Helm Audio Bolt DAC/AMP overview: An astounding ultra-compact converter and amplifier on your headphones


The traditional Greek amphitheater at Epidaurus is universally thought of the acoustic marvel of the traditional world. I might argue that the noble (although oftentimes Sisyphean) quest for acoustic perfection is a basic a part of the human spirit. Sadly, even with all of the developments of contemporary know-how, audio high quality on our mostly used units—our smartphones and tablets—someway takes a again seat.

Processing chips inside these units that convert the digital sign to analog for headphones are both sub-par or downright horrible. Furthermore, they usually aren’t able to delivering the ability high-performance headphones want.

Including an outboard DAC or headphone amplifier to get that efficiency historically meant sacrificing portability. Because of Helm Audio, that tradeoff is a factor of the previous. Helm Audio’s Bolt DAC/AMP is a superb-sounding, ultra-portable DAC and amplifier that decodes the complete vary of at this time’s premier high-res audio codecs for a mere $99. Learn on why I fell in love with Helm Audio’s Bolt and named it an TechHive Editors’ Selection.

Very good match and end

When unboxing the Helm Bolt, the very first thing you’ll discover is that the bundle is Spartan. It consists of the Bolt DAC/AMP, a USB-C feminine to USB-A adapter, and a branded, self-closing carrying pouch. That’s it.

Theo Nicolakis / IDG

What’s included within the field.

Holding the Helm Bolt in my palms, it felt like a high-quality product with premium supplies. The oblong headphone enter was sealed with a matte black end and checkered quadrant that permit me get a strong grip on the Bolt for plugging and unplugging headphone jacks. Even with moist or sweaty palms, I had a assured grip. It’s a pleasant consideration to element you’ll admire with prolonged use. I can not remark if this excellent end will put on over time.

Excessive efficiency in an ultra-compact type issue

The guts of the Helm Bolt is the ESS Sabre 9281A Professional, a 32-bit, two-channel DAC and headphone amplifier in a single. One of many key promoting factors is that the ESS Sabre DAC sports activities a {hardware} MQA renderer for MQA playback. That is along with DSD, WAV, and each main lossless codec. The Helm Bolt will help PCM pattern charges as much as 384kHz. The Helm Bolt’s signal-to-noise ratio is 115dB.

I’ve examined a number of outboard DAC/AMP options over time. Whereas they’ve smitten me with their efficiency, bulk has been their largest detractor. Helm Bolt’s ultra-portable, versatile type issue is a significant differentiator.

The Bolt DAC/AMP’s takes a cue from Apple’ Lightning-to-headphone adapter: On one finish of the Bolt DAC/AMP you’ll discover a USB-C connector and on the opposite a 3.5mm enter that additionally homes the Bolt’s excessive tech electronics. A braided nylon cable connects the 2 parts. The top result’s a mere 3.75-inches lengthy.

Helm Bolt adapter size compared to Apple’s lightning to headphone adapter and USB-C to headphone ada Theo Nicolakis / IDG

Helm Bolt adapter dimension in comparison with Apple’s Lightning to headphone adapter and USB-C to headphone adapter.

I discovered the Bolt’s small, ultra-flexible type issue to be essentially the most sensible and useful of any outboard DAC I’ve used with a cell gadget (or a pc for that matter). It was straightforward to slide into any pocket, jacket, or backpack. At about 1.2 ounces, it didn’t weigh me down. The versatile design by no means gave me main hesitations of tucking it away. And the truth that the Bolt didn’t require recharging or obtained super-hot sealed the deal.

The Bolt DAC/AMP doesn’t want a driver. It contains a USB-C enter that’s appropriate with MacOS, iOS, Home windows 10, and Android. For iOS units (like my iPhone 12 Professional) and computer systems with no USB-C port, Helm Audio features a USB-C-to-USB-A converter within the field. Join the converter and voila! You need to use the Bolt DAC/AMP throughout an unlimited array of units.

To connect with legacy devices, the Helm Bolt comes with a USB-C female to USB-A male adapter. Theo Nicolakis / IDG

To attach with legacy units, the Helm Bolt comes with a USB-C feminine to USB-A male adapter.

Whereas Apple’s newest iPads function a USB-C connector, you could be questioning the way you bridge the hole with iPhones or Lightning connector-based iPads. The reply is easy, simply choose up both the Apple Lightning-to-USB Digicam Adapter or the Apple Lightning-to-USB-3 Digicam Adapter. I bought each adapters for this overview. Each function a Lightning-to USB-A connection and carried out identically.

