Hello FETHead,
For a former I used an old ceramic sewer pipe with a couple of custom boards pieces on each side. Yes I actually HAND wound them which took me quite some time.
The enamel coated copper wire is the same stuff they used to build my transformer. The transformer shop here in Christchurch (NZ) is only a 2 min drive and they only charge by the weight (for ANY size guage wire). Including GST I think it's about $14/kg NZ$ (around $2.75 US / LB or $6 US/Kg). They will even let me borrow the whole roll - take as much off it and return it - then pay the difference.
BQ
For a former I used an old ceramic sewer pipe with a couple of custom boards pieces on each side. Yes I actually HAND wound them which took me quite some time.
The enamel coated copper wire is the same stuff they used to build my transformer. The transformer shop here in Christchurch (NZ) is only a 2 min drive and they only charge by the weight (for ANY size guage wire). Including GST I think it's about $14/kg NZ$ (around $2.75 US / LB or $6 US/Kg). They will even let me borrow the whole roll - take as much off it and return it - then pay the difference.
BQ
Inductors
Nelson Pass recommended the Erse 14 Ga Super Q coils
at Zalytron.com
They do have a metal core but
I think he said they didn't saturate when he was running over 6 amps DC through them. Since you need 2 for each channel (one per rail) that means 12amps I think.
Could someone confirm that they split the load?
That is a pretty good sized SOZ (about 15 watts/ch?)
A great advantage of them is the DCR of a 2 mh is .10
They also only cost 7.52 each.
Super BBQ:
How many feet did it take to make your monster 10 AWG coils?
I don't think my store will let me take the roll home
Thanks,
Mark
Nelson Pass recommended the Erse 14 Ga Super Q coils
at Zalytron.com
They do have a metal core but
I think he said they didn't saturate when he was running over 6 amps DC through them. Since you need 2 for each channel (one per rail) that means 12amps I think.
Could someone confirm that they split the load?
That is a pretty good sized SOZ (about 15 watts/ch?)
A great advantage of them is the DCR of a 2 mh is .10
They also only cost 7.52 each.
Super BBQ:
How many feet did it take to make your monster 10 AWG coils?
I don't think my store will let me take the roll home
Thanks,
Mark
Length of wire
Mark:
Using the following inductor calculator
http://www.colomar.com/cgi-bin/inductor_proc
I never bothered measuring. What I did was when I thought I had enough wire wrapped around, I would bring out my LCR meter and measure it's inductance. Then I would continue winding until I coil looked pretty (balanced) and until the right value was reached.
I'm pretty confident with the amount of heatsinks I used - I could do at least 40 watts x 2. But then with 25w x 2 right now - it's pretty loud on a pair of 90db 1w/1m efficient speakers.
BQ
Mark:
Using the following inductor calculator
http://www.colomar.com/cgi-bin/inductor_proc
I never bothered measuring. What I did was when I thought I had enough wire wrapped around, I would bring out my LCR meter and measure it's inductance. Then I would continue winding until I coil looked pretty (balanced) and until the right value was reached.
I'm pretty confident with the amount of heatsinks I used - I could do at least 40 watts x 2. But then with 25w x 2 right now - it's pretty loud on a pair of 90db 1w/1m efficient speakers.
BQ
Keep in mind that this thread was started with
common mode inductors, which only filter the
noise common to two lines. These can be quite
small but have high current ratings, but will not
filter non-common mode current, and most of what
you are going to want to filter is not common mode.
This type of coil is good for common mode RF suppression,
not audio range supply filtering.
common mode inductors, which only filter the
noise common to two lines. These can be quite
small but have high current ratings, but will not
filter non-common mode current, and most of what
you are going to want to filter is not common mode.
This type of coil is good for common mode RF suppression,
not audio range supply filtering.
Do huge coils make sense?
Super BQ:
I don't know much about electronics, but it appears to me that the huge coils you made don't really solve some of the problems
that the SOZ tends to create.
I went to the web site you mentioned and they state that
to get a 3.18 Mh inductor with AWG 10, and you wind a diameter coil the size they recommend (smaller), you get a DCR of .22 ohms
Your huge coils have a DCR of .60 I guess because of the tremendous length of wire you used
I guess they cool better because they have more surface area
proportionally, but you are wasting a LOT of power with that much resistance. And creating a lot more heat that needs to be
dissipated.
A kindly person on this site gave me these Ohm's Law formulas:
If they are wrong please tell me:
You have a 25w/ch SOZ with 2 coils.
Lets use one channel data, and use the specs for one coil.
(although the two coils supply 2 channels)
One channel:
From the Pass charts re 25 watt SOZ:
600watts/38volts supply= 16 amps
.6 ohms DCR *16= 9.6 volts
So you lose 9.6 volts across the inductor?
9.6 volts*16 amps= 154 watts needed to dissipate
I think this is reallly conservative, because you will need to crank up the voltage to compensate for the losses.
If you use the recommended coil diameter:
.22 ohms*16= 3.52 volts
This way you only lose 3.52 volts
3.52* 16= 56 watts needed to dissipate.
If you get 3 Erse 14 ga. mag core 9 MH inductors in parallel:
.243 ohm DCR/3= .08 ohms DCR
.08 ohms*16= 1.28 volts
This way you only lose 1.28 volts
1.28* 16= 20.5 watts needed to dissipate.(7 watts apiece)
3 of the Erse inductors are $36
If you run the SOZ under 20watts, you could probably get by
using 2 1.5 mh in series for a cost of $15 'cause the smaller
values are cheaper.
Also Mr. Pass says that 2MH is adaquate
Of coures the theme for SOZ is : More is better!!! Buahahahaah!
Someone please correct me if these thoughts are wrong, because I am about to order the inductors
Thanks, Mark
Super BQ:
I don't know much about electronics, but it appears to me that the huge coils you made don't really solve some of the problems
that the SOZ tends to create.
I went to the web site you mentioned and they state that
to get a 3.18 Mh inductor with AWG 10, and you wind a diameter coil the size they recommend (smaller), you get a DCR of .22 ohms
Your huge coils have a DCR of .60 I guess because of the tremendous length of wire you used
I guess they cool better because they have more surface area
proportionally, but you are wasting a LOT of power with that much resistance. And creating a lot more heat that needs to be
dissipated.
A kindly person on this site gave me these Ohm's Law formulas:
If they are wrong please tell me:
You have a 25w/ch SOZ with 2 coils.
Lets use one channel data, and use the specs for one coil.
(although the two coils supply 2 channels)
One channel:
From the Pass charts re 25 watt SOZ:
600watts/38volts supply= 16 amps
.6 ohms DCR *16= 9.6 volts
So you lose 9.6 volts across the inductor?
9.6 volts*16 amps= 154 watts needed to dissipate
I think this is reallly conservative, because you will need to crank up the voltage to compensate for the losses.
If you use the recommended coil diameter:
.22 ohms*16= 3.52 volts
This way you only lose 3.52 volts
3.52* 16= 56 watts needed to dissipate.
If you get 3 Erse 14 ga. mag core 9 MH inductors in parallel:
.243 ohm DCR/3= .08 ohms DCR
.08 ohms*16= 1.28 volts
This way you only lose 1.28 volts
1.28* 16= 20.5 watts needed to dissipate.(7 watts apiece)
3 of the Erse inductors are $36
If you run the SOZ under 20watts, you could probably get by
using 2 1.5 mh in series for a cost of $15 'cause the smaller
values are cheaper.
Also Mr. Pass says that 2MH is adaquate
Of coures the theme for SOZ is : More is better!!! Buahahahaah!
Someone please correct me if these thoughts are wrong, because I am about to order the inductors
Thanks, Mark
Air Core vs. Fe Cores
Hi Mark,
I know this thread is getting off topic...
"I don't know much about electronics, but it appears to me that the huge coils you made don't really solve some of the problems
that the SOZ tends to create. "
The large inductor certainly solved the problem I had - and that is to prevent overheating by reducing the amount of heat dissipation. Using a regular digital multimeter, the original MCM inductors had a HIGHER resistance value then the hand made ones. I don't claim that the digital MM is accurate (ie RMS rated) - but I did use the same meter for both coils and do know that the 2.0mH MCM ones dissipates more watts.
"I went to the web site you mentioned and they state that
to get a 3.18 Mh inductor with AWG 10, and you wind a diameter coil the size they recommend (smaller), you get a DCR of .22 ohms"
The diameter of the coil (inside diameter) is as close as to what the chart recommends (over 6"). Please keep in mind that the .22 ohm value is extremely difficult to achieve if you don't have perfect lay widings and right distance for each wind - so naturally the wire is going to be a LOT longer. A proper winding machine would do the job but I don't think it's feesable to make or buy one if you're only going to make a pair.
"If you get 3 Erse 14 ga. mag core 9 MH inductors in parallel:
.243 ohm DCR/3= .08 ohms DCR "
1st thing that comes to my mind on magnetic core inductors is thier saturation point (loss of inductance as the DC Bias current increases). Most places don't advertise these specs so I would rather stick with unsaturateable air core inductors. There is a whole area of inductors that will do circles around my mind (ie. core loss (Eddy currents), Leakage Effects, Magnetostriction) and one can find this info off the net.
With a 38V 1000VA transformer, you can easily get around 25 amps. Now the question is can 3 of the 9 mH steel core inductors handle that kind of current without being saturated? Even more important, how effective are these in filtering noise/ripple (the audiable noise) that air cores are known to filter out?
BQ
Hi Mark,
I know this thread is getting off topic...
"I don't know much about electronics, but it appears to me that the huge coils you made don't really solve some of the problems
that the SOZ tends to create. "
The large inductor certainly solved the problem I had - and that is to prevent overheating by reducing the amount of heat dissipation. Using a regular digital multimeter, the original MCM inductors had a HIGHER resistance value then the hand made ones. I don't claim that the digital MM is accurate (ie RMS rated) - but I did use the same meter for both coils and do know that the 2.0mH MCM ones dissipates more watts.
"I went to the web site you mentioned and they state that
to get a 3.18 Mh inductor with AWG 10, and you wind a diameter coil the size they recommend (smaller), you get a DCR of .22 ohms"
The diameter of the coil (inside diameter) is as close as to what the chart recommends (over 6"). Please keep in mind that the .22 ohm value is extremely difficult to achieve if you don't have perfect lay widings and right distance for each wind - so naturally the wire is going to be a LOT longer. A proper winding machine would do the job but I don't think it's feesable to make or buy one if you're only going to make a pair.
"If you get 3 Erse 14 ga. mag core 9 MH inductors in parallel:
.243 ohm DCR/3= .08 ohms DCR "
1st thing that comes to my mind on magnetic core inductors is thier saturation point (loss of inductance as the DC Bias current increases). Most places don't advertise these specs so I would rather stick with unsaturateable air core inductors. There is a whole area of inductors that will do circles around my mind (ie. core loss (Eddy currents), Leakage Effects, Magnetostriction) and one can find this info off the net.
With a 38V 1000VA transformer, you can easily get around 25 amps. Now the question is can 3 of the 9 mH steel core inductors handle that kind of current without being saturated? Even more important, how effective are these in filtering noise/ripple (the audiable noise) that air cores are known to filter out?
BQ
Howdy BQ
Well I agree that the 10 AWG ones you made are better then your 18 AWG originals, and have less DCR . My point was maybe making them so big is contraproductive, because the DCR goes way up. The site with the calculator does say that the inside radious should be 3", So I agree that you made them on the right core, but they come up with a DCR of .22
This discrepancy between their DCR and yours, is the difference
between me wanting to make a coil and not wanting to make a coil. I guess the perfect wound ones have some advantages. As I stated about the cored inductors: NP says they are good for over 6 amps ea. , so we do know that they work. That was part of my point.
I also pointed out that the 3 were for 25 watts/ch power output because you said it was silly to run the amp higher than that.
It's possible that you can't get max power out of your amp anyway due to the coil resistance in your power supply.
So we now have 3 options: machine wound, hand wound,
Erse mag cores. Pick the one that works for you!!
I am also very concerned about the saturation, because I am using the inductors right after the rectifier, to lower the voltage. If they saturate, I figure that the voltage will jump up to 1.2 times the transformer output. You can be sure that I will be gingerly turning up my Variacs to find that saturation point!!!
I hope to have my SOZ come out as well as yours when I'm done.
At the moment it is all attached to a 1x6 plank and is no candidate for the Pass Gallery!!
Mark
Well I agree that the 10 AWG ones you made are better then your 18 AWG originals, and have less DCR . My point was maybe making them so big is contraproductive, because the DCR goes way up. The site with the calculator does say that the inside radious should be 3", So I agree that you made them on the right core, but they come up with a DCR of .22
This discrepancy between their DCR and yours, is the difference
between me wanting to make a coil and not wanting to make a coil. I guess the perfect wound ones have some advantages. As I stated about the cored inductors: NP says they are good for over 6 amps ea. , so we do know that they work. That was part of my point.
I also pointed out that the 3 were for 25 watts/ch power output because you said it was silly to run the amp higher than that.
It's possible that you can't get max power out of your amp anyway due to the coil resistance in your power supply.
So we now have 3 options: machine wound, hand wound,
Erse mag cores. Pick the one that works for you!!
I am also very concerned about the saturation, because I am using the inductors right after the rectifier, to lower the voltage. If they saturate, I figure that the voltage will jump up to 1.2 times the transformer output. You can be sure that I will be gingerly turning up my Variacs to find that saturation point!!!
I hope to have my SOZ come out as well as yours when I'm done.
At the moment it is all attached to a 1x6 plank and is no candidate for the Pass Gallery!!
Mark
How big a donut hole?
Here is a photo of inductors made by Northcreek.
They are a very respected maker of crossover componants
http://www.northcreekmusic.com/COILS.html
The photo on the right is an 8 AWG coil (!)
