Orchard Audio BOSC / Starkrimson Monoblock Amplifier
I could give you four reasons to like a Class D switching amplifier and four reasons to prefer a classic tube amplifier. It seems to me its always been like that. But as the years have passed the lines have blurred. These distinctive qualities have inevitably merged and become more and more a moot subject. Remaining are two camps, neither one right neither one wrong.
Warp forward and here I sit looking into a cardboard box. Inside the box there are two black aluminum boxes. I see that the top cover of the box has a very stylized logo of a tree silk-screened in white paint This pair of black boxes are the 150 Watt per channel (BOSC /Starkrimson, same amplifier two different names) switching amplifiers. They are only 2" high and 4.5" wide and 4" deep. Digging a little deeper I unwrap two large black power supplies. They are rated at 56 Volts DC and 4.5 Amps. At one end they have a socket for an IEC power cord and at the opposite end, the cord is terminated in a four-pin Molex plug.
That Molex plug Locks into and powers the amplifiers. Along with the supplied connecting cords I asked for and received a set of 1.5-meter speaker cables. One of the advantages of these small box amplifiers is the ability to place them directly behind your speakers. You can order the amplifiers in two configurations. The first version places all the connections on one side of the amplifier, so the speaker connections and the XLR jack and the 4 pin Molex connector from the power supply are grouped together. The other option is to order the amplifier with the speaker binding posts on one side and the XLR and Molex connection on the opposite side. Either version of the Orchard Amplifiers is priced at $1499.99.
Instead of the word BOSC printed on my two amplifiers they have the word Starkrimson silk screened on the cover. I had to ask the designer and founder Leonid (Leo) Ayzenshtat what that meant. He replied that they are the names of two types of pears. "Well I guess there is logic in that since they are manufactured by Orchard Audio."
Since GaN devices can switch faster the dead time is far less than their Silicon counterparts. The GaN transistor allows the Bosc amplifier to switch at frequencies up to 800 kHz. The higher switching frequencies allows a standard LC (Inductive and Capacitor) filter network to work extremely well. The direct result is that the switching artifacts of the Orchard Amplifier are reduced by a factor of 40dB.
This is a functional diagram of the dual feedback system (Patent Application) or PWM (Pulse Width Modulator) controller. The DC Modulator works with the feedback network both pre and post to essentially eliminate DC offset at the output. The design enjoys the benefits of the highest quality and larger than necessary board-mounted components, inductors, and filter capacitors. All of these are placed on a four-layer circuit board. It uses a custom stack-up on a high-end dielectric material and ENIG (Gold) finish. Note: Additional information will be appended at the end of this narrative.
Music From The GaN
But let me be cautious and not jump to conclusions, I need to put some more hours on these black boxes. After thirty or forty more hours they do seem to have become slightly quieter. My reference and preference is and has been the sound of a human voice. If anything would be the antithesis of digital sound then it would have to be an analog vinyl disk. It very well may be able to highlight some digital artifacts, that's if any are present. Of course, you need to select a very good recording to hear any of these minute details.
Let's try one of my favorite go-to albums, Christopher Cross' Another Page [Warner Bros 9-23757-1].The liner notes list additional guest vocals by Micheal McDonald, Carl Wilson, Art Garfunkel, J. D. Souther, Don Henley, Karla Bonoff, and a long list of great guest musicians. This is a studio album but done in such a way that you can look into the mix and pick out some of the people backing the lead vocal along with layers of accompanying instrumentation. On track two, "Baby Says No", when we get to the line: "I really think I've got it bad this time". You can hear a plaintive baritone voice that echoes deep in the background and repeats the words "So Bad".
There's enough clarity and pitch definition that I can hear through the mix to the source, the voice belongs to Micheal McDonald. Cut to the chase, from the beginning till the end the album has, detail, clarity, and focus. At this point, I can't find anything wrong to hang a verb on. Moving right along let me try one of my reference albums, Diana Krall CD that I bought for $4 at my local flea market. This is Ms. Krall's very first debut album: Stepping Out [Justin Time, Just 50-2]. This is a record label based in Montreal Canada. My favorite track is, "Do nothing till you hear from me". She forms the third part of a trio. And accompanying Ms. Krall on the piano is Jeff Hamilton on Drums and John Clayton on String Bass.
With the Orchard Audio's BOSC / Starkrimson monoblocks pushing notes, there is an unexpected reality that moves forward and sits in my lap. Clayton's bass conveys a crystal clear bass line. That gets resolved to the sound of his finger friction stroking those fiddle strings. Clayton's bass is the sound of a wooden chamber that projects and propels the music into my room. When the lights in my room are turned down low, Ms. Krall's words and phrasing are intimate and real as she seems to sing just for me.
Even now I still have my Sony SACD deck plugged into and powered by an isolation transformer. The Orchard amplifiers have two separate dedicated 56 Volt DC power supplies and therefore are essentially isolated from the rest of the systems AC power source. Today none of that seems necessary. The parts quality and simplicity of this Class D solid-state design impressed me as near foolproof and extremely quiet and durable.
I said it previously, yet it is worth repeating. I can find no obvious faults to the way Orchard Audio's BOSC / Starkrimson amplifier reproduces music. At the same time, it is not a SET (single-ended triode) amplifier lovers cup of tea. There is no harmonic halo around any element of the music. Within the useful frequency capabilities (45Hz to 43kHz) of my Aurum Cantus two driver monitor speakers. Additionally, they are constrained by practical small room limitations. The Orchard amplifiers at $1499.99 set a new benchmark for value, laser-like clarity, and inner detail at this price range. Highly recommended.
Remember to Enjoy The Music and from me Semper Hi-Fi.