I received a message from Dr. David Robinson, Managing Editor of Positive Feedback, asking me if I could write about the three new ranges of carbon/silver audio resistors from Lefson in Wormhout, France, and he put me in touch with owner Xavier Lefebvre so we could talk about the possibilities.
Lefson makes an impressive array of high-performance studio & home audio products like the DCAD signal distributor for microphones, instruments, line sources, and loudspeakers; the C-MOD (25-50V) and C-MOD HV (630V) capacitors; the C-MOD SPK coupling modules (a specialized style of capacitor exclusively for loudspeakers); and now the Premium, Supra, and Ultra line of resistors, which will be the subject of the upcoming review at Positive Feedback.
Lefson describes their new lines of resistors thusly:
"The Lefson Resistor is a very high performance pure silver/carbon audio resistor. It contains a pure graphite resistive element and two pure silver leads. Suitable for speaker crossover or Emitter/Source resistor of transistors in preamplifier/amplifier, the Lefson Resistor is pushing up the limits of sound reproduction."
The Premium resistor from Lefson is made with a carbon resistive element and silver leads, and is available in values from 0R68 (0.68 Ohms) to 200R (200 Ohms), with power ratings of 4-10 watts.
Lefson Premium Resistors.
The Supra resistor from Lefson is made also made with a carbon resistive element, but with double-wound silver leads, and is also available in values from 0R68 (0.68 Ohms) to 200R (200 Ohms), with power ratings of 4-10 watts.
Lefson Supra Resistors.
The Ultra resistor from Lefson is made with dual carbon resistive elements, with double-wound silver leads that are gold-coated, and available in values from 0R33 (0.33 Ohms) to 100R (100 Ohms), with power ratings of 6-15 watts.
Lefson Ultra Resistors.
I suggested to Xavier that we try his custom, hand-crafted, resistors in my Altec A5 Voice of the Theatre loudspeaker project crossovers.
Altec A5 Voice of the Theatre loudspeakers in primary music system.
Xavier reviewed the A5 project crossover schematic ...
... and suggested that he send 2 examples from each Lefson Resistor line to try in various positions in the A5's crossovers:
- 2x 100R - 4/6 W (RESISTOR Supra)
- 2x 10R - 6/10W (RESISTOR Premium)
- 2x 10R - 10/15W (RESISTOR Ultra)
Xavier said:
"So you could make many tests between Premium and Ultra Lefson Resistor, replacing R3-1, R3-2, or R5."
"The power rating is expressed with two values (example 6/10W). The first one is the maximum allowed power without any heatsink. The second one concerns the maximum allowed power when the Lefson Resistor is fixed on a heatsink or to a reliable case."
"All these power values were measured with direct current. When AC operating (audio), the maximum allowed power is significantly higher. During our post-manufacturing tests period, the Lefson Resistor is stressed with current peaks, up to 25/30W."
The FedEx package from Xavier last night, and this morning I unpacked the Lefson Resistors to take a look at them.
Lefson Resistor family photo: Premium (top), Supra (middle), and Ultra (bottom).
Wow! They're gorgeous! My photos really don't do the Lefson Resistors justice, they are just stunning to look at!
They are also huge, as you can see in the photo below, where they are sitting on top of my Acoustic Revive RL-30 LP Demagnetizer, with an LP for scale.
Lefson Resistors with LP for scale.
Here's a photo from another angle.
Lefson Resistors with LP for scale.
As I proceed towards the Positive Feedback review I'll be interviewing Xavier for more detail about all things Lefson, and I'll be sharing my listening impressions as I go, as usual.
Stay tuned, there's much more to come!
As always, thanks for stopping by, and may the tone be with you!