They don't seem to feel it is necessary to make a 6" core size.
I almost feel like the coil calculator people:
http://www.colomar.com/cgi-bin/inductor_proc
have made some sort of mistake to spec such a big core.
Those monster coils aren't the proportions I am used to seeing
for inductors. I'm wondering the if anyone knows what the
tradeoffs would be for a 3" DIAMETER core vs. a 3" RADIUS core.
It would sure as hell have a lot less DCR!
NELSON!!! Did I take your name in vain when I claimed you
said the Erse 14 AWG inductor would take 6 amps or more?
I did a search and can't find that statement anywhere.
Here is a photo of inductors made by Northcreek.
They are a very respected maker of crossover componants
http://www.northcreekmusic.com/COILS.html
The photo on the right is an 8 AWG coil (!)
They don't seem to feel it is necessary to make a 6" core size.
I almost feel like the coil calculator people:
http://www.colomar.com/cgi-bin/inductor_proc
have made some sort of mistake to spec such a big core.
Those monster coils aren't the proportions I am used to seeing
for inductors. I'm wondering the if anyone knows what the
tradeoffs would be for a 3" DIAMETER core vs. a 3" RADIUS core.
It would sure as hell have a lot less DCR!
NELSON!!! Did I take your name in vain when I claimed you
said the Erse 14 AWG inductor would take 6 amps or more?
I did a search and can't find that statement anywhere.
Big Donuts are GooD
Actually there is a good reason for having a large donut. I can't remember the exact reason but it did come out of this Air Core inductor handbook I read last year (from the local library). The book mentions that a good air core inductor should proportional to the size of the donut hole. It is also important that the width & length of the windings itself (not the air core) is to be in a square proportional. By using a smaller donut hole would mean having more windings and the w x l wouldn't be optimized (possibly more likely to be saturated?).
I do know that in Solen coils, their donut holes for higher mH and larger guage wire values increases. Maybe NorthCreek is encomizing in size for shipping? For a 3mH 10awg coil I think their price is insane ($74.10 usd EACH!). Maybe they use some super high grade copper wire to generate such a low DCR value? But for power supply filtering, I would much rather use a higher voltage spec. transformer and who cares about the amount of watts gobbled up by a high DCR value inductor.
If it were for passive xovers in speakers - then that's a horse of a different colour.
Actually there is a good reason for having a large donut. I can't remember the exact reason but it did come out of this Air Core inductor handbook I read last year (from the local library). The book mentions that a good air core inductor should proportional to the size of the donut hole. It is also important that the width & length of the windings itself (not the air core) is to be in a square proportional. By using a smaller donut hole would mean having more windings and the w x l wouldn't be optimized (possibly more likely to be saturated?).
I do know that in Solen coils, their donut holes for higher mH and larger guage wire values increases. Maybe NorthCreek is encomizing in size for shipping? For a 3mH 10awg coil I think their price is insane ($74.10 usd EACH!). Maybe they use some super high grade copper wire to generate such a low DCR value? But for power supply filtering, I would much rather use a higher voltage spec. transformer and who cares about the amount of watts gobbled up by a high DCR value inductor.
If it were for passive xovers in speakers - then that's a horse of a different colour.
*WAAYYY* off topic !
Um, Guys,
I hate to bring you back to reality, but in the original post gnomus asked:
My question is how many amps can I expect from a 30 Volt DC supplied SOZ?
Has anyone tried a Choke input SOZ? Or can share the general difference one
can expect betwween choke input VS PI?
Back to the present train of thot, in-duck-dance vs. hole size: I can not find the formula for donut inductors, but for solenoid coils, the inductance is roughly (diameter^2 * number of turns^2)/(18*diameter + 40*the length) (from a radio handbook) So diameter squared is in the numerator and diameter is in the denominator. And the length of the wire is the circumfrance which is diameter * pi. So it looks like the bigger the hole the better.
I have not seen all of these iron core chokes you guys have been discussing, but if a choke is wound around a bar of iron or iron plates it is unlikely to saturate because most of the magnetic path is thru the air. Too much current in these will usually just cause a foul oder in the room.
So, for gnomus, how many amps can you expect from a 30 volt SOZ?
Um, Guys,
I hate to bring you back to reality, but in the original post gnomus asked:
My question is how many amps can I expect from a 30 Volt DC supplied SOZ?
Has anyone tried a Choke input SOZ? Or can share the general difference one
can expect betwween choke input VS PI?
Back to the present train of thot, in-duck-dance vs. hole size: I can not find the formula for donut inductors, but for solenoid coils, the inductance is roughly (diameter^2 * number of turns^2)/(18*diameter + 40*the length) (from a radio handbook) So diameter squared is in the numerator and diameter is in the denominator. And the length of the wire is the circumfrance which is diameter * pi. So it looks like the bigger the hole the better.
