind the end of the neon display, where much energy is radiated. It also changes layers in this area (between the pink dots), possibly increasing susceptibility. It is genrally good design practice to minimise the length of the inverting input node to minimise stray capacitances, and to reduce the scope for parasitic oscillation and instability. In this case the noise is probably being coupled through the RCH inverting node, and to a lesser extent through the trace from the DAC. To try and reduce this I made a quick and dirty shield from aluminium foil, insulated with mylar tape. I fitted this between the back of the neon display and the PCB, then soldered a wire to the incoming power ground. Here is a noise floor measurement done after the mod, of the worst case situation (brighteness max -1) encountered before the mod: as you you can see, the noise is virtually gone. This mod may cause problems with the wifi reception though (because there is now a shield over most of the front). Also don't do this unless you're happy voiding the warranty, maybe destroying your SB, and also probably violating some FCC rules ;) Anyway, something can and should be done to fix this problem in the next hardware revision. +---+ |Filename: modded-brightness-max--1.jpg | |Download: http://forums.slimdevices.com/attachment.php?attachmentid=3317| +---+ -- *Isaac* *Isaac*'s Profile: http://forums.slimdevices.com/member.php?userid=13183 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] High Frequency tone in the noise floor on SB3 R channel
This was an old thread, with other threads tracking the issue more closely. This is a known issue, seen by Stereophile's review and acknowledge by Slim. The issue is that the gain is too high between your SB source and power amp. The resolution is to add attenuation between your SB3 and the power amp - either turn down your preamp or add passive attenuators. See the ConnectToPowerAmp wiki page in the "Other Power Amp direct connection problems" section. -- Eric Carroll Transporter-Bryston 3B SST-Paradigm Reference Studio 60 v.4 SB3-Rotel RB890-B&W Matrix 805 SB3-Pioneer VSX-49TXi-Mirage OM7+C2+R2 ReadyNAS NV+ Eric Carroll's Profile: http://forums.slimdevices.com/member.php?userid=9293 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] High Frequency tone in the noise floor on SB3 R channel
measurements are: -measurement system noise floor -brightness 4 -brightness 3 -brightness 2 -brightness 1 -brightness 0 display off in that order. Sorry about the formatting, haven't posted much before. -- *Isaac* *Isaac*'s Profile: http://forums.slimdevices.com/member.php?userid=13183 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] High Frequency tone in the noise floor on SB3 R channel
heres with the display off. you can see there is still some junk there but mostly out of band. Sorry the images are kind of big. +---+ |Filename: noise floor Brightness display off.jpg | |Download: http://forums.slimdevices.com/attachment.php?attachmentid=3315| +---+ -- *Isaac* *Isaac*'s Profile: http://forums.slimdevices.com/member.php?userid=13183 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] High Frequency tone in the noise floor on SB3 R channel
hi, here are some measurements taken with an maudio transit. The transit baseline measurement is taken with the input unterminated so the noise floor below ~400Hz is about 3dB higher than it when it is connected to a low impedance output, but is sufficient to allow good measurements as it is still 3 - 9 dB lower than the device under test. You can clearly see (and hear in a quiet room) the junk getting coupled to the right analog output, even with the display off. I don't know if this is specific to to my unit, or is a genral property of the SB. +---+ |Filename: noise floor Brightness max -3.jpg| |Download: http://forums.slimdevices.com/attachment.php?attachmentid=3314| +---+ -- *Isaac* *Isaac*'s Profile: http://forums.slimdevices.com/member.php?userid=13183 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] High Frequency tone in the noise floor on SB3 R channel
Eric Carroll;173867 Wrote: > I just finished recommissioning my old Rotel system as the world's > largest distributed alarm clock in the bedroom. 180Wpc ought to wake me > up! > > My alarm clock configuration is SB3 -> Rotel RB-890 -> B&W Matrix 805 > bookshelf speakers. Note that the SB3 is about 6.5 dB hot on line > levels for the RB890 (1V input sensivity). I *do not* have proper > analog attenuators installed yet (still looking for an easily orderable > Canadian source), so the noise floor is definately double the volume it > should be. I have the Preamp Volume Control set to -6.5 dB to keep me > from being blown out of bed in the morning by accident. > > > Since the RB890 has no trigger I leave the amp on even when the SB3 is > in powered off mode (not really off...). The SB3 is set not to turn off > audio when "powered off". > > I have noticed that on the right channel only, with no music playing, > there is a perceptible high frequency tone. It is very low volume, > right in the noise floor. Because the room is so small and quiet, I do > hear it even a few feet away. My hearing has always been very sensitive > to very high audio frequencies (although this is definately falling off > as I age). > > I have tried the following steps to debug this: > 1. I swapped the R/L channels at the SB3. The tone follows the channel > (i.e. when I swapped L for R the tone moved to the L speaker). > 2. I flipped the SB3->RB890 RCA cable R/L on both sides. Problem > remained on the R channel. > 3. I tried a second SB3 I have on hand, same results. > 4. I moved the wall wart switcher PSU from right beside the amp to > around a corner, far away from the amp. > 5. I have changed the brightness levels. > > (1) implies the problem is either the SB3->RB890 interconnect cable or > the SB3 itself (problem moved channels, so it is not the amp or > interference on the speaker cables) > (2) eliminates one side of the cable as the problem (if it was the > cable problem should have moved to L