| clem_o |
Give it a go and let us know!
And yeah - 6ft glassy barrels - certainly nice where you live... ! :-)
Cheers
Clem |
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| georgehifi |
| quote: | Originally posted by clem_o
Could the DAC be 'running out of steam'? I.e. the capacitive loading of the i-v converter, which combines the function of initial LPF...
Cheers
(though this seems perfectly acceptable as per Burr-brown's app circuit)... |
clem_o, wouldn't the capacitive input of the ad825, if it did cause the trouble, happen regarless of which level db of the 1000hz digital was played, or only when the d/a chips analog output amp was being pushed to it's highest level.
I think it will be like a power amp when you put a 1uf across it's output to check stablity, it will ring the same whether at 2vpp or 20vpp no more no less.
I tend to think it's not the capacitive input of the AD825, it's a PITB to take out and exchange for the NE5532 only to see that it's going to be the same.
Cheers George |
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| clem_o |
Hi georgehifi,
If it's a stability problem, then yes, but I think this is different. The DAC's output is a current which changes proportionately with the binary input amplitude. Since that is the variable that is supposed to be exactly held constant wrt the binary value input, capacitive loading of the output of the DAC should only result in a 'drooped' amplitude - exactly what is expected with a filter... duh... so yeah, it's probably not the capacitance of the AD825 inputs...
OTOH, what happens if virtual ground presented by the op-amp isn't 'true' - i.e. a non-zero voltage is created there... that would create the modulation effects... but that should only happen if the op-amp is too slow or it's outputs can't swing the required levels...
Arrrgh...
Clem |
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| rfbrw |
It might be an idea to establish whether or not you have a real issue or are simply running up against the limits of numerical representation.
Convert the offending track to a .wav file and look at its binary representation. If you see a series of maximum valued samples, the maximum positive value being 0111 1111 1111 1111 and maximum negative value, 1000 0000 0000 0000, then the top of the sine wave is clipping and there is nowt you can do about that. |
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| clem_o |
Hi rfbrw,
georgehifi is using a couple of test disks - pierre verany (spell?) and a denon I think, it's a couple of posts back. So the assumption here is that the digital signal is 'clean' - it happens on both, and we suppose that such manufacturers would get the signal right.
Cheers |
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| peranders |
| quote: | Originally posted by Elso Kwak
The digital filter from Sony; CXD1244 clips on the ringing of a 0dB square wave....... |
A typical technical comment, hardly any problem with real music. :no: |
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| georgehifi |
| quote: | Originally posted by rfbrw
It might be an idea to establish whether or not you have a real issue or are simply running up against the limits of numerical representation.
Convert the offending track to a .wav file and look at its binary representation. If you see a series of maximum valued samples, the maximum positive value being 0111 1111 1111 1111 and maximum negative value, 1000 0000 0000 0000, then the top of the sine wave is clipping and there is nowt you can do about that. |
rfbrw, I have no idea how to do that.
But trying to do it, I just played the tracks on my computer and they all sound the same after volume was adjusted. There was no overtone present at 0db digital, maybe my computers speakers are no able to give it to me is another thing, but they all souned pure. ******!!!!!!!!!!!!!!!!!
Cheers George |
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| clem_o |
Download a program like Goldwave, install it. It'll allow you to edit wav files. I think it's capable of importing audio files from CD as well.
The editor lets you see the waveform, much like an oscilloscope, - closer to a DSO anyway, and you can move cursors around using your mouse...
Cheers |
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| peufeu |
Since you have a pretty fancy Tek scope, and the distortion you want to see is probably in the high order harmonics, I suggest the following :
- use a sinewave at 0bDfs (where you can hear but not see distortion).
- have the output of your DAC pass through a second-order linkwith-riley high-pass filter (easily built with a dual opamp and a few passive components) whose corner frequency will be about 20x the test frequency (ie. 20 kHz if you use a 1 kHz sine to test).
This will attenuate the fundamental and let you see the harmonics. You can listen to the output, too.
Now, use the scope and zoom in on the filtered waveform to hunt the harmonics. |
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| clem_o |
I have another idea, may be easier: have one channel work at 0dbfs, where the problem lies. Have the other channel run at -3dbfs, where there appears to be no problem.
Sum the two channels together with the weaker channel inverted and boosted by 3db.
