RL 1.5 loudspeakers and F1 amplifier

as reviewed by John Mazur

Technical Sidebars by Greg Weaver, PFO Senior Assistant Editor & Jennifer Crock, PFO Senior Technical Editor

The seventeen years that I have been seriously involved in this two-channel audio hobby have been difficult, to say the least. Maybe my ears and listening biases are different from others in the hobby. Maybe one of the culprits that complicated the trip is the fact that I have aged and my hearing has changed. Nevertheless, the numbers reflecting the amount of equipment, wires, speakers, and tweaks that I have gone through during those years are frightening. The fact that I live in an audiophile no-man's land is especially frustrating because I have to search far and wide to find an equipment selection that is reflected by the high-end press. Surprisingly, there are many dealers hesitant to send equipment out for home evaluation when it requires long distance shipping. Much of my equipment has been purchased new and some has been purchased on the plentiful used market. For the most part, the journey has never brought about the sound that I thought could be achieved. About three years ago, I threw up my hands, sold everything, save for the Maggies, bought a Harley Davidson Electra Glide and began the ultimate diversion from the bane of this audio hobby. 

I have been a Magneplanar fan since the first days of my high-end audio quest. I have tried other speakers from Theil, Vortex, Audio Artistry, some horns, and a few others, before ending up back with Maggies. It felt like I was home again with the Maggies, and I stayed there while I upgraded electronics and cables around them. However, as I made the upgrades something else detrimental was happening. More and more of my music software was sounding unacceptable. At the same time, the truly fabulous recordings were sounding so much better. Finding a smaller and smaller portion of my music library to have truly great sound was a frustrating journey all its own. Last fall, after riding three weeks in the mountains of Arkansas on the Harley, something hit me: when I came home and walked into the listening room, the size of the Maggies was so overwhelming it surprised me. Over the course of the next few months, I never shook that sensation. 

While I was searching for speakers that were not so room dominating, a long time friend, and fellow audio junkie, called me one morning to tell me of a dream he had the previous night about cylindrical speakers. Unable to go back to sleep after this dream, he got up and did a web search to see if such a product existed. One of the search results pointed to a small company called Decware, the manufacturer of a radial speaker called the RL 1.5. 

The next day, I called Steve Deckert, designer and owner of Decware, and we had an informative conversation concerning the speakers and his listening biases. My meter was pegged when I learned that, not only was he also a Maggie fan, but that he had voiced the 1.5's with that in mind. Since Decware offers a 30-day, money-back, auditioning policy, it was time to let the games begin. 

The RL 1.5's are indeed a cylindrical speaker that stands about 33 inches tall. It is a two-way design that uses its main 8-inch driver as a 360-degree sound radiator and an 8-inch passive radiator, mounted in the bottom of the cylinder, to augment bass. According to Steve Deckert, the radial driver circumvents the problem of room reflections that can confound imaging with many forward-firing speakers (1). He designed this driver with the motor underneath the cone so nothing would impede the sound dispersion above it. Being a light paper material and weighing only 4 grams, it resembles Mount Fuji.

The high frequency driver is a ribbon tweeter mounted on a flexible bracket above the main driver that allows for changing the angle of the ribbon, up or down. The crossover consists of a single capacitor. The tweeter output is easily adjusted to suit the listener's taste by changing an external series resistor, conveniently located across a second set of five-way binding posts (not meant for bi-wiring). Sensitivity is advertised as 93dB with an impedance that stays around 10 ohms and dips to 4 ohms only in the lower bass region. All of this means that these speakers are good candidates for use with single-ended triode, as well other low powered, amplifiers. Higher-powered amplifiers are by no means excluded.

Listening to these speakers is a pure joy. I used an ATI 1502, a 150 watts per channel solid-state amplifier, and the combination produced music that was divorced from the speakers themselves. They just flat-out disappeared as apparent sources. The Decwares provided much better soundstage depth than any of the systems I have assembled before their arrival. My front wall may as well not even be there, their depth is so good. This soundstage is one that I can almost fall into. The sweep of the soundstage is also impressive, extending out beyond the "edges" of the cabinets. They tender an ease of listening that appears to be laid-back perspective at first. After listening and becoming adjusted to their perspective, they sound as live music sounds, with a naturalness and image quality that is not hyped or artificial.

Dynamic contrasts are so much more apparent with these speakers than I was used to that I had to readjust the way I use the volume control. In previous systems, I kept turning the volume up, more, and then often even more, to try to get the realism I was seeking. This always resulted in listening fatigue. With the Decwares, clarity, articulation, and intelligibility are nothing like I have experienced before.

One of the CD's that I always take with me for speaker evaluations is the rock group Creed's, Human Clay (Wind-Up 13053-2). All of the speakers I evaluated previously, including one that resembles the Energizer Bunny, made this CD sound thick, compressed, flat, and not at all involving. I was unprepared for how the Decwares would transform the sound. The music now was infused with space between the performers. Lyrics became understandable and the clarity of the presentation was so much better that, for the first time, I was able to listen to the CD all the way through. I rediscovered music from a band that I loved so much but could previously only listen to on the kids' boom boxes.

Bass performance was lacking at first while the drivers loosened up. After run in, bass was fast and quick with no overhang or tubbiness, and was another area that took some getting used to. Yet after hearing drums reproduced on this system, that quickness lent itself to the recreation of drum notes that were both propulsive and conveyed the roundness of the drum itself. However, the lowest of bass was just not there.

High frequencies were so good that I never missed the ribbon tweeters of the Maggies. Smooth, without shrillness or bite, the sound of the Decware tweeter just washed over me without the fatigue that often comes from the exaggerated high frequency response of some tweeters. In fact, I found that reducing the tweeter attenuation via the resistor on the second set of 5-way posts from 6 to 2 ohms seemed to get it just right. Midrange did not have the sultry, husky, sexy, Diana Krall-whispering-in-your-ear sound that the Maggies conveyed. Yet, I have to come back to the natural sound these speakers are capable of creating. It is as if instead of the performer being in the room with you, you are at the performance with the performer. As good as the RL 1.5's were with the ATI 1502, things were about to get even better!

A few weeks after I started using the Decwares, I ordered the Nelson Pass-designed First Watt F1 amplifier. This amplifier, of which only 100 were made, is a class A, single-ended, solid state, zero feedback, current-source amplifier developing 10 watts per channel. The key descriptor in the previous sentence is "current-source.” A tube amplifier, for example, is designed as a voltage amplifier. Transistors, on the other hand, are supposed to pull duty as current amplifiers. Up to this point, most solid-state amplifiers on the consumer market have been used as voltage-source amplifiers. The output voltage of these amplifiers is a larger copy of the amp's input voltage. Crossover designs used in multi-driver speaker arrays dictate the current that the associated speaker's voice coil receives, as well as other variables such as voice coil temperature. Simply put, a speaker is a motor, and electric motors require current to operate. With that in mind, the speaker motor often does not receive proportional current accurately reflecting the voltage component of the music signal.

The First Watt changes all that. In theory, when driven by a current-source amplifier such as the F1, the speaker coil now receives current delivery that is proportional to the amp's input signal. Compared to a conventional solid-state amplifier, a number of things are different with the First Watt. The output impedance is much higher than that of more conventional amplifier designs. With an output impedance of 80 ohms, the F1 does not offer the high damping characteristics that are usually the province of solid-state amplifiers.

As a current-source amplifier, 99% of all speaker crossovers will not work with the First Watt (2). Design parameters are reversed in a crossover when using such current-source amplifiers (3). Crossover networks are now in parallel instead of in series, placing the driver in direct connection with the output of the amplifier. Coils are now used for high-pass applications, and capacitors are used for low-pass. Designing speakers for use with current-source amplifiers is an upside-down, inside-out world. As such, Nelson Pass designed this amplifier for use primarily with single driver, high sensitivity speakers and, it was built to tinker with and tweak. The owner can design networks to change either the response of the single driver or the damping factor of the amplifier for personal fine-tuning. The listener can now indulge in a little do-it-yourself project without getting carried away.

After looking over the manual and consulting with Nelson Pass, I initially hooked the Decwares up with no networks of any sort on the F1. As great as the sound was with the ATI amplifier (a sleeper, in my opinion), the sound was utterly transformed by the First Watt. The sound now had soul. There was a human, emotional connection; a connection between the performers and the performance they were giving. This is very evident in live music when the audience becomes engaged in the sound of the performance and "locks-in,” everyone nodding their heads in groove with the performers. It is a profound experience: an intangible power that artists hold over an audience.

That essential component of the music was being conveyed to me by the F1. My head was nodding with everything I played. The First Watt had such control over the speakers that drama was reproduced as I have never before experienced from my system. The tension and release that is the foundation of music was there and seemed to invigorate and drain my emotions with every swell and ebb. I found myself hanging on to each note and being seduced by every one to come after. The music was now so convincing that the timing and the pace were restored.

The portrayal of the production of the recording was also much more evident. I was now experiencing recordings as they were intended. I no longer had to try to convince myself that I was listening to a spontaneous performance. No extra effort needed to "con" myself into the final triumph over that last 20% that is typically held back by electronic reproduction to make the performance believable. I closed my eyes and luxuriated in a performance at a different club with every disc I played.

Listening to Trio, from Dolly Parton, Linda Ronstadt, and Emmylou Harris (Warner W225491), was an "experience" like none before. I say I experienced this recording instead of "heard" it because that's what happened. I have never had the illusion of those three performers in front of me as created as convincingly as it was with the First Watt/Decware combo. Neither have I heard Tony Bennett use so much of his anatomy to reach his notes listening to Tony Bennett and Bill Evans Together Again (Concord CCD-2198-2). Man, can that guy belt out some notes. I also have a better appreciation for Bill Evans and his ability to make the piano sound so beautiful. I have always had trouble with the reproduction of piano on my previous systems. Now, I have a better idea of instrument position, microphone placement, and the performer's technique.

I was hearing things that I have never experienced before. Even old recordings that I had written off as being "bad recordings" had a newfound quality that had me shaking my head. Those recordings, while not being transformed, now had character that was missing when playing them with other equipment. While walking through the room, FM broadcasts from the college classical station had me stopping and sitting down, sometimes for as long as an hour. I was enjoying the ability to listen into the performances, even on the radio. With this combination of equipment showing up around Christmas, my productivity was sorely reduced because I couldn't get my butt out of the chair. I now often see Friday nights grow into Saturday mornings because this equipment has the capability to deliver the "real deal.”

My friend the audio junkie, who had the dream about the Decware speakers, was busy with work and was not able to visit right away to audition the new system. When he finally made it, I had replaced the First Watt with the ATI 1502. He thought the system sounded great with the ATI in place. I let him get used to the sound, and then substituted the F1. He was astounded.

I was busy upstairs getting dinner ready so I didn't get to experience all his reactions first hand. But it didn't matter. I could hear him laughing with each new disc he put in. On one disc, I heard him exclaim, "I can't believe it,” over again and again. I have never heard him react that way to the other systems I have assembled over the years. He summed it all up by saying, "I have never heard a system that has the sheer entertainment quality of the system you have now.”

Stereophile's Test CD 3 (STPH 006-2) was in the player when he left. I cued it up after dinner to recreate his experience for myself. Track 6, Jimmy Rogers' "Blue Bird,” was so good I could almost see and smell the smoke in the club. Hell, I was even enjoying the snap and pluck of guitar strings from Sara K's, "History Repeats Itself" on track 5. I can't believe that I could write something like that about Sara K, but the communicative power of the First Watt driving the Decwares is that strong. Transistors have finally found their place!

