Wyred4Sound multi-ch bi/tri amped with DCX2496?
I recently described my experience in an Audiogon discussion thread asking for a comparison of Emotiva Xpa-1 amplifiers with Wyred4sound for driving JBL L300s. I have tested several amps including these Emotivas to drive a pair of JBL’s M9500s, the best of their K2 series that listed for $40,000 in the late 90's. Each speaker has two 15" woofers, stagger-tuned in separate stacked enclosures with a compression driver/horn between them and weighs over 300lb. JBL’s L300s have similar heavy woofers and compression drivers, so my experience described here should be relevant. My system includes a versatile Behringer DCX2496 electronic crossover with level 1 mods by Cullen Circuits.
I found that Emotiva XPA-1s, connected one per M9500 woofer, cannot accurately control their motion. Bass was boomy and poorly defined. The heavy woofers require a high damping factor, which is the ratio of speaker impedance (ohms) to amplifier internal and circuit impedance. A higher number indicates that the "rubber band" connecting the “towing vehicle to the trailer” is stiffer, so trailer motion follows more accurately. Speaker cables are part of the driving circuit; so heavier, lower-resistance cables increase the damping factor and their contribution is usually audible. Emotiva's DF is around 200. Various amps were tested, ranging from Adcom to Stella, Classe, Lexicon and Proceed HPAs by Levinson. The Adcoms and Proceed HPAs with 600+ damping factors produced firmer and more accurate bass. The Classe CA2200 produced the most transparent highs and clearly brought a small pair of Kefs to life, but could not control the M9500 woofers as its DF is relatively low, I understand the Classe amps have zero or near zero negative feedback.
I very much liked the sound from a friend’s $4000 Bel Canto amp with B&O's class D Ice modules with a damping factor over 1000. This resulted in my purchase of a Wyred4 Sound 7-channel x 500 watt (250@8ohms) version. A dedicated amp per woofer not only doubled the damping factor (2000+) but avoided an approximately 90% distortion increase when going from 8 ohm to 4 ohm loads. The 500 watt model was chosen in lieu of the 1000 watt version due to its slightly higher damping factor, higher bandwidth and lower distortion (below 0.005%) at my typical listening levels. The JBL M9500s are 96db efficient which produce SPLs equal to the 1000 watt versions for 93db speakers or 2000 watt/ch for 90 db speakers, etc.
Someone reported on another thread that changing his 120vac power cables to his W4S amplifier made an noticible improvement. Since I had already run a 240v 10 awg 30-amp circuit to my component location in addition to two 12-guage 120vac circuits, I ordered this 7-channel W4S amplifier with two 240 vac connectors, greatly diminishing any transient voltage dips into the power supplies. I found it best to take all ac power directly from my ac breaker panel. This eliminates differences in ground potential that would occur when connecting parts of the system to nearby wall outlets.
Achieving a high DF for a solid-state amplifier is usually accomplished with high negative feedback, resulting in less transparent midrange and highs. This was especially the case with the Adcoms which had a noticibly muddy midrange. The Levinson/Proceeds were better but still not nearly as transparent and dynamic as the Wyred4sound which has remained connected to the M9500s for the last two years as my amplifier of choice. It seems the best of both worlds with a high DF and no loss of transparency in the midrange and highs. I was told by 3 of 3 listeners that have auditioned the $40,000+ Wilson Maxx’s that my M9500s driven by the multi-channel Wyred4sound easily outperform them.
The six-channel McIntosh MC-7106 was acquired months after installing the Wyred4Sound. I connected it with one channel per woofer and 1 per compression driver as was the W4S. It sounded ok but didn’t come close to the richness, transparency, and tight bass to which I had become accustomed. A few weeks later I resold it to a young engineer who was an avid McIntosh fan. He listened for awhile with the JBL M9500s, liked what he heard and was excited and pleased to have acquired it. After cash exchanged hands, we disconnected and reconnected my Wyred4Sound amp. I then made the mistake of asking if he wanted to listen. After a few minutes, his joy and excitement were gone. The obvious superiority of the Wryed4Sound amp was easily apparent, and a look of confusion and despair explained his lack of words as he carried his McIntosh down the stairs. To this day, I regret having done that because I know I ruined his day.
In fairness, I should add that most speakers have less massive woofers, perhaps 8, 10 or 12 inch, and are much easier to drive. For smaller, lighter woofers the advantages of a high DF is somewhat less apparent.
Contributing to these results was the addition of the Behringer DCX2496 electronic crossover with level 1 modifications by Cullen Circuits of Paso Robles, CA who are also the builders of Wyred4Sound amplifiers. For the W4S amplifiers, Cullen includes 14awg ofc and silver internal wiring to WBT terminals that list for about $90 each if bought separately. Their work also adds FET input stages that raise the Ice amp’s 9k input impedance to 62k and converts voltage to current as Krell does. After some shopping, I found compatible gold-plated WBT spades for my speaker cables with an online price around $60 each. With damping factor in mind, such details become highly relevant and obviously appropriate! In conclusion, the Wyred4sound amplifiers would be my choice and are clearly in a different league in terms of quality and performance. I have periodically checked W4S used prices on Audiogon. They seem to hold their value as does a new Mercedes. A two-year old model sells for at least 80% of new retail.
Any helpful thoughts and comments would be appreciated.