Well its the most seen question here , WHERE CAN I GET SOME CHEAP TRANNIES >?
Hi, since i have a winding machine and cant find any of market trannies that work well (for me). 🙁 i just bought some teroids 6 volt 35VA from amplino good brand, but when i have 2 in paralel and the 220 volt section in series, i have a roll of in high that starts at 12 Khz. complete useless 🙁 again 20 euro down the drain. im now kind of sick of it(have a box full of other trannies ). All other tranies i know of cost around 200 euro, they work well but heey 200 no way. then there are 6 volt trannies , when multiple used they MIGHT work, but i for one would love to see just one trannie that works well and that the average guy can afford!
Is there anyone out there that is willing to share(or sell me or Pm me) a good trannie design for the folowing specs
step up ratio must be around 125 - 150
frequency response 150-20.000 hz
No teroid, since i can only wind bobbins.
Prefered C cores from the standard sizes used in normal transformer works.
Prices to produce in bigger quantities must be low so no extra ordinairy core material (mostly ******** anyways, look at quad)
i am a complete noob with transformer theory. i do have some stuff to wind them , and i got some time to spare.
Whats in it for you ? well if the design is good im willing to pay for the design, or i can make a few for you ?(all material will be on my acount).
Im hoping we can make some tranies that are higher step up ratio then the mostly used antec ones. and being able to suplly some Diyers with trannies, for a decent price.
Im not looking for big money here, i just want to be able to suplly myself and maybe the people that are willing to get some cheap but good working trannies.
just need some major help on the technical detail.
BTW for all diyers that have the same problem pls let us know what you find a fair price for a trannie? (just to see if we can get there)
best regards Joppe
Hi, since i have a winding machine and cant find any of market trannies that work well (for me). 🙁 i just bought some teroids 6 volt 35VA from amplino good brand, but when i have 2 in paralel and the 220 volt section in series, i have a roll of in high that starts at 12 Khz. complete useless 🙁 again 20 euro down the drain. im now kind of sick of it(have a box full of other trannies ). All other tranies i know of cost around 200 euro, they work well but heey 200 no way. then there are 6 volt trannies , when multiple used they MIGHT work, but i for one would love to see just one trannie that works well and that the average guy can afford!
Is there anyone out there that is willing to share(or sell me or Pm me) a good trannie design for the folowing specs
step up ratio must be around 125 - 150
frequency response 150-20.000 hz
No teroid, since i can only wind bobbins.
Prefered C cores from the standard sizes used in normal transformer works.
Prices to produce in bigger quantities must be low so no extra ordinairy core material (mostly ******** anyways, look at quad)
i am a complete noob with transformer theory. i do have some stuff to wind them , and i got some time to spare.
Whats in it for you ? well if the design is good im willing to pay for the design, or i can make a few for you ?(all material will be on my acount).
Im hoping we can make some tranies that are higher step up ratio then the mostly used antec ones. and being able to suplly some Diyers with trannies, for a decent price.
Im not looking for big money here, i just want to be able to suplly myself and maybe the people that are willing to get some cheap but good working trannies.
just need some major help on the technical detail.
BTW for all diyers that have the same problem pls let us know what you find a fair price for a trannie? (just to see if we can get there)
best regards Joppe
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Joppe, you cannot buy cheap good transformers as it takes a great design, good quality materials and excellent winding techniques. All those things cost money and time. Having spent thousands of hours reading both design and construction techniques I can tell you from experience its far from easy. Buying small quantities of M6 iron for DIY use is expensive.
To be honest its more cost effective to get the transformers made by a company such as Sowter or your local supplier as long as they have a good reputation. They buy their materials in bulk and have experience in winding.
Unfortunately what you ask for does not have enough detail to even start a design, is it an Interstage or Output transformer or something else. You are short on a whole pile of technical details.
I do not mean to be negative just trying to save you hours of frustration. I do build my own transformers as I spent a lot of money on materials and kit but mostly I buy them now as its a complete pain in the ****. Apart from mains transformers you can never be sure exactly how the output or interstage transformers will work until you have actually built and tested them. Typically a design used to take 30-40 pages of A4 paper for all the calculations until I automated with a program.
