Hy Guys,
I just came in from doing an A/B sound comparison between the Wolverine and CFA-XH mod BV. Aside from the Wolverine having ever so slightly more gain, I could not hear a difference between them. There is just nothing missing in the audio on either amp. Next is to check the appearance of square waves between them. I will try to take pics and post them.
Blessings, Terry
I just came in from doing an A/B sound comparison between the Wolverine and CFA-XH mod BV. Aside from the Wolverine having ever so slightly more gain, I could not hear a difference between them. There is just nothing missing in the audio on either amp. Next is to check the appearance of square waves between them. I will try to take pics and post them.
Blessings, Terry
Worst thing you can do for distortion measurement.. Any input (soundcard, amplifier..) should be driven from lowest possible impedance, because any amp (discrete, operational amplifier..) have voltage dependent input capacity (nonlinear), and driving impedance in both inputs (inverting, noniverting) of such amp should be the same, if possible (or keep it as low as you can). If you use high impedance source (series resistor for driving input of soudcard), it will create frequency dependent and nonlinear divider with this nonlinear input impedance , what means.. increasing distortion with frequency. Try to search something about "common mode distortion" . And high impedance is more prone to be affected by disturbing signals, as mains hum and so (increased distortion at low frequencies? ),and noise is also higher.
Use for measurement low impedance divider (it is no problem for power amp to drive 1k load ), something like 1K/2W+33R, or even lower. Sound card input will "see" this 33R as source impedance. And I suppose, you will get exact copy of soundcard loopback.
Last edited:
Terry,
I was having the same problem with 5th's images until I reloaded them. After reloading they seem to fit back on the normal screen size. Hope this works for you also.
Steven
I was having the same problem with 5th's images until I reloaded them. After reloading they seem to fit back on the normal screen size. Hope this works for you also.
Steven
Hi BV,
Are saying to hook up a 1K/2W resistor in series with a 33R/2W between the + output of the amp in test and the input of the sound card? Does the ground of the output go straight through?
Are saying to hook up a 1K/2W resistor in series with a 33R/2W between the + output of the amp in test and the input of the sound card? Does the ground of the output go straight through?
Simple voltage divider, 33R is in paralel to soundcard input, 1 k from soundcard input ("live")to amp +output , amp output GND to soundcard input GND (via cable shield). 33R is sufficient e.g a type 0207 SMA resistor ,metalized 0,7W.
Interesting BV I will see if that makes a difference. Needless to say the results however do seem to be dominated by the amplifier as can be seen in the comparisons I've made all when done at the same signal levels. If the resistor divider was dominating something surely the results wouldn't change. Either way the proof is in the pudding and I'll give it a go and see what happens.
Last edited:
Today I listened, in a treated room meant to sell the high-end gear, one very good system, we swapped only new Devialet 200 and Soulution 710, both having better graphs than any above and oh man how different do they sound, seriously.
Did you swap them instantly or was there setup in between? I'm telling you, I used to try to A/B amps all the time and would swear they were different. It wasn't until I made a good A/B setup that I saw how little difference there really is between well designed amps. what fools us is gain and memory. My A/B setup uses stepped attenuators. Once the gain is equalized, the amps sound identical. If I give one only one click on the pot you will swear the one that is one click louder has so much more headroom, bass, soundstage..........
Equalize them again and search for a difference. Most folks won't want to do this because all of their beliefs will be crushed. They will be stuck looking at lines on a scope and computer screens to satisfy the need to believe they have built something better.
My 2 cents
Blessings, Terry
Today I listened, in a treated room meant to sell the high-end gear, one very good system, we swapped only new Devialet 200 and Soulution 710, both having better graphs than any above and oh man how different do they sound, seriously.
You got any measurements for the D200? I can find the D premier and that has fairly horrendous distortion performance at low output powers.
The S710 is a different kettle of fish entirely, but I don't see how.
Is any less impressive at low output powers. Which is all I've built it for.
You tell 'im Terry 😀
I know full well I can't hear tiddly squat with a lot of these changes and differences but that isn't what drives me.
But it is better. It is technically superior. Even if you cannot hear it, it measures better. It's one of the reasons I enjoy this hobby, troubleshooting, figuring stuff out and making something better, even if it's only better (sometimes) on paper.
I do apologise for the images. If you attach a large-ish image file (useful if you want to see things in detail) DIYaudio will rescale them to fit on the page, but it appears that you do have to refresh the page for it to do so. I do not know why, it would be nice if they could fix that in the code, so that it does it right away.
Attachments
I should mention that I've tried BVs lower impedance resistor divider and it didn't really do much at all. Things seem a little bit more consistent, but it's by no means a night and day difference and the previous set up was perfectly acceptable for troubleshooting problems.
One thing I will say though is that this is probably dependent on the hardware you are using. I've read a little about common mode stuff before and it never sticks, I guess I need to read more 😀 But I would assume that the degree to which the different impedances affect the hardware will depend heavily on what the hardware actually is.
One thing I will say though is that this is probably dependent on the hardware you are using. I've read a little about common mode stuff before and it never sticks, I guess I need to read more 😀 But I would assume that the degree to which the different impedances affect the hardware will depend heavily on what the hardware actually is.