I have not seen all of these iron core chokes you guys have been discussing, but if a choke is wound around a bar of iron or iron plates it is unlikely to saturate because most of the magnetic path is thru the air. Too much current in these will usually just cause a foul oder in the room.
So, for gnomus, how many amps can you expect from a 30 volt SOZ?
I beg for mercy
The title of the thead starter is "SOZ Choke Input filter"
His question was answered in the first reply- The info is on the passDIY website. Clearly there is no one who has made a choke supply or is willing to answer to give a reply based on an actual supply.
BUT I think the inductor discussion is relevent to the topic of SOZ
Choke Input filter because the inductor IS the choke we are discussing. And I am making a choke supply and need to decide on an aproach. When I finish it, I will post my results.
Here is my premise: Air core chokes barely work for the purpose.-
-especially over the 2.0 mh that Nelson Pass says will work
I have read various posts from people that have built the SOZ and
say something pretty much along these lines: The resistor heatsinks aren't getting that hot-what a miracle!
BUT they then describe their inductors as stinking (literally) hot
Clearly the coils are acting like resistors, and the output of the amp is way less than they think
Mr BQ is suggestiong that a huge coil is a solution for people to save money. My point is that the DCR of air coils makes them ALMOST unusable for large amperages. Big voltage drop, so add more voltage, so then the coil gets hotter, so make a huger coil that has high DCR and you are back where you started.
Those huge coils must have $50 of copper in them, My overpriced? surplus store wants $6/lb. for wire) They have a DCR of .6 ohm even with 10 AWG wire (!) My suggestion would be to try a 10 awg about half the diameter.Maybe less efficient a filter, but probably one quarter the DCR; That way you aren't fighting a losing battle
You can get an AIR core coil from Zalytron or Parts Express of 3.3 mh in 14 AWG forabout $15 AND its DCR is a lot less: .45
or put two 1.5 in series for $20 Or stick with 2.0 mh.
Just some ideas, I won't beat this further....
Mark
The title of the thead starter is "SOZ Choke Input filter"
His question was answered in the first reply- The info is on the passDIY website. Clearly there is no one who has made a choke supply or is willing to answer to give a reply based on an actual supply.
BUT I think the inductor discussion is relevent to the topic of SOZ
Choke Input filter because the inductor IS the choke we are discussing. And I am making a choke supply and need to decide on an aproach. When I finish it, I will post my results.
Here is my premise: Air core chokes barely work for the purpose.-
-especially over the 2.0 mh that Nelson Pass says will work
I have read various posts from people that have built the SOZ and
say something pretty much along these lines: The resistor heatsinks aren't getting that hot-what a miracle!
BUT they then describe their inductors as stinking (literally) hot
Clearly the coils are acting like resistors, and the output of the amp is way less than they think
Mr BQ is suggestiong that a huge coil is a solution for people to save money. My point is that the DCR of air coils makes them ALMOST unusable for large amperages. Big voltage drop, so add more voltage, so then the coil gets hotter, so make a huger coil that has high DCR and you are back where you started.
Those huge coils must have $50 of copper in them, My overpriced? surplus store wants $6/lb. for wire) They have a DCR of .6 ohm even with 10 AWG wire (!) My suggestion would be to try a 10 awg about half the diameter.Maybe less efficient a filter, but probably one quarter the DCR; That way you aren't fighting a losing battle
You can get an AIR core coil from Zalytron or Parts Express of 3.3 mh in 14 AWG forabout $15 AND its DCR is a lot less: .45
or put two 1.5 in series for $20 Or stick with 2.0 mh.
Just some ideas, I won't beat this further....
Mark
SOZ choke
For SOZ of 20 volts or more if you do not want your coils to get too hot and have a low DCR then use 10ga air cores. I used 2 mH 12 ga air cores and they got fairly hot. I then tried 3 mH 10 ga and they ran cooler. I even tried 6.2 mH 10 ga and these just got fairly warm. The draw back with air core is high cost, much larger size compared to the same inductance iron core and they should to be kept way from critical signal paths as they spray 100 Hz signal in your chassis. The 6.2 mH 10 ga air core was about 2 inches thick and 6 inches in diameter. Air cores will not saturate. Iron cores can saturate. But that does not mean the inductance will go to zero and it will just act as a roll of wire. The inducatance may just go down depending on the the specifications of the iron core and the excess current running through the coil. You can also get slightly more inductance in an iron core running less current throught it than its specifications. I am going to try an inductor input power suppy for SOZ and compare it to the double PI filter I had tried. The double PI worked great. You could not tell the amps were on unless your ear was almost touching the speaker cone. And that was single ended input. The voltage was rock solid. I am experimenting a lot as I am in the process of shrinking the SOZ down in size. For that I willl be using iron core inductors. I am shooting for a compact as possible high end construction 15 to 20 watt mono block SOZ. Shrinking the SOZ in size is not easy with off the shelf non custom parts! It will take me some time to finish this.
For SOZ of 20 volts or more if you do not want your coils to get too hot and have a low DCR then use 10ga air cores. I used 2 mH 12 ga air cores and they got fairly hot. I then tried 3 mH 10 ga and they ran cooler. I even tried 6.2 mH 10 ga and these just got fairly warm. The draw back with air core is high cost, much larger size compared to the same inductance iron core and they should to be kept way from critical signal paths as they spray 100 Hz signal in your chassis. The 6.2 mH 10 ga air core was about 2 inches thick and 6 inches in diameter. Air cores will not saturate. Iron cores can saturate. But that does not mean the inductance will go to zero and it will just act as a roll of wire. The inducatance may just go down depending on the the specifications of the iron core and the excess current running through the coil. You can also get slightly more inductance in an iron core running less current throught it than its specifications. I am going to try an inductor input power suppy for SOZ and compare it to the double PI filter I had tried. The double PI worked great. You could not tell the amps were on unless your ear was almost touching the speaker cone. And that was single ended input. The voltage was rock solid. I am experimenting a lot as I am in the process of shrinking the SOZ down in size. For that I willl be using iron core inductors. I am shooting for a compact as possible high end construction 15 to 20 watt mono block SOZ. Shrinking the SOZ in size is not easy with off the shelf non custom parts! It will take me some time to finish this.
mercy granted
Sorry, Mark (and anybody else), I did not mean flog or flame anybody.
*I* use choke input supplies on my amps and preamps and have posted my opinion of them. Granted, my amp is not exactly an SOZ but a couple of Zens "back to back".
Due to the amount of inductance needed to get a true choke input supply I don't think you can get enough inductance with an air core. (Or it will cost about as much as iron core choke made for the purpose.) But, hey, building and trying are a big part of the fun! Go for it!! And keep us posted!
Sorry, Mark (and anybody else), I did not mean flog or flame anybody.
*I* use choke input supplies on my amps and preamps and have posted my opinion of them. Granted, my amp is not exactly an SOZ but a couple of Zens "back to back".
Due to the amount of inductance needed to get a true choke input supply I don't think you can get enough inductance with an air core. (Or it will cost about as much as iron core choke made for the purpose.) But, hey, building and trying are a big part of the fun! Go for it!! And keep us posted!
Aw shucks, I guess I was getting a little carried away.
It is just exciting to me when I recognized an unexpected pattern such as the bigger coil death spiral.
It looks like Gnomus says 10 GA air cols will work And have low
DcR if they are more like 6" in outside dia.
Until very recently, I was missing an important piece of data. I didn't know there was any option to the
air coils. Until I heard that the Erse cored ones could handle
as much current as the do, I was also afraid to use anything but
air cores because I was afraid they would saturate.
Does anyone have the answer as to whether each leg handles
the full current the amp is using or is it split in half?
Lets assume the amp is drawing 6 amps.
Does each rail carry 3 amps, or does all the current go back and forth between them. Do I need inductors that can handle 6 amps in each rail or 3 amps in each rail?
I'm gonna take Super BBQ's advice and make friends with my local
starter/alternator rebuild shop. Maybe I can get prices on wire like he gets!
But hey! we got some helpful respose from Gnomus and you! (I had read your posts on the subject
Thanks to you both.
It is just exciting to me when I recognized an unexpected pattern such as the bigger coil death spiral.
It looks like Gnomus says 10 GA air cols will work And have low
DcR if they are more like 6" in outside dia.
Until very recently, I was missing an important piece of data. I didn't know there was any option to the
air coils. Until I heard that the Erse cored ones could handle
as much current as the do, I was also afraid to use anything but
air cores because I was afraid they would saturate.
Does anyone have the answer as to whether each leg handles
the full current the amp is using or is it split in half?
Lets assume the amp is drawing 6 amps.
Does each rail carry 3 amps, or does all the current go back and forth between them. Do I need inductors that can handle 6 amps in each rail or 3 amps in each rail?
I'm gonna take Super BBQ's advice and make friends with my local
starter/alternator rebuild shop. Maybe I can get prices on wire like he gets!
But hey! we got some helpful respose from Gnomus and you! (I had read your posts on the subject
Thanks to you both.
both legs get it all!
