[SlimDevices: Audiophiles] Re: Is max volume really max?
Sean, thank you for the tests, I had not intended this to get into an adversarial issue, I'm just trying to find out whats going on here to get the best sound. I appologize if I have cast aspersions on you or your products that has not been my intent. In order to try and get to the bottom of this I took everything all apart and rebuilt it and reinstalled software etc. All the following is with the low jitter clock in the DAC feeding the SB3 and the I2S lines going into the DAC where they are split(taking into account the left justified format), reclocked by the low jitter clock and fed to the DAC chips. The resultant jitter is somewhere at 10 or less ps(its vert tough to measure down there) With some single frequency wave files at various levels and frequencies I get exactly the same output as with the same files sent over USB (but much lower jitter). With music files I get mixed results, some have the same volume as USB and some are lower in volume. This was done using a peak hold feature of the peak to peak measurement in the scope. I finally tracked this down, it was due to replay gain. It turns out that the installation of slimserver was not preserving settings, so even though I had set replay gain to disable, the next time it started it went back to SMART GAIN. Some of the music files had gain tags and others didn't, thus causing the disparity. Due to switching back and forth between SB and USB inputs I had to reeboot the computer often and did not explicetly check all the settings every time slimserver started up. BTW the preamp gain doesn't seem to affect the bits going to the DAC chip, it must be implemented in the attenuator builtin to the DAC chip. The not sounding as good issue turned out to be EMI coming from the SB3. Because the cable between SB3 and DAC is very short they have to right next to each other. I tried a test where I was running data over USB and turned on the SB3 and played music through it, this caused the degradation even though the data was not coming from the SB3. Wrapping the SB3 in aluminum foil got rid of the problem. It didn't even have to be grounded. It does make it difficult to read the display. In the unwrapped mode I tried different display brightnesses and different screen savers and could hear no difference, it doesn't seem to be a display issue. The upshot is that I'm now listening to a rather interestingly styled, very brightly shining, SB3 with replay gain turned OFF, with very low jitter going to my DAC, the results are stunning. Sean, thanks for puting up with me while I worked this out. John S. -- JohnSwenson JohnSwenson's Profile: http://forums.slimdevices.com/member.php?userid=5974 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
Good to hear this John. You will be glad to know that following some debate, 6.5 will default to replaygain turned off for new players - so audiophiles should not get tripped over by this in future... -- Triode Triode's Profile: http://forums.slimdevices.com/member.php?userid=17 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
Argh! I've been burned by replaygain too. Still, it should not have affected the i2s separately from the s/pdif. The only way to do that should be by choosing fixed digital level. Although if your settings were bolloxed... -- seanadams seanadams's Profile: http://forums.slimdevices.com/member.php?userid=3 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
JJZolx Wrote: See if you can force firmware 15 on your SB3 and whether you get the same results. I'd be glad to try. Can someone point me to where the firmware files are available for download and the instructions for loading them into the SB3? I've been trying to find this information and have had no luck so far. All I've been able to find is press the brightness key which doesn't seem to give you much control over which version. Thanks Johns. PS sorry for the delay on this, I just got out of the hospital and am tying to get cought up. -- JohnSwenson JohnSwenson's Profile: http://forums.slimdevices.com/member.php?userid=5974 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
John, Here is a link to a thread where mgalusha has offered a firmware selector http://www.audiocircle.com/circles/index.php?topic=26453.0 He also has firmware 15 available here http://home.comcast.net/~mikegalusha/squeezebox2/squeezebox2_15.bin -- Wayne1 Wayne1's Profile: http://forums.slimdevices.com/member.php?userid=1335 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
I feel I should speak up, lest any passers by encounter this thread and get the wrong idea. Please do NOT expect things to work with firmware 15. This is a very old version and we do not test it with current versions of SlimServer. Even if you can get it to work, you are missing out on a myriad of improvements since then. At full volume you will get exactly the same output as with current firmware. You can verify this by looking at the s/pdif data. If you don't believe the bits, try a blind listening test. For details about how the volume curve changed, 8-bit vs 16-bit coefficients, etc please see the archives. It would be really nice if we could put this one to rest. I ask only becuase the amount of FUD and misinformation out there really seems to be getting out of hand, to the point where we actually get phone calls from people insisting that WE explain how they should go about hacks like this. Witness the muting phenomenon to see how these ideas spread. -- seanadams seanadams's Profile: http://forums.slimdevices.com/member.php?userid=3 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