Hope my past experience goes a little bit on saving you a lot of time.
To be honest its more cost effective to get the transformers made by a company such as Sowter or your local supplier as long as they have a good reputation. They buy their materials in bulk and have experience in winding.
Unfortunately what you ask for does not have enough detail to even start a design, is it an Interstage or Output transformer or something else. You are short on a whole pile of technical details.
I do not mean to be negative just trying to save you hours of frustration. I do build my own transformers as I spent a lot of money on materials and kit but mostly I buy them now as its a complete pain in the ****. Apart from mains transformers you can never be sure exactly how the output or interstage transformers will work until you have actually built and tested them. Typically a design used to take 30-40 pages of A4 paper for all the calculations until I automated with a program.
Hope my past experience goes a little bit on saving you a lot of time.
Thanks for your effort, and you are right, i missed out on some information 🙂, its ought to be used as a step up transformer used in ESL speakers, just for the mid and high frequency's (150-20000hz) since most people want to make a hybride for the first time i thought it would be nice to have some trannies available , without paying major bucks. the reason for the high step up ratio is small panels sizes, when using small panel you can either bumb up the HV or increase the stepup ratio. my experience is that corona on the high voltage or sucking of the menbrame into one stator ocours before flash overs from the transformer. ofcourse you could lower the DC spacing... but that result in lower HV voltage has to be used before sticking into on of the stators again. or support the menbrame more, wich result in higher res frequency. or just go with low stepup small panel and live with the low output.. wich i dont want.
I know i am in the blind on allot of technical details. but the thing is i wind tranformers for a dutch small company that does upgrades for audiostatics and quads. as long as i know how to wind them its no problem. The thing is ofcourse i cant just copy his work, also there is ofcourse debate on if these trannies are great good or crap, at least i tried one ,and they are better then everything i tried and better then some comercial available ones. i believe ESLtranformer a member on this forum thought they where ****, he might be right but still they peform better then any power tranny does.
i know the problem is the design. thats why i asked. I can imagine people that design tranformers might have some more questions. people that are technical enough could translate it to the specs i do have experience with.
as in freq response
max min impedance seen by amplifier (ofcourse hand in hand with the size of esl panel)
step up ratio etc.
You could say this is posible but not with this spec on ur wish list etc. for all i know i ask the impossible.
although i got a trannie here that has a stepup of 1:125 on 2 c cores with 2 bobbines. i wind those bobbines in an hour, with nomex in between every layer. i used one of these in the previous post. and they sound ok to me, i tried some power trannies as well and they all have lower output and higher distortion.
pls remember im not aiming for HIGH END aspirations where everything has to be made out of gold and silver and prices are 100 fold return. why? because i think that the use of an esl lowers the distortion sooo radically that paying 150 euro more for 0.01 perccent of distortion is useless when compared to normal drivers that distort 10-30 folds.
its like a niche marked in between the power trannies and the real deal, i cant imagine there is no room to make a better product for lets say 150-175 euro a pair.
The only trannie that comes close to my specas from sowter are around 140 POUND each. even for 1:70
so for a set 380 euro.. for real ? still have half the thing i wanted for (step up ratio, and maybe its not possible).. thats ok but 380 euro ??
I know i am in the blind on allot of technical details. but the thing is i wind tranformers for a dutch small company that does upgrades for audiostatics and quads. as long as i know how to wind them its no problem. The thing is ofcourse i cant just copy his work, also there is ofcourse debate on if these trannies are great good or crap, at least i tried one ,and they are better then everything i tried and better then some comercial available ones. i believe ESLtranformer a member on this forum thought they where ****, he might be right but still they peform better then any power tranny does.
i know the problem is the design. thats why i asked. I can imagine people that design tranformers might have some more questions. people that are technical enough could translate it to the specs i do have experience with.
as in freq response
max min impedance seen by amplifier (ofcourse hand in hand with the size of esl panel)
step up ratio etc.
You could say this is posible but not with this spec on ur wish list etc. for all i know i ask the impossible.
although i got a trannie here that has a stepup of 1:125 on 2 c cores with 2 bobbines. i wind those bobbines in an hour, with nomex in between every layer. i used one of these in the previous post. and they sound ok to me, i tried some power trannies as well and they all have lower output and higher distortion.
pls remember im not aiming for HIGH END aspirations where everything has to be made out of gold and silver and prices are 100 fold return. why? because i think that the use of an esl lowers the distortion sooo radically that paying 150 euro more for 0.01 perccent of distortion is useless when compared to normal drivers that distort 10-30 folds.
its like a niche marked in between the power trannies and the real deal, i cant imagine there is no room to make a better product for lets say 150-175 euro a pair.
The only trannie that comes close to my specas from sowter are around 140 POUND each. even for 1:70
so for a set 380 euro.. for real ? still have half the thing i wanted for (step up ratio, and maybe its not possible).. thats ok but 380 euro ??
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Hi Wrinex
I'm not an expert on transformer design - is something I mean to explore more soon - but I have investigated how transformers must be matched to the application.
The modelling is a bit tricky for some cases but for all applications the amplifier/transformer/ESL system looks like a second-order low-pass filter with the cutoff frequency determined by the total inductance and total capacitance.
The capacitance comes from two places (I) the ESL, and (II) the transformer winding capacitance (usually measured on the high voltage side).
The inductance also comes from two places (I) the leakage inductance of the transformer (measured on the secondary side), and (II) the amplifier output inductance, which when seen through the transformer is increased by N^2, where N is the step-up ratio. For example a 1 uH inductance (amplifier) seen through a 1:100 transformer adds 10 mH to the high voltage circuit.
There are three distinct cases
Single segment ESL (very common DIY design)
Single segment ESLs have a very high capacitance - anything from a few hundred pf to a couple of nF. This means that you must make every effort to keep the inductance down - toroidal transformers are essential as they have a low inductance, high step-up ratio transformer ( >70) definitely out, you will struggle to get a wide bandwidth unless you use a very good amplifier with no OP inductor. As far as I know - all commercial ESL transformers are made for this case.
Line-source segmented ESL (less common DIY)
The load impedance presented by a line-source segmented ESL is exactly half way between resistor and capacitance phase wise, with the capacitance about 100 pF. The best transformers require close matching with a similar capacitance and modest leakage inductance (a couple of hundred mH). I've made my transformers by stacking 16 small toroids (8 each side), but purpose built C-core or R-core transformers using bobins are much cheaper (I just don't have the machinery). The step up ratios for these ESLs can be pushed up to 200 with care. Commercial ESL transformers are bad for these ESLs
Point-source segmented ESL (rare for DIY)
The load impedance for these is almost pure resistance - practically zero capacitance, and the best bandwidth is obtained using narrow bobbin wound transformer - narrow to minimise the capacitance. Toroids must be avoided. The QUAD Transformers are about 1.5H and 20 pF and have a step up ratio of 300 in total.
In all three cases you will need to tweak the resistance on the primary side of the ESL (usually 1 ohm or so) to adjust the Q of the LC resonance to get a flat high-frequency response.
regards
Rod
I'm not an expert on transformer design - is something I mean to explore more soon - but I have investigated how transformers must be matched to the application.
The modelling is a bit tricky for some cases but for all applications the amplifier/transformer/ESL system looks like a second-order low-pass filter with the cutoff frequency determined by the total inductance and total capacitance.
The capacitance comes from two places (I) the ESL, and (II) the transformer winding capacitance (usually measured on the high voltage side).
The inductance also comes from two places (I) the leakage inductance of the transformer (measured on the secondary side), and (II) the amplifier output inductance, which when seen through the transformer is increased by N^2, where N is the step-up ratio. For example a 1 uH inductance (amplifier) seen through a 1:100 transformer adds 10 mH to the high voltage circuit.
There are three distinct cases
Single segment ESL (very common DIY design)
Single segment ESLs have a very high capacitance - anything from a few hundred pf to a couple of nF. This means that you must make every effort to keep the inductance down - toroidal transformers are essential as they have a low inductance, high step-up ratio transformer ( >70) definitely out, you will struggle to get a wide bandwidth unless you use a very good amplifier with no OP inductor. As far as I know - all commercial ESL transformers are made for this case.