channel). > > (4) requires more explaination because it is the only change that > impacts the tone I have made so far. > > The SB3 has 5 brightness levels (0 - off, 1-4 from dimmest to > brightest). > > On display brightness 0, 4, and 1 there is no tone that I can pick out. > Brightness 3 has the loudest tone. 2 is much less noticable. > > The pitch of the tone is related to how much text is displayed on the > SB3 screen (the tone changes between lots of text and a little text are > not large). > > If I had to guess i would say the R channel in the SB3 is picking up > some RFI from the computing cycles. > > This rates as a "nit" not a big problem, because I do not hear this > tone when playing music (usually at volume 40-50 right now). Its just > an issue when not playing music because I leave the amp powered up and > the tone is somewhat evident. Also I did *not* notice this in the > previous room that I had the SB3/RB890 in (now replaced by > Transporter/Bryston) - it was a much larger room and I was much further > away from the speakers. > > Has anyone else experienced this? > > Will this go away with proper attenuation? > > Are there any other suggestions to resolve this? Suggestion for attenuation. Have noe expirence with it my self, but i have read some pro audio/home studio use it or an other m - patch version. http://www.smproaudio.com/index.php?option=com_content&task=view&id=24&Itemid=68 -- eiret eiret's Profile: http://forums.slimdevices.com/member.php?userid=11521 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] High Frequency tone in the noise floor on SB3 R channel
*Isaac*;227245 Wrote: > I just measured the noise floor of my SB; it has a sharp peak at 7.9kHz > and at 17.8kHz. This seem to be related to the display, as the relative > level of the peaks change when the display brightness is changed, also > the peaks disappear when the brightness is turned down until the > display is off. > seems like a pretty significant and avoidable design weakness, I hope > R&D fix it in the next revision. What do you mean by sharp? how far down is this peak. I'd hardly call this a significant weakness, since: a - you will never hear this in normal usage (see the OP for example of not normal!) b - you can turn the display to "off" - just like many expensive audio design - for the same reasons -- Phil Leigh You want to see the signal path BEFORE it gets onto a CD/vinyl...it ain't what you'd call minimal... ...SB3+TACT+Altmann+MF DACXV3/Linn tri-amped Aktiv 5.1 system and some very expensive cables ;o) Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
Re: [SlimDevices: Audiophiles] High Frequency tone in the noise floor on SB3 R channel
I just measured the noise floor of my SB; it has a sharp peak at 7.9kHz and at 17.8kHz. This seem to be related to the display, as the relative level of the peaks change when the display brightness is changed, also the peaks disappear when the brightness is turned down until the display is off. seems like a pretty significant and avoidable design weakness, I hope R&D fix it in the next revision. -- *Isaac* *Isaac*'s Profile: http://forums.slimdevices.com/member.php?userid=13183 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] High Frequency tone in the noise floor on SB3 R channel
I just finished recommissioning my old Rotel system as the world's largest distributed alarm clock in the bedroom. My alarm clock configuration is SB3 -> Rotel RB-890 -> B&W Matrix 805 bookshelf speakers. Note that the SB3 is about 6.5 dB hot on line levels for the RB890 (1V input sensivity). I *do not* have proper analog attenuators installed yet (still looking for an easily orderable Canadian source), so the noise floor is definately double the volume it should be. I have the Preamp Volume Control set to -6.5 dB to keep me from being blown out of bed in the morning by accident. Since the RB890 has no trigger I leave the amp on even when the SB3 is in powered off mode (not really off...). The SB3 is set not to turn off audio when "powered off". I have noticed that on the right channel only, with no music playing, there is a perceptible high frequency tone. It is very low volume, right in the noise floor. Because the room is so small and quiet, I do hear it even a few feet away. I have tried the following steps to debug this: 1. I swapped the R/L channels at the SB3. The tone follows the channel (i.e. when I swapped L for R the tone moved to the L speaker). 2. I flipped the SB3->RB890 RCA cable R/L on both sides. Problem remained on the R channel. 3. I tried a second SB3 I have on hand, same results. 4. I moved the wall wart switcher PSU from right beside the amp to around a corner, far away from the amp. 5. I have changed the brightness levels. (1) implies the problem is either the SB3->RB890 interconnect cable or the SB3 itself (problem moved channels, so it is not the amp or interference on the speaker cables) (2) eliminates one side of the cable as the problem (if it was the cable problem should have moved to L channel). (4) requires more explaination because it is the only change that impacts the tone I have made so far. The SB3 has 5 brightness levels (0 - off, 1-4 from dimmest to brightest). On display brightness 0, 4, and 1 there is no tone that I can pick out. Brightness 3 has the loudest tone. 2 is much less noticable. The pitch of the tone is related to how much text is displayed on the SB3 screen (the tone changes between lots of text and a little text are not large). If I had to guess i would say the R channel in the SB3 is picking up some RFI from the computing cycles. This rates as a "nit" not a big problem, because I do not hear this tone when playing music (usually at volume 40-50 right now). Its just an issue when not playing music because I leave the amp powered up and the tone is somewhat evident. Has anyone else experienced this? Will this go away with proper attenuation? Are there any other suggestions to resolve this? -- Eric Carroll Eric Carroll's Profile: http://forums.slimdevices.com/member.php?userid=9293 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
