I took a few pics a while ago with a 1k square wave, heres a few I could find, Buffalo does not look bad compared to some others, a PCM1794 based dac had quite a bit of pre and post ringing.
Tim/div wasn't set to the same for all these, I just wanted to see how each of the square waves looked
1khZ squarewave Buffalo (output of IVY using original input filter values)
1khz squarewave from PCM1794 based dac
1khz squarewave from AYA dac (TDA1541S2)
Tim/div wasn't set to the same for all these, I just wanted to see how each of the square waves looked
An externally hosted image should be here but it was not working when we last tested it.
1khZ squarewave Buffalo (output of IVY using original input filter values)
An externally hosted image should be here but it was not working when we last tested it.
1khz squarewave from PCM1794 based dac
An externally hosted image should be here but it was not working when we last tested it.
1khz squarewave from AYA dac (TDA1541S2)
IVY revisisted.
Hi Folks,
Any of you with a Buffalo/IVY setup will want to read this thread:
http://www.twistedpearaudio.com/forum/default.aspx?g=posts&m=2864ର
What I found was that using feedback caps when operating the OPA1632 in low input impedance (I/V) mode just is not advisable.
This information came out of some testing we were doing for IVY II/BUF32S.
Anyway, I strongly suggest removing C1-4.
Cheers!
Russ
Hi Folks,
Any of you with a Buffalo/IVY setup will want to read this thread:
http://www.twistedpearaudio.com/forum/default.aspx?g=posts&m=2864ର
What I found was that using feedback caps when operating the OPA1632 in low input impedance (I/V) mode just is not advisable.
This information came out of some testing we were doing for IVY II/BUF32S.
Anyway, I strongly suggest removing C1-4.
Cheers!
Russ
Russ White said:Hi Leo,
Any chance you could check it now that you have the IVY tuned up?
Just curious as I have not looked it it on a decent scope yet.
Cheers!
Russ
Sure, I'll do my best to try it sometime this weekend
I also highly recommend this latest mod posted by Russ
Apart from sounding better (to me at least anyway) the OPA1632's are running cooler too.
Another thing I noticed which I'm pleased about is that I sometimes used to get some HF noise (possible instability? ) on the edges of some notes, since doing this filter change I've not had any noise at all !
Once again, could someone PLEASE measure the TIME in usec or msec of ONLY the "overshoot"??
You want to expand the waveform and read off the divisions in width... with a split timebase scope that is very easy, with a regular scope you just have to turn the timebase knob and up the brightness (usually) and turn the horizontal position or trigger until that part of the square wave shows up.
(Please check ur horizontal calibration first with the 1kHz calibrator square wave and note any deviation from it showing up at the right time in terms of divisions.)
I want to know what frequency that works out to... Ok?
And yes the lack of ringing on the rest of it is very impressive.
How they do that is another discussion...
You want to expand the waveform and read off the divisions in width... with a split timebase scope that is very easy, with a regular scope you just have to turn the timebase knob and up the brightness (usually) and turn the horizontal position or trigger until that part of the square wave shows up.
(Please check ur horizontal calibration first with the 1kHz calibrator square wave and note any deviation from it showing up at the right time in terms of divisions.)
I want to know what frequency that works out to... Ok?
And yes the lack of ringing on the rest of it is very impressive.
How they do that is another discussion...
bear said:
Bear,
As I mentioned before the picture I posted is a precise 1khz sq wave this means the period is 1ms so you can measure any bit of it you like to with a ruler off the screen and work out the frequency using cross multipication.
This seems pretty straight forward to me and I can't understand why you want someone else to do it for you.
cheers
mike
To be quite blunt about it, that's not how to measure it.
I don't see a reasonable way to do it as you described.
The image posted isn't accurate, and that's not how to measure it.
The way to measure it properly is to (as I said) use the split timebase feature (if you have a good scope) and spread the leading edge out so that you get a really good look at it spreading across the screen (several divisions worth), then figure out the actual amount of time, and then know the frequency pretty well.
If you don't see any significance to the overshoot and its frequency, what can I say?
And how difficult is it to do the test properly anyhow?
Another interesting test would be to try say a 100Hz square wave and note if the frequency (width) of the overshoot changes or remains the same. One would hope and expect it remains the same.
_-_-bear
I don't see a reasonable way to do it as you described.
The image posted isn't accurate, and that's not how to measure it.
The way to measure it properly is to (as I said) use the split timebase feature (if you have a good scope) and spread the leading edge out so that you get a really good look at it spreading across the screen (several divisions worth), then figure out the actual amount of time, and then know the frequency pretty well.
If you don't see any significance to the overshoot and its frequency, what can I say?
And how difficult is it to do the test properly anyhow?
Another interesting test would be to try say a 100Hz square wave and note if the frequency (width) of the overshoot changes or remains the same. One would hope and expect it remains the same.
