Re: Well many of us then perfer them in some way......
I used to use 324s and thought they were great, until I used the TL0xxs. Well, the 324s aren't bad with a light load. But under heavy load (I were bootstraping them in a power amp), they didn't do too well.
it must have been the power cords,
jewilson said:
I used to use 324s and thought they were great, until I used the TL0xxs. Well, the 324s aren't bad with a light load. But under heavy load (I were bootstraping them in a power amp), they didn't do too well.
jewilson said:
it must have been the power cords,
John, I have a hardcopy, but sorry it is on the other side of the Earth. I can send it to you not earlier than a New Year. If you are in a hurry you could order through AES for $5:
http://www.aes.org/publications/preprints/search.html
Alternately, you can download Wurcer US patent 5,166,637
http://patft.uspto.gov/netacgi/nph-...txt&S1=Wurcer.INZZ.&OS=in/Wurcer&RS=IN/Wurcer
http://www.aes.org/publications/preprints/search.html
Alternately, you can download Wurcer US patent 5,166,637
http://patft.uspto.gov/netacgi/nph-...txt&S1=Wurcer.INZZ.&OS=in/Wurcer&RS=IN/Wurcer
setup: non-inverting amplifier with a(I chose this gains figure to use the OPA637 and the resistors were handy at that time) gain of five times and a 50k pot at the front end.a typical single opamp Pre-Amplifier
distortion could be a little lower if I used lower gain settings... as the setup was equal to all opamps,this cannot be blamed
about the null test like I said before, there is a lot of input about this test made by my friend Tube Dude in this forum, just search...
in short terms, it's a differential test that directly compares the input with the output leaving only the thing that cant be nulled, all nonlinearities created by the amplifying stage! lower the value, more the output resembles the input! one thing great about the test is that the distortion of the generator isn’t a problem like the typical distortion tests and that severely limits resolution of those tests
about the file, it's a word file
cheers
Ricardo
distortion could be a little lower if I used lower gain settings... as the setup was equal to all opamps,this cannot be blamed
about the null test like I said before, there is a lot of input about this test made by my friend Tube Dude in this forum, just search...
in short terms, it's a differential test that directly compares the input with the output leaving only the thing that cant be nulled, all nonlinearities created by the amplifying stage! lower the value, more the output resembles the input! one thing great about the test is that the distortion of the generator isn’t a problem like the typical distortion tests and that severely limits resolution of those tests
about the file, it's a word file
cheers
Ricardo
??
First of all.. It can be blamed.
Design you circuit to match the opamps you are using.
1. A good example is the OP275GS/GP from analog. On page 9 in the datasheet there is a section called "Attention to source impedance Minimizes distortion"
There is descriped how a source impedance of more than 2Kohm and unballanced will affect its distortion performance alot.
That is because of capacitance modulation.
2. The AD797 outperforms the NE5534. There was an article in EW about capacitance distortion. The author have made a very pure sine wave oscillator. The distortion dropped below the NE5534 when he added a series resistor of 100R to the Cf. Reason .. Because of the very low rbb of the input diff. pair it needed a series resistor to dampen the capacitive interactions.
Look at page 10 in the datasheet.
So when it all sums up. The tests have to take there working conditions into account before comparing the specs and sound quality.
Sonny
First of all.. It can be blamed.
Design you circuit to match the opamps you are using.
1. A good example is the OP275GS/GP from analog. On page 9 in the datasheet there is a section called "Attention to source impedance Minimizes distortion"
There is descriped how a source impedance of more than 2Kohm and unballanced will affect its distortion performance alot.
That is because of capacitance modulation.
2. The AD797 outperforms the NE5534. There was an article in EW about capacitance distortion. The author have made a very pure sine wave oscillator. The distortion dropped below the NE5534 when he added a series resistor of 100R to the Cf. Reason .. Because of the very low rbb of the input diff. pair it needed a series resistor to dampen the capacitive interactions.
Look at page 10 in the datasheet.
So when it all sums up. The tests have to take there working conditions into account before comparing the specs and sound quality.
Sonny
whit a 50k pot that gives you about 10k of output inpedance at mid point position, fet amplifiers should be at home, and bipolar amplifiers should perform much worse... that wasn’t the case!
did you verify this with a null test? remember that the null test isn’t a typical thd test! all non linearity’s are measured.
about that resistor I don’t believe that was the case... I believe that Mr. Bateman had a parasitic oscillation when he inserted the AD797 on the circuit, and that resistor dampened that oscillation, and off course, distortion was lower, so nothing more than a base stopper...
now look at the typical diy'er, normally the topology is the same and only opamps are swapped...that was what I did but instead of listening, I was measuring
it's fairly easy to do a null test , so do it yourself and find your results...
cheers
Ricardo
I like the NE5532, shoot me I don't care. I find it to be the best sounding small-signal opamp I've tried, and I've fiddled with many others. Maybe I didn't implement the others correctly enough, or maybe it's just easier to achieve good sound with the NE5532/NE5534 than others. Either way, to each his own...
did you verify this with a null test? remember that the null test isn’t a typical thd
Still you still have not answered the question. What types of test are you running? Can’t you be just a little more specific regarding you claims?