Mark,
To answer your question, if the SOZ amp takes 6 amps, then 6 amps flows thru the positive leg AND the negative leg. Under normal circumstances, NO current flows thru the ground connection to the SOZ. (Or just a tiny amount.) And if you have + and - 30 volts coming from your power supply, I calculate one SOZ will draw 6 amps (thru each leg). (Two will take 12 amps and so on.)
Nelson made his post (above) after I started typing this and before I got it posted. If you still want to try winding coils yourself, read on:
Here is something else to think about: inductance increases with the SQUARE of the number of turns. Thus twice as many turns gives four times the inductance. So if you are going to wind two coils, one for plus and one for minus, I suggest you mount them side by side so they 'share the same field'. This should quadruple (or nearly so) the amount of inductance you get from the two coils with no increase in DCR! (If you are really a glutton for punishment, make one toroid with two strands of wire wound side by side and on top of each other. Don't worry about total symitry, close is close enough.) You will have to connect the coils correctly to the psu and SOZ and I will explain how that is done.
Lets assume you wind both coils exactly the same way. Each coil will have two leads. I am going to call the lead which is connected to the first turn you make the 'start lead' and the lead that is connected to the last turn put down the 'finish lead'. Connect the start lead of the first coil to the + output from your bridge. Connect the finish lead from the first coil to the + of your filter cap(s) and + of SOZ. Connect the start lead of the second coil to the - (MINUS) filter cap(s) and - of SOZ. Connect the finish lead of the second coil to - output of your bridge. If you get this wrong, the coils will cancel each other out and you will have (almost) no inductace.
If you have an L (inductance) meter you can test the coils by shorting the leads that (will) go to the SOZ and measuring the inductance on the leads that (will) go to the bridge. You should have some amount of inductance. Then reverse the leads of *one coil only* and remeasure. You should have a lot less inductance. (When you have this correct you will have the differential choke mentioned earlier in this thread.)
(You might visualize it this way: electricity comes out of the + of the bridge, runs around the coil in one direction, runs thru the load (SOZ), runs around the other wire in the same coil in the same direction and goes back to the bridge. If that confuses you then ignore this paragraph.)
If you have +/- 30 volts coming out of the psu and your SOZ takes 6 amps you are going to need at least .005 henry (5 millihenries) in each leg between the bridge and the filter cap(s) for a total of .01 henries. (see earlier posts)
Finally, GOOD LUCK! and let us know how it turns (pun intended) out!
Mark,
To answer your question, if the SOZ amp takes 6 amps, then 6 amps flows thru the positive leg AND the negative leg. Under normal circumstances, NO current flows thru the ground connection to the SOZ. (Or just a tiny amount.) And if you have + and - 30 volts coming from your power supply, I calculate one SOZ will draw 6 amps (thru each leg). (Two will take 12 amps and so on.)
Nelson made his post (above) after I started typing this and before I got it posted. If you still want to try winding coils yourself, read on:
Here is something else to think about: inductance increases with the SQUARE of the number of turns. Thus twice as many turns gives four times the inductance. So if you are going to wind two coils, one for plus and one for minus, I suggest you mount them side by side so they 'share the same field'. This should quadruple (or nearly so) the amount of inductance you get from the two coils with no increase in DCR! (If you are really a glutton for punishment, make one toroid with two strands of wire wound side by side and on top of each other. Don't worry about total symitry, close is close enough.) You will have to connect the coils correctly to the psu and SOZ and I will explain how that is done.
Lets assume you wind both coils exactly the same way. Each coil will have two leads. I am going to call the lead which is connected to the first turn you make the 'start lead' and the lead that is connected to the last turn put down the 'finish lead'. Connect the start lead of the first coil to the + output from your bridge. Connect the finish lead from the first coil to the + of your filter cap(s) and + of SOZ. Connect the start lead of the second coil to the - (MINUS) filter cap(s) and - of SOZ. Connect the finish lead of the second coil to - output of your bridge. If you get this wrong, the coils will cancel each other out and you will have (almost) no inductace.
If you have an L (inductance) meter you can test the coils by shorting the leads that (will) go to the SOZ and measuring the inductance on the leads that (will) go to the bridge. You should have some amount of inductance. Then reverse the leads of *one coil only* and remeasure. You should have a lot less inductance. (When you have this correct you will have the differential choke mentioned earlier in this thread.)
(You might visualize it this way: electricity comes out of the + of the bridge, runs around the coil in one direction, runs thru the load (SOZ), runs around the other wire in the same coil in the same direction and goes back to the bridge. If that confuses you then ignore this paragraph.)
If you have +/- 30 volts coming out of the psu and your SOZ takes 6 amps you are going to need at least .005 henry (5 millihenries) in each leg between the bridge and the filter cap(s) for a total of .01 henries. (see earlier posts)
Finally, GOOD LUCK! and let us know how it turns (pun intended) out!
