Sunday, January 23, 2022

Nelson Pass B1 with Korg Triode Preamp Kit

Introduction

The B1 with Korg Triode was introduced by Nelson Pass in 2017 at the Burning Amp Festival. The B1 is an established design which is as about as easy as it gets - a buffered passive preamp. 

The Nutube from Korg is a vacuum fluorescent display that operates similarly to a triode vacuum tube. The green glow reminds me of the old computer monitor that came with my cousin's Apple II computer ages ago. This also gives this kit a cool factor that only audiophiles are able to appreciate. The rest of the world probably just thinks that we are dorks! 

Why not just use a vacuum tube? Vacuum tubes use considerably more power and have short operating lives. The typical vacuum triode would have a lifespan between 2000 to 5000 hours. In comparison, the Nutube has a continuous life expectancy of 30000 hours (about 3.4 years) and 2% of the power consumption of a vacuum tube.   

Korg's Nutube website would be a great place to read up more on this device - https://korgnutube.com/en/

This is an ideal kit for a beginner that has some experience in building a kit or two, and comfortable with a soldering iron. The kit as supplied from diyAudio is powered by a 24V wall-wart which makes this a safe project too - no messing around with mains voltage. 

Put simply, there is an input buffer, followed by the Nutube, and an output buffer. The input buffer is required to lower the output impedance of the potentiometer used, while the output buffer lowers the output impedance of the Nutube, which is necessary to drive a typical power amplifier load.

You can read the following links for more information about the technical design. 


The kit from diyAudio Store is priced at USD 299 for the full kit with all parts you need. The enclosure is well made, with a thick solid aluminum face plate. There are only two inputs, although this should be enough for most users.  


The complete kit

The chassis

Sorting out the resistors

Assembly

This is pretty straightforward and you should be able to get everything done in an evening or two, depending on how fast you are. The build instructions are very clear and the PCB is easy to work with. In fact, the most challenging part of this kit is getting your hands on one. They are made in limited quantities, and disappear in a flash when available. Otherwise, the hardest part for most people would be soldering the transistors and Nutube. The latter in particular requires very precise soldering as the pins are very close together. 

Stuffing the resistors

Setting the plate voltage

The comforting green glow from the Nutube

All wired up

The completed product

Back panel

Adjustment of the two voltage pots at T7 and T8 adjust the plate voltage, which affect the level and phase of 2nd order distortion to suit your taste.

Audiophiles have experimented with boutique parts with varying degrees of success. The coupling capacitor pads are spaced for electrolytic capacitors, so you will need to be creative if you want to use film capacitors instead. 

The Nutube is microphonic and some builders I know have encountered problems with ringing. I damped the gap between the Nutube and PCB, and also used silicon spacers to damp the PCB standoffs. My unit is well-behaved, even when flipping switches or tapping on the chassis.

Unlike most of my DIY projects, this worked fine from the start. I imagine that most builders with an intermediate level of experience would have similar success.

I kept this build as stock as possible, although I did use some solid silver wiring and KLEI RCA jacks just to satisfy the audiophile in me.      

Sonics

Tonally, the B1 Korg is neutral, with a slightly soft edge. Music flows with a fluid and noticeable warmth. The effect is not overdone, and detail, speed and dynamics are still delivered intact. Where the B1 Korg stands above its competition, is the dimensionality imparted to the soundstage. Instruments and vocals are able to glow and occupy acoustic space. Many preamps are able to provide sharp and precise imaging and staging, but in a flat and 2-D manner.  The subtle flavour of romance offered will not suit the cold, hard and clinical listeners out there though.  

From a quality point of view, I would be comfortable recommending the B1 Korg for use even  in entry-level high end systems.    

Conclusion

This is an excellent kit to start off your DIY journey. The build is easy, and you end up with a simple preamp that sounds really good too - Best Buy 

B1 with Korg Triode - USD 299

https://diyaudiostore.com/products/korg-nutube-b1?variant=39438124482633


 

Thursday, January 6, 2022

Audiophile DC Power Supplies Supertest

Introduction

In a simple world, switched-mode power supplies should end up in the bin. Linear power supplies rule because that is what everyone says. Let's have a look at whether there is any wisdom in conventional audiophile thinking?

