Hello guys,
I have a gyrator at the top of a 300B tube and am looking to hook up a parafeed cap to a cheap 1:1 or step-up transformer that would be used to produce the balanced drive for electrostatic headphones.
Anyone know how I would go about determining specs on a transformer suitable for electrostatic headphones? As the transformer is hooked up parafeed, it doesn't need a gap for DC. I was thinking something cheap such as the Hammond 1182G117 toroidal, however here are the measurements that Hammond sent me for this transformer:
"The results at 60Hz are as follows:
Primary connected for 120V is 42.4H at 1V 60Hz.
Primary connected for 240V is 112H at 1V 60Hz.
The leakage inductance connected for 120V is 1.68H at 1V 60Hz.
The leakage inductance connected for 240V is 7.13H at 1V 60Hz.
Leakage inductance at 1kHz is 17.24mH"
I have a gyrator at the top of a 300B tube and am looking to hook up a parafeed cap to a cheap 1:1 or step-up transformer that would be used to produce the balanced drive for electrostatic headphones.
Anyone know how I would go about determining specs on a transformer suitable for electrostatic headphones? As the transformer is hooked up parafeed, it doesn't need a gap for DC. I was thinking something cheap such as the Hammond 1182G117 toroidal, however here are the measurements that Hammond sent me for this transformer:
"The results at 60Hz are as follows:
Primary connected for 120V is 42.4H at 1V 60Hz.
Primary connected for 240V is 112H at 1V 60Hz.
The leakage inductance connected for 120V is 1.68H at 1V 60Hz.
The leakage inductance connected for 240V is 7.13H at 1V 60Hz.
Leakage inductance at 1kHz is 17.24mH"
That toroidal doesn't seem to have a screen. This might be quite useful to reduce noise. Isn't noise a typical issue with this kind of headphones?
At low frequency it sounds good as the 300B has low plate resistance.
I don't think other PSU toroidals of similar construction have much different leakage but you could ask AnTek. They make most of their toroidals, if not all, with screen by default...
Among the true audio transformers off-the-shelf I don't think you have a choice for one reason or another, unless you go for a custom design which might not be cheap as you like.
At low frequency it sounds good as the 300B has low plate resistance.
I don't think other PSU toroidals of similar construction have much different leakage but you could ask AnTek. They make most of their toroidals, if not all, with screen by default...
Among the true audio transformers off-the-shelf I don't think you have a choice for one reason or another, unless you go for a custom design which might not be cheap as you like.
I'm not too worried about noise getting through, the B+ supply and other power supplies will be extremely well filtered.
Moreso just unsure of how to go from the values for inductance and leakage inductance provided by a manufacturer, to determining the high and low frequency roll-off into a pair of electrostatic headphones.
E.g. does a particular PSU toroid with 17.24mH of leakage inductance measured at 1kHz have significant roll-off at high frequencies into an electrostatic headphone load?
If anyone knows formulas to calculate this it would be great.
Moreso just unsure of how to go from the values for inductance and leakage inductance provided by a manufacturer, to determining the high and low frequency roll-off into a pair of electrostatic headphones.
E.g. does a particular PSU toroid with 17.24mH of leakage inductance measured at 1kHz have significant roll-off at high frequencies into an electrostatic headphone load?
If anyone knows formulas to calculate this it would be great.
A center-tapped push-pull output transformer could be driven on one end, with the CT grounded, to get balanced output. You don't need the secondary winding, but such transformers are widely available at all price and quality levels, and are usually designed specifically for balanced operation. You can always use the secondaries to drive dynamic phones and/or speakers.
The leakage inductance will resonate with the headphone plus winding capacitances, so the frequency is easy to calculate. The damping (Q of the resonance) is more complicated.
Well, without real numbers it's hard to say. But the high impedance of the phone could be the key for good response.
If the transformer is cheap you can find out rather quickly. I strongly suggest you do it for real as estimating all actual capacitances is a nightmare....
If it doesn't work a good power supply transformer can always be useful....
If the transformer is cheap you can find out rather quickly. I strongly suggest you do it for real as estimating all actual capacitances is a nightmare....
If it doesn't work a good power supply transformer can always be useful....