Offset , THD , Gain, BW, Phase, Slew Rate, Transient , Noise
What is your null?
Still you still have not answered the question. What types of test are you running? Can’t you be just a little more specific regarding you claims?
Offset , THD , Gain, BW, Phase, Slew Rate, Transient , Noise
What is your null?
use the search function of this site please...
http://www.diyaudio.com/forums/showthread.php?s=&threadid=13415&highlight=null+test
http://www.hafler.com/techsupport/pdf/XL-280_amp_man.pdf
cheers
by the way, i use Jorge test...
http://www.diyaudio.com/forums/showthread.php?s=&threadid=13415&highlight=null+test
http://www.hafler.com/techsupport/pdf/XL-280_amp_man.pdf
cheers
by the way, i use Jorge test...
> What is the file type?
MS-DOC inside a ZIP. But it is just 1K of text:
the null test results - cheers - Ricardo
[Opamp _ _ _ _ _ _ _ 100hz _ _1khz _ 10khz _ _20khz _40khz
NE5534(signetics) _ 2,6mv _ 3,0mv _ 3,4mv _ _4,4mv _ 6,4mv
NE5534(TI) _ _ _ _ _ _2mv _ _ 2mv _ 3,2mv _ _4,6mv _ _ 7mv
AD797 _ _ _ _ _ _ _ 4,6mv _ 4,6mv _ 4,6mv _ _6,4mv _ _ 7mv
OPA627BP _ _ _ _ _ _2,4mv _ 3,3mv _10.8mv _ 20.2mv _ _40mv
OPA604AP _ _ _ _ _ _2,8mv _ 5,6mv _ _12mv _ 20.2mv _ _40mv
OP27GP _ _ _ _ _ _ _2,2mv _ _ 5mv _ _20mv _ _ 40mv _ _75mv
TLO71 _ _ _ _ _ _ _ _10mv _12,6mv _ _40mv _ _ 80mv _ 156mv
OPA134PA _ _ _ _ _ _ _3mv _ 4,2mv _16,6mv _ 33,6mv _ _67mv
Whit 1k load:
NE5534(signetics) _ 2,8mv _ _ 3mv _ 4,2mv _ _5,4mv _ 9,0mv
AD797 _ _ _ _ _ _ _ 4,6mv _ 4,6mv _ 5,2mv _ _6,4mv _10,6mv
OPA627 _ _ _ _ _ _ _5,6mv _ 5,6mv _15,2mv _ 25,8mv _41,6mv
OPA604 _ _ _ _ _ _ _6,4mv _ 6,4mv _17,6mv _ 25,8mv _41,6mv
OPA134 _ _ _ _ _ _ _6,2mv _ 6,4mv _17,6mv _ 35,2mv _70,4mv
To convert mv to dB: dB= 20log (v\vref)
This test was made with a 2volt peak to peak input voltage(vref)
> the null test isn’t a typical thd test! all non linearity’s are measured.
> This is not a standard recognized test in the audio industry.
No; and perhaps because it is one of the most embarassing things you can do to an amplifier. It can also be called a "Total Garbage" test: everything wrong stands out. The numbers are probably not important except for the most general classification. But it is a widely-used design-bench test, because it is easy and a look at the O'scope display tells the savvy designer if he/she has phase shift, noise, low-order distortion, or a lot of high-order crapola, and if it happens on peaks or at zero-cross or some intermediate point (marginal instability). I've seen null-tests published in reviews, though I think you need to do a lot of such tests yourself to get a good feel for what it may be able to tell you.
> It is not like a true measurement of performance like distortion or a spectral analysis or noise.
Ah, but what is "TRUTH"? It has been clear for 50 years (actually since pentodes and feedback) that THD-number isn't "truth". Spectra are so messy. And there are so many ways to lie about noise. The total-garbage out of an amp is arguably no worse than most of our other "measurements", many of which have little to do with how we hear.
I thank Ricardo for the numbers, but without knowing how much of the number is phase-shift, noise, low- or high-order distortion, or if the test rig was optimally adjusted for each amp (in ways we could do in the real world), I don't trust it without trying things on the scope.
