I was wondering if you could use a transformer without a center tap for an esl by using something like 32 1 megaohm resistors in series connected to the primaries and connecting the HV supply between the 16th and 17th resistor and the membrane.
Also I was wondering how these small 1,5 VA transformers would work when using 10 of them, connecting all the primaries in parallel and all the secondaries in series, their frequency response could be very bad, but at 60 cents a piece it might be worth a shot.
Also I was wondering how these small 1,5 VA transformers would work when using 10 of them, connecting all the primaries in parallel and all the secondaries in series, their frequency response could be very bad, but at 60 cents a piece it might be worth a shot.
Attachments
Small trannies saturate much quicker than large ones.The larger, the better... It is recommended to put a small value resistor ~0.5 ohm at amp's output. ESL to amp looks like a large cap , so resistor can prevent oscillation , which could destroy output transistors.
A simple amp for driving ESL can be built from LM3886 , as it is easy to build , and is very hard to destruct.
Regards,
Lukas.
A simple amp for driving ESL can be built from LM3886 , as it is easy to build , and is very hard to destruct.
Regards,
Lukas.
I might have a better option, 60 VA 100 volt line transformers from amplimo, I have sent them an email about what turn ratio they have but I have received no reply as of yet.
And another question, would it be ok to use a 5 meter 3 wire cable to carry both the audio signal coming from the transformer as well as the 3500 volt polarizing supply? The isolation is normal pvc.
And another question, would it be ok to use a 5 meter 3 wire cable to carry both the audio signal coming from the transformer as well as the 3500 volt polarizing supply? The isolation is normal pvc.
toroids
Hi,
beeing power trannies, the toroids don´t saturate that easily. As standard trannies they are usable for mid-high-frequencies only -no fullrange mode- which reduces saturation probs further. a pair of 50VA types is sufficient to even drive big high capacitance panels. The voltage rating of the insulation is quite high and can be improved further by vacuum dipping with a varnish.
jauu
Calvin
Hi,
beeing power trannies, the toroids don´t saturate that easily. As standard trannies they are usable for mid-high-frequencies only -no fullrange mode- which reduces saturation probs further. a pair of 50VA types is sufficient to even drive big high capacitance panels. The voltage rating of the insulation is quite high and can be improved further by vacuum dipping with a varnish.
jauu
Calvin
bobo1on1 said:
Line transformers may have even lower turns ratio then mains toroids.I don't know about amplimos line trannies.You should ask for more parameters , like frequency response ,etc.
I have tried one 250W 220V/12V main toroid at 20 volts input(Reversed).The output was somewhere near 400V , and THD @ 1 khz was around 0.1% .Interestingly , THD rose with input voltage, probably due to increasing core saturation.
Frequency response went up to 20 kHz and more.Lower limit at this voltage was ~100-150Hz.
The transformer also produced quite much of sound itself
)Here is a quote from amplimo's website:
They seem to be rather good quality, I still don't know their turns ratio though.
I am going to call the store that sells them.
I was thinking about the normal the normal power cord used for 230 volt applications, the isolation is 0,5 milimeter I think.
I have a better idea, if I use the wire to transport 24 volt ac I can feed that to the polarizing supply at the esl.
They seem to be rather good quality, I still don't know their turns ratio though.
I am going to call the store that sells them.
hilbren said:
I was thinking about the normal the normal power cord used for 230 volt applications, the isolation is 0,5 milimeter I think.
I have a better idea, if I use the wire to transport 24 volt ac I can feed that to the polarizing supply at the esl.
Simple math:
If the input voltage is 100V , output Z = 4 ohms , P = 60W.
So, Vout=60/4=15 volts.
Turns ratio is 100/15 = 6.6
Not so good.
if P is lower , output V is lower too , and turns ratio is higher.
Search for old tube amp trannie , if you can get it.
For now i am building a headphone direct drive amp , maybe it will be able to drive small ESLs in low volumes - i will try if i succeed... a prototype works at 100V Rms output , but final project is targted to 400VRms.
Regards,
Lukas
If the input voltage is 100V , output Z = 4 ohms , P = 60W.
So, Vout=60/4=15 volts.
Turns ratio is 100/15 = 6.6
Not so good.
if P is lower , output V is lower too , and turns ratio is higher.
Search for old tube amp trannie , if you can get it.
For now i am building a headphone direct drive amp , maybe it will be able to drive small ESLs in low volumes - i will try if i succeed... a prototype works at 100V Rms output , but final project is targted to 400VRms.
Regards,
Lukas
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