To all,
I am obviously way behind many or most of you when it comes to understanding electronic circuits. I am trying my best to learn, mostly by building and problem solving. As far as listening to music I do not think of myself as an amateur. I play music professionally for years as well as running sound for large churches and had my own home recording studio. It is my belief that those who think these power amps have great differences in sound have not actually used a good A/B setup. Believe me, I wanted to hear a difference. I'm not saying there are no differences at all, but they are all so close it would surprise most of you. If you are like me and enjoy building and testing amps, you should really take the time to build a simple setup like mine. The only way to do a true A/B blind comparison is to have both amps playing through the same set of speakers and being driven by exact same source. The output level has to be matched as well. If there is any lag between amps your memory will not be good enough to notice if something is missing or added. It needs to be instantaneous.
I am obviously way behind many or most of you when it comes to understanding electronic circuits. I am trying my best to learn, mostly by building and problem solving. As far as listening to music I do not think of myself as an amateur. I play music professionally for years as well as running sound for large churches and had my own home recording studio. It is my belief that those who think these power amps have great differences in sound have not actually used a good A/B setup. Believe me, I wanted to hear a difference. I'm not saying there are no differences at all, but they are all so close it would surprise most of you. If you are like me and enjoy building and testing amps, you should really take the time to build a simple setup like mine. The only way to do a true A/B blind comparison is to have both amps playing through the same set of speakers and being driven by exact same source. The output level has to be matched as well. If there is any lag between amps your memory will not be good enough to notice if something is missing or added. It needs to be instantaneous.
Just two things.
1) The winner from this test didn't will come from measurements but from listening tests only.
2) I have two at least INP which comes ahead
I agree that blind tests say the truth.
We hear by ears not with analyzers.
1) The winner from this test didn't will come from measurements but from listening tests only.
2) I have two at least INP which comes ahead
I agree that blind tests say the truth.
We hear by ears not with analyzers.
Input protection
It is mistake in explanation.., In two channel mode there is no chance to damage reference channel (right), because here is only simple loopback, card out - card in, no amp in loop. Measuring channel is only one (left), so there is card input protection needed. Other channel serve as time reference (impuls measuremets) for exact measurement of acoustic phase.
It is mistake in explanation.., In two channel mode there is no chance to damage reference channel (right), because here is only simple loopback, card out - card in, no amp in loop. Measuring channel is only one (left), so there is card input protection needed. Other channel serve as time reference (impuls measuremets) for exact measurement of acoustic phase.
If we can not to distinguish by ears only, for me, the winner is better measuring amp, if subjective impression are the same.
Blind test says only, if we are really able to distinguish two or more sources.
It is not competition in "beauty", the minimal change of input signal is what counts . If someone will to change signal according his taste, IMO it is best to use some DSP for this purpose, not amp.. At least, it is no problem than bypass this.
Try to change signal source internal impedance (series resistance) in simulation to e.g. 100k, and amplitude so , that you get the same output from amp as for source impedance in area 10-100ohm. And compare spectra of distortion . I get more than 3 times worse results at 10kHz with CFA mod.2 simulation.
Terry, I support your view on this. I have also got a studio, high-resolution source recordings, good DACs, etc., and certain "listening" experience, and I also saw many cases of comparisons organized simply the wrong way. Our brain works in a way that it tends to prefer what you like to prefer, according to your knowledge, understanding, personal favors, etc.
So the blind test must be completely blind, with exactly the same setup and same sound levels (precisely aligned with appropriate measurement), and for the listener, not knowing what option sounds when.
Practical experience shows, that in such conditions, most of the results will follow the "normal distribution" rule. Of course, assuming the amps (cables, power supplies, etc. - whatever you test) are of the similar high level of quality. I will most likely hear the difference between $200 and $2000 amps. But the ones of the equal "top class" - very difficult, if possible.
When you try to assess, say, different front-ends (with 1-2ppm distortion), connected to the same power section (even though it's very good one), most of the distortion (even though it's low) is still coming from that power section. So distinguishing the difference is even more difficult (if possible).
Now, take some really good one. For example, a well known Burmester's huge class-A "cube". Some people write in review comments - I tried this one - and nothing special, my 20-years-old Technics (nothing against Technics 😉) sounds better. Bull**it. This simply means that person used the precise instrument the wrong way.
Real blind test in equal environment rules.
Cheers,
Valery
Today is a day for a listening test . I started listening all my INP again.
I'm afraid that this hard modified cfa is at the last position.
I'm afraid that this hard modified cfa is at the last position.
Hi Thimios,
Looking forward to your assessment. I am building the last OS modded CFA today and then will try to do some A/b testing of the 4 versions I now have. Original CFA XH, BV mod #1, BV mod #2 and OS mod #1. The first three look a little different on the scope above 20K but look very similar from 20K down. It will be interesting to see if any of it is audible.
Valery has designed an IPS with tubes to drive the Slewmonster. I'm just waiting for him to finish up the gerbers and I will be ordering boards for that. It will be my first venture into building anything with tubes in it. 😱 Can't wait!
