Hi, sorry if this topic has been discussed before, but I'm curious about differences between transformers. At the moment I use two 1:75 Audiostatic transformers per ESL. They sound rather good in my opinion. But I'm wondering if there are better transformers out there.
I'm curious about different transormers: do they sound different (better / worse)? For instance, the Amplimo / Plitron toroidal transformer. Unfortunately they are too expensive to just buy and test. How do they compare to cheap toroidal power transformers?
I'm curious about different transormers: do they sound different (better / worse)? For instance, the Amplimo / Plitron toroidal transformer. Unfortunately they are too expensive to just buy and test. How do they compare to cheap toroidal power transformers?
Hi,
the original Audiostatic transformers are of very low quality.
They have a high stray inductance which leads to a reduction in upper bandwidth limit due to the resonace peak that forms together with the panel´s capacitance.
Even though the panels are of the segmented type and have a reduced capacitance towards the upper end, the trannies don´t even allow for 20kHz bandwidth.
On the other hand the required series damping resistor and the high losses reduce the burden for the amplifier considerably .... which leaves You with a greater choice of less capable/stable amplifiers.
The Amplimos are clearly far better.
But that does not necessarily show up in praxis.
I once was asked if I could replace the original transformers of a ML Sequel with Amplimos.
In the end it shopwed that though the ML transformers were equally crappy as the Audisotatics, the end result with the Sequel didn´t improve.
I also compared the Amplimos with power toroids on my non-segmented panels (2pcs. 230V/9V/120VA).
The most noteable differences were
a) the Amplimos can be used fullrange, while the power toroids are useable almost only for hybrid concepts >100Hz.
b) the upper bandwidth limit at a panel load of ~2nF was a bit higher (~22kHz vers. 18kHz)
c) sonically there was no difference to my ears.
jauu
Calvin
the original Audiostatic transformers are of very low quality.
They have a high stray inductance which leads to a reduction in upper bandwidth limit due to the resonace peak that forms together with the panel´s capacitance.
Even though the panels are of the segmented type and have a reduced capacitance towards the upper end, the trannies don´t even allow for 20kHz bandwidth.
On the other hand the required series damping resistor and the high losses reduce the burden for the amplifier considerably .... which leaves You with a greater choice of less capable/stable amplifiers.
The Amplimos are clearly far better.
But that does not necessarily show up in praxis.
I once was asked if I could replace the original transformers of a ML Sequel with Amplimos.
In the end it shopwed that though the ML transformers were equally crappy as the Audisotatics, the end result with the Sequel didn´t improve.
I also compared the Amplimos with power toroids on my non-segmented panels (2pcs. 230V/9V/120VA).
The most noteable differences were
a) the Amplimos can be used fullrange, while the power toroids are useable almost only for hybrid concepts >100Hz.
b) the upper bandwidth limit at a panel load of ~2nF was a bit higher (~22kHz vers. 18kHz)
c) sonically there was no difference to my ears.
jauu
Calvin
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That is the cross-over network. Can't see the whole schematic but if this is a hybrid, it separates the lows for the woofer and the mid/highs for the panel.
It may also provide equalization of the freq response and/or impedance flattening to make life for the amp a bit easier.
Calvin will know more details.
Jan
It may also provide equalization of the freq response and/or impedance flattening to make life for the amp a bit easier.
Calvin will know more details.
Jan
Link to post describing how the Audiostatic transformers are wound to achieve the intentionally high leakage inductance.
DIY ESL
As Calvin mentioned, unless your segmented ESL has very low capacitance you may have issues with roll-off in the top octave. However, the high leakage design will have a much more resistive phase angle in the upper 3 octaves than for the Amplimo or Plitron toroidal. This will often results in amplifier frequency response being considerably different in the HF range...often peaking with the toroidal making you think there is more detail. When performing comparisons between the two, it will be important to measure the response at the primary winding to ensure they are the same. Otherwise you may draw a false conclusion about transformer quality when it is just the amplifier’s frequency response that has changed.
In my experience, the quality of the HF was not audibly different between toroid and high leakage design as long as the frequency response was equalized between the two.
If the main primary winding gives 70:1 step-up ratio, connecting to the CT gives 140:1 step-up ratio. This provides additional flexibility in equalizing the dipole roll-off of the ESL panel when the wavelength gets longer than the panel width.
Dipole phase-cancellation in ESL speakers
For Fullrange designs, it could be used similar to the Audiostatic Mirror drive setup.
Audiostatic's "mirror drive": DIY possible?
In the Odyssey, ML appears to use it to help shape the equalization of the dipole roll-off.
A smoother, less peaky curve is achieved than the usual underdamped 2nd order HP filter approach.
Toroids for ESL's
In older designs, ML connected shunt inductance to the CT rather than actively driving it.
My only thought on this was that it allows the use of lower value inductors, so might have been cheaper or just physically smaller.
Toroids for ESL's (compare Figure A vs Figure B)
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