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Equipment Review
July 1998

Power Modules Belles 150A Power Amplifier

by Dave Duvall

Follow-ups can be fun or very difficult; there's no in-between ground. They’re fun if your experience with a product somewhat parallels the words of your fellow teammate, and very difficult if you disagree with his enthusiasm or disdain. The other parameter that comes into play is that the product is probably going to be heard in two rather dissimilar systems. The purpose of a follow-up though is to offer our readership a second opinion, and hopefully further perspective on the sound afforded by the product under review.

With the Belles 150A amp, I'm pleased to report that just as Doug Blackburn found the amplifier to be a real performer, I too walked away impressed. Walk away? Hell, I bought it and sold my McCormack DNA-1. While I'd have told you straight up if I didn't agree with Doug's opinions, this follow-up will fall into the "fun" category to write.


The 150A was auditioned with the Muse Model Five transport, linked via I2S to a Muse Model Two Plus DAC. The analog signal was shoveled off to an Audible Illusions L-1 preamplifier and to the Belles 150A or McCormack DNA-1 amps by means of Cardas Golden Cross interconnects. Kimber PowerKords added to the mass-o-wires behind my home-built rack. Speaker cables used were Kimber BiFocal-XL and Cardas Golden Cross, either of which moved a bunch of current to the nominal 4-ohm PSB Stratus Gold speakers. Room-acoustics tuning was provided by Acoustic Sciences Corporation Tube Traps and/or home-brew methods.

Get on with it. This isn't a novel here.

The 150A sent to me was a third-generation product, with the original full review having been written on a first-generation amp. Rated at 100Wpc into 8 ohms, and 160Wpc into 4 ohms nominal (20Hz-20kHz), the 150A is capable of putting out over 15 amperes of peak current, yet I was surprised at how small the chassis actually is. Weighing in at only 28 pounds and measuring but 17" wide by 6.25" high by 13" deep, the 150A had "reviewer friendly" written all over its face. Actually, the only thing written on its face is "Belles 150A," with a green LED and round power button filling out the otherwise routine black faceplate.

Around the back side, the gold-plated RCA inputs for single-ended interconnects are just slightly below, and between, the speaker-cable binding posts. This location is a tinge difficult to negotiate when scrunching beside and around the rack to attach speaker cables. On the other hand, the physical location of the interconnect and jack actually throw an obstacle in the way of your speaker cables’ + and - connectors, and could possibly save you from shorting out your amp when a little love nudge wants to create sparks of the depressing kind. The power cord is no longer hard-wired, but of the detachable IEC variety; experiment with high-end power cords all your little heart desires. I found the Kimber PowerKord to be a significant improvement over the stock AC cord; better at detail retrieval and allowing cymbal sheen to come through like this ol' boy likes.

The speaker-cable binding posts leave something to be desired mechanically, but Dave Belles assured me they were chosen for their sonic qualities at the price point considered. I had a tough time attaching the Kimber BiFocal-XL cables to them, and the Cardas Golden Cross told me to forget about it. The plastic nuts (gesture of middle appendage on left hand raised to the notion of plastic binding-post nuts on any high-end product) would not open wide enough, though other brands of cables may fit without a hitch. These posts resembled the posts on the rear of the Near 50Me II speakers that were reviewed by yours truly last year, though I don't recall having any trouble getting Cardas Cross cables on them. Seems if one leg of a thick spade is a little out of line with the other (viewed from the side), there isn't enough room on the stock 150A binding posts to allow for the offset. Even with the Kimber spades, I needed to push them on quite firmly. When I did get them on, it was a tight fit and didn't leave me much room to tighten the plastic nuts down. This situation was going to need to be looked at in depth, but we'll get to that later.

dB had told me that the latest revision to the 150A sonically was that a little extra decay had been added to the sound, as the model he had reviewed was a pinch drier in its presentation. Opening up the amp, and referencing the picture shown in the manual, I could tell a major upheaval had occurred since generation one. Either that or the shipping company jostled this one around to the point where everything inside had gravitated to different positions. The torodial transformer no longer is supported so that it appears to be standing on edge, but now lays flat as in most designs I'm accustomed to seeing. The output-driver printed circuit boards are no longer laid out with standoffs on the chassis floor, but are turned 90 degrees and directly attached to the sidewall heatsink fins. The capacitor banks are no longer attached horizontally behind the previously on-edge transformer, but laid out vertically on a PCB attached to the chassis bottom.

The manual recommends a minimum of 96 hours of burn-in, which in my experience is not to be taken lightly. After 100 hours I hunkered down and put the Belles 150A through the motions. I can tell you there was a lot right going on here, but until I hit the 170-hour point, the midrange demonstrated an edge that didn't sit totally comfortably with me. The stock AC cord lessened this edge, but at the cost of resolution compared to the Kimber PowerKord. Rock and a hard place, but the Kimber became the AC power cord of choice.