The power supplies on test will be divided into two groups. The first group will be used to power  a Melco N100 Digital Music Library, which accepts a 12V power supply. The second group will be used to power a Weiss INT204 USB/SPDIF bridge that accepts a 6-9V power supply. 

Identical power cords will be used in all cases - an Oyaide Black Mamba. The power supplies will also be switched on one hour before any critical listening is done. Three tracks were played, To whom I give my heart by 2V1G, Colleen's dream by Pat Coil, and Chitlins Con Carne by Kenny Burrell.

12V Power Supplies 

Asian Power Devices DA-48T12 - FOC

This is the laptop brick power supply that is bundled with the Melco N100. It is rated for 4A of current. Unlike all of the other power supplies on test here, the AC inlet is a figure of eight type instead of an IEC inlet. A suitable converter was used to ensure that the same power cord could be used here. This turned out to be an important factor. Using an aftermarket figure of eight power cord (a more modest model compared to the Oyaide Black Mamba) killed the sonics of the Asian Power Devices brick. 

The sonics from the stock power supply was passable at their best. Bass lines while smooth and rounded, lacked depth and power. Vocals while warm and pleasant, were also lacking in clarity and definition. The two vocalists in the 2V1G track as an example, could not be clearly distinguished in the soundstage. The better power supplies in comparison clearly placed one singer in the center, and the other, a few feet away on the left. High frequencies were also lacking in crispness, extension and were a bit dull sounding.


Farad Super3 Power Supply - EUR 489




The Super3 is a double regulated 3A super capacitor linear power supply. A super capacitor is similar in many ways to a battery. Farad claims that the EDCL supercaps used are made for 24/7 operation and long-term reliability. 

Care has also been taken to reduce power supply noise, with the use of Schottky rectifiers and choke pi-filters. 

This is a very nice sounding power supply, with very low noise-floor and high levels of detail. It has a very precise sound and good high-frequency extension. Bass power and authority are about on par with the Kingrex PSU Mk II. It reminds me very much of the SOtM sPS-500 but with the low frequency heft to balance things out.   


Ferrum Hypsos - EUR/USD 1195

The Hypsos is an unusual design. Based on a hybrid linear and switching design, the Hypsos promises the best of both worlds - low ripple and noise, as well as fast transient response and high efficiency. Voltage is user selectable from 5-30V with up to 6A of current delivery. This makes the Hypsos powerful enough to power a small NAS or most Intel NUC models.  


iFi iPower Elite - USD 299.99

Featuring iFi's latest Active Noise Cancellation 2 technology, this is one pretty big switched-mode power supply. Shaped very much like a big wedge of cheese, the chassis is a unibody aluminum chassis with fins on the top surface that act as a heatsink.

Claiming to have a noise floor of less than 1uv, the iPower Elite is available in 4 models rated at 5V/5A, 12V/4A, 15V/3.5A and 24V/2.5A. Like iFi's other power supplies, adaptors are provided for 2.1mm and 2.5mm tips. A reverse-polarity adaptor is also included for the rare equipment that require center-negative power supplies.  


Jay's Audio LPS25VA - USD 168

This is a super-regulated design derived from Walt Jung's super-regulator circuit. High-quality parts are used like a 25VA Talema mains transformer, Phillips BC reservoir caps, and Panasonic FC decoupling caps. This is a surprise given the modest price tag of the LPS25VA.

A front LED panel shows the output voltage, and a trimmer pot on the rear permits fine adjustments to the output voltage.

Somehow this power supply failed to float my boat. There was nothing particularly offensive about the sonics, but nothing to write home about either. While this is a more "quiet" sounding power supply compared to the Asian Power Devices and Meanwell bricks, there is a lack of attack and extension on both the low and high frequencies.   


Kingrex PSU Mk II - USD 419

An oldie but goodie. The Kingrex used to be a popular recommendation, but newer products on the market are more sophisticated from a technical point of view. Nevertheless, this model is still worthy of consideration. Featuring a 48VA toroidal transformer and a massive power supply, the Kingrex can be picked up at an affordable price on the pre-owned market.