Hunt for residuals in the ouput. |
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| mrshow4u |
As far as that Piere Varnay disc goes. Any sine wave greater than 0 dB FS on the disc will/must be distorted by any DAC. If a DAC makes it clean, the DAC is broken!! Sometimes digital domain amplitude values are expressed as "FFS" Fraction of Full-Scale. A 0 dB FS, or 1.00 FFS sine wave uses all of the quantization steps. The positive peak and the negative peak of the sine are A Full-Scale square wave measures 1.41 FFS, but still uses all of the quantization steps. It has to do with the crest factor of the signal. The crest factor for a pure sine is 3.01 dB, the crest factor for a pure square is 0 dB. If a sine wave is 0 dB FS (1.0 FFS), that is the maximum level that a sine wave can be produced cleanly. If you scale your binary bits through multiplication (say X2), that will increase the sine wave by 6 dB. There are no more bits to quantize the new level. It will flat top or "clip". Think of the bit depth as power supply rails. Once you hit the limit, it's out of gas.
Now there may be a problem if you hear distortion playing the 0 dB FS tone. I think you're on the right track for skulling that one out. .....but you will never get the the +3, or +6 dB FS sine waves to ever play cleanly. |
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| anatech |
Hi mrshow4u,
I use the Pierre Verany disc all the time to check muting transistors on CD players. As you say, it works fine. I have not tested any new CD players, but I do have some Cyrus units around I can test. They are current.
George,
Any digital signal over the maximum level will give you a clean clipped signal. It is possible you are chasing a bug in a DSP chip. Nice if that's the case. Too bad you can't see the samples before the reconstruction filter gets the signal. That would be at the input of the op amp. Too small to see I think. I was thinking you may see a sample or two wrapping around due to an over range condition.
-Chris |
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| georgehifi |
Sorry for my ignorance anatech, but the DSP chip is that the "digital servo processor" that would be in the Teac VRDS-T1 transport? If so, why would that be "nice if that's the case" ? Is that going to be an easy fix?
Cheers George |
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| anatech |
Hi George,
Sorry. I am lazy and therefore abbreviate my posts where possible.
Digital Signal Processing (DSP) can occur in the transport or the external DAC. An filter does this as does the oversampling bits. Error correction may as it interpolates.
Fixing a bug in a DSP chip is not easy. Either the manufacturer of the chip releases a pin for pin replacement chip (or someone else), or an entirely new board is required. A smaller "daughter board" may do the trick. A "daughter board" would contain a new chip and support circuit to adapt it for use in another chip's footprint.
But first, you need to find out where the problem exists. from there you look at options.
-Chris |
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| mrshow4u |
Hi Chris and George. George, can you offset your scope channel and increase the vertical sensitivity to just zoom in on either the positive or negative peak? ...while listening, just to make sure the setup loading etc. doesn't change.
I have to clrify a couple things I said. I said something or other about +3 and +6 "always will distort" and "never play cleanly". Just to be clear, I mean the waveform will be faithfully reproduced (distortion free representation) of a distorted signal. Does that make sense? garbage in (+3 and +6 dB sines), garbage out.
Have you tried putting the NE5532 back in yet, just to see? Maybe a good place for a machined pin socket:D
Good Luck, I hope for the good outcome.
...Is your prime reason for using the AD amp to remove coupling caps due to the better DC drift performance? |
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| anatech |
Hi mrshow4u,| quote: | | I have to clrify a couple things I said. I said something or other about +3 and +6 "always will distort" and "never play cleanly". Just to be clear, I mean the waveform will be faithfully reproduced (distortion free representation) of a distorted signal. Does that make sense? garbage in (+3 and +6 dB sines), garbage out. |
That's it exactly, however I wouldn't call the reproduced signals at +3 and +6 garbage. They are exact, clean representations of the expected waveform. They just don't sound nice. ;)
I think to actually see what is going one, you would need to subtract the fundimental frequency. A THD meter or FFT would show the issues nicely. The newer 'scope input circuits do not take kindly to being over ranged.
One of the mixed signal DSO's from Agilent would be perfect for this. You could see the digital sample and the analog output word for word. I think you can even set the trigger for a specific digital word. :cool:
-Chris |
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| georgehifi |
mrshow4u, yes I can zoom in and have a closer look at the +&- peaks.
I also understand what you said about the +3 and +6 that they should be clipped.
And yes the reason for the AD825 is one I found they sounded better than the NE5532's and also they only gave out 2-4mv offset which was easy to trim out to zero where the NE5532's had 20-50mv dc offset.
And when I tried DC coupling with the AD825 the sound was fast tight and grain free then I thought I'll put the coupling cap back in a Blackgate NX Bi-Polar 6.3v 220uf and it sound clearly softened in comparsion, so dc coupling for me is a must have.
I have no NE5532's to try at the moment, but I will look at the scope again tomorrow, it's 1am now here in Aus and I'm starting to see two keyboards.
Cheers and good night George |
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| georgehifi |
mrshow4u, here are the two shots + and - tops of the 1001hz 0dfs sine waves, looks good to me, there must be something else.
Have any of you a test disc you can listen to with -10dfs
-5dfs and 0dfs. You will not reconize the slight overtone unless you listen to the -10dfs first and it may come across as ok unless you pre condition your self with the undistorted one first, it's that slight, and of course a pair of esl's would help as they have the least distortion at that fequency.
Cheers George |
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| georgehifi |
| And the positive. |
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| clem_o |
Hi georgehifi,
Ok, let me have the weekend to generate those wav files and I'll give it a try as well. I don't have a suitable set of headphones though...
OTOH, can you differentially scope, say the output of the AD825 versus the output of the headphone amp, both at 0dbfs and -3dbfs?
Clem |
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| mrshow4u |
Hi George, Good Morning:D Thanks for sharing the scope shots. Those do look good. A distortion measurement is the only thing that could get closer to seeing what isn't right. A distortion measurement will remove the fundamental tone with a steep deep notch filter. This will leave everything else to be examined. (Harmonics and Noise). If you have a digital soundcard on your computer, I can make you some signals. I've got Adobe Audition, so I can generate some signals for you in the digital domain. They might be large file and make it hard for some e-mail systems. I also have an Audio Precision System One, but I think it'll complain if I try to generate a signal above -0 dB FS. Mathematically, it's all very possible but I think the software would stop me. If you only have a CD/DVD transport, I could burn you some signal files.
A side story. Just be weary. I used to work at a stereo store that sold used gear and raw speakers. The owner was checking some drivers with a tone generator that had a big dial to change the frequency. He was checking these drivers and said "Wow, three bad drivers in a row". I was curious and said "let me hear". He dialed the frequency where the "distortion" was apparent. I couldn't hear it. He went and had a hearing test and it turned out his ear was distorting. I don't remember if it was a perforation in the eardrum, or what. I'm not try to worry you, just to say make sure that your experiment double checks the test method. I usually get through a repair using instruments. Scopes, dist meters, counters, etc. I do a final listening check, but being at the top of your careful listening game in a production environment isn't always possible. The scope pictures you have are beautiful. Unfortunately, what you might be hearing is small and the scope shots are dominated by the fundamental frequency. The best way to see what doesn't belong is to remove the fundamental frequency.
Let me know what kind of digital output device you have and we can figure out some way to hone in on what's what. |
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| clem_o |
| quote: | Originally posted by mrshow4u
I also have an Audio Precision System One, |
Whoa - that's got me curious - how much does one of those things go for now???
Cheers |
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| mrshow4u |
Hey clem_o, System One?? It varies. I paid 4k USD, but I have the service manual, 1 kHz bandpass filter, CCIR2K filter, wow&flutter option, IMD module and the full tilt DSP. I think e-bay has had some for 1k (with the serial number "rubbed off":whazzat: ). The thing has an awesome analog front end. I also have a Sound Technology 1701A. I love it, but the Ap is great for sweeps, etc.
For generating signals, Adobe is a little easier to use. ...Matlab too. You can do anything in Matlab and make a .wav file. Matlab has something called "wavwrite" that wraps your custom pcm with a .wav header. You can go nuts in Matlab. BTW, sourceforge has a Matlab impersonator (for free) called Octave. I think it works on Windows, Linux, and UNIX. It's a little more clunky, but the price is right!! |
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| clem_o |
Hi mrshow4u,
Thanks for the info - always wanted to have one of those, but price is way out of range, unless one is professionally into audio... sigh...
Yup, we use both Matlab and Octave here, for those savvy with these programs. I never really got into it - I just usually code a prog in VB or something. Editing, use Goldwave or even Nero WAV editor. Adobe Audition is nice, but it costs... I'm doing things the slower way I'm sure, but us dinosaurs are a bit hard to retrain... hehehe...
Cheers
Clem |
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| anatech |
Hi Guys,
Sadly, I know where there is a system one sitting unused. He's missing the interface card and software but won't part with it.
-Chris |
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| clem_o |
Hi Chris,
How'd that happen?
Ah well, mouth watering... drool....
Clem |
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| mrshow4u |
Hey clem_o,| quote: | | Adobe Audition is nice, but it costs. |
....even in Manila?? Isn't there a Flea market?? Sorry, I shouldn't encourage anybody to buy that "affordable" software. That's the same as that serial number "missing".
Chris, System One unused because of the inteface card?? That is a shame. The software is freely downloadable. The interface card is $200.00 bucks USD. ...that's a shame it's really a nice instrument. This is such a sad story, I'd offer an EISA interface card that I have that's gathering dust. .....assuming you can find a motherboard with EISA slots. |
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| georgehifi |
Hey guys you forgot about me in your drooling over equiptment, just kidding in about 1/2hr I'll have a Meridian G0-8 to put on the system and all will be revealed I hope, I'll post back in 1hr with results, who knows maybe all cd players do this and nobody has found it yet.
Cheers George |
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| mrshow4u |
........sorry George, That's thread stealing gone bad:dodgy: :smash:
That's awesome about getting a Meridian!! ...you didn't have to buy it $$$ did you? |
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| clem_o |
Hi George,
So sorry, all my fault - couldn't resist asking about the AP1...
If the Meridian produces the same problem that would be an awesome revelation... or a reason to have ears checked(?!!)
Cheers
Clem
ps: mrshow4u - spot on, but it's not as rampant as it once was - it's now tons of dvds and video-cd's... |
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| anatech |
Hi George,
No, not all CD players do that. Sorry. :(
Yeah, I've tried to get that unit for a while. I don't think he got anything but the main box. EISA slot!! I like IBM as much as the next guy, but avoided that system. I would buy a PCI adapter new.
Clem knows, if that thing were possible to obtain, it would be sitting on my bench right now. Okay, pipe dreams. What I'd really love, an Agilent 3585A, 4395A, 6000 series scope or equiv. Tek. Leaning towards Agilent on this one. 100 grand and shopping at the Agilent store. Wow. I could spend more than 100 grand without even trying I bet. I'll send you guys a picture if I ever win a lottery.
We bring you back to our regularly scheduled life. :apathic:
-Chris |
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| georgehifi |
Guess what guys, it did the same, and to confirm the owner of the Meridian GO-8 (Art Audio) a member here pick it to, on both machines, so guys if these two very expensive machines do it chances are all do everywhere.
Ideas to get rid of it, common it's a must do???????????????????
Cheers George |
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| clem_o |
Straaaange! I'm gona try this over the weekend, on a disto analyzer.
Clem |
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| mrshow4u |
So the cup is half full!!!! The AD I/V stage is at least as good as the Meridian, for this test.
Boy this goes against the grain. The theory goes: The larger the digital signal, the lower the distortion. This is because the quantization steps (each bit level) are all the same size (in theory) and so the more bits you use to make the signal, the further you get from LSB error. I attended a Yamaha digital seminar once and instead of referring to "distortion", Yamaha called it "Signal to Error". That made a lot of sense. It's kind of like reading distortion as a ratio, the smaller the signal fundamental, the more the noise floor becames a larger portion of the measurement.
....Hmmm. Maybe Pierre Varnay messed up? I don't know what to think now, my whole world is collapsing:bawling: :D
So, is this a done deal?? |
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| georgehifi |
mrshow4u, It wasn't just the Pierre Varnay test disc but the Denon as well, that's a double shot in the head.
Now mrshow4u you seam to have a head full of 1's 0's, lets fix this. and you'll become an overnight digital guru.
Cheers George |
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| mrshow4u |
.....I get the feeling that putting a pillow over your midrange driver isn't going to satisfy you:D
I'm out of gas as far as solving a problem. I guess the good news is; With music content, full-scale signals will be very intermittent.
With the complex harmonic structure of music, it will be exxxxxxtreeeeemely hard to pick out this distortion. I think the single tone test you were doing is a test that sugically focuses on amplitude related distortion. Perhaps this could be a good test to pick out a specific performance difference in DAC's??
....allright, I can't take it anymore!! I'm going to make some plots!!
I'll do a Amplitude vs. distortion sweep and an FFT for varying levels. Give me a couple days. I've got a Dyna Stereo-70 with future shellac making exoskeletons strewn inside.:dead: I'll make some pictures and post to this thread. I've never posted pictures before. I've read some have had problems. Any tricks to that? |
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| georgehifi |
No problems just keep them under 102k in size and less than 1000x 1000 pixals. If too big it can all be changed with a free program called Irfanview.
Go mrshow4u you can do it, you'll be the next Nelson Pass of the digital world.
Cheers George |
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| rfbrw |
| quote: | Originally posted by mrshow4u
I'm out of gas as far as solving a problem. |
Don't listen to 0dBFS sine waves ? |
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| georgehifi |
| quote: | Originally posted by rfbrw
Don't listen to 0dBFS sine waves ? |
Common now, don't give up with a wimpy sentance like that.
My most dynamic cleanest sounding cd is also the one that is the quietest recording I have The Tony Dagcadi Trio, I'm not kidding it's at 3pm on the volume control where most are at 11am and the super loud ones at 9am, this says to me that if the quietest one is giving me the best sound dynamicly and smoothest grain free sound, that it's the least disorted and maybe not getting to 0dbf but under maybe -3dbf?.
And the loud ones that have to be played at 9am are usually the ones I can't stand the sound of for too long maybe because of them hitting the 0dbf point too much and distorting?
This is hitting home very much to me.
Cheers George |
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| rfbrw |
You have to be realistic about this. Different engineers and labels have different approaches. Unless you intend to use a compandor or the audio equivalent of a video clipper, neither option particularly pleasant from an audio POV, there is not much you can do short of remastering each offending disc.
PS. Now I think about it, there is something that can be done, that would allow one to exceed 0dBFS in a number cases but I am not so sure it is worth the effort, especially if you cannot build it yourself. |
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| georgehifi |
| quote: | Originally posted by rfbrw
PS. Now I think about it, there is something that can be done, that would allow one to exceed 0dBFS in a number cases but I am not so sure it is worth the effort, especially if you cannot build it yourself. |
Well?
Cheers George |
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| mrshow4u |
Hi George, I made some plots. I made these on an old Ap (System One). It's not very fancy as far as it's digital capabilities, yet it shows excellent performance at -0 dB FS. This makes the mystery deeper for me. When you made those scope shots (the great looking ones), did you monitor what the Quad's and the headphones were "seeing". In other words, were you right at the speaker teriminals?? I'm just wondering if there could have been some kind of input overload issue. I can't see the earlier posts from this page and I'm too lazy to re-type everything, but I remember something about 22V or so rails?? If those potentially large output levels aren't padded down, they might cause some input overload.
rfbrw said:| quote: | | PS. Now I think about it, there is something that can be done, that would allow one to exceed 0dBFS in a number cases but I am not so sure it is worth the effort, especially if you cannot build it yourself. |
.....Hmmmmm. I'm not too sure about that. The overloaded signal in in the data, it isn't generated by the DAC. ....it is reproduced by the DAC. The only way that I see to remove the distortion components is to bandpass the fundamental. This would only be good if you waned to listen to 1 kHz all of the time. You might already be bored about that:D
Okay so I made some plots. The first plot is a digital amplitude vs. distortion sweep. I saw an interesting little bump at -30 dB FS but it looked really good at -5 ~ -0 dB FS. |
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| mrshow4u |
| ...This is -0 dB FS 16-bit, 44.1 kHz to mimick a CD. |
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| mrshow4u |
....and -30 dB FS
You talked about the best sounding CD's that you have had required large volume settings. Yeah, they're making good use of the 96 dB Dynamic range that CD's offer. Good for them. It sounds like they don't want to compress. Most pop and rock is very compressed, leaving a high average volume level. Your "quiet" CD's probably do get very close to full-scale, but use very little compression. Intermittent use of the full-scale output sounds the best to me. These dynamic recordings are the best ones to show off a good sound system. |
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| rfbrw |
| As I said in a number of cases. You have to decide what the problem is. If the disc has clipped samples then there is nothing you can do. If, OTOH, the disc has been recorded close to the edge and there is a little gain in the digital signal path then you can attenuate the data digitally as has been done by someone else in the forum. |
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| anatech |
Hi guys,
Running a CD at a 0 Vu level was a standard test I did for years, but haven't lately. I have never run into this.