Detail view of how to connect to one of Apple’s ligntning to USB adapters. Theo Nicolakis / IDG

Element view of how to connect with considered one of Apple’s Ligntning-to-USB adapters.

Some minor hiccups

I’ll observe two minor hiccups I skilled throughout my overview interval: I used the Helm Bolt through its USB-C connector on a Mac, a Home windows 10 PC, and a USB-C primarily based iPad. The whole lot labored splendidly effectively except an odd anomaly on the Mac that I narrowed right down to the Qobuz desktop app when used along with the Helm Bolt.

When first plugging within the Helm Bolt, the Mac units the Bolt’s Grasp quantity within the Audio MIDI app (situated within the Utilities folder on the Mac) to 1.0 (100%). Tidal gave me an alert that the quantity was too loud and routinely adjusted it. Apple Music Apps dealt with it gracefully inside the app’s quantity management.  Not Qobuz.

The quantity was so loud it practically blasted out my ears and something over 5 % quantity inside the Quobuz app was ridiculously too loud. The one method I discovered to repair the issue was to enter the Audio MIDI app and cut back the grasp quantity to 50 % or much less. I’ve skilled some oddities with the Qobuz desktop app earlier than, and for those who use the Helm Bolt with Qobuz on a Mac, you need to be cautious about this quantity anomaly I skilled.

Detail view of the Helm Audio Bolt’s USB adapter. Theo Nicolakis / IDG

Element view of the Helm Audio Bolt’s USB adapter.

The second anomaly I skilled began after I related the USB-C-to-USB-A adapter to be used on my iPhone 12 Professional. Though the Bolt’s energy/idle mild indicator would illumine blue, the Bolt DAC/AMP wouldn’t work on my iPhone 12—or any USB-A pc port for that matter. Audio would come solely from my iPhone audio system and the Bolt would by no means present up as a speaker output choice. Helm Audio despatched me out a alternative USB-C-to-USB-A adapter and bingo! The whole lot labored flawlessly. Within the unlikely occasion you run into the same concern, the USB adapter is the probably drawback.

THX Licensed

The Bolt DAC/AMP is THX Licensed, which is a giant deal. THX certification is the gold-standard within the A/V world for high quality and efficiency. The THX Certification course of entails placing a product by means of greater than 400 exams. The product should additionally meet exact manufacturing requirements. And the product is re-tested once more for compliance after manufacturing. Helm Audio says the Bolt DAC/AMP’s THX Certification is for ultra-low harmonic, crosstalk, and crossover distortion.

Helm Audio notes that its design is an intrinsic a part of this low distortion. The Helm Bolt bodily isolates the DAC from the USB connector. The Helm Bolt additionally makes use of a three-oscillator design to lock onto the frequency. The corporate claims these two design options dramatically enhance the Bolt’s efficiency.

Automated impedance and sign sensing

The Bolt DAC/AMP routinely detects your headphone’s impedance and units the output degree accordingly (1V for impedances lower than 150 ohms, and 2V for impedances of 150 ohms or greater).

The Bolt DAC/AMP provides you a visible indicator of the present sample-rate playback. Blue signifies that the Bolt DAC/AMP has energy (idle state) or a sign lower than or equal to 48kHz. Pink signifies a high-res sign higher than 48kHz. Magenta signifies MQA content material whatever the sampling price. The LED indicator may be very efficient and my solely constructive remark is that the Helm Audio workforce ought to think about altering the idle state coloration to a different coloration (inexperienced maybe), so that customers can debug any potential anomalous scenario. I additionally famous that when enjoying MQA content material, the magenta LED appeared to be a mix of a separate blue and crimson mild. Subsequently, when seen off angle, the sunshine would appear dominantly blue or dominantly crimson.

The Helm Bolt has an LED indicator to show you the signal format and sampling rate. Mangenta indicat Theo Nicolakis / IDG

The Helm Bolt has an LED indicator to point out you the sign format and sampling price. Magenta signifies the presence of an MQA sign.

A revelatory listening expertise

I examined the Helm Audio Bolt DAC/AMP on an iPhone 12 Professional, iPad Professional, and Macbook Professional. For testing on the iPhone 12 Professional, I used the beforehand talked about Apple Lightning-to-USB adapters. Tidal served up all supply materials. I positioned an emphasis on spinning up tracks categorised as Tidal Masters, that are encoded with MQA.

I used quite a lot of headphones throughout my take a look at interval together with the Oppo PM2 planar magnetic headphones, B&W PX, and Beyerdynamic Amiron Residence; however my feedback beneath will mirror my expertise with the Focal Clear and B&W P9 Signature headphones.

