About eighteen months ago I purchased the Marchand 126s – 2EZK two way electronic tube crossover with balanced I/O and stepped attenuators for volume control (list price of $1700). This is the kit with pre-wired circuit boards. The XM126s comes in two chassis: power supply and x-over unit connected by a short umbilical cord.
In spite of the fact that the boards were pre-wired it still took me about 5-6 days (about 24 hours) to assemble the kit. I damaged a few connectors in the process and Phil was very responsive in sending me free replacements (applying sustained heat to some connectors while soldering causes the connectors to become deformed). The instructions were average in clarity and assume some level of prior experience. I had ordered stepped attenuators volume control with the balanced option. The balanced option required the installation of 4 Jensen JT-11-EMCF output transformers. The holes were not predrilled on the chassis. Consequently, I had to drill two holes, for each transformer, with some difficulty, through a relatively thick steel chassis. The kit came with 9 tubes (7 Sovtek 12AX7WA and 2 Jan Phillip 12AT7). The parts quality was good except for the hook-up wire, which could be better. The finished product was robust with an industrial feel.
Note: I replaced the 7 Sovtek 12AX7WA with vintage Mullard 12AX7 (60’s version) and the 2 12AT7 with Mullard M8162 CV4024 (1983).
Phil was always available, helpful and patient in responding to my numerous questions while assembling the kit. Later, I experienced some intermittent problems with my power supply and because of my busy schedule I was unable to trouble shoot the problem so I decided to return the whole XM126 to Marchand. Marchand repaired the power supply and corrected my wiring mistake on the volume control of the crossover and retured the unit with free shipment and no charges in less than two weeks. This demonstrates that Phil Marchand is committed to providing full support for his prodcuts
Setting up of the system turned out to be complex and required many hours of experimentation. Integrating two different amplifiers in a biamp configuration is difficult by itself. The difficulty was increased, markedly, because I had to blend in a stereo pair of Sunfire Signature subwoofers that are driven directly from my ARC LS25 preamp.
I am using the Marchand XM126s with ARC VT100 mkII for the treble/midrange and Kenwood L07M monoblocks on the bass of my MG 3.5. I settled on 18 dB/octave @ 200 Hz (low Pass) and 12 dB/octave @ 200 Hz (high pass). I also experimented with 24 dB/Octave @ 200 Hz (both high and low pass) and 18 dB/octave @200 Hz (low pass) and 6 dB/Octave @ 250 Hz (high pass). The symmetical 24dB /octave @ 200 Hz was too lean and amusical, whereas the 18 dB/octave @200 Hz (low pass) and 6 dB/Octave @ 250 Hz (high pass) was too muddy in the midbass. I set the high pass volume control at 0 dB and the low pass at –5.0 dB for the best balance between the high/midrange and bass. An unexpected benefit of the controls offered by the Marchand allowed me to tame a midbass to upper bass bump in the response of the maggies in my dedicated listening room (25’x 15’x 8.5’).
After much frustration, I discovered that the integration of the drivers was improved significantly by reversing the polarity of the midrange/treble connections to the speakers. Prior to reversing the polarity, there was a midrange “suckout” and the bass was “too much” compared to the rest of the spectrum. The actual phase relationships depend on the x-over slopes.
Note: Crossover slopes and values can be changed quickly by replacing x-over frequency modules made from 1% metal film resistors and polypropylene capacitors (about $10.00 each).
The integration appears to be seamless with x-over settings: 12 dB/Octave @ 200 Hz (high pass), 18 db/Octave @ 200 Hz (low pass). The Kenwood amps are very smooth and musical, in spite of their solid state character, which helps in facilitating blending with the ARC VT100 mkII. It is clear that active biamplification raises the dynamic capabilites of the MG 3.5 to very satisfying levels. The biamped MG 3.5 has so much more punch and articulation especially in midbass. The sound is improved in every respect: greater sense of ease, power and scale; better definition and transparency across the frequency spectrum coupled with a more robust and full midrange. The presentation is also markedly smoother with greater inner detail, and musical intimacy. I am surprised at the extent of the improvements, because I considered my system, prior to active biamping, to be very satisfying and musical.
A large part of the credit for the successful biamping of my Magnepan 3.5 goes to the Marchand 126s. At first, I was concerned about the introduction of another active device in the signal path. However, the Marchand is very transparent and introduces no easily detectable grain or electronic artifacts. It is dead quiet with the noisy fan turned off (the unit does not heat up significatly and can be used safely with the fan turned off). The Marchand XM126s tube electronic crossover is an excellent product and has brought me much closer to the music. If you are interested in biamping your speakers, the Marchand 126s is highly recommended and should be on your short list of possible electronic crossovers irrespective of the pedigree of your system. Associated gear Click to view my Virtual System