I have a question on the output laterals.
I joined a group buy recently and got 4x2 the lower power Exicon ECX10P20/ECX10N20
As stated by fab, needed is:
ALF16P16W, alt= Exicon ECW20P20
ALF16N16W, alt= Exicon ECW20N20
questions:
Is ECX10P20/ECX10N20 possible?
Can I parallel the ECX10P20/ECX10N20 output mosfets without sound quality loss?
Is Profusion the only source for the Exicons?
I joined a group buy recently and got 4x2 the lower power Exicon ECX10P20/ECX10N20
As stated by fab, needed is:
ALF16P16W, alt= Exicon ECW20P20
ALF16N16W, alt= Exicon ECW20N20
questions:
Is ECX10P20/ECX10N20 possible?
Can I parallel the ECX10P20/ECX10N20 output mosfets without sound quality loss?
Is Profusion the only source for the Exicons?
Yes, in the remarks section asked for closest matching on order screen, red/orange preferred.
The ECX10 is a normal single die Mosfet but ECW is double die Mosfet which means 2 identical transistors in parallel in the same package. The advantages of double die are:
1) More available power since equals 2 transistors
2) best match possible since manufactured in same wafer and adjacent
3) double the transconductance and half equivalent RDSon
In this specific topology this is the transconductance that provides an higher open loop gain which also increases the damping factor.
PASS F5 topology has been tried with single die lateral Mosfet but the resulting damping factor is so low (lower than my own criteria) that the bass is not controlled enough amongst other things ...
Even double die Mosfet is not sufficient so that is why an additional Mosfet driver is inserted in the circuit. Therefore both Mosfet driver and double die Mosfet are required to get the expected sound.
Doing parallel single die Mosfet can of course be done but at the expense to have difficulty to get a real good match between the same channel type (N or P) thus may require higher source resistor value to get proper current sharing which in turns will reduce the open loop gain and also damping factor,... also the pcb can not received 2 pairs of Mosfet thus would require wires to the Mosfet which is not optimal...
Fab
For clarification The selected version is not mandatory. It can mainly be useful for the USSA-3 If you can get red or orange color band to optimize the possibility to get an higher damping factor (because ussa-3 has an implicit lower damping factor than ussa-5). Even then this is more the transconductance that is the main criteria and this parameter selection is not offered.
For the ussa-5 the possible higher damping factor with red color band Mosfet selection has not an overall significative effect. However, having any color band but the same for the same channel (N or P) can ensure 2 channels (left and right) with closer identical characteristics. But generally if both Mosfet (one per channel) of the same type (N or P) are from the same lot than they are close enough. That was the case with the Alfet Mosfet where no selected VGS option was available.
Fab
Thanks asanden
That is probably more simple to order not selected Mosfet output to get about the same result anayway...
That is to say that the benefit of ordering specific selected parts may be marginal but it cannot hurt. But I did not do it for my own amp.
Fab
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Thanks. I saw that, I wasn’t sure if that meant red pair AND orange pair, red OR orange pair, each pair one red and one orange and so on.
Now I’m clear. If you can’t tell already I’m not Canadian ;-)
Painfully explicit is the American way... for better or worse.
Fab I just wanted to comment on your use of Polymer caps.
I seem to be also in this small minority who believe them to be the superior choice- most still reach for Silmic II, Nichicon Muse, Blackgate and so on. I see no contest where the voltages and values are appropriate.
It’s rare to see Polymers in a BOM here to be honest.
Maybe they are too newfangled and suspect to be cool yet...
I see it as a similar dilemma with C0G.... still can’t get a foothold on the diehard mica crowd.
I seem to be also in this small minority who believe them to be the superior choice- most still reach for Silmic II, Nichicon Muse, Blackgate and so on. I see no contest where the voltages and values are appropriate.
It’s rare to see Polymers in a BOM here to be honest.
Maybe they are too newfangled and suspect to be cool yet...
I see it as a similar dilemma with C0G.... still can’t get a foothold on the diehard mica crowd.
If you look at the specs of the polymer caps that Fab employs in the BOM you realise this: they are excellent products-very low esr, high ripple, high temp.
I built my amp using exactly what he specifies in the BOM because I wanted to hear his design. Which brings me to my point- the order of importance in a build:
1. Design
2. Active components
3. Passive components
Cheers,
Greg
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1) Cresnet, Jordan
2) ernesternest
3) trung224
4) sthcoaster, UK or Indonesia
5) hallcon83, USA Texas - 2 stereo sets
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Thanks Fab. I am flying the NZ flag as that is my origin/nationality but I am based in Indonesia but if these boards are available during August I can receive at "home" in the UK. Thanks.
2) ernesternest
3) trung224
4) sthcoaster, UK or Indonesia
5) hallcon83, USA Texas - 2 stereo sets
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Thanks Fab. I am flying the NZ flag as that is my origin/nationality
but I am based in Indonesia but if these boards are available during August I can receive at "home" in the UK. Thanks.
When I made my first USSA I knocked Fab out of many questions to replace parts by others and Fab always answered me with very convincing technical arguments.
