Me too
I will give this a try to see what happens. If it does not work I will post to confirm that you were indeed correct. If it does work I think that I can tell by now if it is in my head or in my ears. Either way I'll let you know. But if it does work you guys with edumakashun will have to carry the torch forward to figure out why. That's why you guys were given the responsibility of figureing things out ya got the extra noodles. Best regards Moray James.
I will give this a try to see what happens. If it does not work I will post to confirm that you were indeed correct. If it does work I think that I can tell by now if it is in my head or in my ears. Either way I'll let you know. But if it does work you guys with edumakashun will have to carry the torch forward to figure out why. That's why you guys were given the responsibility of figureing things out ya got the extra noodles. Best regards Moray James.
I also lowered the value of the HV series resistor in my Acoustat 11 panals to 25Mohm.
The improvement is remarkable: much better mids and highs.
Why is this ?
The high voltage must be a little higher but it doesn't explain to me the much more detailed sound.
An other explanation could be that each powersupply should have a LOW series resistance, like we all experience in our amplifiers.
So the next question is, how low can we go ?
If we add a big cap from output to ground of the powersupply and there is no or low series resistor,
besides very dangerous, it can burn a hole in the foil if it touches one of the stators.
Anyway, what do you guys think of this ?
The improvement is remarkable: much better mids and highs.
Why is this ?
The high voltage must be a little higher but it doesn't explain to me the much more detailed sound.
An other explanation could be that each powersupply should have a LOW series resistance, like we all experience in our amplifiers.
So the next question is, how low can we go ?
If we add a big cap from output to ground of the powersupply and there is no or low series resistor,
besides very dangerous, it can burn a hole in the foil if it touches one of the stators.
Anyway, what do you guys think of this ?
I try the choke mods
I use an hammond 157G (30H)
As I_forgot said, the choke is useless because is there no current thru it.
And the sound is inchanged. I perceived NO change, nothing.
I`ll try to bypass the load resistor to hear how the sound become... (not 100% bypass but use 1Kohm for security if is there an arc)
Regards
I use an hammond 157G (30H)
As I_forgot said, the choke is useless because is there no current thru it.
And the sound is inchanged. I perceived NO change, nothing.
I`ll try to bypass the load resistor to hear how the sound become... (not 100% bypass but use 1Kohm for security if is there an arc)
Regards
Don't drop the series resistor below about 20 Mega Ohms.
The resistor is there for two purposes.
1) It ensures constant charge operation of the speaker (along with the high resistance of the diaphragm coating) by limiting the current that can charge/discharge the diaphragm as it moves. This ensures low distortion, especially at low frequencies.
2) It is a safety device that reduces energy available from the bias supply, such as when the speaker arcs. This preserves the speaker's diaphragm by reducing the likelyhood of holes being burned into it.
This is definitely NOT a situation where you want low power supply impedance. That would be dangerous at these voltage levels and completely unnecessary. Low impedance is what you want if you are trying to supply current. The bias supply in an electrostatic speaker is not there to supply current. It is there to supply charge to the diaphragm, and should supply it only as fast as it leaks off the diaphragm into the air and through leakage resistance to ground.
I_F
The resistor is there for two purposes.
1) It ensures constant charge operation of the speaker (along with the high resistance of the diaphragm coating) by limiting the current that can charge/discharge the diaphragm as it moves. This ensures low distortion, especially at low frequencies.
2) It is a safety device that reduces energy available from the bias supply, such as when the speaker arcs. This preserves the speaker's diaphragm by reducing the likelyhood of holes being burned into it.
This is definitely NOT a situation where you want low power supply impedance. That would be dangerous at these voltage levels and completely unnecessary. Low impedance is what you want if you are trying to supply current. The bias supply in an electrostatic speaker is not there to supply current. It is there to supply charge to the diaphragm, and should supply it only as fast as it leaks off the diaphragm into the air and through leakage resistance to ground.
I_F
Choke choking?