seanadams Wrote: I feel I should speak up, lest any passers by encounter this thread and get the wrong idea. Please do NOT expect things to work with firmware 15. This is a very old version and we do not test it with current versions of SlimServer. Even if you can get it to work, you are missing out on a myriad of improvements since then. At full volume you will get exactly the same output as with current firmware. You can verify this by looking at the s/pdif data. If you don't believe the bits, try a blind listening test. For details about how the volume curve changed, 8-bit vs 16-bit coefficients, etc please see the archives. It would be really nice if we could put this one to rest. I ask only becuase the amount of FUD and misinformation out there really seems to be getting out of hand, to the point where we actually get phone calls from people insisting that WE explain how they should go about hacks like this. Witness the muting phenomenon to see how these ideas spread. har har, that's what you get when you have a forum specifically for voodoo shamans,...I mean audiophiles. -- CFP CFP's Profile: http://forums.slimdevices.com/member.php?userid=6915 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
seanadams Wrote: At full volume you will get exactly the same output as with current firmware. You can verify this by looking at the s/pdif data. If you don't believe the bits, try a blind listening test. I just tried version 15 firmware and I don't see any difference volume wise with 48 so that is not an issue (I never said it was). What I do know is that at full volume the bits going to the DAC chip itself produce lower volume signal in my DAC than when I feed the same file over USB to my DAC, and I AM taking into account that its left justified not I2S. The S/PDIF interface does not have this issue, its something different between the data sent to the DAC and the data sent to the S/PDIF encoder. I also tried taking S/PDIF out into a S/PDIF to USB converter and recording that on the computer. The resultant file produces the same output direct to my DAC or sent back to the SB3. Because it is possible to deliberately make the analog out and the S/PDIF out have different volume levels (through a couple of different methods) I don't think its a correct statement to say that because the S/PDIF out has bit perfect output that data sent to the DAC is also inherantly bit perfect, if they were both connected to the same trace on the board you could make that claim, but since they are not I don't think it is a legitamate claim. From everything I have been able to measure, somewhere along the line, either in the firmware or in the FPGA the data going to the DAC chip itself does not go up to full volume when the volume control is at full. I've been very careful to disble replay gain and set the preamp volume to zero in all these tests. Since the issue seems to only happen with the DAC data not the S/PDIF data it seems that its appropriate to look at whats different between them. Since I don't know anything about the firmware and this does also seem to show up in softsqueeze I'm going to do some poking around in softsqueeze code and see if I can come up with anything that makes any sense. There is something going on here, unfortunately I have no clue what it is. I'm trying to come up with some hopothesis and experiments to test them. Unfortunately winding up in the hospital and being flat on my back right know are making that slow going. (I'm typing with my laptop resting on my tummy right now!) There are two issues 1) volume is lower 2) sound quality is not at as good. Tapping into the data going directly TO the DAC chip and feeding that to my DAC (taking into accound left justified/I2S differences) does not sound as good as the same file sent to the DAC over USB, even when the analog volume has been adjusted so the levels match) I didn't even notice this at first. Other people found this out when I played my SB to DAC on thier systems. After I heard it in other systems, I did notice it in mine but its not as obvious. (this arrangement DOES improve some aspects of the sound (much lower jitter) and I was focusing on that) 1 is easy to measure 2 is not measurable. Softsqueeze has the same quality degradation as the bits to the DAC. Squeezeslave has higher volume and does not have the quality degradation (ie sounds as good as the same file sent over USB) My current wild stab in the dark guess is that there is something in the implementation of the volume control in both the firmware and softsqueeze (which of course is trying to emulate the firmware) which is somehow not getting to full value for the DAC but IS for the S/PDIF out. John S. -- JohnSwenson JohnSwenson's Profile: http://forums.slimdevices.com/member.php?userid=5974 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
JohnSwenson Wrote: My current wild stab in the dark guess is that there is something in the implementation of the volume control in both the firmware and softsqueeze (which of course is trying to emulate the firmware) which is somehow not getting to full value for the DAC but IS for the S/PDIF out. The PCM1748 datasheet shows that the volume control is part of the DAC chip itself, not something external that scales the bits before they go into it. -- andy_c andy_c's Profile: http://forums.slimdevices.com/member.php?userid=3128 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
JohnSwenson Wrote: [...] There are two issues 1) volume is lower [...] 1 is easy to measure [...] My current wild stab in the dark [...] I agree, it's easy to measure. So why on earth are you taking a wild stab in the dark at the cause of a phenomenon that you haven't even credibly established EXISTS in the first place? That is exactly how we end up with things like the Ding Dong theory. Here, I'll show you the bits. This took me one hour to set up, test, and illustrate. Since I did the work this time, may I please have the benefit of the doubt next time? Test setup: http://www.slimdevices.com/temp/i2s_vs_spdif_setup.jpg Results: http://www.slimdevices.com/temp/i2s_vs_spdif.gif -- seanadams seanadams's Profile: http://forums.slimdevices.com/member.php?userid=3 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
seanadams Wrote: I missed this the first time i read this thread. When you say grabbing the bits - can you explain exactly how? The DAC interface is not i2s, but left justified. It's the same thing but shifted right by one bit. In i2s the MSB comes one slot before the LRCK transition, but in left-justified it is immediately after. So if you are reading the bus as i2s then it will be -6dB. One tool which you may find helpful is the built-in full-scale sine wave test. Press 3 on the splash screen to activate. I have probably at one time or another used i2s as shorthand to describe the internal bus - sorry about that! I soldered some wires from a ribbon cable (alternating ground and signal) to the DAC side of the resistors going from the FPGA to the DAC chip. I very quickly realized it was left justified rather than I2S, this is easy to take into account since I use a CPLD to do the I2S to DAC conversion (I'm using mono DAC chips so I have to split the stream) I'll try the full scale sine tonight and see what happens. The interesting thing in all this is that I get the same results using softsqueeze. I have slimserver feding softsqueeze and get lower volume than when I feed the file direct to the DAC using a USB to I2S converter (this is under Linux so I don't have to worry about any of the weird things Windows does). When I use squeezeslave which does NOT implement a volume control I get the same volume as the file sent directly to the DAC. This seems to indicate that there is something in the implementation of the volume control in the SB3 AND softsqueeze that is not going to full volume when the volume control is not set to full. John S. -- JohnSwenson JohnSwenson's Profile: http://forums.slimdevices.com/member.php?userid=5974 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
JohnSwenson Wrote: This seems to indicate that there is something in the implementation of the volume control in the SB3 AND softsqueeze that is not going to full volume when the volume control is not set to full. Could this be the explanation behind the cult of firmware 15 bunch? See if you can force firmware 15 on your SB3 and whether you get the same results. I'd be very interested in knowing the outcome. If there is something going on in later firmwares, it would be nice to finally flush it out of the system. -- JJZolx Jim JJZolx's Profile: http://forums.slimdevices.com/member.php?userid=10 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
JohnSwenson Wrote: Yet when I grab the bits going to the DAC chip itself in the SB3 the volume is lower than when I send the same file through a normal player to my external DAC. I missed this the first time i read this thread. When you say grabbing the bits - can you explain exactly how? The DAC interface is not i2s, but left justified. It's the same thing but shifted right by one bit. In i2s the MSB comes one slot before the LRCK transition, but in left-justified it is immediately after. So if you are reading the bus as i2s then it will be -6dB. One tool which you may find helpful is the built-in full-scale sine wave test. Press 3 on the splash screen to activate. I have probably at one time or another used i2s as shorthand to describe the internal bus - sorry about that! -- seanadams seanadams's Profile: http://forums.slimdevices.com/member.php?userid=3 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
Yet when I grab the bits going to the DAC chip itself in the SB3 the volume is lower than when I send the same file through a normal player to my external DAC. Are the analogue gains in both systems the same? Exactly the same digital data, with a different DAC o/p spec and analogue gain post-DAC, will result in different levels. Is your I2S design such that the combined DAC o/p voltage + subsequent analogue stage gains are identical to the SB3's internal gains? This sems to point to something in the volume control processing that just goes to the analog outs and not the digital out. Whatever this is also seems to be effecting softsqueeze in the same way as the actual hardware. The volume control for both is done at exactly the same place as far as I understand it. It's not done within the DAC, but in the data before the DAC, so the both the digital out and the data to the DAC are the same, hence the question above. Andy. -- Andrew L. Weekes Andrew L. Weekes's Profile: http://forums.slimdevices.com/member.php?userid=573 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
I tried a DTS file and from the digital out its fine, so at max volume the digital out is good. Yet when I grab the bits going to the DAC chip itself in the SB3 the volume is lower than when I send the same file through a normal player to my external DAC. I also compared softqueeze and squeezeslave, softsqueeze (in which the volume control works) is softer than the direct file, but squeezeslave which is NOT controled by the volume control is the same output level as the direct file. This sems to point to something in the volume control processing that just goes to the analog outs and not the digital out. Whatever this is also seems to be effecting softsqueeze in the same way as the actual hardware. I have replay gain set to disabled and preamp volume set to 0. This bring up an interesting question, how are replay gain and preamp volume integrated in to the main volume? Are all three combined in slimserver and one volume level sent to the player? Are all three sent separately and the player combines them into one volume level and applies that to the signal or are they sent separately and each attenuates the signal in a separate step? I've read a few things about some people liking the sound of some older firmware versions better, I wonder if this volume control issue could be related? John S. -- JohnSwenson JohnSwenson's Profile: http://forums.slimdevices.com/member.php?userid=5974 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
[SlimDevices: Audiophiles] Re: Is max volume really max?
Do you have replaygain on? -- radish radish's Profile: http://forums.slimdevices.com/member.php?userid=77 View this thread: http://forums.slimdevices.com/showthread.php?t=26002 ___ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