Line-source segmented ESL (less common DIY)
The load impedance presented by a line-source segmented ESL is exactly half way between resistor and capacitance phase wise, with the capacitance about 100 pF. The best transformers require close matching with a similar capacitance and modest leakage inductance (a couple of hundred mH). I've made my transformers by stacking 16 small toroids (8 each side), but purpose built C-core or R-core transformers using bobins are much cheaper (I just don't have the machinery). The step up ratios for these ESLs can be pushed up to 200 with care. Commercial ESL transformers are bad for these ESLs
Point-source segmented ESL (rare for DIY)
The load impedance for these is almost pure resistance - practically zero capacitance, and the best bandwidth is obtained using narrow bobbin wound transformer - narrow to minimise the capacitance. Toroids must be avoided. The QUAD Transformers are about 1.5H and 20 pF and have a step up ratio of 300 in total.
In all three cases you will need to tweak the resistance on the primary side of the ESL (usually 1 ohm or so) to adjust the Q of the LC resonance to get a flat high-frequency response.
regards
Rod
Thx allot golfnut for all that info!!,, my main goal would be the second one, Line source. since i dont think its usefull to use a whole panel fullrange. because it induces so much problems on the trannie , and because the beaming is out of this world. how come the latest variant is resistive ? i mean quad used delay lines on there middle parts as well as resistors just like the second option. i dont see the diference except it being round instead of rectangular. ?
by the way C cores are the most easy to make, just buy 2 C cores 2 bobbins and the clamp. , wind the bobins put them on use clamp and ur done. ofc they are a bit more expensive. but labour is more expensive. my guess. if its possible to make them up til 200 then 125 should be the most easy one to design , and would be right in the middle so it still can be used for small panels un segmented, at least i tried it here and works without problem. by the way the use of 8 teroids whas to extend fequency respone ? becaus ei tried 2 in paralel today and was verry disapointed, about the fact it rolled of so quick. on a verry small 2 segment panel total size around 26cm x110. should not be that hard to drive
by the way C cores are the most easy to make, just buy 2 C cores 2 bobbins and the clamp. , wind the bobins put them on use clamp and ur done. ofc they are a bit more expensive. but labour is more expensive. my guess. if its possible to make them up til 200 then 125 should be the most easy one to design , and would be right in the middle so it still can be used for small panels un segmented, at least i tried it here and works without problem. by the way the use of 8 teroids whas to extend fequency respone ? becaus ei tried 2 in paralel today and was verry disapointed, about the fact it rolled of so quick. on a verry small 2 segment panel total size around 26cm x110. should not be that hard to drive
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im sending out some mails to get some prices on C cores. i know they are pretty expensive.
here is a site in dutch that expains a bit on transformers for electrostatic speakers, i might send him an email. my guess is that the company i wind for let him design there transformers as well.
since they are kind of made as he explains.
Elektrostaten Techniek Step-up Trafo
might need google translate to translate although it sucks ofcourse.
here is a site in dutch that expains a bit on transformers for electrostatic speakers, i might send him an email. my guess is that the company i wind for let him design there transformers as well.
since they are kind of made as he explains.
Elektrostaten Techniek Step-up Trafo
might need google translate to translate although it sucks ofcourse.
Hi Wrinex
For the single-segment ESL it is obvious (I hope) why it looks like a pure capacitor.🙂
Proper equalisation of the line-source segmented ESL requires the ESL to be configured as an RC transmission line. In that case, the ESL impedance is sqrt(R/jwC) where C is the segment capacitance and R is the intersegment resistance for the transmission line. Hence the impedance is halfway between resistor and capacitor (45 degree phase shift at all frequencies), with the capacitive part much smaller than for a single segment ESL.
Proper equalisation for a point-source ESL requires the ESL to be configured as an LC transmission line. In that case the ESL impedance is sqrt(jwL/jwC) = sqrt(L/C), which is independent of frequency, so looks like a pure resistor. This is the design adopted by the Quad ESLs.
regards
Rod
For the single-segment ESL it is obvious (I hope) why it looks like a pure capacitor.🙂
Proper equalisation of the line-source segmented ESL requires the ESL to be configured as an RC transmission line. In that case, the ESL impedance is sqrt(R/jwC) where C is the segment capacitance and R is the intersegment resistance for the transmission line. Hence the impedance is halfway between resistor and capacitor (45 degree phase shift at all frequencies), with the capacitive part much smaller than for a single segment ESL.
Proper equalisation for a point-source ESL requires the ESL to be configured as an LC transmission line. In that case the ESL impedance is sqrt(jwL/jwC) = sqrt(L/C), which is independent of frequency, so looks like a pure resistor. This is the design adopted by the Quad ESLs.
regards
Rod
Hi Wrinex
Further information: Transmission line - Wikipedia, the free encyclopedia
See section on telegraphers equations.
regards
Rod
Further information: Transmission line - Wikipedia, the free encyclopedia
See section on telegraphers equations.
regards
Rod
Hi joppe there are lots of books available to help you with transformer theory. Have a look at the following link as a starting point. There is a section on output transformers which you can use as a basis for your step up transformers. Radiotron designers handbook and turner audio output-trans-theory - I learnt a lot by looking at all the pages on the second link. You will have to do all the calculations but all the steps are there. At least you have a good start on actually winding them. Good luck.
Steve
Steve
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Already then!
Let's take some old book "Formulae and tablee for the calculation of mutual and self-inductance" by Edward Rosa, year 1907 and Radio Engineers Handbook, 1943.
For the windings 10 cm high 1 cm thick and core cross-section of 4 cm sq one will get leakage inductance, referred to the seconadary, approximately 3.3H. Radio book gives 2.36H. All calculations done for 100 turns primary and 10000 secondary.
Using the trick of dividing secondaries to the two thus halving ratio we'll get 3.3/4 but two windings are now in series thus 3.3/4*2=1.75H by ROSA or 1.18H by Frederick Emmons Terman.
1000pF yeilds 4.6Khz of resonance frequency. Bingo!
What can be done then?
1. Make windings thinner. Let's say three times => 6.5kHz
2. Lower turns count 2 times => 13kHz
Still no good?
Looking at the formula again: Ls is proportional to N square. On the other hand it's linearly proportional to the turn's mean length. Furthermore, cross section and, subsequently, number of turns at the given flux density is square to the mean length.
Let's double the cross section, N goes down 2 times length goes up 1.4 times Ls is now 1/4*1.41=.325. So 13kHz/(square root of 0.325)=22.8Khz
Almost there.
Going this way one Finnish guy made x-former good to drive 10nF or 20 nF panels if memory serves me right.
Cheers,
Alex
P.S. He was using amorph core(s) for a purpose. Amorph has really low coercive force and rather high permeability thus keeping magnetizing current reasonably low when turns number is low and cross-section is high.
Let's take some old book "Formulae and tablee for the calculation of mutual and self-inductance" by Edward Rosa, year 1907 and Radio Engineers Handbook, 1943.
For the windings 10 cm high 1 cm thick and core cross-section of 4 cm sq one will get leakage inductance, referred to the seconadary, approximately 3.3H. Radio book gives 2.36H. All calculations done for 100 turns primary and 10000 secondary.
Using the trick of dividing secondaries to the two thus halving ratio we'll get 3.3/4 but two windings are now in series thus 3.3/4*2=1.75H by ROSA or 1.18H by Frederick Emmons Terman.
1000pF yeilds 4.6Khz of resonance frequency. Bingo!
What can be done then?
1. Make windings thinner. Let's say three times => 6.5kHz
2. Lower turns count 2 times => 13kHz
Still no good?
Looking at the formula again: Ls is proportional to N square. On the other hand it's linearly proportional to the turn's mean length. Furthermore, cross section and, subsequently, number of turns at the given flux density is square to the mean length.