Well it looks like the choke idea is chokeng up. I still plan to give this idea a try will be next week or weekend before I can. Then I too will know one way or the other.
I_Forgot said that this supply is quiet. Ok it's quiet but why does the speaker sound better when the supply is turned off? I have also thought that the speakers sound better whenever I bypass the load resistor and run the panels off of the supply (useing old Acoustat panels). the only reason I can see for this is that when the load resistor is bypassed the supply can get more charge onto the diaphragm more quickly. That would help to keep the charge more consistant on the diaphragm. Seems that there is an issue of charge migration here. The surfacr resistivity of the Acoustat panels is not all that high with later models being a bit higher. What is that time constant formula? I_ Forgot what is the resistance value required for a fulrange panel that will keep charge from migrateing assumeing say a 30 Hz bottom end? Quad used 30 Meg ohms with thier nylon coating. Thanks Moray James.
Well it looks like the choke idea is chokeng up. I still plan to give this idea a try will be next week or weekend before I can. Then I too will know one way or the other.
I_Forgot said that this supply is quiet. Ok it's quiet but why does the speaker sound better when the supply is turned off? I have also thought that the speakers sound better whenever I bypass the load resistor and run the panels off of the supply (useing old Acoustat panels). the only reason I can see for this is that when the load resistor is bypassed the supply can get more charge onto the diaphragm more quickly. That would help to keep the charge more consistant on the diaphragm. Seems that there is an issue of charge migration here. The surfacr resistivity of the Acoustat panels is not all that high with later models being a bit higher. What is that time constant formula? I_ Forgot what is the resistance value required for a fulrange panel that will keep charge from migrateing assumeing say a 30 Hz bottom end? Quad used 30 Meg ohms with thier nylon coating. Thanks Moray James.
Choke Mod
I got over to my buddies place on Sunday to try the choke mod. I inserted a 7 Henry choke in series with the output of the high voltage supply to the speaker. The difference was immediate. The bass/mid now has real slam and impact like a fine dynamic driver. Every thing is cleaner. The speaker has lost some euphonic qualities as there is less smeer to the sound. I am at a loss as to explain why Martin heard nothing (useing 30 H chokes) as the difference is substantial. I will try putting two 7 Henry chokes in series to see if there is additional improvement (will run both panels off of one supply). Best regards Moray James.
I got over to my buddies place on Sunday to try the choke mod. I inserted a 7 Henry choke in series with the output of the high voltage supply to the speaker. The difference was immediate. The bass/mid now has real slam and impact like a fine dynamic driver. Every thing is cleaner. The speaker has lost some euphonic qualities as there is less smeer to the sound. I am at a loss as to explain why Martin heard nothing (useing 30 H chokes) as the difference is substantial. I will try putting two 7 Henry chokes in series to see if there is additional improvement (will run both panels off of one supply). Best regards Moray James.
I'm not sure about the "no current flow, therefore the choke can make no difference" theory. This would be true with pure DC, but all supplies have some noise and with the capacitive load there would be current flow.
Hey Moray, how's life on the Bow these days? Hope your dwelling came through the flooding ok.
Hey Moray, how's life on the Bow these days? Hope your dwelling came through the flooding ok.
May I make a suggestion?
Fiddling with things that are of questionable value is a nice hobby if you have the time and energy for it, but in the end, you'll have at best, a slightly tweeked speaker for all your time and effort. ESLs are about as good as speakers can get, except for a few very obvious areas that I will come to in a moment.
Peter Walker didn't sit and play with bias supply tweeks for endless years. He made the bias supply good enough and moved on to other problems. THAT is how REAL progress is made. Sure there are folks who would argue that the goal of a hobbyist is to make it better than commercial equipment, but there is a much better way to approach that, if that's your goal.