Looking under the hood, this looks like a simple electronic design, with a three-pin regulator, and a variable resistor to set the output voltage.

I used my personally constructed DC lead for this, a Neotech PCOCC copper cable. The original lead was long lost in my hi-fi jungle.

Listening to the Kingrex brought back good memories. A competent performer in all departments, the Kingrex has good bass, and sparkling extended highs. Cymbals in particular, are reproduced with a crisp strike and decay. The midrange is warm and smooth, but some fine detail is lost. While the bass has weight, it lacked the tightness and slam managed by the best of the power supplies here. 

Pat Coil's piano playing and the saxophonist on Chitlins Con Carne lacked some impact and attack as an example.      


Kingrex SLAP - USD 450

Creative naming from Kingrex's marketing department! The SLAP is a Sealed Lead-Acid Battery Power supply unit. Weighing a whopping 7 kg, this brick is fuss-free with a built-in battery management circuit. Some people think that battery power is the only way to be truly isolated from the nasties on the electricity grid.


Meanwell GST60A12-P1J - USD 18

Meanwell is one of the big names in industrial and commercial power supplies. The model on test here is a 12V/5A brick switched-mode power supply. The Meanwell provided massive bang-for-the-buck. Users of the Melco that are on a tight budget could consider this as a no-brainer upgrade. You get better bass authority and control, clearer and more distinct vocals, and more extended highs. The Meanwell will not pose a threat to any of the better power supplies here, but you can't argue with its value proposition. 


Paul Hynes SR4-12 - GBP 342

The SR4 comes in two models, the SR4-12 which has user-selectable voltage settings from 5 to 12V, and the SR4-19 which has voltage settings from 9-19V.

The SR4 utilises a balanced mains isolation transformer and a discrete regulator circuit. Current output is 2A continuous and 20A for transients. The SR4-12 was tested with a silver wire DC lead that may be purchased from Paul Hynes as an option. 

I enjoyed listening to the SR4-12, although I felt that the sonics were shaped by the silver wire DC lead to a large extent. Quiet and confident-sounding, the Paul Hynes has lovely silky highs that are extended, yet delicate and refined. Authority and control are behind that of the Plixir Elite, and busy mixes did get a little bit messy at times.

If your musical diet consists of small-scale classical and jazz pieces, or female vocals, the SR4-12 will really suit you. 


Plixir Elite BDC 6A - S$ 1,059.30

Proudly made in Singapore, the Elite BDC features a balanced power transformer and three-stage noise regulation. This is the usual power supply used with the Melco. The Plixir has a firm and neutral sound, with good control over transients. This is a highly resolving power supply and a reference standard for me.


Sean Jacobs DC4 - from GBP 5,400 (no typo!)










The DC4 is the power supply that people talk about in hushed tones amongst those in the know. Entry to this hallowed circle requires very deep pockets and one additional rack - this power supply is as big as an amplifier.

The model I had on hand is able of supplying three 12V supplies, so that brings down the cost of ownership somewhat. Current is limited to 2A per rail due to "CX" module fitted in the regulator module, although this can be bypassed for higher current delivery. The stiff asking price buys you premium parts such as a custom-made toroidal transformer, Neotech OCC internal wiring, Vishay Z-foil naked resistors and Audionote Kaisei capacitors in critical sections.

Using a silver wire DC cable from Sean Jacobs, this power supply blew away most of the competition. While this is not the most forceful, incisive or dynamic sounding power supply, the DC4 was able to serve up extremely high amounts of detail while sounding natural and textured. The DC4 nailed timing, sounding just right. It has a level of refinement and quietness that exceeds even the Plixir Elite. However the Plixir has better slam and bass punch, and dishes up a very close level of performance for a lot less money. Like most statement-fi products, whether the price tag is justified depends on personal opinion.


Sbooster BOTW Power & Precision Eco - GBP 260











The Sbooster supports up to 3A of current and has selectable voltage between 12-13.2V. The Sbooster utilises a dual-stage mains filter and Earth line choke. The unit on test is the original model, which has since been replaced by a MkII version.

