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Equipment Review
December 1999

Belles Hot Rod 150A

by Doug Blackburn

Reviewers' Choice Logo
"The Hot Rod 150A never failed to
produce a state of total bliss whenever I
had the chance to listen just for




Review Summary
Sound Neither analytical nor romantic -- sound is "right down the middle," equal parts "balance and smoothness."
Features Many upgraded features including the use of Cromolin constrained-layer damping material and O2 Blocker; IEC power-cord receptacle.
Use Can be improved with small strips of Cromolin (or other suitable damping material) on the underside of the heat-sink fins.
Value "Falls short of the very best amps available only in not possessing the last word in transparency and in lacking super-amp bass power and current."

It has been almost two years since I first heard the Belles 150A amp. The subsequent review was a rave, and the $1195 150A (100Wpc solid state) received a SoundStage! Reviewers’ Choice award in 1998. In the interim, Dave Belles has been offering the 150A with two different extra-cost binding-post options: a standard version of gold-plated brass, and the deluxe version with gold-plated solid oxygen-free copper. Reports were that these binding posts further extended the already fine performance of the 150A for a modest increase in price.

Belles has continued to investigate potential production changes and performance-enhancing options. Several particularly effective changes to the original 150A were discovered. When all of them are performed on the amplifier at the same time, Belles recognized distinctly superior performance compared to the stock $1195 version of the amplifier. The original 150A remains available and is still an amazing sonic value. The new two-channel Hot Rod 150A retails for $1495, while the three-channel Hot Rod will go for $1995. Owners of original stereo 150As who want to go Hot Rod can arrange to have their amp updated for $400. The three-channel Hot Rod upgrade is priced at $600. For upgrades, Dave Belles needs to speak to the amplifier’s owner prior to having the amplifier sent in for upgrading. Contact Dave at (716) 586-0740.

Here’s what makes a stock 150A into a Hot Rod:

  • Removal of original large slabs of damping material from all internal chassis surfaces;
  • Application of Cromolin constrained-layer damping material to strategic points in the chassis as a replacement for the original heavy and soft damping material;
  • Replacement of original plastic-tipped binding posts with deluxe gold-plated oxygen-free copper binding posts;
  • Replacement of stock transformer mounting bolt and pads with a proprietary sandwich isolation system that effectively decouples the transformer from the chassis without introducing shipping problems;
  • Application of O2 Blocker to all non-soldered connections to maintain maximum performance for many years. O2 Blocker cleans and seals electrical connections and stays effective for many years.

There are a few other proprietary changes I was asked not to discuss.

This is a rather noteworthy collection of modifications. For those who believe mechanical resonances are not responsible for any sonic changes in amplifiers or other components, Belles is another example of a manufacturer who does hear differences. Belles has used mechanical-resonance tuning to make a good product perform even better. Nobody who’s paying attention would miss the difference in sound quality between a stock 150A and a Hot Rod.

Whadda ya waitin’ for? How does it sound?

I have never been this captivated by a $1495 amplifier. Two words return over and over again when I tell people about the Hot Rod 150A: stunning and remarkable. The sound is more refined than the stock amplifier. Top to bottom there is balance and smoothness to the sound that is the kind of thing that you generally expect from very expensive products. Strings are just so smooth and rich that it’s hard to believe this is solid state. Furthermore, the soundstage is huge and immersive -- most unlike any other amplifier I’ve heard in this price range. Feed this amplifier a quality audio signal from top-notch components and cables and feed the output to the best loudspeakers you can imagine connecting to a $1495 amp, then double the price of the speakers just for fun.

Associated Equipment

Loudspeakers – Vandersteen 3A Signature with two Vandersteen 2Wq subwoofers.

Preamplifier – Audible Illusions Modulus 3A with Gold phono boards.

Analog – Roksan Xerxes turntable, SME V tonearm rewired with Nordost Moon Glo cable, low-output Cardas Heart cartridge.