What makes a major or useful change to anything? Is it tweeking minor stuff that is of questionable existence, or is it attacking the big problems? If you want to make a real contribution to ESL "knowledge" or performance, you're not going to get anywhere messing with things like bias supplies. Work on the big problems instead. ESL don't play very loudly. Figure out a way to make them do so. ESLs have lousy low bass response. Fix it. ESLs are expensive to make because of the audio transformers. Figure out a way to eliminate the transformers or lower their cost. Figure out an easier way to make the speakers. Some have tried to address some of these problems. Dig up their stuff and learn from it, then try something they didn't.
Just a suggestion...
TD
Fiddling with things that are of questionable value is a nice hobby if you have the time and energy for it, but in the end, you'll have at best, a slightly tweeked speaker for all your time and effort. ESLs are about as good as speakers can get, except for a few very obvious areas that I will come to in a moment.
Peter Walker didn't sit and play with bias supply tweeks for endless years. He made the bias supply good enough and moved on to other problems. THAT is how REAL progress is made. Sure there are folks who would argue that the goal of a hobbyist is to make it better than commercial equipment, but there is a much better way to approach that, if that's your goal.
What makes a major or useful change to anything? Is it tweeking minor stuff that is of questionable existence, or is it attacking the big problems? If you want to make a real contribution to ESL "knowledge" or performance, you're not going to get anywhere messing with things like bias supplies. Work on the big problems instead. ESL don't play very loudly. Figure out a way to make them do so. ESLs have lousy low bass response. Fix it. ESLs are expensive to make because of the audio transformers. Figure out a way to eliminate the transformers or lower their cost. Figure out an easier way to make the speakers. Some have tried to address some of these problems. Dig up their stuff and learn from it, then try something they didn't.
Just a suggestion...
TD
don't knock it till you try it!
Hey I_Forgot: easy to say that the supply mods are no big deal if you have not tried them out. The choke mod makes sence and it works. I am told that the quality of choke used will have a substantial impact on the results. This makes sence also as wider bandwith will damp diaphragm modulation over a wider range. The mod gives the speakers a real boost in terms of dynamic impact and punch. This is something that others have for years tried to do with EQ. The real solution to the problem is to use no insulation on the stators. Mike Wright had this in mind with his gass filled panels.
I hear what you are saying and I appreciate it. I would love to have the kind of technical background that you have. I think though that you are getting needlessly bent out of shape about the supply experiments. The time frame has not been years, months perhaps but that is due more to my own lack of organization and other factors. This mod is a pretty big improvement in the performance of the system. So much so that it makes me want to build non insulated stators to eliminate the issue all together. Please give it a try and tell us what you hear. Sometimes chewing away at the things that you can is the slow way toward improvement. I think that this has been a valid step forward. Best regards Moray James.
Hey I_Forgot: easy to say that the supply mods are no big deal if you have not tried them out. The choke mod makes sence and it works. I am told that the quality of choke used will have a substantial impact on the results. This makes sence also as wider bandwith will damp diaphragm modulation over a wider range. The mod gives the speakers a real boost in terms of dynamic impact and punch. This is something that others have for years tried to do with EQ. The real solution to the problem is to use no insulation on the stators. Mike Wright had this in mind with his gass filled panels.
I hear what you are saying and I appreciate it. I would love to have the kind of technical background that you have. I think though that you are getting needlessly bent out of shape about the supply experiments. The time frame has not been years, months perhaps but that is due more to my own lack of organization and other factors. This mod is a pretty big improvement in the performance of the system. So much so that it makes me want to build non insulated stators to eliminate the issue all together. Please give it a try and tell us what you hear. Sometimes chewing away at the things that you can is the slow way toward improvement. I think that this has been a valid step forward. Best regards Moray James.
Moray,
In these very forums there are people who claim they can hear a difference in a circuit's performance when they reverse the direction of a single resistor. Let's carry that sort of thinking through to its logical conclusion.