MS-DOC inside a ZIP. But it is just 1K of text:
the null test results - cheers - Ricardo
[Opamp _ _ _ _ _ _ _ 100hz _ _1khz _ 10khz _ _20khz _40khz
NE5534(signetics) _ 2,6mv _ 3,0mv _ 3,4mv _ _4,4mv _ 6,4mv
NE5534(TI) _ _ _ _ _ _2mv _ _ 2mv _ 3,2mv _ _4,6mv _ _ 7mv
AD797 _ _ _ _ _ _ _ 4,6mv _ 4,6mv _ 4,6mv _ _6,4mv _ _ 7mv
OPA627BP _ _ _ _ _ _2,4mv _ 3,3mv _10.8mv _ 20.2mv _ _40mv
OPA604AP _ _ _ _ _ _2,8mv _ 5,6mv _ _12mv _ 20.2mv _ _40mv
OP27GP _ _ _ _ _ _ _2,2mv _ _ 5mv _ _20mv _ _ 40mv _ _75mv
TLO71 _ _ _ _ _ _ _ _10mv _12,6mv _ _40mv _ _ 80mv _ 156mv
OPA134PA _ _ _ _ _ _ _3mv _ 4,2mv _16,6mv _ 33,6mv _ _67mv
Whit 1k load:
NE5534(signetics) _ 2,8mv _ _ 3mv _ 4,2mv _ _5,4mv _ 9,0mv
AD797 _ _ _ _ _ _ _ 4,6mv _ 4,6mv _ 5,2mv _ _6,4mv _10,6mv
OPA627 _ _ _ _ _ _ _5,6mv _ 5,6mv _15,2mv _ 25,8mv _41,6mv
OPA604 _ _ _ _ _ _ _6,4mv _ 6,4mv _17,6mv _ 25,8mv _41,6mv
OPA134 _ _ _ _ _ _ _6,2mv _ 6,4mv _17,6mv _ 35,2mv _70,4mv
To convert mv to dB: dB= 20log (v\vref)
This test was made with a 2volt peak to peak input voltage(vref)
> the null test isn’t a typical thd test! all non linearity’s are measured.
> This is not a standard recognized test in the audio industry.
No; and perhaps because it is one of the most embarassing things you can do to an amplifier. It can also be called a "Total Garbage" test: everything wrong stands out. The numbers are probably not important except for the most general classification. But it is a widely-used design-bench test, because it is easy and a look at the O'scope display tells the savvy designer if he/she has phase shift, noise, low-order distortion, or a lot of high-order crapola, and if it happens on peaks or at zero-cross or some intermediate point (marginal instability). I've seen null-tests published in reviews, though I think you need to do a lot of such tests yourself to get a good feel for what it may be able to tell you.
> It is not like a true measurement of performance like distortion or a spectral analysis or noise.
Ah, but what is "TRUTH"? It has been clear for 50 years (actually since pentodes and feedback) that THD-number isn't "truth". Spectra are so messy. And there are so many ways to lie about noise. The total-garbage out of an amp is arguably no worse than most of our other "measurements", many of which have little to do with how we hear.
I thank Ricardo for the numbers, but without knowing how much of the number is phase-shift, noise, low- or high-order distortion, or if the test rig was optimally adjusted for each amp (in ways we could do in the real world), I don't trust it without trying things on the scope.
PRR your correct
PRR,
While some of the standard test may not provide the complete picture of an amp performance, many they are still the best tests we have going. Of course, we cannot hang our hat on THD however there is important information in spectrum analysis.
My self, I really like doing impulse testing with a FFT. However as you stated their no test currently available that tell us one circuit sound better than another does. Having said that, we can get a great deal of truth about the performance of components with these conventional tests.
PRR,
While some of the standard test may not provide the complete picture of an amp performance, many they are still the best tests we have going. Of course, we cannot hang our hat on THD however there is important information in spectrum analysis.
My self, I really like doing impulse testing with a FFT. However as you stated their no test currently available that tell us one circuit sound better than another does. Having said that, we can get a great deal of truth about the performance of components with these conventional tests.
jewilson said:
It isn't hard to tell the difference. But have you ever listened to these BB and AD parts? How do you think they sound vs ne5532?
Samuel Jayaraj said:
Agree!
jewilson said:
That's simply not true. Please explain what such as the op275 does better than ne5532 in a listening test!
TimA said:
WOW! I totally agree!
The FET sound really has an unnatural spotlight somewhere, and yes, it does at first sound more detailed... But try listening to a good classical recording, and you will find that the bipolar actually is more "shaded"/detailed, it just don't advertise it! I think the spotlight produced by fets tend to cover things outside the spot. Try using good recordings of real instruments next time, and tell me what happened!
rickpt said:the null test results
cheers
Ricardo
Thanks! Very interesting!
Mvh Asbjørn
Having played with the null test a bit when I first saw the Hafler XL280 amp manual, I HAVE to agree with what PRR said. My opinion is null testing is useless if you're not going to look at the residuals on a good scope and interpret what you see correctly.
Hmmmm, that could probably be said for THD meters also, now that I see the words.
However, I'll agree it is fun to place around with As usual in this hobby/business, the real benefit comes from understanding the results.
Hmmmm, that could probably be said for THD meters also, now that I see the words.
However, I'll agree it is fun to place around with
As usual in this hobby/business, the real benefit comes from understanding the results.PRR said: