hehe ok, fair enough. i'll just discreetly tiptoe out of this arena now...
p.s. sorry, one last thing, can't resist... someone here HAS indeed measured the differences between the transfer functions of different types of capacitors (paper/oil, polyester, polypropylene, etc.)... it is clearly visible on a scope. lemme see if i can find that thread...
p.s. sorry, one last thing, can't resist... someone here HAS indeed measured the differences between the transfer functions of different types of capacitors (paper/oil, polyester, polypropylene, etc.)... it is clearly visible on a scope. lemme see if i can find that thread...
yes!
http://members.aol.com/sbench102/caps.html
very interesting test results. though it's hard to see in the photos, there are subtle differences in the transfer functions of the different film capacitors types. and of course the non-film types look completely different altogether.
http://members.aol.com/sbench102/caps.html
very interesting test results. though it's hard to see in the photos, there are subtle differences in the transfer functions of the different film capacitors types. and of course the non-film types look completely different altogether.
Gents; No one is forcing anyone to take part in this little project. If you are not prepaired to look at the results and consider them openly, thats up to you. Negitive posts only clog up the thread. If you think this is pointless then please allow use to play our pointless game. We understand you view now and it doesn't need to be repeated over and over, once is enough.
Next subject:
Sy, Dorkus, I like the random switch box idea. Sy, are you willing to build the box? That would be great, and if you can get Nelson Pass to play with us SUPER.
Mrfeedback had some good suggestions for testing and that got me thinking. I don't have the best or newest test equipment at home and the stuff at work is mostly for RF. How do we want to handle the testing? I will do what I can but others may have gear that will give us more information as well. I have no problem with multiple testers. I know that the results will vary from tester to tester. We are trying to find out how to measure those things that we don't understand after all. I think major errors should be detectable. After all what we are looking for is differences not better or worse at this point, we'll figure that out later after we understand how to do the tests.
We should get together a list of listeners and testers. You can do both if you like. We will also need someone to act as test admin. Sy, could I talk you into this too? You seem to have the required skill set.
Anyone who wants to can e-mail me via the forum if you like.
Later
Bruce
Next subject:
Sy, Dorkus, I like the random switch box idea. Sy, are you willing to build the box? That would be great, and if you can get Nelson Pass to play with us SUPER.
Mrfeedback had some good suggestions for testing and that got me thinking. I don't have the best or newest test equipment at home and the stuff at work is mostly for RF. How do we want to handle the testing? I will do what I can but others may have gear that will give us more information as well. I have no problem with multiple testers. I know that the results will vary from tester to tester. We are trying to find out how to measure those things that we don't understand after all. I think major errors should be detectable. After all what we are looking for is differences not better or worse at this point, we'll figure that out later after we understand how to do the tests.
We should get together a list of listeners and testers. You can do both if you like. We will also need someone to act as test admin. Sy, could I talk you into this too? You seem to have the required skill set.
Anyone who wants to can e-mail me via the forum if you like.
Later
Bruce
The signal level was held constant at about 70 volts RMS at 600 Hz across the capacitors. (for about 26mA signal current). This is probably more than you would normally expect, and serves to show the results better.
Yeah. It's about 4-5 times what you would expect. So is a peak of 98 volts.
Yeah. It's about 4-5 times what you would expect. So is a peak of 98 volts.
what's the circuit gonna be for the box?
something that us subjectivists agree is very sensitive to parts quality. actually, i hear SE triodes are very sensitive, but joel seems to think otherwise. i don't like tubes anyway.
maybe Mr. Pass could suggest a circuit... if not, a simple Borbely JFET buffer may be good, as i already have a power supply built for it. it uses a handful of resistors and two capacitors (one .22uF film feedback, and an output coupling cap). could be a good test, although matching JFETs is a pain in the butt.
something that us subjectivists agree is very sensitive to parts quality. actually, i hear SE triodes are very sensitive, but joel seems to think otherwise. i don't like tubes anyway.
maybe Mr. Pass could suggest a circuit... if not, a simple Borbely JFET buffer may be good, as i already have a power supply built for it. it uses a handful of resistors and two capacitors (one .22uF film feedback, and an output coupling cap). could be a good test, although matching JFETs is a pain in the butt.
You can't really do this easily with an active circuit that generates a lot of heat, since it's got to be potted up thoroughly. I would suggest again something simple like a passive filter (or a cascade of two passives), made with crummy wire and Radio Shack parts (maybe even a dread electrolytic!) versus fabulous audiophile wire, amazing magic capacitors, and incredibly transparent resistors. I mean, in a high resolution system, a cheap electrolytic and copperweld steel wire in the signal path ought to be audible to even a tin ear like me, eh?
I'm perfectly willing to contribute construction labor, executing the protocols, and the crummy parts for the A filter. And the cabinet and potting materials. Someone else will have to donate the approved magic wire, caps, and resistors for the B filter. And I'd sure like it if Mr. Pass would spend a few minutes verifying the circuit before I pot it up and send it to the victi... uhhhh.... test subject.
I'm perfectly willing to contribute construction labor, executing the protocols, and the crummy parts for the A filter. And the cabinet and potting materials. Someone else will have to donate the approved magic wire, caps, and resistors for the B filter. And I'd sure like it if Mr. Pass would spend a few minutes verifying the circuit before I pot it up and send it to the victi... uhhhh.... test subject.
does it have to be potted? i'm not sure how good the dielectric quality of potting material is. if you're afraid of cheating, just put some paint over the screws like they do on mass-fi components for warranty purposes... it'll be pretty obvious if i try to cheat, which i won't.
the borbely circuit is super simple (2 JFETs) and doesn't generate any heat really. believe it or not, the one i have right now is made out of mostly Radio Shack resistors... didn't want to bother with expensive parts while i was just prototyping, so it's got a mish mash of cheap metal and carbon films that i had lying around. carbon resistors actually don't always sound so bad anyway... but i won't get into that now. the capacitors are decent quality tho (Solen polyprop, Black Gate coupling).
how about i send you a "tweak" circuit with good parts, and you can do your version w/cheapo parts? i'll supply the JFETs as well.
the borbely circuit is super simple (2 JFETs) and doesn't generate any heat really. believe it or not, the one i have right now is made out of mostly Radio Shack resistors... didn't want to bother with expensive parts while i was just prototyping, so it's got a mish mash of cheap metal and carbon films that i had lying around. carbon resistors actually don't always sound so bad anyway... but i won't get into that now. the capacitors are decent quality tho (Solen polyprop, Black Gate coupling).
how about i send you a "tweak" circuit with good parts, and you can do your version w/cheapo parts? i'll supply the JFETs as well.
It could be that we will need multiple test boxes. Not just so more that one listerner can have access to a box at one time, but so that different applications of a part can be tested. Passive, active SS and active tube are all possible. What parts do we use as victums? What ever we use needs to be low cost, not cheep or shabby but low cost.
Lets take a vote here:
You may indicate more than on choice for a question
1. a) passive
b) active
c) both
2. I'd like to focus on caps to start with;
a) electrolitic
b) plastic film {pick you fav}
c) tantulim
d) ceramic
e) some OH MY GOD high priced part to be named later
3. For active test circuit;
a) discreet SS
b) IC opamp
c) tube {if you pick this one you get ot build it}
Please e-mail me your votes
Later
Bruce
Lets take a vote here:
You may indicate more than on choice for a question
1. a) passive
b) active
c) both
2. I'd like to focus on caps to start with;
a) electrolitic
b) plastic film {pick you fav}
c) tantulim
d) ceramic
e) some OH MY GOD high priced part to be named later
3. For active test circuit;
a) discreet SS
b) IC opamp
c) tube {if you pick this one you get ot build it}
Please e-mail me your votes
Later
Bruce
Sy, Dorkus, exactly what do you suggest for a test circuit? I'm looking for part values here too. I was wondering, do we want buffers on the input and output to address impedance issues? What impedance should we use?
I know what I would do but I'm looking for you ideas or anyone elses for that matter.
Later
Bruce
I know what I would do but I'm looking for you ideas or anyone elses for that matter.
Later
Bruce
Ya, I know, but if we want to ship this thing around for a larger sample base, impedance could be a problem. Maybe the buffer could be part of the test. In sometimes and out on other switch settings, or would that mess up the result?
It's OK to tell me when I'm out to lunch, just be kind, alright.
Later
Bruce
It's OK to tell me when I'm out to lunch, just be kind, alright.
Later
Bruce
You're out to lunch! ;-)
No, seriously, I wouldn't worry about a large base yet. We don't want to dilute the results by mixing good ears with bad. Let's stick with Dorkus or some other person who asserts that he can hear the difference as long as he's using his own system in his own environment with his own control of the switching.
My only caveat would be that the strength of the controls should be in proportion to the financial incentives of the person to whom we hand the switchbox. If it's someone in the business of selling rhodium-plated praesodymium foil capacitors for use in SET amps, I want it potted with all sorts of tampering tell-tales. If it's someone who's just passionate about sound and who wants to honestly test his own preconceptions, a somewhat simpler system of seals should suffice.
No, seriously, I wouldn't worry about a large base yet. We don't want to dilute the results by mixing good ears with bad. Let's stick with Dorkus or some other person who asserts that he can hear the difference as long as he's using his own system in his own environment with his own control of the switching.
My only caveat would be that the strength of the controls should be in proportion to the financial incentives of the person to whom we hand the switchbox. If it's someone in the business of selling rhodium-plated praesodymium foil capacitors for use in SET amps, I want it potted with all sorts of tampering tell-tales. If it's someone who's just passionate about sound and who wants to honestly test his own preconceptions, a somewhat simpler system of seals should suffice.
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