If the resistors are from Pacific, I belive they are wire wound with a byrillium core for better heat dissipation (MIL-R-26 & MIL-R-18546), I do not belive they are beyrillium film.
The power dissipation discussion led to a simple realization that this thing is going to limit damping factor to 320 and below for an 8 Ohm load. (if wired in the speaker lines) It might even be more important to consider the effects on high frequency response of some amps, mainly stability, Again, I recommend that there might be something interesting to see by making recordings of output signals in many different systems where listening description are available. Maybe some square wave burst tests (safely done of course) would be interesting too. It would be nice to have Very high recording bandwidth for the square wave tests even if fidelity is not superbe. Maybe a storage scope.
I don't care about speaker microphone effect or any other ways to get scared of collecting as much data as possible.
I don't care about speaker microphone effect or any other ways to get scared of collecting as much data as possible.
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Beryllium core or beryllia (beryllium oxide) core? Beryllia has the highest thermal conductivity of any nonmetal, except diamond.
John
Beryllia. That's the same kind of confusion one sees in sloppy wording between silicon (chips) and silicone (tits).
In looking at their site, Pacific seems to be all wirewound. And, their site states either alumina, which is aluminum oxide, or beryllium, which is a metal. (of course they mean beryllia).
They do have non inductive styles as well, which is the bifilar style of winding. They also list the resistance temco as 90 ppm/degree C, which would indicate the resistance material.
Yep. Luckily, I've yet to confuse the (two). 😉
Cheers, John
Hi SY,
-Chris
At 0R025, the terminal contact resistances may swamp out the device resistance. I see four contacts (minimum) in series for a speaker to amplifier circuit. Then you may have a relay contact and other connections on top of that.
-Chris
FWIW, 25 milliohms is the equivalent of 25 feet of 10 AWG copper wire (or 1 foot of 24 AWG copper).
SY, did you find any noise reduction? That's what most of the listening tests seem to indicate, as well as the power trace JC posted.
So far, none whatever. To be fair, I don't have enough sensitivity to determine if the addition of the 25 milliohms increases the noise by the amount predicted by the Johnson equation, but there's no noticeable decrease, either.
Do we know which devices were used with the traces JC posted? I seem to remeber those traces were 15 years old or so, and that SY's samples are relatively new products.
jan didden
Hi Jacques,
Once you figure that out, we have insertion loss in the speaker crossover and connection resistance to the drivers as well. Then there is the effective impedance of the actual driver (speaker).
It's pretty easy for the effect of 0R025 to get lost in the woods when installed in a real system. Still, maybe they do make some difference in a system. It really depends on whether anyone can measure any parameter that differs from an equivalent resistor.
-Chris 🙂
Wrong comparison. I was talking about contact resistance between the wire and connections to the amplifier and speaker system. The average connections, not the ones that SY or anyone use to taking measurements would make.
Once you figure that out, we have insertion loss in the speaker crossover and connection resistance to the drivers as well. Then there is the effective impedance of the actual driver (speaker).
It's pretty easy for the effect of 0R025 to get lost in the woods when installed in a real system. Still, maybe they do make some difference in a system. It really depends on whether anyone can measure any parameter that differs from an equivalent resistor.
-Chris 🙂
Chris,
My bad. I didn't intend that to be interpreted as in opposition to your statement, (even though it sure looks that way), only as a palpable reference to something tangible. I too find it hard to believe that 25 milliohms is significant in the context of everything else in the circuit.
Assuming that these are built similar to the QPs that were dissected with a conductive outer shell, I wouldn't be surprised to find some eddy current losses in the shell. That should result in a resistance that increases slightly with increases frequency. Unlike an inductive impedance increase, I would expect an impedance increase from eddy currents to be lossy (i.e., not reactive). That could explain the rising resistance measurements of the previous units.
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