Interesting reference, Andrew. I printed AN003 out for my literature reference collection.
I am using the unbalanced inputs on my amp (1/2 meter Zu Varial cable from Eq to amp), and the equalizer does not have balanced outputs, so 10uF should be fine. The stock output cap was a polarized electrolytic, so that's what I initially substituted with (Muse), but since I clipped that out of the circuit, the transparency is much improved.
I am using the unbalanced inputs on my amp (1/2 meter Zu Varial cable from Eq to amp), and the equalizer does not have balanced outputs, so 10uF should be fine. The stock output cap was a polarized electrolytic, so that's what I initially substituted with (Muse), but since I clipped that out of the circuit, the transparency is much improved.
Since the Toshiba 2SK2013 chips are on their way to me anyway, and I have a few IXYS IXCP10M45S CCS chips lying around from a previous project, I was thinking I might want to take a shot at improving the buffer stage.
What do you think of this idea:
Swap the Toshiba MOSFET for the VN40AD stock MOSFET(pinouts are the same), then use the IXYS chip with an adjustable pot to dial in various bias currents to see what works best. I would wire the IXYS to the source and drain connections for the stock CCS MOSFET on the board, then connect the gate of the IXYS to the cathode using a 500ohm pot. I could then dial in any current level and listen. When I find the best level soundwise, I can replace the pot with a fixed resistor of the same value.
Here's a link to the IXYS datasheet:
http://www.datasheetsite.com/datasheet/IXCP10M45S
Any major issues with this idea? Anyone want to guess what bias current will sound best with the Toshiba 2SK2013?
What do you think of this idea:
Swap the Toshiba MOSFET for the VN40AD stock MOSFET(pinouts are the same), then use the IXYS chip with an adjustable pot to dial in various bias currents to see what works best. I would wire the IXYS to the source and drain connections for the stock CCS MOSFET on the board, then connect the gate of the IXYS to the cathode using a 500ohm pot. I could then dial in any current level and listen. When I find the best level soundwise, I can replace the pot with a fixed resistor of the same value.
Here's a link to the IXYS datasheet:
http://www.datasheetsite.com/datasheet/IXCP10M45S
Any major issues with this idea? Anyone want to guess what bias current will sound best with the Toshiba 2SK2013?
An alternate idea:
Looking for an opinions on what the effect might be of raising the bias current to 50mA or so using the IXYS CCS chips mentioned above, but keeping the stock VN40AD MOSFETs. Might I expect to see improved sonics using a higher current? Is that a general rule with MOSFETs?
Any help is greatly appreciated.
Looking for an opinions on what the effect might be of raising the bias current to 50mA or so using the IXYS CCS chips mentioned above, but keeping the stock VN40AD MOSFETs. Might I expect to see improved sonics using a higher current? Is that a general rule with MOSFETs?
Any help is greatly appreciated.
Magz,
However, to achieve a significant improvement you need to build a crossover with discrete architecture, I`m afraid, in this manner: current buffer-active crossover stage(s)-current buffer. The current requirement for the first two sections is larger, driving the passive elements, while it is moderate for the last one, allowing to use better small signal devices (JFETs).
It is.
However, to achieve a significant improvement you need to build a crossover with discrete architecture, I`m afraid, in this manner: current buffer-active crossover stage(s)-current buffer. The current requirement for the first two sections is larger, driving the passive elements, while it is moderate for the last one, allowing to use better small signal devices (JFETs).
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