I believe that they measure better. That is the purpose of this thread after all. How many folks can actually hear slew rate?
My point is not for guys who enjoy measuring things. I'm very guilty of that. Having a scope and sine generator has made the hobby much more enjoyable.
Probably because I have built so many amps, I get asked all the time by new guys which amp sounds best and which one would I recommend they build. I'd like to be able to gve them a definitive answer but the truth is, they all sound great. Can you hear the difference between .0001 and .0005? I doubt it. Does the VSSA sound better than my KSA50, Symasym, Low TIM, DX Super A, Peeceebee, SKA GB150, Honey Badger? No, it sounds the same. Clear, open, great bass, great highs, clear mids. I can hear the bow as it starts a note on the strings, the finger sliding off the double bass string, the breath slipping past the reed on the tenor sax, the stick on the rim of the snare, the ping of the ride cymbal, it's all there. If you are going to be like me and just want to keep building and learning then just pick one and get going. If you are looking for the best of the best, do want Lazy Cat did and spend a few thousand on factory built stuff that comes with all the hype and specs and build a room with sound treatment and fill it with expensive speakers. Then you can drive yourself nuts trying to decide which one sounds better.
I actually have a very good sound card, the Delta 1010. I used to have a home recording studio. Unfortunately the computer it is installed in is shot. I'll need to get a new tower to use it. I probably will since that seems to be the only real way to see the little benefits from each new design.
Since Kinder told me to refresh the page your screenshot are no longer an issue.
Blessings, Terry
I use 2SA1360 2SC3423 for VAS, pre driver, dan cap multiplier. The IPS is simple CFA like VSSA. I have good result in listening test. But I can not go higher then +-63V for power supply. It is difficult to find 2SC3503 and 2SA1381 at local market here. What are alternative for 2SC3503 and 2SA1381 with VCE max >= 300V?
Terry and that is exactly what is happening here in this thread. Designing the audio gear should mean not only to do simulations and measuring but also listening and comparing too.
Leveling and comparing is not enough, your source feeding the signal is probably so compromised that any difference is not possible to be heard.
All amps sounds the same is a wrong assumption, clearly discarded by the variety of types and topologies present on the market, even here at DIY.
LC,
I often wonder on an amp such as this Slewmaster with a common output section what percentage of each section between the input and the output is the dominant player. Also we have two very distinct feedback topologies between the CFA and VFA versions. I would seem that there should be some kind of discernible differences in the sound between all these variations. If as Terry is saying there is no difference then you would think that just reaching a certain slew rate and distortion level would be all that is important. Perhaps with a horn loaded system the sound quality would be easier to discern but then you wouldn't need anywhere near the power output of these 5-pairs amplifiers! I think that Terry's speakers are using soft dome tweeters and knowing JBL they aren't known for the most sophisticated cross-over networks.
I often wonder on an amp such as this Slewmaster with a common output section what percentage of each section between the input and the output is the dominant player. Also we have two very distinct feedback topologies between the CFA and VFA versions. I would seem that there should be some kind of discernible differences in the sound between all these variations. If as Terry is saying there is no difference then you would think that just reaching a certain slew rate and distortion level would be all that is important. Perhaps with a horn loaded system the sound quality would be easier to discern but then you wouldn't need anywhere near the power output of these 5-pairs amplifiers! I think that Terry's speakers are using soft dome tweeters and knowing JBL they aren't known for the most sophisticated cross-over networks.
can anybody answer this?
What's the meaning ?
If we want to measure left channel only we must not use divider?
What's the meaning ?
If we want to measure left channel only we must not use divider?
Attachments
Last edited:
2 LC
Yes, it is wrong assuption, but this has not been claimed here, only by you.
It is neverending story, but the only proof for claim , "I am able to distinguish" is ABX blind test, with exactly matched signal levels. Everything else is only subjective opinion, nothing realistic with objective validity for all subjects .
If You get repeatedly statisticaly important results in ABX(blind) tests, than you can say it is (at least for you) really distinguishable. Amplifiers with the sets of practically the same parameters (or better to say well below audible treshold), as here (THD, IMD,SR, S/N, DF..) you get the "same "signal at the output, the same signal will create the same sound field. Or You believe in something like extrasensory perception? Do not overestimate your ears, it is so simple to fool them.
Here are many proofs that "goldenears" fails with ABX or blind test, but no one proof that they are really able distinguish what they claim they hear. It is the reason why they refuse such tests. Expectance effect is very strong.
thimios, you must always protect sound card input from excessive voltge, if here is any chance for this.
Last edited:
"thimios, you must always protect sound card input from excessive voltge, if here is any chance for this."
I know this very well ,but this is taken from ARTA help file. I can't explain this and i want to know what other guys can understand.
I know this very well ,but this is taken from ARTA help file. I can't explain this and i want to know what other guys can understand.
can anybody answer this?
What's the meaning ?
If we want to measure left channel only we must not use divider?
I don't know why it is stated this way there, but in fact, for two-channel measurement you need two dividers so that each amp's output is connected to the card's input via a separate divider.
For one channel just use one divider.