_-_-bear
my scope is about 40 years old and has not be calibrated since it was made as far as I know - it has none of the features you describe - so perhaps someone else can get into that
I did work out what u asked and the answer came to about 23,263 hz but I just did it the way u said is not appropriate - but it seemed ok to me
For me the significance of ringing is that I spent years trying to eradicate random noise from my system and I find it somewhat bizarre that some people find it perfectly reasonable that digital reproduction adds it in again.
but despite this the dac still sounds pretty amazing.
mike
I did work out what u asked and the answer came to about 23,263 hz but I just did it the way u said is not appropriate - but it seemed ok to me
For me the significance of ringing is that I spent years trying to eradicate random noise from my system and I find it somewhat bizarre that some people find it perfectly reasonable that digital reproduction adds it in again.
but despite this the dac still sounds pretty amazing.
mike
mikelm said:I did work out what u asked and the answer came to about 23,263 hz but I just did it the way u said is not appropriate - but it seemed ok to me
mike [/B]
Using pixel arithmatic off of Mike's photo:
Average 1k wave half width = 101 pixels
Average distance from overshoot peak to adjacent recovery 'bump" = 9.18 pixels
time between adjacent overshoot peaks = 45.4usec
freq. = 22k
Frank in Mpls.
Sore head?
Any in-band or near in-band artifact is of interest and concern.
Fran, stick to wood turning perhaps?
Anyhow, thanks to those who did the pixel style measurement. It still would be nice to have it done via a better scope.
ALSO, if anyone can pop on a lower frequency square wave and confirm or deny that the overshoot artifact remains at the same frequency, that would be very useful too... if the artifact lowers in frequency that would be of some significant concern.
_-_-bear
Any in-band or near in-band artifact is of interest and concern.
Fran, stick to wood turning perhaps?
Anyhow, thanks to those who did the pixel style measurement. It still would be nice to have it done via a better scope.
ALSO, if anyone can pop on a lower frequency square wave and confirm or deny that the overshoot artifact remains at the same frequency, that would be very useful too... if the artifact lowers in frequency that would be of some significant concern.
_-_-bear
The thing is bear most of here are listening to these DACs every day and for me is the most detailed, musical & realistic sounding DAC that I have heard.
So when you tell us we should be investigating what you think may be a serious problem it doesn't really mean much to us because, if it's the same for others as it is for me, our ears are telling us that we are experiencing less problems with this DAC than we ever heard before.
Why don't you just buy one also, then you can investigate the problems to your hearts content and also enjoy the sound of a really great DAC
So when you tell us we should be investigating what you think may be a serious problem it doesn't really mean much to us because, if it's the same for others as it is for me, our ears are telling us that we are experiencing less problems with this DAC than we ever heard before.
Why don't you just buy one also, then you can investigate the problems to your hearts content and also enjoy the sound of a really great DAC
Look, what you are hearing and listening to depends greatly on your system, your experience (basis for comparison) and your ears.
I'm not looking to tear down anyone's personal situation. What I am interested in is simply a little wee bit of technical information based upon something that someone has already posted. Merely a follow up. So, what is the problem with that??
As far as buying one? Why should I need to fork out $$ to find out something that someone who has already bought one can undoubtedly shed light on?
Furthermore, someone local to to me acquired a Twisted Pear unit, I guess the previous chipset (not sure) and I have listened to it. It wasn't in the best circumstances, and not the worst. It may not be as good as what you have. Doesn't matter. Obviously, I am interested in the chipset, eh?
Just trying to find out a little bit of really very simple technical information here. Isn't the sharing of information what this website is all about? That's what I thought.
Calling names doesn't fit into that model very well.
Providing reasonable information and/or a reply post does.
_-_-bear
I'm not looking to tear down anyone's personal situation. What I am interested in is simply a little wee bit of technical information based upon something that someone has already posted. Merely a follow up. So, what is the problem with that??
As far as buying one? Why should I need to fork out $$ to find out something that someone who has already bought one can undoubtedly shed light on?
Furthermore, someone local to to me acquired a Twisted Pear unit, I guess the previous chipset (not sure) and I have listened to it. It wasn't in the best circumstances, and not the worst. It may not be as good as what you have. Doesn't matter. Obviously, I am interested in the chipset, eh?
Just trying to find out a little bit of really very simple technical information here. Isn't the sharing of information what this website is all about? That's what I thought.
Calling names doesn't fit into that model very well.
Providing reasonable information and/or a reply post does.
_-_-bear
Bear - in all seriousness you are of course correct - I was just messing. Seemed funny at the time. Sorry for any offence caused, you just seemed so crotchety at the time!
I can't do the measurements you want. Just don't have either the technical capability or the intrumentation to do it.
I can tell you that this DAC is the best I've heard yet. I've heard a few others, also DIY offerings, but this is the best. Mind you it costs a good bit more than those as well.
The nearest that comes to it now is the Peter Daniels NOS premium DAC.
I should add that this is spdif>>buffalo>>counterpoint with LCBPS and LCDPS supplies.
Regards,
Fran
I can't do the measurements you want. Just don't have either the technical capability or the intrumentation to do it.
I can tell you that this DAC is the best I've heard yet. I've heard a few others, also DIY offerings, but this is the best. Mind you it costs a good bit more than those as well.
The nearest that comes to it now is the Peter Daniels NOS premium DAC.
I should add that this is spdif>>buffalo>>counterpoint with LCBPS and LCDPS supplies.
Regards,
Fran
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