If the direction of each resistor were audible, and you have an amplifier with 10 reistors in the circuit, how many different combinations of resistors wired "forward" and "reverse" would you have to listen to to find the "best" combination? There are 10 resistors that can each be put in either of two ways in the circuit, so there are 2^10 unique arrangements (that's 1024). Now lets throw in the claims by many of the same people that a Vishay resistor sounds better here, a Caddock sounds better there, a carbon comp resistor sounds better over there, a wirewound resistor sounds best over there, etc. ad nauseum. Now we have 10 resistors in an amplifier, each of which has to be swapped among say 4 types or brands of resistors, and each of which has to also be wired "forward" and "reversed". The number of combinations to test swells to (4*2)^10=1.074x10^9. THAT's a LOT of resistor arrangements to test, and we haven't even thrown the capacitors into the equation yet!
Now let's say that someone actually goes to the trouble of listening to ALL those combinations of resistors in that amplifier and then someone presents a different amplifier circuit to them and says "what should I do with these resistors to make it sound best?". The only possible answer is that every combination of resistor must be tried and listened to.
Of course, this all assumes that the person listening can actually tell a difference between some combinations of all the resistors and ignores any psychological factors affecting their decision making process (a major leap of faith in human capability). We also ignore age related changes in the perceptive abilities of the person doing the listening and in the components themselves during the many, many years that the testing would require.
We therefore conclude that there is no meaningful predictability. How can there be when no one's life is long enough to thoroughly test even a single amplifier?
Now, if you put one guy to work swapping resistors and another to work designing a better amplifier, which path leads to real progress and useful knowledge?
The guy who wants to make real progress makes decisions about when "enough is enough" and moves on.
I made the suggestion about focusing on bigger issues because the path you're pursuing appears (to me, at least) to be as dead an end as swapping the resistors in an amplifier. With so many real deficiencies in ESLs, why pursue the imagined or insignificant ones?
You don't need to be an engineer or physicist to make a real contribution. Real contributions can be made in construction techniques/materials selection/asthetic design and etc., without any engineering knowledge (though it can help here, also).
On the other hand, if you WANT to make a contribution to the engineering end and don't have the necessary education, go get it. ESLs have been around a while and will still be around after you've taken some classes.
Just because you want to hear things that others can't doesn't mean that you can, and just because you think you hear a difference between two resistors doesn't mean there is one. I suggest you have a look at the web linked document in my signature file, below.
TD
In these very forums there are people who claim they can hear a difference in a circuit's performance when they reverse the direction of a single resistor. Let's carry that sort of thinking through to its logical conclusion.
If the direction of each resistor were audible, and you have an amplifier with 10 reistors in the circuit, how many different combinations of resistors wired "forward" and "reverse" would you have to listen to to find the "best" combination? There are 10 resistors that can each be put in either of two ways in the circuit, so there are 2^10 unique arrangements (that's 1024). Now lets throw in the claims by many of the same people that a Vishay resistor sounds better here, a Caddock sounds better there, a carbon comp resistor sounds better over there, a wirewound resistor sounds best over there, etc. ad nauseum. Now we have 10 resistors in an amplifier, each of which has to be swapped among say 4 types or brands of resistors, and each of which has to also be wired "forward" and "reversed". The number of combinations to test swells to (4*2)^10=1.074x10^9. THAT's a LOT of resistor arrangements to test, and we haven't even thrown the capacitors into the equation yet!
Now let's say that someone actually goes to the trouble of listening to ALL those combinations of resistors in that amplifier and then someone presents a different amplifier circuit to them and says "what should I do with these resistors to make it sound best?". The only possible answer is that every combination of resistor must be tried and listened to.
Of course, this all assumes that the person listening can actually tell a difference between some combinations of all the resistors and ignores any psychological factors affecting their decision making process (a major leap of faith in human capability). We also ignore age related changes in the perceptive abilities of the person doing the listening and in the components themselves during the many, many years that the testing would require.
We therefore conclude that there is no meaningful predictability. How can there be when no one's life is long enough to thoroughly test even a single amplifier?
Now, if you put one guy to work swapping resistors and another to work designing a better amplifier, which path leads to real progress and useful knowledge?
The guy who wants to make real progress makes decisions about when "enough is enough" and moves on.
