Hi All
i have sitting around a 300VA transformer and bits to make a power supply of abt +/-50v dc rails (prob just a bit less..)
I am wondering if i can make a higher voltage Aleph M (single pair of irf240 outputs) or even a scaled down Aleph 2 with fewer output mosfets (1 pair??)
(could i use the same PC board values for an Aleph 2 ??)
What happens when you reduce the number of output mosfets and keep everything else the same??
Purpose could be either a tweeter amp . or a headphone amp (Stax electrostatics)
Currently using an Aleph 5 clone which has been chugging away for years
but due to extremely high local electricity costs has a low bias switch for background listening- hence also looking at lower running costs.
Any comments gratefully accepted
Thanks in advance
i have sitting around a 300VA transformer and bits to make a power supply of abt +/-50v dc rails (prob just a bit less..)
I am wondering if i can make a higher voltage Aleph M (single pair of irf240 outputs) or even a scaled down Aleph 2 with fewer output mosfets (1 pair??)
(could i use the same PC board values for an Aleph 2 ??)
What happens when you reduce the number of output mosfets and keep everything else the same??
Purpose could be either a tweeter amp . or a headphone amp (Stax electrostatics)
Currently using an Aleph 5 clone which has been chugging away for years
but due to extremely high local electricity costs has a low bias switch for background listening- hence also looking at lower running costs.Any comments gratefully accepted
Thanks in advance
Not sure what you can do with it. Aleph is single ended class A, and does not go into class AB. Max amps are limited to the level of your bias.
With high rail voltage, you cannot have high bias unless you parallel devices (like aleph 2) to spread the heat. Heat per device is rougly rail voltage times bias divided by number of devices.
Unless you have very, very high impedance speakers, I would forget aleph for that transformer.
If you want to reduce electricity costs, lower your rail voltage and reduce bias to as low as you need to listen to.
With high rail voltage, you cannot have high bias unless you parallel devices (like aleph 2) to spread the heat. Heat per device is rougly rail voltage times bias divided by number of devices.
Unless you have very, very high impedance speakers, I would forget aleph for that transformer.
If you want to reduce electricity costs, lower your rail voltage and reduce bias to as low as you need to listen to.
ZM beat me to it
To stay safe, a 300VA transformer is used up to half the VA rating in Watts.
==> 300 ÷ 2 = 150W
Stereo, so each channel can use half, or 75W
Consider that P = V I
and I = V / R (Ohm's law)
so P = V V / R or R = V V / P
Nelson mainly uses 18V secondary transformers in FW amps, giving roughly 24V rails.
R = V V / P
R = 24 x 24 / 75 = 7.7 Ohm
Most of Nelson's FW amps are designed for 8 Ohm speakers.
At 50V you get:
R = 50 x 50 / 75 = 33.3 Ohm
Not many 32 Ohm speakers ...
There are 32 Ohm headphones but you would not need that much power.
So, use the transformer to build a class AB or class D and buy something else for class A (like an Aleph).
To stay safe, a 300VA transformer is used up to half the VA rating in Watts.
==> 300 ÷ 2 = 150W
Stereo, so each channel can use half, or 75W
Consider that P = V I
and I = V / R (Ohm's law)
so P = V V / R or R = V V / P
Nelson mainly uses 18V secondary transformers in FW amps, giving roughly 24V rails.
R = V V / P
R = 24 x 24 / 75 = 7.7 Ohm
Most of Nelson's FW amps are designed for 8 Ohm speakers.
At 50V you get:
R = 50 x 50 / 75 = 33.3 Ohm
Not many 32 Ohm speakers ...
There are 32 Ohm headphones but you would not need that much power.
So, use the transformer to build a class AB or class D and buy something else for class A (like an Aleph).
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