Digital – Panasonic A-310 DVD player, CAL CL-25 CD/DVD player.

Interconnects – JPS Labs Superconductor, Magnan Signature, Nordost Quattro Fil, Nirvana SL.

Speaker cables – JPS Labs NC Series.

Power cords – VansEvers Pandora and Pandora Photon; JPS Labs Analog, Digital, and Power AC cords; Audio Power Industries Power Link 313; Magnan Signature.

Power conditioners – VansEvers Model 85, Unlimiter, jr. Video, jr. Analog, Reference Balanced 5; Magnan Signature; PS Audio P300.

Room acoustic treatments – Michael Green Audio and Video Designs Pressure Zone Controllers, Argent RoomLens, VansEvers Spatial Lens and Window system.

Put on Toy Matinee’s self-titled album [Reprise 925235-2] or Milla’s The Divine Comedy [SBK Records/ERG CDP-527984], crank the volume to "almost loud" and sit back and be enveloped by the best music you’ve ever heard from a $1495 amplifier. Both of these recordings use phase tricks to produce convincing image effects, and the Hot Rod was excellent at allowing these spatial tricks to develop to their full potential. With more conventionally recorded music, image size and location were right on the money while soundstage size was quite large. Non-audiophile visitors were making me prove, repeatedly, that the center-channel and surround speakers for movie surround sound were not being used and that all that music was coming from just two loudspeakers.

The sound of this amp is not romantic or analytical. You get a sound that is right down the middle. There’s no added liquidity and not a trace of the harsh or hard sound that solid-state amps are often criticized for, especially moderately priced ones. You may not be seduced by "magic," but you won’t be turned off by mechanical or robotic sound either. In fact, this amp is about as good as they get for not bringing attention to itself. I found myself constantly at a loss for words to describe what I was hearing. The sound was so much like how I expect the actual musical signal to sound that there were no cues or clues as to anything that was amiss. I’m not advocating that the Hot Rod 150A is the be-all and end-all of amplifiers. You can certainly exceed its performance if you shop very carefully and if your budget permits spending over $2500. But if your budget requires that you stay somewhere close to the Hot Rod 150A’s price, this is one blistering-hot package of performance.

What the Hot Rod isn’t…

The Hot Rod 150A is not the most transparent amplifier I’ve ever heard. It is better than the original 150A, but not as good as the best solid-state or tube amps. It would be unrealistic to expect a $1495 amp to be as transparent as the best $5000 amps. Even though the Hot Rod 150A may not be state of the art when it comes to transparency, it is excellent in this regard for its price range. The transparency deficit looks like the profit from the sale of 1000 shares of IPO Microsoft compared to the transparency deficit of similarly priced amplifiers -- which is to say that you won’t be complaining.

As good as the bass is, it’s no match for the guts of big Krell or Levinson amps, so no realistic review should leave you with that impression. You do get bass good enough to make you forget the monster amps, at least until the next time you hear one! There’s plenty of slam, power, drive and grip in the bass to be very satisfying. Compared to other moderately priced amps, the Hot Rod 150A has a masterful bottom end -- tight, detailed, and strong.

You can’t drive monster speakers with the 150A either. It does best with speakers rated at 6 ohms or higher with a 4-ohm minimum. Fortunately, most speakers that would be used with a moderately priced amp like this will be fine.

"Come on and tell us…more about that Hot Rod Belles!"