I made the suggestion about focusing on bigger issues because the path you're pursuing appears (to me, at least) to be as dead an end as swapping the resistors in an amplifier. With so many real deficiencies in ESLs, why pursue the imagined or insignificant ones?
You don't need to be an engineer or physicist to make a real contribution. Real contributions can be made in construction techniques/materials selection/asthetic design and etc., without any engineering knowledge (though it can help here, also).
On the other hand, if you WANT to make a contribution to the engineering end and don't have the necessary education, go get it. ESLs have been around a while and will still be around after you've taken some classes.
Just because you want to hear things that others can't doesn't mean that you can, and just because you think you hear a difference between two resistors doesn't mean there is one. I suggest you have a look at the web linked document in my signature file, below.
TD
Moray made a 5-minute tweak that significantly improved reproduction. How can you argue with that? Yes, at some point he or anybody will hit diminishing returns. But the big issues you refer to need a significant amount more investment in time, money, tools etc.
I agree with the "chip away at what you can" approach.
I agree with the "chip away at what you can" approach.
Adding a choke that has little or no current (pico amps) being pulled through it would be the same as having a length of wire the same as the choke winding (to the corner shop and back) inserted in the same place.
This also goes against the other mod of droping the series resitance because of the extra series resistance the choke has.
So the whole idea is spitting in the face of Ohms Law.
I'm totaly backing the coments made by I_Forgot.
It's all voodoo.
The only mod here that makes any sense is the cap bypass on the power supply
Cheers George
This also goes against the other mod of droping the series resitance because of the extra series resistance the choke has.
So the whole idea is spitting in the face of Ohms Law.
I'm totaly backing the coments made by I_Forgot.
It's all voodoo.
The only mod here that makes any sense is the cap bypass on the power supply
Cheers George
About the morray mods.
I`ll try it again to see because I didn`t try it correctly the first time
I use the choke in serial with the load resistor. I didn`t put extra caps.
So:CRL-->esl
I`ll try to separate my last caps to form 2.
So: CRCL-->esl
I don`t know if my result will change but a 5 minutes mods won`t kill me
And about think that we can`t explain in audio, is there a lot.
-Why a blue led under a CDP improve the sound?
-why a CD demagnetizer improve really the playback even if a CD is made from non magnetic material (epoxy,aluminium,plastic acrylic)
...
regards
I`ll try it again to see because I didn`t try it correctly the first time
I use the choke in serial with the load resistor. I didn`t put extra caps.
So:CRL-->esl
I`ll try to separate my last caps to form 2.
So: CRCL-->esl
I don`t know if my result will change but a 5 minutes mods won`t kill me
And about think that we can`t explain in audio, is there a lot.
-Why a blue led under a CDP improve the sound?
-why a CD demagnetizer improve really the playback even if a CD is made from non magnetic material (epoxy,aluminium,plastic acrylic)
...
regards
Cheap parts work
I replaced the 500 MegOhm resistor with a 20 MOhm one and added a .022uF 6000 volt capacitor to the high voltage circuit in each interface. The change in sound is really nice in terms of clarity, dynamics, and perceived low and high frequency extension. The improvement is immediately obvious to my friends who are not into audio at all. They commented on the better sound even though I did not tell them that I had modified the interfaces. They all like it very much.
Like paulb said: "Moray made a 5-minute tweak that significantly improved reproduction. How can you argue with that?"
Please keep at it, Moray. Thanks.
Noel
I replaced the 500 MegOhm resistor with a 20 MOhm one and added a .022uF 6000 volt capacitor to the high voltage circuit in each interface. The change in sound is really nice in terms of clarity, dynamics, and perceived low and high frequency extension. The improvement is immediately obvious to my friends who are not into audio at all. They commented on the better sound even though I did not tell them that I had modified the interfaces. They all like it very much.
Like paulb said: "Moray made a 5-minute tweak that significantly improved reproduction. How can you argue with that?"
Please keep at it, Moray. Thanks.