Another thing to check are the "0" crossings. FFT would catch that as well.
I might get a chance to look at the new Cyrus units today. I can even run those into some Audio Alchemy DAC boards I have lying around.
-Chris |
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| georgehifi |
| quote: | Originally posted by mrshow4u
...This is -0 dB FS 16-bit, 44.1 kHz to mimick a CD. |
mrshow4u the bottom of the 1k spike at 0dfs has to step up in this pic where all the others -5 -10 and -15 don't have to step up as much? Is this some form of distortion, excuse my ignorance.
Cheers George |
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| clem_o |
Hi georgehifi,
That's an artefact of the sampling process and the windowing used to truncate the signal for FFT'ing purpose.
The noise floors are similar in both plots, and more importantly, no other spikes show up in the whole band above 1KHz, up to 20KHz. This means essentially there isn't any distortion that the AP1 can pick up - at least nothing above -130dbfs...
That AP1 is a nice machine... :-)
Cheers! |
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| mrshow4u |
| Hi George, any differences at the base of the fundamental's spike is not likeley wht your hearing. It's in the basement -120 -130 dB FS. I don't know what kind of DAC Audio Precision is using. It's 24 bit capable, but it's old too. The plots are old DAC performance. I think stuff available on consumer gear these days should be as good if not better than the Ap's DAC performance. I'm going to check to see if I have the Pierre Varney disc. I may, I have a couple of Sony and Philips test discs around. I don't think I have the Denon one though. |
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| anatech |
Hi George,
I just tried a vintage Luxman D-103 and a current Cyrus CD8. Neither of these machines displayed the defect you have witnessed. The THD residuals were predominately noise for the CD8 and second harmonic for the Luxman. That second harmonic looked pretty clean too!
Since the Cyrus is current, try and borrow one if you can. Home demo or some such.
-Chris |
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| georgehifi |
| quote: | Originally posted by anatech
Hi George,
I just tried a vintage Luxman D-103 and a current Cyrus CD8. Neither of these machines displayed the defect you have witnessed. The THD residuals were predominately noise for the CD8 and second harmonic for the Luxman. That second harmonic looked pretty clean too!
Since the Cyrus is current, try and borrow one if you can. Home demo or some such.
-Chris |
Chris I take it from this that you were listening not measuring?
Cheers George |
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| anatech |
Hi George,
I listened to both in the same setup. I then ran each unit though my THD analyzer and had a good look at the residual on the scope.
The residuals were vastly different. The Cyrus was generally random noise whereas the Luman had a very clear second harmonic with some lower odd harmonic content. The Luxman measured about 1/2 the total THD and noise of the Cyrus. THe Luxman has an analog filter with three tuned inductors. This would be familiar to any "old" CD tech. I am sure this would cut much of the random noise I measured. I did not have the opportunity to run it into my computer for an FFT analysis.
I used track 13 on disc one of the Pierre Verany set. Track 14 is digital silence, so it wouldn't pin my meter. This would be a danger on other tracks where there is a full reference signal followed by other audio tracks.
-Chris |
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| georgehifi |
Yep, track 13 1k 0db de-emf off, this has me stumped now as 2 machines did it and two people heard it. Chris did you listen first to -10dfs first to get your ear accustomed the with a volume change to equal the level listen to the 0dfs?
Cheers George |
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| anatech |
Hi George,
No. There should be no reason to do so. What you have described would be immediately obvious. Anything but a pure tone in the midrange is easy to pick out. I do this on a regular basis when testing amplifiers and speakers. I did this quite a lot when doing warranty for various speaker brands.
I will however try this later. It will have to be on Monday. I can't do this any sooner.
One thought. Is it possible your input on the preamp is misbehaving? Many use IC's to switch sources.
-Chris |
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| georgehifi |
| quote: | Originally posted by anatech
Hi George,
No. There should be no reason to do so. What you have described would be immediately obvious. Anything but a pure tone in the midrange is easy to pick out. I do this on a regular basis when testing amplifiers and speakers. I did this quite a lot when doing warranty for various speaker brands.
