My audio gear

Again in July 2019, I informed you concerning the combo of Massdrop’s x Grace Design Customary DAC:

and its companion Massdrop Goal 2 Headphone Amp: Desktop Version (Massdrop is now simply Drop, by the way in which, and is now owned by Corsair):

that I’d lately acquired for listening to computer-sourced audio over headphones in a quality-upgraded trend past simply the DAC (and amp-fed headphone jack) constructed into my Mac. That very same two-device stack:

stays on my desk and to my proper to this very day, albeit subsequently joined by an even greater high quality balanced audio stack to my left:

combining a Topping D10 Balanced DAC:

and a Drop + THX AAA 789 Linear Headphone Amplifier:

The Monolith

However I digress. At present’s dissection showcase is of none of those. As an alternative, I’ll be analyzing the center of the Monolith by Monoprice Liquid Spark Headphone Amplifier by Alex Cavalli:

It’s comparable in measurement to the Massdrop Goal 2 Headphone Amp: Desktop Version I discussed originally of the writeup:

And what a couple of companion digital-to-analog converter? That’s a narrative all by itself. It initially had one, the unsurprisingly named “Monolith by Monoprice Liquid Spark DAC by Alex Cavalli”:

primarily based on an Asahi Kasei Microdevices (AKM) Semiconductor DAC chip. Nonetheless, in October 2020, simply as COVID was normally throttling the tech economic system, audio gear suppliers obtained a double-whammy: a large three-day hearth at AKM’s semiconductor facility in Japan, which clobbered its output. Some AKM prospects, reminiscent of Fiio and Schiit (the latter, for instance, redesigning and renaming its Modi 3 DAC because the Modi 3e, with “e” brief for ESS Expertise), redesigned their programs to make use of chips from different suppliers as an alternative. Others, like Monoprice, threw within the towel. That mentioned, for the reason that Monoprice Liquid Spark headphone amp has typical RCA (unbalanced) analog line inputs, you should utilize it with any normal DAC.

A little bit of background data

A number of definitions earlier than continuing with the dissection. “Monolith” is Monoprice’s audio merchandise model. Alex Cavalli is a now-retired, well-known audio amplifier designer who, along with promoting each self-branded Cavalli Audio gear (now repaired by Avenson Audio since his retirement) and equipment branded by Monoprice (clearly) and Massdrop/Drop, additionally printed full design documentation units for others to make use of in constructing their very own gear, DIY model. Alex is a recent of one other audio amplifier “wizard” whose identify could also be extra acquainted to you: Nelson Move.

And eventually, why do I categorize it as being for “entry-level audiophiles”? The characteristic set, for one factor. I’ve already famous that it doesn’t provide balanced inputs and outputs, for instance, the magnitude-of-benefits of that are debatable, anyway. That mentioned, not like the Massdrop Goal 2 Headphone Amp: Desktop Version, it does embrace preamp outputs, the good thing about which I’ll elaborate on shortly. And its efficiency is nothing to sneeze at:

• Producer-published spec sheet (PDF)
• Producer-published take a look at measurement graphs (PDF)
• Independently printed testing outcomes (Audio Science Evaluate)
• Independently printed testing outcomes (Tremendous Finest Audio Buddies)

And the worth, though that’s an imperfect-at-best barometer of high quality. That mentioned, Schiit’s present high-end solid-state Mjolnir 3 headphone amp (the corporate additionally sells tube-based merchandise) goes for $1,199-$1,299, relying on coloration. Conversely, when the Liquid Spark Headphone Amplifier was launched in 2018 (a yr after Alex Cavalli introduced his retirement, curiously), Monoprice bought it for $99. Its listing worth is now $129. However (in explaining how I first got here throughout it) I’ve lengthy subscribed to Monoprice’s periodic promotional emails, and again in March of final yr, I stumbled throughout a smokin’ deal; $32.49 every plus an extra 25%-off low cost. I purchased two at $50.29 complete (with tax), one for a buddy’s birthday, the opposite for me.

What I’ll be taking aside right now is neither of those units, nevertheless. Final October, whereas looking for a Liquid Spark DAC mate to my headphone amplifier, I stumbled throughout “as-is” Liquid Spark amps on eBay for $29.99 plus tax and $9.99 for transport. The vendor notes mentioned:

Pulled from knowledgeable working surroundings. Examined for energy, no additional testing was achieved. On account of lack of expertise and having the correct gear to completely take a look at these models, we’re promoting AS-IS for elements/not working. Unit exhibits some indicators of scuffs/scratches throughout the unit. Please consult with the images for extra detailed info on the beauty situation.

As I’ve talked about (and exemplified) many instances earlier than, such “for elements solely” listings are excellent for teardown functions. I ended up getting one for $20.99 (plus the aforementioned gross sales tax and transport). I’m unsure how the vendor “examined for energy”, because it didn’t include the requisite “wall wart”. And as you could have already seen from the again panel “inventory picture” proven earlier, it’s an unusual one, outputting 36V at 1.25A min (that mentioned, no less than it’s obtained a DC output; Schiit’s are all simply AC transformers).

Overview

I do not know if this one truly works, and I’m not going to likelihood zapping my private amplifier’s purposeful PSU to search out out. That mentioned, right here it’s in all its cosmetically imperfect glory, as regular accompanied by a 0.75″ (19.1 mm) diameter U.S. penny for measurement comparability functions (the unit has dimensions of 4.6″ x 3.7″ x 1.5″/117 x 94 x 38 mm and weighs 9.6 oz./271g):

Left-to-right are the facility change, a ¼” TRS headphone jack, a 3-or-6 dB acquire change (to accommodate headphones of various impedance), and a rotary quantity management knob. Now, about that again panel (following up on my earlier “teaser” remark concerning the RCA output set):

Most headphone amps on this worth vary have unbalanced RCA inputs, however their solely output is an unbalanced TRS headphone jack (of various diameter) up entrance. However this one additionally has a pair of unbalanced RCA outputs. They usually’re not simply easy line stage pass-throughs, both; they route by means of the interior preamplifier first, though they (clearly) then bypass the headphone amplifier circuitry. Why’s this good? Nicely, you possibly can join them to an exterior energy amplifier to drive a set of audio system from the identical audio supply. And, as a result of the preamp remains to be within the loop, the headphone amp’s quantity management manages speaker quantity, too.

The one factor I don’t know (and haven’t examined with my unit) but, and the consumer handbook doesn’t make clear, is whether or not the 2 output units function concurrently or (as is the case with Schiit’s machine equivalents) in a one-or-the different trend. Mentioned one other approach, once you plug in some “cans”, does this additionally mute the sound that might in any other case come out the related audio system?

Onward: the left and proper sides:

The highest:

and backside:

full with a label closeup:

I admittedly loved fondling this machine, each in an absolute sense and relative to the scores of predominantly plastic-based merchandise I’ve taken aside prior to now (and can undoubtedly proceed to take action sooner or later). It’s heft…the solidity of its all-metal building…very good!

Teardown time

Talking of that all-metal building, let’s begin by getting the entrance panel off, beginning with the Torx head screws on each ends:

A part of the way in which there…

Let’s see what’s behind that quantity knob, which was snugly hooked up however pulled off after a little bit of muscle-powered coercion:

Unscrew the nut, take away the washer:

and this a part of the entire activity is efficiently accomplished:

Try that gloriously thick and in any other case stable PCB!

Now for the again panel. Six screws there and one other one under:

And the panel-still-attached PCB slides out the rear:

Voila!

Leaping ahead to the long run for a second, I went again and perused the product web page after the teardown-in-progress and located this, which I hadn’t seen earlier:

It wasn’t stunning. It was, conversely, validating. Fact be informed, even earlier than I took this amp aside, I’d suspected I’d encounter a discretes- (vs op amp-) primarily based design. And after I noticed the horde of tiny ICs scattered everywhere in the prime of the PCB, my in-advance hunch was validated.

Earlier than diving in, let’s first flip the PCB over and try the opposite facet:

Not as a lot to see right here, other than this closeup:

The biggest two ICs proven, which curiously don’t have their very own PCB-marking notations, versus the resistors and capacitors surrounding them (maybe the marks are beneath the chip packages) are labeled as follows, together with what I suppose is a STMicroelectronics emblem:

071I
GZ229

Any thought what they’re, readers? Again to the entrance for a close-up of essentially the most attention-grabbing part:

The biggest packaged elements on this facet are a mixture of what I consider to be QJ423 p-channel and QJ444 n-channel MOSFETs, each curiously recognized in on-line specs as meant for automotive purposes. And look, Alex even manufacturers his PCBs!

I’ll shut with just a few facet views of the solid-construction circuit board:

And that’s all I’ve obtained for you right now. I’ll maintain onto the disassembled machine for some time in case you could have any particular questions on the markings on a number of the different, tinier ICs and/or passives. And, as at all times, I welcome your ideas within the feedback. Bonus factors for anybody who is ready to dig up an Alex-authored DIY schematic that corresponds to this design!

—Brian Dipert is the Editor-in-Chief of the Edge AI and Imaginative and prescient Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the corporate’s on-line e-newsletter.

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