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December 2006
Enjoy the Music.com Review Magazine
JuicyMusic Merlin Preamplifier
A wonderful tube preamplifier for less than $1K
Review By A. Colin Flood
Click here to e-mail reviewer


JuicyMusic Merlin Preamplifier  In the land of tweaking audiophiles, there is a little niche marketer, who is slowly building an avid following from some of the most golden ears you will ever meet. On Grizzly Bluff Road in the California Redwoods, five hours away from San Francisco, Mark Deneen ("DEN-EEN") makes sweet sounding tube amplifiers that have the odd but memorable names of Blueberry, Peach and now, Merlin. After spending about a year doing the development of his initial BlueBerry tube preamplifier, Deneen is shipping products for over 2 years. Many a die-hard tube lover graduates to his preamplifiers, never to move on again.

Deneen wanted an Internet-based cottage business after retiring from the computer industry... because of his past experience in starting Paragon Audio in the 1970s. He designed his products to have the live, juicy quality of berry fresh off the bush: an explosion of taste and sensation. He strives for clarity, 3-dimensionality and balanced tone.

Deneen admits that objective analysis of preamplifier sound is difficult. To some degree, output impedance and amplifier sensitivity define what a preamplifier can comfortably drive, he says, "but nothing will describe with precision how well it will all work, or sound."

Tube amplifiers are better today than years ago because they are steadily improving. Deneen says one reason is that there are more people designing and building them, and for another, there is more creativity being applied to tube circuits such as the use of current technologies merging with the tube technology. "Also," he says, "designers are not constricted today by economics in their designs. The primary market in the heyday of tubes was the "average" or middle of the road market. Cost and market price were dominant factors. Today, the tube amp is strictly a high-end sale, and cost is not a constraint." He designed the Merlin to have the essential JuicyMusic sound quality at the most affordable price possible.

Deneen makes the Merlin using the same basic circuit topology as his Peach preamplifier, but he simplified it down to the essence of a great line stage. "The Merlin was designed very specifically to fit that price, he says. Naturally, it has less features than our other preamps, but the sound is still remarkably similar to the Peach, which costs 2X as much." At a foot wide and 2 inches taller than the typical black box on the audio rack, the Merlin looks and feels stocky, solid, capable and expensive. It is boxed on both ends with panels of tan Walnut wood. (It would be a shame to hide such a good-looking unit in a equipment rack.) Exemplifying thoughtful design, the wood panels extend a digit past the back plate, protecting the RCA connectors and the fuse cap.

No other woods are available. Like Apple Computer, Deneen tried color themes of peach, orange or green shades with his BlueBerry and Peach preamplifiers. The Merlin is not designed in that way. Sounding a bit like Henry Ford, he says "95 percent of the audio buying public still prefers black over any other color."


The Knobs
A red power button and green LED dominate the center of the black Merlin faceplate. Gray screws make it appear robust. All markings are first-rate professional. Although only an inch of pink Styrofoam protects the Merlin, Fed Ex delivered it in perfect condition. A thorough sheet of instructions answered many of the questions I posed to Deneen. The page explained how to use the unique controls, the power-up sequence and location ("about 1 inch of top ventilation").

The Merlin allows you to choose between two line level inputs — no phono; that is available in Deneen’s other models — and between tape or source. There are no tone controls or EQ inputs. There is only one set of outputs. White Mohawk lines mark the tops of all knobs, making them easy to see during candle-lit listening sessions.

On the right side of the unit is a unique three-knob arrangement of left, right and volume. All JuicyMusic preamplifiers use this system, instead of typical volume and balance controls. The 3-way system sets channel balance AND amplifier sensitivity control, along with volume. Deneen says the reason for this arrangement is that many power amplifiers have an input sensitivity of less than 1-volt. With conventional level and balance controls, the preamplifier has very little use of the volume control before the amp is too loud. The range of the typical volume is too small. This is particularly true with my reference big ole horns. It is tricky to be quiet and easy to be too loud. The Merlin works with amplifiers having either a 5 or a mere 0.5-volt sensitivity.