Because I used the McCormack DNA-1 for reference in my Workin' Man rig for so long, the leanness on Rebecca Pigeon’s vocals during "Spanish Harlem" (The Chesky Ultimate Demonstration Disc [Chesky UD95]) prior to completed burn-in was not just different, but difficult. The missing "undertones" (a Duvall-esque term for sure) seemed to settle back in; re-associating the chest resonance along with the vocal chords on female vocals, and the body back to saxophone, trumpet, and especially string bass. Stripping away the "undertones" from a complicated series of tones such as music leaves behind a bleached-out version that loses its emotional attachment. The before-and-after difference on "Splanky," featuring Christian McBride, Ray Brown, and Milt Hinton (Gettin' To It [Verve 314 523 989-2]) was educational to say the least. Prior to the amplifier’s burn-in, the trio of basses sounded more similar than different. Once burned in, the amp brought back subtle resonances of each bass, and added that final touch that would draw you back into the performance rather than having you reach for something to read while playing background music.

After 170 hours, the Belles 150A had worked its way to a point smack-dab between its previous leanness and what bit of bloat I had become used to hearing from the McCormack amp. This became a comfortable place for me, and one that I decided I could live with long-term. Not to say that the midrange edge had completely disappeared, but it had relaxed a bit.

Running through "May This Be Love," a duet by Emmylou Harris and Daniel Lanois, (Wrecking Ball [Elektra/Asylum 61854-2]), I distinctly noticed Lanois vocals as being more prominent than with the DNA-1 amp. This improved resolution (or would re-soul-ution be more appropriate?) made his contribution more easily understood as an equal part of a duet, and not resigned to the role of backup vocals. The Belles 150A was more transparent than the McCormack amp, and made it easier to hear deeper into the recording, with less obscuring of detail. The Belles was extremely quick through the entire frequency range, and in particular, never lent itself to bass that lagged behind the rest of the spectrum. Resolution and transparency were best offered with the amp plugged into the wall outlet and not the TAD (Bybee) Power Purifier. While the Power Purifier doesn't limit current to the amp, it does change the sound of attached equipment (what doesn't?). With the McCormack amp, there was a level of grain and noise that required the use of the Power Purifier, but the Belles is extremely quiet and grain-free. I felt the Belles 150A was more dynamic straight out of the wall, though it would be difficult to justify that due to the fact there is no current-limiting with the amp outlets on the Power Purifier. In this configuration, it also preferred partnering with the Audible Illusions L-1 preamp when the Seimens 7308 tubes were used in place of the Sovtek 6922s.

Late-breaking news!

The Power Modules Belles 150A amplifier was transformed from a very good product to and excellent performer with two changes to its stock status. The first was the addition of the Kimber PowerKord as mentioned previously, and the second came about almost accidentally. I had been talking to Dave Belles when I mentioned the trouble I was having getting the stock binding posts to open up wide enough to accept the thickish spades of the Cardas Golden Cross speaker cables. Dave suggested purchasing a pair of Vampire BP-HEX binding posts, as the nut will come all the way off if I so desired. In that same conversation I mentioned the edge I had been hearing, and Dave commented that that too would ease up with the new binding posts. With all the changes I've heard in wire, isolation devices, and even the more voodooish CD degaussing (who'd have ever thought?), I certainly wasn't going to dismiss the designer’s claim that binding posts can sound different from one make to another. When thinking about why these binding posts weren't already a part of the stock product, I realized that they would probably have added a couple hundred dollars to the retail price. The $1,195 price point sounds a bit more catchy than something near $1,500. Compromise is what audio design is all about when price points are factored in.

I promptly ordered a pair of the binding posts from Sound Connections International (813-948-2707; Bob Deyarmond was the pinnacle of customer service) and had them installed by my local stereo-shop tech. I don't work on my own cars, or attempt to cut my own hair either. One day when there's more time in my life, I hope to spend time learning how to modify and build components (I'd love to have the time to tackle the Parts Connection tube amplifier kit Todd Warnke reviewed a few months ago), but for now I'd rather let someone else screw it up who can also take care of it when something goes wrong. Dave Belles was right on the mark in all regards. I could put the Kimber BiFocal-XL speaker cables on easily, the Cardas Golden Cross spades would now fit, and I was able to tighten down the gold-plated nuts with an open-ended wrench. Nice touch on the PSB Stratus Gold speakers when they strayed from the oh-so-easy-to-get-away-with plastic nuts on an affordable product. The big payoff was the fix afforded the mid- and upper-midrange presentation. Forget edge; an appropriate balance had been struck between resolution of detail and a more relaxed and natural timbre through the coveted midrange. Roundness and liquidity were in place of the edge and sharpness detected on the attack of a note, without any veiling or loss of detail. I settled back on my couch day after day with no further concerns about the Belles 150A amp.

So the bottom line would be?

In its stock $1,195 list-price incarnation, the Power Modules Belles 150A amplifier had bettered the $2,095 McCormack DNA-1 (no slouch in its own right!) in my system.

I'm not going to say that it's a giant killer, and I don't think the Levinsons or the Krells of the world need to be concerned. But with the Kimber PowerKord and the Vampire BP-HEX binding posts added, I'm all kinds of curious to stack the humble-looking 150A up against the $3,000 to $4,000 range of amplifiers. A lot has been accomplished sonically for the $1,195 stock price, and I feel confident in claiming that Dave Belles has done the Workin' Man (or Woman) real justice in bringing this amplifier to market.

...Dave Duvall

Power Modules Belles 150A Power Amplifier
Price: $1,195 USD

Power Modules, Inc.
479 East St. Pittsford, NY 14534
Phone: 716-586-0740
Fax: 716-586-4203

E-mail: selleb@aol.com
Website: www.powermodules.com

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