I'm hoping Jason will be wrapping up his Gerbers for the Symasui and maybe I can place a single order to save on shipping time and costs.
Blessings, Terry
Looking forward to your assessment. I am building the last OS modded CFA today and then will try to do some A/b testing of the 4 versions I now have. Original CFA XH, BV mod #1, BV mod #2 and OS mod #1. The first three look a little different on the scope above 20K but look very similar from 20K down. It will be interesting to see if any of it is audible.
Valery has designed an IPS with tubes to drive the Slewmonster. I'm just waiting for him to finish up the gerbers and I will be ordering boards for that. It will be my first venture into building anything with tubes in it. 😱 Can't wait!
I'm hoping Jason will be wrapping up his Gerbers for the Symasui and maybe I can place a single order to save on shipping time and costs.
Blessings, Terry
Terry,
You have any idea what the power supply requirements are going to be to light up those vacuum tubes? Probably not going to run on the same power supply but I guess we'll have to wait and see.
You have any idea what the power supply requirements are going to be to light up those vacuum tubes? Probably not going to run on the same power supply but I guess we'll have to wait and see.
Terry,
I will be curious if you can hear any differences between the four versions of the CFA, perhaps they will only be measurable differences? At the same time we just had Thimios's comment that he had the CFA at the bottom of his list of best sounding input sections, very curious how he is making the comparison and having such different results from yours.
I will be curious if you can hear any differences between the four versions of the CFA, perhaps they will only be measurable differences? At the same time we just had Thimios's comment that he had the CFA at the bottom of his list of best sounding input sections, very curious how he is making the comparison and having such different results from yours.
If my playing around with the CFA XH BV2 mod is anything to go by setting the input pots correctly is quite important to achieving the best performance and more importantly with the output stage biasing too. The wolverine seemed way more forgiving in this respect.
Hi Kind,
I'm struggling with the latest OS mod IPS today. It works alone with only 470R resistors tied to the NFB but when I try to hook it up to the OPS the LEDs flicker and the the test light burns brightly. Something is amiss. Once I get it figured out I will run some scope and listening comparisons.
I'm struggling with the latest OS mod IPS today. It works alone with only 470R resistors tied to the NFB but when I try to hook it up to the OPS the LEDs flicker and the the test light burns brightly. Something is amiss. Once I get it figured out I will run some scope and listening comparisons.
I had some flickering of the VAS LEDs in the BV mod 2 when first turned on, but that went away after the first minute or so. It didn't do this with the MJE340/350 pre drivers only with the faster 3503/x versions. I guess you could try swapping the pre drivers and see if that helps.
Another thing to offer is that some of the changes might alter the bias operating point, have you tried measuring the voltage across RE with the bulb tester on and tried changing the bias?
Another thing to offer is that some of the changes might alter the bias operating point, have you tried measuring the voltage across RE with the bulb tester on and tried changing the bias?
Hi 5th,
Yes I tried adjusting the bias on both the IPS and the OPS. I dialed the OPS bias all the way down and that got rid of the flickering LEDs. However, I think something is oscillating. With my DMM probes across the PD+ ND- things will settle down. When I remove them the offset starts jumping around and the voltage across the output emitter resistors starts jumping. I ran a spice sim and wrote down expected voltages and then checked them against the board and everything lines up pretty nicely. Once attached to the OPS everything gets out of whack. All the other IPS boards play nice with this OPS so it is the board. OS changed quite a few values on this last mod so I think I will just set it aside until he gets back and he can help me work through it. Funny thing is, I hooked up the scope to it as just an IPS and everything looks really nice.
Blessings, Terry
Yes I tried adjusting the bias on both the IPS and the OPS. I dialed the OPS bias all the way down and that got rid of the flickering LEDs. However, I think something is oscillating. With my DMM probes across the PD+ ND- things will settle down. When I remove them the offset starts jumping around and the voltage across the output emitter resistors starts jumping. I ran a spice sim and wrote down expected voltages and then checked them against the board and everything lines up pretty nicely. Once attached to the OPS everything gets out of whack. All the other IPS boards play nice with this OPS so it is the board. OS changed quite a few values on this last mod so I think I will just set it aside until he gets back and he can help me work through it. Funny thing is, I hooked up the scope to it as just an IPS and everything looks really nice.
Blessings, Terry
Hi Kind,
No, I can't hear any difference and to be honest, the original provides the cleanest square waves. Mod 1 has a slight overshoot and Mod #2 has the worst looking Squares of the three. As I said in the earlier post, I can't get the Latest OS mod to play nice so I can't speak to that one. I have had the original stock one playing for the last hour. Beautiful, Really beautiful.
Blessings, Terry
I have this CFA MODIF.3 at the bottom of my list because i have listen all INP playing the same music track again and again. .In this track there is a bell playing
It is crystal audible with some INP and not with others.This modif.CFA isn't clear (crystal) playing this bell.
Simple CFA-X is one of crystal playing.
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Terry,
I would love to be able to get a pair of the tube front end boards that valery worked up. Let me know how to help make this happen.
Evan
I would love to be able to get a pair of the tube front end boards that valery worked up. Let me know how to help make this happen.
Evan