I'm sure you're not suggesting that only the most complicated circuits have
any merit when it comes to sound quality.?
Have a listen to a Nelson Pass class A amp for instance - as simple as it gets.
Are they emitter follower outputs or sziklai?
I don't care for Darlington pairs, very difficult to keep under control.....
That's the bias transistor it can be fitted where the blank pads are or on the main heat sink, I chose the latter.
Does anyone have a rough idea of the price of these yet,I have an old Avondale ampVI that iam thinking of upgrading with these
Clive
HI Les, how much does the BOM differ from the NCC200? I have everything here to build a pair (been sat here for 8 months or so) and am considering switching the build.
Having built both NCC200s (at least six pairs) and the new Qudos boards I would definitely recommend you go with the latter. The BOMs are very similar, there are six MFR5 resistors whose values are changed, you lose a 1N4148 and 100R resistor from the output stage and TR10 changes from an MJ15003 to an MJ15004. It is advisable to fit TR5 on the main heat sink which involves an extra tapped hole on the sink and a change from 2N5551 to BD237, you will need the new board for this as it has additional tracks on the upper surface to enable it. Alternatively you can stick with the 2N5551 as the original pads for this are still present but you lose the improved thermal tracking. The choice of feedback capacitor is a mystery as the ones I received were tightly sleeved. I also had an option of a BC128 or film capacitor for the input coupling and chose the latter.
Good luck,
Malcolm
I have already got MJ15003 's for TR10 for the NCC200 's I was planning to build. Can Les or Malcolm advise if I can use these instead of the MJ15004 's
for the QUDOS ? If so is there a downside ?
Thanks in advance for the advice
Having built both NCC200s (at least six pairs) and the new Qudos boards I would definitely recommend you go with the latter. The BOMs are very similar, there are six MFR5 resistors whose values are changed, you lose a 1N4148 and 100R resistor from the output stage and TR10 changes from an MJ15003 to an MJ15004. It is advisable to fit TR5 on the main heat sink which involves an extra tapped hole on the sink and a change from 2N5551 to BD237, you will need the new board for this as it has additional tracks on the upper surface to enable it. Alternatively you can stick with the 2N5551 as the original pads for this are still present but you lose the improved thermal tracking. The choice of feedback capacitor is a mystery as the ones I received were tightly sleeved. I also had an option of a BC128 or film capacitor for the input coupling and chose the latter.
Good luck,
Malcolm
The late JV said of Naim's use of quasi-complimentary stages that PNP and NPN output transistors were like "a man and a woman pushing on opposite sides against the same wall" or something like that, i.e. they had different capabilities. It was decades ago, though, and things have moved on a lot since then, not least semiconductor technology and feminism.
He also said you couldn't reset the trip on the 250 power supply board. I wrote the board test program that did!