Radii ALP-01R Remote Line Preamplifier

Radii ALP-01R Remote Line Preamplifier


  • Output Impedance: 800 ohm
  • Frequency Response: 10Hz to 100,000Hz
  • Harmonic Distortion: less than 0.1% Tube Complement: 12AU7 x3, 5AR4 x1
  • S/N Ratio: -85dB
  • Power Consumption: 30W
  • Dimension(W x D x H): 275 x 280 x 185mm
  • Weight: 7Kg (16 lbs)
  • Features: IR Remote Control Volume UP, DOWN and MUTE Price: $ 799

The simplest of all components……..

Ah, the preamp, how could something so simple be the bane of so many audiophiles’ enjoyment? It has long been a personal headache of mine. There are many great ones with proud price tags. As a matter of principle, I am least likely to shell out a lot of money for one. Don’t ask me why. I know they are the heart of every great system, and one of the most important components. The principle is simple: take a small signal and make it louder, while offering volume attenuation and source switching without mucking up or coloring the original input signal.

Keeping with that thought, I decided to do just that, obtain a simple line-level preamplifier that seemed to offer good value and a simple circuit. Based on the success and value of the Vista i84 tube amp, I emailed Boris Sasic of Vista Audio. Vista is the sole USA Distributor of Radii products and Boris feels the line fits right in with his highly praised Vista offerings.

A Word With The Distributor

Boris and I exchanged many emails on how he comes to select products to distribute and represent alongside his Vista line. We all know and see the many overseas items selling for basically shipping costs on the auction sites. If you are anything like me, you have at least wondered if there are any gems out there. Well, lucky for all of us, there are people such as Boris who spend considerable time seeking products that offer exceptional value.
I interviewed Boris, and would like to share some of my questions and his answers. Please note that some of the comments were edited for length.

DF: How did you come to choose Radii to distribute in the US?

Vista: I evaluated Radii products for quite some time before accepting representation of the company. After receiving uniformly positive feedback from my friends and couple of audio dealers, I decided to get on board. One of the things I like about all Radii products is that they are built with good quality parts and they are very accessible inside and easy to modify for even better performance.

DF: Tell me a little about the ALP-01R.

Vista: The ALP-01R preamp is a well-engineered unit with super-wide bandwidth and very low distortion -on a par with good solid-state amplifiers. I have taken oscillograms of the square waves, (similar to what Stereophile does) and the preamp has an excellent reproduction of square waves of 100kHz!! It also works well with a wide range of tube
and solid state amps.

DF: What can customers expect when buying products through Vista?

Vista: US warranty and service. I inspect every unit inside and out, test it on the bench, and do a short burn-in. There is a 1-year warranty on electronics and 90 days on tubes. This ensures that every unit is operating in top order.

The Set Up

The Radii arrived safely, in a double-walled box with suspended foam insert that kept the preamp and tubes in the center of the box. The shippers didn’t manage to hurt anything, but I would prefer a bit more protection. The unit is a unique size that continues to grow on me with its thick front trapezoidal face and volume and source knobs mounted on the top deck. The transformers are mounted under a decorative shroud that is not potted. The weight for a simple line stage is substantial and no doubt there are some good sized transformers under that shroud. Two nice-sized vertical caps are mounted behind the single 5AR4 rectification tube. The machined aluminum remote features volume up/ down and mute. The buttons were a bit flimsy, but since this nice a remote is hard to come by these days at any price, it didn’t bother me one bit.

This is a no-nonsense preamp with no frills, no phono stage, no sub or loop out, single ended inputs and outputs only. This is just what I was looking for. Why pay for a phono stage if you don’t need one? I would prefer that all my money went into the line stage, and that is just what the Radii offers. Positive polarity is observed and comes with three switchable inputs and one output. I suspect some would like to have an additional set of outputs to run subs or biamp. These would be nice features, but my system is not set up for any of these configurations at the moment.

Radii ALP-01R Remote Line Preamplifier inside

The Radii has a 90-second delayed soft start and blue mute indicator that lets you know not to keep cranking the volume for sound. At very low volume and muted, the Radii is quite but not completely silent, as there is a slight amount of tube hiss from a distance of about two feet away. I could not hear anything from the listening seat, but this would be information to consider for very high sensitivity speakers or horns. The slight noise was there with cheater plugs and two prong cords, but irrelevant with any amount of volume. The remote tracks well and is easy to adjust for small volume increments–a small feat in itself, as many affordable preamps overand undershoot the desired volume setting.

Listening Impressions

Right from the beginning, the Radii Pre shows a knack for excellent resolution, clarity and detail, with a soundstage that is layered and focused. It doesn’t take much warmup or break-in for the Radii to settle in. This may be due to the run in Boris gives the units before shipping. I personally appreciate the efforts to offset the long and annoying break-in periods associated with many components. The Radii preamp is not for those wishing to add tube bloom or roundness to the front end. It is a very detailed high resolution preamp that simply passes the signal downstream. That is not code for harsh highs or bright presentation; the Radii simply leans to a highly resolved, uncolored presentation, leaving it to other components to lend a more dominant signature.