Inside The Marvel
Deneen accomplishes transparency in a low-cost preamplifier by keeping the circuits natural and simple. "Natural, he says, "means not forcing the tube do anything it wasn't designed to do. It is very easy and very tempting to over design a line stage. Keeping it essentially simple retains the transparency and makes the unit economical to build."

The Merlin uses vacuum tube diodes, not solid-state ones, to rectify the incoming AC voltage to DC. He sues a dual diode rectifier with 6.3V filament. "Tube rectifiers are smoother," he says, "quieter and retain the tube vibe, which is the reason someone would want a tube preamplifier in the first place. A pair of solid-state diodes would cost 10-cents. A rectifier tube and socket is more like $12. So, clearly if we thought soild-state diodes were as good, we could save 99 percent of the cost of rectifiers. But the tube rectifier is superior, so we use it even in the low cost Merlin."

Zero feedback is important in both the preamplifier and the amplifier, he says. "Since the preamp however is first, any smearing caused by excessive feedback in the preamp can never be recovered later on in the amplifier. You can't UNSMEAR a signal." The 6922 tubes provide a perfect amount of gain for a line section without feedback, Deneen says. They have "wide frequency response, low noise, low output impedance, low voltage operation and most of all excellent sonic transparency."

Do not place the Merlin on top of large amplifier transformers, he says, and allow an hour to warm-up the unit. The unit can feed 2 subs in line. Deneen says when the sound becomes thin, flat and there is a loss of gain, or when audible distortion sets in, it is time to replace both tubes. Tubes are single-ended, Class A triodes and should last 5 years. Replacement tubes are $20 per set, available from him.

The Merlin was not designed for headphones. Yet, a set like Sennheisers will work, except for the deepest bass. Deneen says the Merlin properly drive all headphones. One suggested tweak audiophiles can make to this model is to try New Old Stock (NOS) tubes in place of the OEM tubes. For tweaking audiophiles, NOS tubes add the ability to tailor the sound to taste.

Deneen’s products are available direct, through Audiogon or his recently created in-home shopping network. You can touch, feel and hear JuicyMusic products by contacting registered representatives listed on his web site. Deneen accepts credit cards and Pay Pal. Although warranty is a long two-years, the return policy is a short 7-days. So if you don’t like it, send it back immediately. Yet he says, "we've never had a single dispute, with any customer regarding returns."


The Sound
Popping smooth jazz favorite Norah Jones’ Feels Like Home, my first impression of the Merlin was immediate. It has smoothness, little vocal edginess, gentleness, excellent imaging and soundstage far exceeding its modest looks and price. In fact, I instantly hopped up from my sweet listening spot to angle the big ole horns a noodge further apart to widen the soundstage. There is impressive neutrality. It sounds quite free of artifact and grunge. The treble seems delicate, not sparkling, but not withdrawn either.

Although the Silver patch cable shoot-out was a test of patience, reviewing the Merlin was simple joy. The silver cables were not used in this review. Some pieces of equipment are quite colored. They add a lot of their own personality to the rendition of music. (Although usually not as much to movies.) OK, I admit it, horn and electrostatic loudspeakers are certainly in that category. The beefy Delta Studio 6s33s amp is in that category. So are the wonderful CAR Cinema Ensembles.

When a reviewer comes across such unique voicing, the equipment can — or can not be — be quite pleasing. When the coloration, the voice the equipment adds to the music is pleasant, the result is often a long and lengthy "disc–overy" and re-discovery of the music in the reviewer’s rack. In other words, if I like the way the equipment affects the sound, I listen and listen and listen some more.


Now, follow me closely here, because this is not a criticism. It may, in fact, be one of the highest compliments that a reviewer can pay to any piece of equipment. The Merlin did not lead to a long and lengthy "re-disc-overy" of my CD rack. It yielded no major surprises, noticeable colorations, interesting acoustic anomalies, grunge or artifacts. To call it transparent or neutral or even, accurate, is it to label it as cold or sterile. One could say the same things about most modest solid-state equipment. yet same words apply to this incredibly charming and competent tube gear.

Take Jack Johnson’s Brushfire Fairytales. With the Delta 6s33s, I loved the way this massive tube amp opened up instruments, giving them energy and space. Especially the rim shots — it makes them separate and distinct, not merely a background sonic doo-dad. This is not so with the modest Merlin. Even with a passive bi-amplification provided by my massive Pioneer amp (see bio), the rim shots are there. They are not weak nor powerful either, yet they are not missing. Instead, the feeling is that the shots are played faithfully, without undue influence.

The Merlin brings to mind the enjoyment of the Omega TS1s. Although these single driver speakers do not have the thunking bass and sparkling treble, which tweaking audiophiles often use as benchmarks of superb speakers, these smooth and coherent speakers grow easily on you — they are very listenable and let you enjoy the music. As it is with the T1s, so it is with the magical Merlin.  It is an incredible value in long-term enjoyment. It is neither obviously wonderful, nor clearly deficient. The Merlin is an always competent and solid, with focus on the lead performer. In that same regard, the treble is a little soft; accurate, and not as sparkly as other equipment makes it.

At 104dB/W/m sensitivity, big ole horns are as sensitive to tiny twists on the dial as a racehorse is to the crop – any slight twitch makes them go. Normally pre-amp volume controls provide a skinny range between way too soft and way too loud. Often, 7:00 on the dial just won’t do and 7:15 or 7:30 is too much. The Merlin has a master stereo volume control, with two separate volume controls for each channel. This unique innovation not only lets you set the volume (and therefore the balance) with each channel, but then lets you create a greater volume range for the master control. A very thoughtful and useful approach.

Another problem with super sensitive speakers is that hum and line noise become problems. The Merlin was quiet, even for a tube amp. It is as quiet as other pieces of quality equipment, like the Delta 6s233s, but it was not as dead quiet as the amazingly Pass X250 monster amplifier.

Surprisingly, the tubes for the Merlin were already installed. Making it more of a plug and play unit than any other tube gear I remember using. Perhaps my unit was broken in; I did not notice a significant difference in sound after hours of play.  Some tube and solid–state units open up after they warm up. I did not find that with the Merlin. It sounded adept right out of the box and never varied in its performance during its long visit to my abode.


The Summary
Artists often blow up objects with so much hot air, they float above the crowd. They exaggerate slight differences sky-high. Writers are no different. Therefore, it is hard for me to describe the truly honest merits of this remarkable unit without sounding like a used-car salesman.

Either I have reviewed a succession of wonderful equipment lately, or my curmudgeonly distaste is ebbing away with my hearing. Because the solid little Merlin is quite a capable unit. It sounds natural and effortless. It reflects thoughtful design at an amazing price point, providing an excellent value for tube lovers. Mark Deneen deserves whatever rewards come his way for this notable piece of intelligent design and workmanship.

This doesn’t mean the miserly grader is gone. Of course, most components must still rank three Blue Notes — average. Nothing wrong with that. They perform as expected. Once again, I sparingly grant 4 Blue Notes on those categories for which the component is clearly above average, compared to the others auditioned for EnjoyTheMusic.com. Only the best it could ever be, regardless of cost, wins 5 coveted Blue Notes.

My own Enjoyment category is higher than most other products. Long-term impression is of a wonderfully reliable, solidly built, thoughtfully engineered and excellent long-term value.



Sub-bass (10Hz - 60Hz)


Mid-bass (80Hz - 200Hz)

Midrange (200Hz - 3,000Hz)

High-frequencies (3,000Hz on up)



Inner Resolution

Soundscape width front

Soundscape width rear  
Soundscape depth behind speakers

Soundscape extension into the room


Fit and Finish

Self Noise


Value for the Money


Type: Vacuum tube preamplifer

Tube Compliment: 6922 and 6X4

Frequency Response: 5Hz to  45kHz

Inputs: Two AUX and one Tape

Outputs: Tape and Main

Noise: 85dB below 2V output

Line Gain: 20dB

Input Z: 90K Ohms

Output Z: 920 Ohms

Dimensions: 12 x 4 x 10 (WxHxD in inches)

Weight: 10 Lbs.

Price: $795


Company Information
1551 Grizzly Bluff Rd.
Ferndale, California 95536

Voice: (707) 786-9736 
Fax: (707) 760-3505 
Email: info@juicymusicaudio.com
Website: www.juicymusicaudio.com












































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