I could rant on and on about all the things this amplifier and speaker combo does right. I have owned over thirty amplifiers from well-regarded, high-end, manufacturers, and have auditioned a good deal more. The Decware RL 1.5 speakers were great to begin with on the ATI amplifier. The First Watt F1 amplifier morphed the sound of the Decwares from that of seeing the performers behind a clean plate of glass, to that of having their physical presence in front of me. The grip and control the F1 had on these speakers was a revelation. This is the sound quality people are trying to get with the hi-rez formats like SACD and DVD-A. I was getting it with conventional, Red Book CD's! All of this combines for a menagerie of sound that just pulls me in with hardly any effort at all. The combination of the Decware speakers and Nelson Pass' First Watt F1 amplifier is almost psychedelic, perhaps to the point that it should be considered illegal! John Mazur

RL 1.5 speakers
Retail: $1295, plus shipping, factory direct

Decware
High Fidelity Engineering
1202 N.E. Adams Street
Peoria, IL 61603
TEL: 309. 671. 2428
web address: www.decware.com

F1 amplifier
Retail: $2500

First Watt Distributor
Reno Hi-Fi
870 Singingwood Drive
Reno, NV 89509
TEL: 775. 829. 7332
web address: www.renohifi.com
web address: www.firstwatt.com

SIDEBAR - PFO Senior Assistant Editor, Greg Weaver and PFO Senior Technical Editor, Jennifer White-Wolf Crock

While doing the final edit on John's wildly enthusiastic piece, I spotted several statements that I could not substantiate, by ether researching the manufacturer's websites or my own electronics reference library. Enter PFO Senior Technical Editor, Jennifer WhiteWolf-Crock on the matter… She expands upon three specific statements.

1. "According to Steve Deckert, the radial driver circumvents the problem of room reflections that can confound imaging with many forward-firing speakers."

Actually, omnidirectional or torroidial pattern acoustic radiation only ADDS to the amount and the complexity of the room reflections. The ratio of direct to reflected sound is also different from narrow radiation speakers, actually generating more total reflected energy! The sound from Omni or torroid radiation pattern speakers IS pleasant, and the complex reflected energy seems to be integrated less by the brain's Hass effect, than in less complex short reflection path setups. This results in an 'apparent' increase in resolution, by actually reducing the comb filter effects our brain internally creates when confronted with simple reflected waves inside the time window of the Hass Integration Zone. This approach has been used in many speaker systems occasionally over the past decades. It was popularized in a low cost system mass marketed in the mid 60s, not sold in specialty audio stores, but in department stores and the like. I think it was Soundesign. They were real cheap, and actually sounded pretty good for the money thanks to the high-reflected energy ratio. Wolcott revisited the theme in the late 70s or 80s with a rather large enclosure sporting many mid range drivers on the surface, pointing all around. A central tweeter array on the top had two domes, one facing up, and another facing down, with the domes almost touching. One of my friends had a set. It was interesting in a large room, this example being about 30 by 45 feet, especially after we added 8 15-inch bass drivers so the system could play pipe organ at realistic levels. There is also the MBL, a torroidial radiator made in Deutschland [Germany, to those of you who insist on calling it by the 'popular' name]

2. "As a current-source amplifier, 99% of all speaker crossovers will not work with the First Watt."

They will function, but not REALLY well. What will work BEST in 2-way speakers are series shunt type crossovers, usually avoided by most speaker designers because of many complex problems associated with their use. However, series shunts can be made to work tolerably well if used in only simple 2-way systems, with only first order filtering, and with drivers of characteristically flat impedance curves. They will 'usually' perform better with a current source drive than a voltage source drive. The optimal application for this type of amplifier is one with no crossover at all. In multi-driver speaker systems, this means having one amplifier per driver and the frequency dividing being done at 'line level' before each amplifier. In so-called ‘full range,' one-driver systems, there is of course no frequency dividing at all, IE: the single driver gets the full bandwidth signal. It is for application in such systems that the First Watt was conceived...they say so on their own website.

3. "Design parameters are reversed in a crossover when using such current-source amplifiers."

If you are designing a speaker specifically for a current source type amplifier, then yes. See the comments just above about series shunt crossover networks.