Roender's FC-100 Rev.1 Group-Buy

[zsaudio]

Maybe it's time to buy the last pieces from the market.

2SA1360?Bipolar Transistors?TOSHIBA Semiconductor & Storage Products Company

[Rudi_Ratlos]

Patrick,

the max. grid of the input DC-blocking input capacitor is 15mm.

Everybody has to decide by himself, if he needs an input-cap at all.
If he is sure that all of his music - sources are AC-coupled, he doesn't need.

If not:

I recommend to use of MKT1822 bypassed by MKP1837.
I use this combination myself: I "glued" the MKP on the solder-side and then soldered it.

The value: max. value with a grid of 15mm.

Do you have any other recommendation?

Best regards - Rudi

[meanman1964]

At a dutch forum someone is offering Vishay-Roederstein 1820/10µF MKT's for a fair price.You always can bypass them with the MKP1837

[julius20]

I used this one: IT-Tronics - 5x MKT Kondensator radial 10uF 100VDC RM27,5 ; RoHS ; 1822610015

they will be 5€ for five pieces ( Roederstein MKT1822/100V )

[10y]

Hi Rudi,

I am in for one set output transistors, shunt pcb, speakers protection and turn on delay pcbs.

Count on me for any support you need for this GB.

Thank you !

Anto

[jprco]

Rudi, can this version of the F100 use the NJL1302DG/NJL3281DG pair without any modifications?

[AndrewT]

If you can find an old stock polycarbonate folded film (rather than wound) then it is almost as good as polypropylene at half the price and half the size.

I think the carbonates are better than the various esters and terephthalates.

Polyethylene terephthalate (sometimes written poly(ethylene terephthalate)), commonly abbreviated PET, PETE, or the obsolete PETP or PET-P,

[Rudi_Ratlos]

Julius, the 10µF MKT1822 has a grid of 27.5mm , whereas the PCB offers space for a 15mm grid capacitor only.

The input capacitor C15 blocks DC; together with resistor R26 it defines a highpass - filter.
It is not essential to use a 10µF on this position. I myself use a 2.2µF MKT1822.

And, please remember: "The best filter is no filter at all!" Mihai does not use this capacitor in his original schematics!
Maybe all of your music-sources are already AC coupled: then you need not install C15 but use the jumper.
For me, it is a "Must have", because I am DIYing all kind of music-sources (Pre-AMPs, DACs, ...), and maybe that one of my builds is not working properly.

Anto: you are very welcome!

Jean: maybe, I never tested this, but I would not use the NJL1302D/NJL3281D pair of transistors.
The reason why: the output capacitance (COB) of the pair of NJL1302D/NJL3281DG is much higher (600pF) compared to the COB
of a pair of NJL0302D/NJL0281D, which is 400pF.
The drivers have to load/unload this excess of capacitance, and I am afraid that this will affect the overall operation.

Perhaps somebody else knows it better.

Best regards - Rudi_Ratlos

P.S. Andrew: thank you for your hint.

[AndrewT]

Don't make the input cap too big.

The filter, if you decide to fit it, must set the LF bandwidth.

That bandwidth MUST be properly amplified by the Power Amplifier.
That requires all the following filters to be wider band than the input filter.
Even the PSU filter must be wider than the input filter.

Your sch shows 10uF and 22k+2k for a 240ms time constant.
That gives a F-3dB = 0.66Hz.

That would require that the amplifier can handle frequencies down to that level.

A 3u9F or 3u6F would suit me. Try it. Even 3u3//22n might be good enough.

[Rudi_Ratlos]

Andrew, I will correct the schematics im my "Builder's Manual".

I will send this manual to all participants of this group-buy at the time, the group-buy is closed.

Best regards - Rudi