Hey, FEThead
Well, your info about the inpedance increasing by the square
got me thinking. I checked at my local metal surplus shop and they are selling thick coil wire for less than $3 Us per pound.
To synopsize your comments about flow through the coil (I'm pretty sure I DOunderstand) the point is that the current has to always be flowing in the same direction through the coils, ie if you are looking through the hole in the center, and the juice is flowing clockwise through one coil, then the adjacent coil must have the juice flowing in the clockwise direction too.
More interesting to me was that the store had SQUARE section 12 GA coil wire at the same price as round. That would sure make it easier to wind! Also more compact I'll bet! Any downside to the square section? I'll bet it is expensive normally.
So you are saying winding a bifilar coil (two strands at once)
would be if anything better for inductance, but harder to wind -right?
I may be winding coils soon!
The square stuff makes me tempted to try-
Mark
Well, your info about the inpedance increasing by the square
got me thinking. I checked at my local metal surplus shop and they are selling thick coil wire for less than $3 Us per pound.
To synopsize your comments about flow through the coil (I'm pretty sure I DOunderstand) the point is that the current has to always be flowing in the same direction through the coils, ie if you are looking through the hole in the center, and the juice is flowing clockwise through one coil, then the adjacent coil must have the juice flowing in the clockwise direction too.
More interesting to me was that the store had SQUARE section 12 GA coil wire at the same price as round. That would sure make it easier to wind! Also more compact I'll bet! Any downside to the square section? I'll bet it is expensive normally.
So you are saying winding a bifilar coil (two strands at once)
would be if anything better for inductance, but harder to wind -right?
I may be winding coils soon!
The square stuff makes me tempted to try-
Mark
square is good
Hi Mark,
You checked the surplus metal store, GOOD JOB! I have no connection with those guys but I have bought a lot of wire from the local one.
(My "other" hobby is amateur radio and I have a yard full of wire antennas.)
You DO understand: the current has to flow the same direction around the hole (core).
The square wire is great for what you want to do. In fact for what you are doing it is probably better than round because the square stuff will fill the "winding window" better. There is no dissadvantage that I am aware of for this purpose. You do NOT want to buy it new!
Winding the turns bifilar is SLIGHLY better than individually because you are more likely to have the same number of turns on both coils. They don't have to have EXACTLY the same number of turns if you do them individually, but the closer the better. If bifilar is a lot more trouble than individually, use the latter.
One more thing about scrap metal places: about once a month they sell their inventory to someone who melts it down. Before you wait too long, call the place up and ask when they sell their scrap metal. Obviously you want to get there first. But in another month they will have a new selection.
Good luck! Let us know how it, um, turns out.
Thot for the day: If Root Means Square (RMS), does rootless mean hip?
Hi Mark,
You checked the surplus metal store, GOOD JOB! I have no connection with those guys but I have bought a lot of wire from the local one.
(My "other" hobby is amateur radio and I have a yard full of wire antennas.)
You DO understand: the current has to flow the same direction around the hole (core).
The square wire is great for what you want to do. In fact for what you are doing it is probably better than round because the square stuff will fill the "winding window" better. There is no dissadvantage that I am aware of for this purpose. You do NOT want to buy it new!
Winding the turns bifilar is SLIGHLY better than individually because you are more likely to have the same number of turns on both coils. They don't have to have EXACTLY the same number of turns if you do them individually, but the closer the better. If bifilar is a lot more trouble than individually, use the latter.
One more thing about scrap metal places: about once a month they sell their inventory to someone who melts it down. Before you wait too long, call the place up and ask when they sell their scrap metal. Obviously you want to get there first. But in another month they will have a new selection.
Good luck! Let us know how it, um, turns out.
Thot for the day: If Root Means Square (RMS), does rootless mean hip?
SOZ doesnt increase power
Hi all,
perhaps you can help me:
i build a soz with the capacity-multipler PSU described in esp.
all works fine until about 15 volts per rail.
when i increase the suplly voltage to 35 volts per rail, the power of soz doesnot increase too. This means, the speakers dont get louder, only the transistors in my capacitor-multipler psu runs hot and hotter.
If i shloud build the original SOZ Psu with the chokes - can hope for more power?
regars,
Ralf
Hi all,
perhaps you can help me:
i build a soz with the capacity-multipler PSU described in esp.
all works fine until about 15 volts per rail.
when i increase the suplly voltage to 35 volts per rail, the power of soz doesnot increase too. This means, the speakers dont get louder, only the transistors in my capacitor-multipler psu runs hot and hotter.
If i shloud build the original SOZ Psu with the chokes - can hope for more power?
regars,
Ralf
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.