The primary and most pure query that got here to my thoughts (and I assume yours) is how does the Helm Bolt evaluate to the built-in headphone output on a pc or the Lightning- to-headphone adapters Apple sells.

Effectively, it didn’t take lengthy to complete that comparability.

Beginning off, I pitted the Helm Bolt to Apple’s Lightning-to-headphone adapter. The Helm Bolt’s impression on the music was nothing wanting astounding. Listening to the Helm Bolt’s musical presentation was like going into that hallowed again room in each high-end audio retailer. The musical soundstage snapped into an instantly discernible, three-dimensional layer. Devices and vocals tightened up, standing in a agency house and time. Devices particularly exhibited extra refinement, texture, and air.

To use with an iPhone or iOS device with an lightning connector, I used one of the lightning to USB Theo Nicolakis / IDG

To make use of with an iPhone or iOS gadget with a Lightning connector, I used considered one of 

Apple’s Lightning-to-USB adapters.

Listening on my iPhone 12 Professional by means of the Apple Lightning adapter was a downer by comparability. Music was flat, coming from a two dimensional sound stage. The all-important midrange was muddier. I usually famous bass bloat. And the highest finish? It was uninteresting. It lacked the delicacy, air, shimmer, and pleasure that the Helm Bolt delivered.

Listening to the one thing so simple as the Tidal Grasp of Sting’s “Fragile (Reside)” from the album My Songs laid naked the variations within the two adapters.

The Helm Bolt reveled in bringing “Rise” by Dominique Fils-Aimé to life. Percussive notes snapped with authority, weight, precision, and relentless assault. That is how actual bass must be skilled. The identical notes had been comparatively uninteresting, robbed of dynamics, and flat on the Apple headphone adapter. Listening to the identical tune by means of the 2 completely different adapters is a totally completely different emotional expertise.

Should you like backside finish authority, then you definately’ll love what how the Helm Bolt will render bass notes. Bass drums on the Aaron Copeland’s “Fanfare for the Widespread Man” by the Minnesota Orchestra carried out by Eiji Oue rumbled with gravitas and anvil-like authority. But all of the whereas, bass notes had been taut, articulate, and delicately textured. Should you pair the Helm Bolt AMP/DAC with high-performance headphones, you’ll have the ability to see deep into the music and peel again nuanced instrument layers as you’ll by means of any excessive efficiency headphone DAC/AMP.

Listening to Lisa Gerrard’s “Elegy” from Immortal Memory was a working example. Listening with the Focal Clear, the Apple adapter had a penchant for smearing Ms. Gerrard’s vocals. In actual fact, going again to the Apple adapter had a fatiguing impact on me basically. With “Elegy” particularly, the listening expertise made me bodily anxious. Once I switched and listened to “Elegy” by means of the Helm Audio Bolt with the Focal Clear, my physique bodily reacted and relaxed. I used to be instantly drawn into the tune’s haunting notes with Ms. Gerrard’s etherial vocals and idioglossic lyrics.

Using the Helm Bolt with the Tidal desktop application. Theo Nicolakis / IDG

Utilizing the Helm Bolt with the Tidal desktop utility.

The expertise was the identical irrespective of the style or artist: Classical, rock, jazz, you title it. The Helm Bolt liberated Linda Ronstadt’s crystalline vocals on “(I Love You) for Sentimental Causes” from the album For Sentimental Causes. The Bolt DAC/AMP rendered Ms. Ronstadt’s vocals with distinctive purity, element, and air—lifelike. What Apple’s headphone adapter did in contrast was downright prison. Piano notes lacked element and air, and Ms. Ronstadt’s vocals had been rendered flat—and dare I say uninvolving. Forwards and backwards I went, shaking my head in disbelief every time on the distinction. And when the sax traces on “Sentimental Causes” kicked in by means of the Helm Bolt with an exceptionally easy, clear, prime finish I used to be bought.

An audiophile no-brainer

Helm Audio’s Bolt DAC/AMP is a kind of merchandise whose value, efficiency, construct high quality, and type issue make it a veritable no-brainer. For a mere $99, the Bolt DAC/AMP noticeably improved the audio high quality, dynamics, and emotional engagement of each tune I examined with it on each gadget and with each headphone. Helm Audio’s Bolt is a hands-down winner and I anticipate will quickly be an audiophile darling.

Should you’re on the lookout for a ultra-slim type issue DAC and amp that can decode each main high-res format—together with MQA—in an ultra-compact type issue, then seize your self a Bolt DAC/AMP. I do know in my view, I plan on buying my overview pattern and giving it a everlasting residence in my moveable audio assortment. Extremely beneficial.



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