Noel
Choke mod
Hi, my first post here. I was the one responsible for telling Moray James about the choke mod developed by some friends and I for Acoustats. I am gratified that he has been open minded enough to try it and has experienced similar improvements to me.
That said I am disconcerted at the mean spirited not to mention logically tortured arguments raised by people who have not tried it but who feel they have the explanation as to why it can't work...
I am not sure who takes the cake... the fellow who reckons it can't work because of the 'low currents' involved or the one who reckons it is of marginal if any value because Peter Walker didn't do it 30 years ago... oh and it is equated with hearing Resistor directionality in the same breath.
George, how is it that you think that the capacitor bypass mod has some merit on the one hand but that the currents are so low
that the choke cannot work on the other? If there is no current flow there can be no noise induced by the power supply to the diaphram So it follows that the capacitor mod is doing nothing... If we were dealing with perfect components i.e. a 500 meg resistor that is purely resistive then nothing we do on the supply side will make a difference. 500 meg is huge isolation.
Hi, my first post here. I was the one responsible for telling Moray James about the choke mod developed by some friends and I for Acoustats. I am gratified that he has been open minded enough to try it and has experienced similar improvements to me.
That said I am disconcerted at the mean spirited not to mention logically tortured arguments raised by people who have not tried it but who feel they have the explanation as to why it can't work...
I am not sure who takes the cake... the fellow who reckons it can't work because of the 'low currents' involved or the one who reckons it is of marginal if any value because Peter Walker didn't do it 30 years ago... oh and it is equated with hearing Resistor directionality in the same breath.
George, how is it that you think that the capacitor bypass mod has some merit on the one hand but that the currents are so low
that the choke cannot work on the other? If there is no current flow there can be no noise induced by the power supply to the diaphram So it follows that the capacitor mod is doing nothing... If we were dealing with perfect components i.e. a 500 meg resistor that is purely resistive then nothing we do on the supply side will make a difference. 500 meg is huge isolation.
Re: Choke mod
1 The cap change increases the the charge voltage, hence changes the efficiency, and can only make the pannels more easily start to leak, because a HT cancer track can form quicker with higher voltage
2 Change the 500meg for a lower value and you introduce a constant charge principal, good for leaky pannels or humid conditions, if you hear a difference, your pannels can not be getting to full charge because they are either leaking or you live in Singapore where the humidity sucks the charge off the pannels.
I've owned 1+1`s, 2+2`s, 2`s and my friend has 6's, and unless you own a electrostatic voltmeter you have no idea of the charge state of the pannels, as they all leak now that they are all old, the plastic honeycomb stator suports are getting chalky and absorb moisture and leak from the mounting bolts though the chalky plastic to the conductive coating HT tab. I,ve ground out the cancerouse tracks that forms on many pannels of my own and friends , it's a never ending constant thing to do now that they are old, and it can only get worse they older they are getting.
3 As far as the choke, it's simply Ohms Law, you do'nt argue with it .
Cheers George
Robert F said:
1 The cap change increases the the charge voltage, hence changes the efficiency, and can only make the pannels more easily start to leak, because a HT cancer track can form quicker with higher voltage
2 Change the 500meg for a lower value and you introduce a constant charge principal, good for leaky pannels or humid conditions, if you hear a difference, your pannels can not be getting to full charge because they are either leaking or you live in Singapore where the humidity sucks the charge off the pannels.
I've owned 1+1`s, 2+2`s, 2`s and my friend has 6's, and unless you own a electrostatic voltmeter you have no idea of the charge state of the pannels, as they all leak now that they are all old, the plastic honeycomb stator suports are getting chalky and absorb moisture and leak from the mounting bolts though the chalky plastic to the conductive coating HT tab. I,ve ground out the cancerouse tracks that forms on many pannels of my own and friends , it's a never ending constant thing to do now that they are old, and it can only get worse they older they are getting.
3 As far as the choke, it's simply Ohms Law, you do'nt argue with it .
Cheers George
Choke mod
Hi, my first post here. I was the one responsible for telling Moray James about the choke mod developed by some friends and I for Acoustats. I am gratified that he has been open minded enough to try it and has experienced similar improvements to us.
That said I am disconcerted at the mean spirited not to mention logically tortured arguments raised by people who have not tried it but who feel they have the explanation as to why it can't work...
I am not sure who takes the cake... the fellow who reckons it can't work because of the 'low currents' involved or the one who reckons it is of marginal if any value because Peter Walker didn't do it 30 years ago... oh and equates the mod with hearing resistor directionality in the same breath.
George, how is it that you think that the capacitor bypass mod has some merit on the one hand but that the currents are so low
that the choke cannot work on the other? If there is no current flow there can be no noise induced by the power supply to the diaphragm So it follows that the capacitor mod is doing nothing... If we were dealing with perfect components i.e. a 500 meg resistor that is purely resistive then nothing we do on the supply side will make a difference. 500 meg is huge isolation. The fact we do hear improvements by lowering supply noise is testament to the fact that the 500meg resistor is anything but perfect. If it were properly spice modelled it would have a decent sized capacitor in parallel to it which essentially bypasses the resistive component at high frequencies thereby providing a nice series feed for noise at high frequencies. So all is not as it seems at first glance.
I think the key to the choke is to look at the speaker in AC not DC terms. Of course there is little DC current flow, but the speaker diaphragm leaks with excursion, the more it approaches the stator the more it leaks, i.e. the leaking is music related. A hypothesis is either that the choke supplies sufficient current to smooth this (so not inconsistant with Moray's theory about the effect of lowering the resistance to 20meg) or that it reduces leakage back through the 500meg resistor to the supply. Either way subjectively the speaker has a much improved bass and lower midrange performance amongst other things to the extent that it evens out the subjective dip in the lower midrange on these speakers which used to remove the chest from male voices. Yes we still have volume and efficiency limitations, but dynamics are improved.
Anyway this post is overly long but hopefully provides some food for thought.
Rob.
Hi, my first post here. I was the one responsible for telling Moray James about the choke mod developed by some friends and I for Acoustats. I am gratified that he has been open minded enough to try it and has experienced similar improvements to us.
That said I am disconcerted at the mean spirited not to mention logically tortured arguments raised by people who have not tried it but who feel they have the explanation as to why it can't work...
I am not sure who takes the cake... the fellow who reckons it can't work because of the 'low currents' involved or the one who reckons it is of marginal if any value because Peter Walker didn't do it 30 years ago... oh and equates the mod with hearing resistor directionality in the same breath.
George, how is it that you think that the capacitor bypass mod has some merit on the one hand but that the currents are so low
that the choke cannot work on the other? If there is no current flow there can be no noise induced by the power supply to the diaphragm So it follows that the capacitor mod is doing nothing... If we were dealing with perfect components i.e. a 500 meg resistor that is purely resistive then nothing we do on the supply side will make a difference. 500 meg is huge isolation. The fact we do hear improvements by lowering supply noise is testament to the fact that the 500meg resistor is anything but perfect. If it were properly spice modelled it would have a decent sized capacitor in parallel to it which essentially bypasses the resistive component at high frequencies thereby providing a nice series feed for noise at high frequencies. So all is not as it seems at first glance.
I think the key to the choke is to look at the speaker in AC not DC terms. Of course there is little DC current flow, but the speaker diaphragm leaks with excursion, the more it approaches the stator the more it leaks, i.e. the leaking is music related. A hypothesis is either that the choke supplies sufficient current to smooth this (so not inconsistant with Moray's theory about the effect of lowering the resistance to 20meg) or that it reduces leakage back through the 500meg resistor to the supply. Either way subjectively the speaker has a much improved bass and lower midrange performance amongst other things to the extent that it evens out the subjective dip in the lower midrange on these speakers which used to remove the chest from male voices. Yes we still have volume and efficiency limitations, but dynamics are improved.
Anyway this post is overly long but hopefully provides some food for thought.
Rob.
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