Let's double the cross section, N goes down 2 times length goes up 1.4 times Ls is now 1/4*1.41=.325. So 13kHz/(square root of 0.325)=22.8Khz
Almost there.
Going this way one Finnish guy made x-former good to drive 10nF or 20 nF panels if memory serves me right.
Cheers,
Alex
P.S. He was using amorph core(s) for a purpose. Amorph has really low coercive force and rather high permeability thus keeping magnetizing current reasonably low when turns number is low and cross-section is high.
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Thanks Alex ! for the effort! that makes my head spin 🙂 i see i am greatly out of my confort zone to be sure 🙂. in the case of a transformer i rahter wind one then deisgn one, seems everyone that commented already have a pretty well idea how such a tranformer would look like and how to calculate all the different parameters . to bad i still cant work with any of it.
by the way its a funny subject that reaches back to verry old books 🙂
I wish I could use original Maxwell equations...
Nevertheless,
stray inductance is proportional to the volume defined by the lines at the center of windings. Usual approach is to replace the winding with single turn of the same volume. It's simple algebra after that.
Elektrostaten Techniek Step-up Trafo is covering yet another problem, interwinding or stray capacitance which adds up to panel one.
The solution offered was to use wire with rather thick insulation (outrageously expencive by the way, unless you could find old overstock).
That's what you can do:
wind primary on your core of choice,
1/2 of secondary winding thickness using cardboard or paper
single layer of secondary. Now you are ready to measure Ls.
You will get pretty good idea of what to expect of the final x-former.
In case of C-core you need to wind only one leg.
P.S. It's well known that Maxwell just derived equations out of years long experiments by Faraday. And it was a gesture of good will on his side.
P.P.S. There is ESL trafo design on Russian audio forum but I am under impression that you've decided to figure out it all by your self.
Nevertheless,
stray inductance is proportional to the volume defined by the lines at the center of windings. Usual approach is to replace the winding with single turn of the same volume. It's simple algebra after that.
Elektrostaten Techniek Step-up Trafo is covering yet another problem, interwinding or stray capacitance which adds up to panel one.
The solution offered was to use wire with rather thick insulation (outrageously expencive by the way, unless you could find old overstock).
That's what you can do:
wind primary on your core of choice,
1/2 of secondary winding thickness using cardboard or paper
single layer of secondary. Now you are ready to measure Ls.
You will get pretty good idea of what to expect of the final x-former.
In case of C-core you need to wind only one leg.
P.S. It's well known that Maxwell just derived equations out of years long experiments by Faraday. And it was a gesture of good will on his side.
P.P.S. There is ESL trafo design on Russian audio forum but I am under impression that you've decided to figure out it all by your self.
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Thanks allot ! i indeed read the Elektrostaten Techniek Step-up Trafo topis on the esl club, since its in dutch and its rather made simple, wich is good for me. he propposed dual bobines on one complete C core. the transformers hes talking about look like the ones i wind for the small bussiness (only the bobines i wind), my guess is its his design, i might give the transformer he calculates there a try.
Please be aware of the particular secondary wire used. It does have really high breakdown voltage along with high ozone resistance which allows it to work long time without impregnation... please share your build details as you proceed. Thus the community will save you from some "pain".
its normal grade 2 magnet wire used in these stepups, i researched the whole internet today for prices on the c cores, or tape cores , they are called sometimes. only thing i could find whas prices on the strapping band of 4 euro :0 probrable have to buy 30 or something silly
what is it ? complete trannie or a core ? either way 360 dollar..... i got some help from ESLtransformer member on this forum, with some guidelines. and now im looking to find materials. ofcourse a price is mostly influenced by material cost. at least when its about small quantity's.
i hope wescap makes a decent price tag for me on the bobbines and cores 🙂
Hi Joppe,
The site you are refering to is run by Rob de Lugt (Audio4.nl) for the Dutch ESL club, as far as I know. The theory comes from Rutgers (www.by-rutgers.nl/), interesting guy I think.
I believe Rob manufactures trannies applying this theory. He used to have 2nd hand Quad and Audiostatic trannies for reasonable prices and he is based in Den Haag. Worth a try to contact him maybe?
-Rolf
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