After some weeks, I stopped making any excuses for anything extra I wanted from the Radii and threw out the idea of comparing it to only other affordable preamps in its price range (The ARC LS-7 was in need of a check-up anyway). The Radii is a very competent component and deserves consideration for anyone wanting a basic preamplifier. You see, the problem wasn’t with the Radii, it was with me. I’m a guy who firmly believes a little too much is just right. I slightly oversalt my food, think an extra clove of garlic is just right, and I think taking the dropper ring off the tabasco is, well, you know… Direct comparison to a favorite highly rated $4,000 Cary SLP 98 was what I needed to put this little Radii in its place.

Radii ALP-01R Remote Line Preamplifier back

Bring out the Big Dog.

This might seem totally unfair, but the Radii has some very similar characteristics, similar S/N Ratios, same Alps volume control, and robust power supplies. What’s more, the Radii remote puts the Cary’s to shame. The SLP moniker stands for “sweet little pre amp,” and the 6SN7 tubes do have a sweet, fleshed-out presentation. This provided an interesting lesson, both in terms of cost/performance and musical presentation.

The detail retrieval of the Radii can absolutely keep pace with that of the Cary SLP98. The differences become more apparent in the presentation of the soundstage. On Leon Russells’ third albumCarney, “Magic Mirror,” the Radii presents a deeper stage depth with clearly defined layering and space between the different players. This is partly accomplished by presenting Leon Russell closer to the front plane of the speakers, as opposed to the slightly deeper stage presentation of the Cary. The overall soundscape is bigger in height and width with the Cary and those 6SN7s, but the Radii is the clear winner in the depth and layering.

On “Shall we dance?” from Stacey Kents’ In Love Again, the Radii again presented sharp, clearly defined imaging, but lacked the extra bit of flesh and density that the Cary provides in spades. The Radii is always clean and detailed, able to present the most subtle nuance of a performance with a good dose of musicality. It can’t quite match the Cary’s thick, rich tone and stereotypical tube warmth. This is not a knock against the Radii, but a personal preference. I understand others are looking for exactly what the Radii preamp offers in terms of detail retrieval, clearly-presented soundstage and fast snap that is never harsh. I would prefer a bit more texture and tone from the Radii when comparing female vocals and stringed instruments. The soundscape and space between players was still clear and readily defined without becoming disjointed.

Various orchestral recordings produced great detail and spatial rendition with the Radii conducting, but again I miss a bit of the finer tone of bowed and resonating wood instruments. Also, I felt the Radii could become a tad congested during complex pieces when compared to the Cary at the same volume. This last comment should be taken with a grain of salt, as the Radii seemed to be able to produce more dynamic swings than the well-mannered Cary, thus proving difficult to level match in such short bursts of musical energy. In other words, the culprit was not the Radii, but rather my small floorstanders and the headroom available. This was not a problem a notch down on the volume control.

Again, a unique character of the Radii is delineated layering and depth of stage, starting at the plane of the speakers and extending to the rear. The Cary produces all these layers also, though they are presented as a more homogenous mix that is closer together and less clearly defined. I enjoyed this unique aspect of the Radii and never found it to be “collaging” the musical performance or going to the extreme.

Final Thoughts

I enjoyed my time with the Radii. It proved to be a great value with many attributes for a small, affordable line stage. Many of you will find it a great addition to your current system and enjoy its excellent detail retrieval, clearly defined soundstage, and its panache for great dynamic swings. It is with very little fault and clearly personal preference that I ultimately prefer a little more colored preamp that is able to flesh out bowed and stringed instruments, but I realize a huge segment of the Hi-Fi crowd is striving for a supremely neutral preamp with plenty of gain that adds little to the recorded performance.

I have a couple of additional functional details that readers might want to know. Changing of driver and input tubes produced very slight changes in sound. I did not change rectifier tubes but the 3 12AU7s were replaced with early RCA cleartops, to a detriment in overall width and height to the soundstage. This was surprising to me, and one of the few times I have encountered that NOS tubes didn’t make a marked difference over current production. Second is that with a higher than standard output voltage source (modded), there can be some bleedover when the higher voltage source is still playing and the selector switch is in a different position. As always, it is better to have other sources muted or off.

There is no doubt that the Radii plays well above its price level. While it does not fit into a category as or directly below the $4000 Cary, it offers quality that’s pretty rare in terms of performance (simple, open design, with an overbuilt power supply, remote control and very good parts). All of your money is going towards the line stage without tons of useless features, gimmicky LEDs, or noise-inducing displays. I was rather sad to part with it, but have a few more preamps in house for audition. Besides, I know where to find it again!

Associated Equipment:

  • Sonos Wireless Music Server-Aiff Encoded
  • GR Research Dac-60
  • H20 Audio S100 (On Review)
  • Mcintosh MC7200/H20 S100(On Review) Bella Extreme Signature 3205
  • Cary SLP-98 (on loan)/Audio Research LS-7
  • Triangle Zerius
  • KCI, Element, Dared, Electraglide, Green Hornet, DIY Cables
  • Brick Wall Power Conditioning
  • Room 20X12X8
  • Second Evaluation System: Njoe Tjoeb 4000
  • Cary SLP-98
  • Consonance M800
  • Martin Logan Odyssey
  • KCI Cables
  • Monster Signature Power Conditioning
  • Room 21X13X8

from affordableaudio, By David Finlay