To give you an idea of what you can expect from the Hot Rod 150A, for several months, except for brief comparisons, I listened to no other amplifier in my reference system. Coupled with $3500 loudspeakers, a $2500+ tube preamp, $3000+ digital front-end, and an analog front-end approaching $10,000, the Hot Rod 150A never failed to produce a state of total bliss whenever I had the chance to listen just for pleasure. When I was in evaluation mode, the Hot Rod 150A was well up to the task of revealing subtle and not-so-subtle differences in power conditioners, cables, DAC mods, feet, and 24/96 vs. 16/44.1 discs. This is not normal for me. I usually don’t expect products at this price point to be able to dish out sound like this amp does. I was suspicious that I was missing something, some hidden flaw. I repeatedly put the Hot Rod 150A under the microscope trying to find out where it was going wrong and kept coming away empty-handed. Whatever I dealt to the HR 150A may not have come back as a royal flush, but consistent four-of-a-kind and straight-flush hands is remarkable performance for this price.

The Hot Rod 150A delivered mystery when fed Loreena McKennitt’s The Book of Secrets [946719-2 Warner Bros. 1997]. The soft but densely instrumented melodies and haunting female vocals filled the room with wistful mystery. There was no tendency to recess the vocals behind the speakers unless there was intent in the recording to have the vocals further back. Some amps actually suck out the midrange to place vocals and instruments in the midrange farther back in the soundstage and thus produce an artificially enhanced sense of depth. There is none of that in the Hot Rod 150A.

Exuberance and flash were dealt by the Hot Rod 150A when it was fed Sam Bush’s Howlin’ At the Moon [Sugar Hill SHCD 3876, 1998], some mandolin driven jazz-grass. The Hot Rod decisively delivered the sound of the mandolin being expertly wrapped around the melody then squeezing the melody within an inch of its life. The sound of the mandolin has three major parts: string sound, body sound and pick sound. All are rendered by the HR 150A as you hear them live -- separate but unified. Prefer poetry in your music? Feed the Hot Rod some Mozart and literally feel the music speaking to you. Joy, yearning, playfulness, passion -- all are well served by the HR 150A’s combination of power, richness and subtlety. Getting this level of musical involvement and detail in a single package at this moderate price is virtually a miracle. It’s also a hallmark of true high-end performance.

Anything else I should know?

Somewhere along the line the 150A lost the captive power cord and gained an IEC connector. The Hot Rod also has an IEC connector, and experimenting with power cords is worthwhile. Damping the heat-sink fins is another way to extend the performance of the Hot Rod (or original) 150A even further into the high-end realm. There are a number of ways to achieve this. Moderately expensive bits of custom cut Cromolin constrained-layer damping material can be applied to the bottom edge of each heat-sink fin. For a low-budget solution, small pieces of rope caulk (for use around windows in residences as a replacement for the caulking gun, less than $3 worth would complete this job) squeezed onto the bottom of each fin do the trick. Whatever solution you select, keep it down very low on the fins so that heat transfer to the air is not affected. Heat rises in heat-sink fins just like heat rises in air or water. The bottom edge of the fins is relatively cool under most circumstances while the tops can get quite warm.


The Hot Rod 150A expands on the performance of what was already a classic budget high-end amplifier. For a modest increase in price, you get a level of musical involvement above and beyond what audiophiles limited to this price point have been able to expect. The Hot Rod 150A falls short of the very best amps available only in not possessing the last word in transparency and in lacking super-amp bass power and current. Compared to other amps near this price range, you will find the Hot Rod 150A’s performance to be very fine indeed. Top to bottom, the sound is exceptionally satisfying and well balanced. Many owners will find this an amplifier that may never need replacement because of obvious sonic shortcomings, such is the level of musical enjoyment it is capable of delivering. The Hot Rod 150A gets my highest recommendation as a price-and-performance leader and continues the 150A tradition. It’s a Reviewers’ Choice.

...Doug Blackburn

Belles Hot Rod 150A Amplifier
Two-channel version, $1495 USD or $400 to update existing amp; three-channel version, $1995 or $600 to update existing amp.
Warranty: Five years parts and labor.

Power Modules, Inc.
479 East St.
Pittsford, New York 14624
Phone: (716) 586-0740
Fax: (716) 586-4203

E-mail: info@powermodules.com
Website: www.powermodules.com

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