Firstly find a 5W resistor that does not cost you a fortune that has a lower resistance.
Secondly what is the tempco of the transconductance of the MOSFETs ?
Thirdly, the MOSFET current increases with temperature.
That means a positive tempco for transconductance, or negative tempco for effective source resistance.
When the MPC74 has a positive tempco, it counteracts that of the MOSFET (at least partly), and hence enhance thermal stability and reduces bias change with heatsink temperature.
Not always a perfect resistor is good everywhere. Horses for courses.
All well thought through.
Patrick
Secondly what is the tempco of the transconductance of the MOSFETs ?
Thirdly, the MOSFET current increases with temperature.
That means a positive tempco for transconductance, or negative tempco for effective source resistance.
When the MPC74 has a positive tempco, it counteracts that of the MOSFET (at least partly), and hence enhance thermal stability and reduces bias change with heatsink temperature.
Not always a perfect resistor is good everywhere. Horses for courses.
All well thought through.
Patrick
Actual Coefficient Unknown
I do not know what the actual temperature coefficient of resistance that this part has - but it would probably be a number such as +0.004, factor of resistance change per degree C.
It would be a value between +0.003 and +0.006 depending on the composition of the metal or metal alloy they use.
The spec sheet for the MPC71 series lists the variability of the temperature coefficient (presumed to be over the operating temperature range) as +/- 0.000350, that is under 10%.
The MPC74 series is said to be more linear than the MPC71 series as intended for audio amplifiers. Maybe it is 9% or 7% - who knows.
What matters more to the thd (distortion) result is the matching accuracy if you are using a Class B (also known as "push-pull") configuration.
I do not know what the actual temperature coefficient of resistance that this part has - but it would probably be a number such as +0.004, factor of resistance change per degree C.
It would be a value between +0.003 and +0.006 depending on the composition of the metal or metal alloy they use.
The spec sheet for the MPC71 series lists the variability of the temperature coefficient (presumed to be over the operating temperature range) as +/- 0.000350, that is under 10%.
The MPC74 series is said to be more linear than the MPC71 series as intended for audio amplifiers. Maybe it is 9% or 7% - who knows.
What matters more to the thd (distortion) result is the matching accuracy if you are using a Class B (also known as "push-pull") configuration.
yeah he was definitely being ironic, thus me laughing enough to spit coffee out of my nose
I guess you want news.
If I am not wrong, the matching is done, and ready to ship.
But the GB leaders and the regional distributors of the Case GB are discussing how many items to send together.
It is quite a bit of organising, especially all by email with different time zones, etc.
But perhaps Horio can give a more precise update.
Patrick
If I am not wrong, the matching is done, and ready to ship.
But the GB leaders and the regional distributors of the Case GB are discussing how many items to send together.
It is quite a bit of organising, especially all by email with different time zones, etc.
But perhaps Horio can give a more precise update.
Patrick
Me too
That is not possible yet unfortunately because all parts from the US (Fukus, PRPs, regulator MOSFETs, Keratherm pads) will be shipped in a single package to me - the European distributor - in order to save postage. Sorry about that.
Once I receive this big parcel, I should be able to send out all your items within a single day to the European participants.
I hope that Horio and/or Fred will give you an update here soon.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.