I will however try this later. It will have to be on Monday. I can't do this any sooner.
One thought. Is it possible your input on the preamp is misbehaving? Many use IC's to switch sources.
-Chris |
Passive pre!
This is where your hearing thinks the 0dfs sounds ok, like I said it's slight, but definatly there, when you go from hearing -10dfs then listen to 0dfs.
I even experimented with my mate who owns the Meridian G08 and he thought the 0dfs souned fine at first then I played the -10dfs and then went back to the 0dfs and only then he heard it definatly.
Like I said it's only a slight overtone, unless you hear it pure first it's hard to pick.
Cheers George |
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| clem_o |
I don't have any decent headphones, but here's the setup I used:
Player: Sony CDP-X33ES (single-bit)
Disk: Denon Hi-Fi Sound Check (Track 39 - 0dbfs, 997Hz)
Distortion Analyzer: Tektronix AA5001 on a 5003 frame
'Scope: Tek TDS-210, set to average 16x on each channel
Capture of distortion/main waveform done via TCM on the TDS-210 and the Wavestar software.
Result: Distortion at 0dbfs is below the noise floor of the AA5001 (0.0024%, as can be seen in the pic attached). |
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| clem_o |
And if you want to see the actual distortion residual:
Cheers!!
Clem
ps: remember, this is averaged 16x. Without the averaging, it looks very noisy. And, the distortion is 0.0024%...
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| rfbrw |
| Well, folks, is the sky falling and if it is how do you plan to prop it up ? |
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| clem_o |
Squawk like a chicken and run in circles, waving hands widely!
:-)
Cheers |
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| georgehifi |
| quote: | Originally posted by clem_o
Squawk like a chicken and run in circles, waving hands widely!
:-)
Cheers |
Totally with you there, make as big a noise as you can, better than sitting back and coping it on the chin, and saying oh well some of my cd collection has inbuilt clipping.
This is abhorrent to be finding it's way in into audio, especially if your into high end audio. It wouldn't worry me in the car or as lift music.
Cheers George |
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| clem_o |
Hi George,
Just how subtle is the sound difference you guys are picking up from 0dbfs and -3dbfs? Do you think it's audible on a good pair of dynamic loudspeakers? I've junked the idea of ever buying a pair of headphones - the good ones simply don't last long where I live, am guessing corrosion of the coil winding.
Cheers |
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| georgehifi |
| quote: | Originally posted by clem_o
Hi George,
Just how subtle is the sound difference you guys are picking up from 0dbfs and -3dbfs? Do you think it's audible on a good pair of dynamic loudspeakers? I've junked the idea of ever buying a pair of headphones - the good ones simply don't last long where I live, am guessing corrosion of the coil winding.
Cheers |
Imedeate, when going from -3dfs then to 0dfs.
Cheers George |
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| anatech |
Hi George,
Well, I'll give listening to a lower level first, then 0 dB. Level matched of course.
The thing is, I am very used to listening to pure sinewaves while checking for other noises and artifacts. I really don't think it exists on the units I listened to.
I still have the Cyrus, and also a Denon DCD-800 I can compare.
Hi Clem,| quote: | | Squawk like a chicken and run in circles, waving hands widely! |
Are your arms tired yet? Throat sore? ;)
-Chris |
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| clem_o |
Hi Chris,
Nope - legs tired out before that happened... collapsed and went to sleep...
:-)
Cheers |
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| anatech |
Hi Clem,
Good thing, you may have generated lift. Imagine that thread!
I'll be hitting the hay soon my self.
-Chris |
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| rfbrw |
| quote: | Originally posted by georgehifi
Totally with you there, make as big a noise as you can, better than sitting back and coping it on the chin, and saying oh well some of my cd collection has inbuilt clipping.
This is abhorrent to be finding it's way in into audio, especially if your into high end audio. It wouldn't worry me in the car or as lift music.
Cheers George |
But I doubt it will be any more effective as if it is inbuilt you are stumped. If you write to one of the larger labels, good luck convincing them, nevermind the cd hardware manufacturers. Chances are they'll ignore you or at best see it as an oppprtunity to sell you the same thing on DVD-A, SACD or via MP3 download. |
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