nOrh ACA2b Preamplifier front review

nOrh ACA2b Preamplifier

What does nOrh mean? The company is based out of Thailand, so my original thought was that it must be Thai for “Wonderful Audio Bargain.” But it turns out that it is a clue, referring to their signature product, the horn shaped loudspeaker. So to answer the question, nOrh simply is an anagram for horn. I have also heard these speakers and I have to agree that if I built them, I would name my company after them, too. Unfortunately, I don’t have a pair on hand to review, but I do have the certified bargain all-tube ACA2b preamp. Through a bizarre set of circumstances, I stumbled across this preamp in a pawn shop for a bargain-of-the-century used price, but at $399 shipped from Thailand to the US, this product is more than just affordable.


  • 3 inputs, 1 Record Output, 2 Main
  • Outputs
  • 90 second delay warm up (soft start) Frequency Response at 2 Volts RMS
  • 10 – 100,000 Hz
  • Gain 11dB THD ~ 0.07%
  • Input Impedance 100,000
  • Output Impedance 10,000
  • Tube Complement: 6922 x 2 – Sovtek or equivalent
  • Power Consumption 30 watts Dimensions H 3.5 x W 15 x D 8 inches Weight ~11 lbs (5kg)

nOrh ACA2b preamp review

This is a beautiful piece of equipment. The chrome chassis with a black face plate has always received wonderful compliments from even the most snobbish of audiophiles. The only cosmetic problem anyone has ever pointed out is that the ACA2b is smaller than standard size. But the design doesn’t require all that extra space, so why use the extra materials? This unit is also pretty light, easily and safely carried in one hand. The single, somewhat large transformer in the rear is the only part of particular weight.

nOrh ACA2b Preamplifier front

While I don’t usually pop the hood on bargain audio gear, the nOrh website made some pretty steep claims on what components they included in their sub $400 preamp. What I found inside was indeed impressive. All of the internal wiring is neat and cleanly routed around the perimeter of the chassis and appears to utilize a single star style grounding point. This effectively removes the sonic characteristics of the particularly dirty power at my house. The ACA2b is built using a circuit card instead of point-to-point wiring. This brings up one of my very few complaints about this product: the tube sockets are mounted directly on the board. This is not much of an issue for lightweight tubes like the 6922s, but the added weight of any tubes can lower the life of a circuit card. The rest of the circuit card seems pretty well laid out, giving ample room to the larger components, and keeping the power circuit separate from the audio signal path. Top-quality name-brand components are in fact used to make this budget product; for instance, platinum coated switches and ceramic sockets are used. The solder joints are all clean and attractive, nicer then what I have found in other equipment from low-priced overseas manufactures. The volume pot is indeed a nice quality ALPS. This can easily be upgraded, but there doesn’t seem to be enough room in the chassis for a stepped attenuator. The 90-second soft-start circuit should protect the tubes, and the mute switch completely disconnects the output stage. This feature is excellent for wire changes and other quick tweaks.

The front panel of the ACA2b is somewhat austere. I like this look, but some might not. It is just a simple matte black metal panel with two switches and two dials: one power switch, one mute switch, one input selector knob, and one volume knob. The switches and knobs are all chrome, and they add some sparkle look to an otherwise very plain faceplate. The knobs have a nice sturdy weight to them, but they feel kind of small in your hand. Each control is clearly labeled, and the functionality and ease of use is very impressive. The rear panel is also very clearly labeled, and has sturdy good quality RCA connectors. None of the controls front or back has even the slightest wiggle. I give this product very high marks for quality workmanship.

nOrh ACA2b Preamplifier review

nOrh doesn’t seem to have an instruction manual for the ACA2b preamp. I don’t really know what an instruction manual for a piece of equipment this straightforward to operate would say, but it is still nice to have a couple of bound pages to flip through when you get a new piece of equipment. I, for one, like to see some tube handling notes included with any affordable tube gear. We were all once tube newbies, and even experienced tube rollers could possibly learn something new.

The output stage on the ACA2b is pretty impressive for any price. The gain is the standard 11db, but there is one recording output in addition to the two standard outputs. The dual outputs are a nifty feature that I have used several times in the past. The ACA2b accepts up to 6 volts input and outputs up to 60 volts. This is enough power to use longer lengths of interconnect cables and still have enough juice to power almost any amp on the other end. I have used this preamp with several amplifiers including Quicksilvers, Antique Sound Labs AV20s, and an Audio Research 225 watt amp all with 6-10 foot interconnects, and the sound was fast and clean even with the difficult Audio Research load.

So, the nOrh ACA2b looks great, it’s well built and easy to use, but how does it sound? In a word, pristine. Compared to Carver, B&K and Parasound preamps I have heard in my system, all costing much more then this little guy, it sounds like a crisp breath of fresh air has blown into my entire system. The lower end bass is more subtle than with any of these performers, but the timbre and clarity in the entire midrange field that is indicative of the 6922 tube was certainly in residence. I would honestly call this preamp an even draw with the Quicksilver Line Stage. To me, it just comes down to different tubes’ sonic signature. I prefer the 6922’s laid-back presence, while others prefer the 12AX7’s more edgy and forward sound. While the sound isn’t at the level of the Blue Circle BC21.1 that I have also spent quite a bit of time listening to, the feeling conveyed by the shared driving tubes made a clear connection between the two pieces. Even though the Blue Circle has a beefier power supply, and that wonderful Shalco stepped attenuator, the Blue Circle and the nOrh could be cousins. The only clearly perceivable difference between the sound of these two pieces was that the Blue Circle has more weight in the lower midrange and on through the bass scales, and the nOrh has a slightly more forward soundstage and presentation. As a budget-conscious audiophile, I honestly don’t think I could pay the cost difference for the sonic differences between these two products.

The nOrh ACA2b was very sensitive to cable changes. This feature, mixed with the multiple available outputs, makes it a great piece of equipment for interconnect or source comparisons. I personally have found this extremely helpful when trying to find the perfect synergy between multiple devices. I have tried several interconnect options with this device. The LC-1 cable from Blue Jeans Cables provided the blackest background of the group, while the Dayton Interconnect from Parts Express let through a wonderful warmth and color. The Sidewinder from Parts Express was the most analytical of the group. While it is normally not something I would recommend, I am currently using the Blue Jeans LC-1 as the input cable, and the Dayton Interconnect as the output. This combination seems to give me a little bit of the best of both worlds. Cable synergy pundits would shun me for this practice, but I have learned it is best to listen with my ears and not my head. While it may not exactly be fair, the best sounding speaker cables for the Norh/ Quicksilver combination was by far the Audioquest CV-4. While they cost the same amount of money as this preamp, the improvement was well worth it. It really is nice to have a piece of equipment that is wonderful on its own, but has this ability to become something new, different and equally wonderful with some simple cable swapping.

With the ACA2b, the soundstage is slightly in front of the speakers and spread nicely from speaker to speaker, occasionally surprising me by going beyond the left and right on well recorded pieces. On the Neil Young album Live at Massey Hall, the transition from “Old Man” to “Journey through the Past” has some interesting things happening around the stage. All of these small nuances are wonderfully portrayed with the ACA2b. The transition from guitar to piano is very clear through the nOrh. The piano in “Journey through the Past” is very involving. I didn’t quite feel like was there, but I could still feel some of the stage and audience presence with the nOrh ACA2b in a way that only a well-matched system can create.

nOrh ACA2b Preamplifier

My imaging standard has always been Alison Krauss and Union Stations “Unionhouse Branch.” The ACA2b didn’t disappoint me here, either. The image was precise enough to easily pinpoint any specific instrument on the stage. Usually with more budget-priced equipment, the mandolin and banjo become tangled up, or the mandolin and the fiddle become indiscernible during the more complicated portions. In the worst case scenario, all three are a jumbled, single-instrument nightmare, but not so with the ACA2b. All of the performers were clear, crisp, and even musical. I was impressed with the image, soundstage and presence of the nOrh ACA2b in every type of music I could throw at it.

Something interesting that I have noticed about nOrh is that my used piece seems to have been a very lucky find indeed. In my searches of Audiogon and other used audio hangouts I almost never see more than one or two, if any, pieces from this manufacturer. I think this is partially attributable to the company’s small size, but I also have to assume that many people just can’t seem to let the nOrh stuff they purchase go. I have one or two special pieces of equipment which, even though I don’t use them very often, I am just unable to part with. The nOrh ACA2b fits very nicely into this category.

A common concern about tube gear in general is that tubes may become unavailable or too expensive in the near future. While New Old Stock (NOS) tubes can be very expensive, the Russians, Slovakians, and Chinese are still massproducing some great tubes. Europe and Asia are both experiencing something of a tube renaissance, and the tube manufacturers seem to be taking notice. A close friend who has been a tube aficionado since the ‘50s recently commented, “…[I]t seems to me that there are more tubes available today than even fifteen or twenty years ago.” Not to say that there are not some very expensive tube options available: it is entirely possible to spend more on NOS tubes for the nOrh ACA2b than the shipped retail price. But there are more affordable options, including the Electo-Harmonix for $12-$20 each. The ACA2b came with Sovtek 6922s; a replacement set of these would cost around $12. I wouldn’t worry too much about replacements, though. The 6922 tubes are usually rated to last between 5 and 10,000 hours of play, depending on use. With that in mind, unless you’re looking for a different sound, I wouldn’t plan on changing these tubes for awhile. I haven’t done any tube rolling with the ACA2b, but rumor has it that Upscale Audio could have some NOS 6922s coming in, and Kevin’s deals can be hard to beat. (Sorry I couldn’t resist the pun….)

nOrh ACA2b Preamplifier back

Remote controls can be a dividing line for people looking for a preamp. I have never been a fan of bells and whistles and extra things that may be unnecessary, so the lack of a remote control with this preamp hasn’t been an issue for me. I usually only listen to one source, and I typically listen at around the same volume level. People on the other side of that line who really need a remote will unfortunately need to look elsewhere as it doesn’t appear that nOrh is looking to add that feature any time soon. Inexpensive remote control volume pots can be problematic, so I can see how maintaining the $395 price point could really get in the way of that addition.

Usually a piece of equipment can be put into a nice little category to wrap up a review, and I would easily call this the “Best in Class” for sub $400 preamps. I just feel that this is so much nicer than a typical $400 piece of equipment. Honestly, I would call this wonderful piece either the “Bargain of a Lifetime” or my “Favorite Preamp under $1000.” It is nice to occasionally stumble across a piece of equipment that just doesn’t fit in the typical audiophile mold.

Even though nOrh doesn’t really mean anything in Thai, their pieces are still sure to be conversation pieces around any home.

Equipment used for review:

  • Roku Soundbridge M1000 Network Music Player
  • Quicksilver Audio Silver Mono amplifiers Antique Sound Labs AV-20 Mono amplifiers Anthem Pre1l Preamp
  • Blue Circle 21.1 Preamp
  • Fritz Frequencies loudspeakers Dayton Audio interconnects (3 foot) Blue Jeans LC-1 interconnects (3 foot)
  • Audioquest Sidewinder interconnects (3 foot) Audioquest CV-4 speaker cables (10 foot)

from affordableaudio, By Jeff Brown