The thing about Mallorys' is that they are cost effective and still sound good and supposed to be the closest thing to NOS mustard caps? The other stuff like SoZo, et al is that they are pricey$$$.
Now, we're calling the 150 Mallorys' "yellow caps" and these are metal film/metalized polyester but there's also yellow metalized polypropelene - more expensive than the 150s but not too much. Maybe these would be the ones to go to or compare to?
Another thing thing I've read about is how the caps all have a beginning and an ending or outside foil position, except types like ceramic & silver mica. The reputed sound difference is said to be noticeable when paying attention to their orientational placement in this way. Maybe this could be or make the difference for some? Afterall, Aiken, Weber, & others write about this:
The proper way to connect the outside foil is to the low impedance side of the circuit, which, in the case of coupling caps, will normally be the plate of the previous stage. If it is a bypass cap to ground, connect the outside foil to the grounded side. If it is a bypass cap from a signal to B+, connect the outside foil to B+. The outside foil will act as a shield against electric field coupling into the capacitor, so you want it to have the lowest impedance return path to ground.
For AC signals, the power supply rail is effectively at ground potential, just as the ground rail is. This is why it makes a good point to use as a shield ground. This concept is sometimes difficult to understand, but if you think about how a capacitor works, it will become clear. A capacitor has a capacitive reactance that calculated as follows:
Xc = 1/(2*Pi*f*C)
where: Xc is the capacitive reactance
f = the frequency of the signal being passed through the capacitor
C = the capacitance of the capacitor.
As you can see from the above equation, the frequency term is in the denominator, so as the frequency increases, the capacitive reactance decreases. Since reactance is effectively a measure of the "AC resistance" of the capacitor, the capacitor will exhibit a very low resistance at higher frequencies, while looking like an open circuit for DC and frequencies low enough to make the capacitive reactance significant. This means that the large electrolytic bypass capacitors in the power supply are effectively "short circuits" to AC signals above a certain very low frequency. For all practical shielding purposes, connecting the outer foil to the power supply rail is just as good as connecting it to ground. As a side note, electrolytic capacitors have an internal resistance that tends to rise with frequency, which can make the capacitor less than ideal as a bypass at higher frequencies. For this reason, it is sometimes a good idea to bypass electrolytic capacitors with a smaller value foil or other type capacitor.
Proper orientation of the capacitors will make the amplifier much less susceptible to outside noise, including hum, interference from fluorescent lighting, and tendency towards oscillations or frequency-response peaks and dips due to unwanted feedback from nearby signals within the amplifier, which can affect the tone of the amplifier (and is the reason why some people claim the amp sounds different if the caps are oriented in the opposite way - if there is no accidental coupling, there will be no tonal difference, but there will still be a noise benefit gained from orienting the caps the correct way).
Topic: New Mallory M150 White Capacitors (Read 17987 times)