Syn08, I am result (sound) oriented, not debate oriented. And I do not forget measurements, as you know. I am neither subjectivist, nor objectivist. I say both is important. For this reason I have problems both with subjectivist and objectivist camps.
I have a lot of work and do not have time for everlasting nothingsolving debates. Many of the objections were examined far before they have occured in posts, most of the recommended literature was already studied. Not enough time to spend in useless discussions.
I have a lot of work and do not have time for everlasting nothingsolving debates. Many of the objections were examined far before they have occured in posts, most of the recommended literature was already studied. Not enough time to spend in useless discussions.
Syn08,
getting such low noise levels with a decent sound card is not that difficult if you have good software to match it.
Here's my USB soundcard's THD and THD+N and SNR. Line out - > Line In. Balanced mode.
FFT size is 1024k.
Adding average makes a clean noise floor.
Sigurd
getting such low noise levels with a decent sound card is not that difficult if you have good software to match it.
Here's my USB soundcard's THD and THD+N and SNR. Line out - > Line In. Balanced mode.
FFT size is 1024k.
Adding average makes a clean noise floor.
Sigurd
syn08 said:
Attachments
PMA said:
I would say sales oriented (and then it's obvious why you don't feel like talking technical matters) but it's ok, I was only trying to help.
One last free advice: if you want to be successfull in any business, you'd better change your atttitude and tone. At least until you get the same stature and prestige as your master JC.
Sigurd Ruschkow said:
That's what I was guessing.
By the way, if the problem is more prone to one channel and you've scrutinized the bejesus out of the circuit, doesn't it make sense that there is a problem with the layout?
Just a thought.
"Syn08, I am result (sound) oriented, not debate oriented. And I do not forget measurements, as you know. I am neither subjectivist, nor objectivist. I say both is important. For this reason I have problems both with subjectivist and objectivist camps."
You are a rationalist.
Welcome!
🙂
You are a rationalist.
Welcome!
🙂
Sigurd Ruschkow said:
Line out -> Line in balanced mode is like the AP self test. The problems are starting when connecting to the outside world (ground loops, EMI radiation, etc...). Otherwise said, I'm not surprised by the intrinsic noise floor of the sound card but by the low noise of the entire measurement setup. In post #338 http://www.diyaudio.com/forums/showthread.php?postid=1704731#post1704731 while measuring the preamp, the noise floor is -132dB, and this is not even in a balanced configuration! That's why I'm asking about details on the measurement configuration.
What sound card are you using? I have tried last year a Lynx L22 and I was unhappy with the results. Of course averaging helps but it took forever to average down to a reasonable floor.
A question I was never able to get a good answer for: if soundcards + software are that good, how come AP is still in business?
syn08 said:
Sales oriented? 😀
My hobby branch with several PCBs and modules sold, that's all. If I were sales oriented, I would not disclose and acknowledge HF oscillation mistake, but would rather point to someone's wiring and grounding incapabilities. It hummed, didn't it? So it must be wiring and grounding 😀 😀
About tone: it is fine when I am permanently attacked, and I am advised to be submissive? If I were sales oriented, I certainly would!
syn08 said:
Well, there is no mystery, though it is not so very easy. Clean background depends a lot on:
- generator used
- sound card used
- coupling used (interconnecting cables, ground loops - loopback method is unusable, higher frequency ground loops through capacitance of power supplies etc. etc.)
Several hints:
- use very clean signal generator
- use battery supplied PC or isolation transformer before PC
- minimize length of interconnecting cables
- use differential measurement (if possible) even for single ended measurements, i.e. subtract possible hum voltages on ground return
- use transfomer coupled generator if available.
Anyway, I can achieve very clean background even in a real audio chain setup with CD/SACD player, standard cables used (RG-59), no transformers, no differential channels:
Attachments
I only wanted to show you how good a cheap soundcard can be. Not how to get that good performance in a test setup. To get good performance in a test setup you have to do the normal
measurement performance work - and maybe some more work as
there is not much signal conditioning made.
One of the reasons for useing an AP instead - much less hazzle, and traceability, easy of use, programability, support, training, calibrations made et etc. AP is not "only" a measurement box.
The soundcard I showed is the EMU Tracker Pre costing about 150 USD!!
It is a USB soundcard and I prefer the soundcards to be external.
Sigurd
measurement performance work - and maybe some more work as
there is not much signal conditioning made.
One of the reasons for useing an AP instead - much less hazzle, and traceability, easy of use, programability, support, training, calibrations made et etc. AP is not "only" a measurement box.
The soundcard I showed is the EMU Tracker Pre costing about 150 USD!!
It is a USB soundcard and I prefer the soundcards to be external.
Sigurd
syn08 said:
Hi Pavel,
have you considered Hitachi mosfets 2SJ76/2SK213 configured simply as SF for output?
Thanks.
have you considered Hitachi mosfets 2SJ76/2SK213 configured simply as SF for output?
Thanks.
Sigurd Ruschkow said:
Hello,
I was planning to get one too. Is it easy on a laptop battery, or it helps consume it noticeably faster? With or without phantom power on for loudspeaker measurements with condenser mics or studio recording (if you do such) does it consume noticeably different?
Thanks in advance.
Hi estman,
most of all I would like to use simple JFET output buffer with 2SK170/2SJ74 and to avoid this diamond buffer story. But first of all I want to use available components, no unobtainium. I believe that the diamond buffer HF behaviour is solved, as feedback from my customers tell.
I would like to mention that only thanks to feedback of my customers and a number of units sold and soldered we have discovered these diamond buffer oscillations, as they had occurred only at several preamps. My modules have not oscillated, and without feedback of my customers I would not have known about the problem.
most of all I would like to use simple JFET output buffer with 2SK170/2SJ74 and to avoid this diamond buffer story. But first of all I want to use available components, no unobtainium. I believe that the diamond buffer HF behaviour is solved, as feedback from my customers tell.
I would like to mention that only thanks to feedback of my customers and a number of units sold and soldered we have discovered these diamond buffer oscillations, as they had occurred only at several preamps. My modules have not oscillated, and without feedback of my customers I would not have known about the problem.
I would like to ask Scott Wurcer if he or his team has experienced UHF local oscillations in output of opamp stages, especially diamond buffers. Thanks for ev. answer.
Hi,
I agree with PMA. I have some 2SK389BL/2SJ109V and I use them for buffers. They are great, however I have them less than a dozen. And this is a real big handicap and important point that should not be overseen.
I plan to try BF862 (did anyone tried them for a buffer?).
This is why I like this design very much (I also use BJTs) - you buy hundreds of BJTs for almost nothing and match them very easily within <1%.
Matej
I agree with PMA. I have some 2SK389BL/2SJ109V and I use them for buffers. They are great, however I have them less than a dozen. And this is a real big handicap and important point that should not be overseen.
I plan to try BF862 (did anyone tried them for a buffer?).
This is why I like this design very much (I also use BJTs) - you buy hundreds of BJTs for almost nothing and match them very easily within <1%.
Matej
Pavel, have you checked the datasheet and app note for the BUF634? Something there was mentioned about instability under certain conditions.
You can run the Tracker Pre on a separate battery if you wish.
I do not know about power consumption - check datasheet.
Sigurd
I do not know about power consumption - check datasheet.
Sigurd
salas said:
Pavel - the
2SJ74 / 2SK170 are very easy to get at many places on the planet.
Not sure the JFETs sound as good as MOSFETs for output stages, though.
Sigurd
2SJ74 / 2SK170 are very easy to get at many places on the planet.
Not sure the JFETs sound as good as MOSFETs for output stages, though.
Sigurd
PMA said: