options for the capacitors
I bought this 5.0uF AuriCap for the Mid/bas Capacitor change:
AuriCap 5 0uF 10 400V AUR505K400VA
And some cheaper capacitors from ClarityCap for the tweeter:
https://www.madisound.com/store/product_info.php?products_id=8148
https://www.madisound.com/store/product_info.php?cPath=404_5_351_353&products_id=8147
What is really wierd is that the blue capacitor on my crossover is a 4.7uF capacitor and according to the schematic it should be a 4.2 so have not ordered the last capacitor yet, is it better to pick a 3.9uF?
/Mattias
Hi Mattias,
you have done things in the reverse of the usual audible priorities with the capacitors you have bought.
Usually one would would use any better audio quality caps in the tweeter filter, as any advantages would be more audible there than in the bass filter,
because the treble caps are in direct Series connection with the tweeter,
but in the bass filter that particular capacitor is a shunt bypass,
from in between two inductors to ground,
thus its audio signature is modified by the inductors to greater degree than will be the case for the caps in the treble circuit.
A modern low Dielectric Absorption capacitor, which Polypropylene caps are,
and that is otherwise well designed and not faulty in assembly will be quite adequate in the bass filter.
I would install the ClarityCap PX 5.0uF there.
That 5.0uF Auricap is ridiculously expensive for a +/- 10% Tolerance component !
With +/- 10% tolerance variations, you may get 4.5uF or 5.5uF, and worse is that you may get one of each !
... and that will cause an audible difference between the two loudspeakers.
As you have ordered 4.7uF in a +/- 5% Tolerance cap for the treble, I recommend that you send the 5.0uF Auricap back and ask for exchange for a 5.6uF polypropylene cap that is AT LEAST in +/-5% Tolerance,
plus include two 27 ohm/10 watt resistors in the order.
A 27 ohm resistor connected in Parallel with the Kef tweeter will reduce its mid-band Impedance sufficiently to allow 4.7uF and 5.6uF to work with it,
AND, the resistor will in-part reduce the effect of the tweeter's resonant frequency -{ Fs }- on the circuit.
"in-part" - it will NOT completely remove the effect of the tweeter's Fs, which is what the ab T-network does,
but it will produce a response that is towards that and better than without any resistor.
Ideally the inductor in the treble filter should be reduced a little in mH also, after the 27 ohm resistor is installed,
but for initial listening try with simply the caps changed, then Post here about the audible change.
After that you can buy a slightly smaller mH inductor for the treble circuit at the same time as you buy new inductors for the bass circuit after you have decided which of the Tap settings you and your girlfriend prefer from the large inductor.
If you like aspects of two adjacent settings of the tapped inductor, then an in-between mH inductor can be put in there, as there are plenty of options available currently.
ClarityCap PX are quite good audio quality. The Auricap may cause better sound in the treble circuit, but ONLY if it is close to its Nominal Specified capacitance, and not 4.5uF !
If both the Auricaps measure 5.5uF, or very near to that, then they will be suitable in the treble filter instead of a 5.6uF cap there,
but if they aren't near 5.5uF, or if you can't measure them, then I advise you exchange them unused, as I described above.
You do not need Auricap price components with Kef 104.
What does the seller have in 5.6uF at +/-5% Tolerance or better, at reasonable price ?
You can then obtain the 27 ohm resistors to fill your Credit balance.
If that does not entirely fill the Credit balance, then request two 2.2 ohm resistors in at least 5 watt rating
{though higher power is better to ensure they stay cool during high signal levels}.
These I will advise where to install when you buy the new inductors.