This is definitely a good step-up from stock power supplies, with a very quiet background and an increase in resolution and control. Bass has less authority than the Plixir and there is subtle grain and splash in vocals and transients. The midrange is also forward, which results in soundstage that is projected forward. 


SOtM sPS-500 - USD 500

Unlike its competitors, the sPS-500 is a switched-mode power supply. It has user-selectable voltages ranging from 7-19V and is capable of supplying up to 5A of current at 12V and 3.3A at 19V. The DC output socket uses a Hirose connector that will test your soldering skills if you intend to construct your own DC cable. As the supplied cable is annoyingly short, you will likely need to order an aftermarket cable.

This sPS-500 has a very precise presentation, with very focused imaging and soundstaging. Bass is nimble, tight and deep, but drier compared to most of the other power supplies on test there. Subjectively, music sounds brighter with a noticeably uplift in treble energy and "air". Vocals also have a subtle degree of projection. Music has a very crisp presentation to it, although vocals have more sibilance compared to the rest of the power supplies. 


Uptone Audio JS-2 - USD 925

The JS-2 has two independent and separately adjustable regulated outputs ranging from 5-12VDC with 5A current capability. Uptone took the unusual path of using a choke filtered power supply, an approach that is more commonly used in tube equipment and is less popular due to the increase in weight and cost. You get two power supplies for the price, which makes it easier to swallow.


6-9V Power Supplies

Meanwell GS25A07 - FOC

This is the stock power supply that is bundled with the Uptone Audio Ultracap. The model is discontinued, but the successor retails for around USD20. Voltage is 7.5V and the current rating is 2.93A.   


SOtM mBPs-d2s Battery Power Supply - USD 500

This is a battery power supply designed to be used specifically for compatible SOtM products, although you could use it with any product that runs on 9V. There are two battery packs that are charged by the supplied switched-mode wall wart. When one battery is exhausted, the mBPs-d2s automatically switched to the other bank. The exhausted battery is then charged. The front panel LEDs indicate which battery is being used, and which battery is being charged or exhausted - all very clever thinking on the part of SOtM.


Uptone Audio Ultracap LPS-1 - USD 395

Based on super or ultra-capacitors, the LPS-1 was a ground-breaking product at its time. Voltage is selectable between 3.3, 5 and 7V with 1A current rating. Charging and bank-switching is handled by a microprocessor. Some users report that the LPS-1 runs hot and in my experience, it does if you are running it close to the upper limit of its current rating.

From a sonic point of view, the LPS-1 sounds pretty good for the price, with a detailed and clear sound. There is a tendency for music to sound bright, with a noticeable high-frequency emphasis, so do match with care. There is a bit more midrange presence compared to the LPS 1.2, with vocals sounding more forward in the soundstage. 

Uptone Audio Ultracap LPS-1.2 - USD 435

The successor to the LPS-1 covers voltages between 5 and 12V. Current rating at all voltages is 1.1A. New output voltage regulators are used in parallel to reduce noise as well as output impedance. Think of this as an improved LPS-1, with much improved low frequency punch and tightness. Imaging and staging is also more precise, with improved depth. Considering the small difference in price, the LPS 1.2 is definitely the one to go for. 

To be continued ... 

 

Wednesday, January 5, 2022

WFH Special #1 - Creative SXFI Gamer USB-C Gaming Headset

Introduction

The SXFI Gamer is a wired USB-C gaming headset with Super X-Fi technology and a flexible goose neck microphone (Creative Technology refers to this as "CommanderMic"). 

I am not suggesting that you play computer games during office hours while on your work-from-home stints. Instead, use your SXFI Gamer for conference calls, listening to music, and gaming sessions. You won't get the evil eye from your spouse too when justifying your purchase.

The recommended retail price is very reasonably priced at S$ 179.

Description

Super X-Fi  is Creative's proprietary technology that seeks to create a life-like soundstage that is akin to the music experience of listening to speakers. Regular headphone users will know that the soundstage is trapped in your head, which greatly diminishes the realism of the listening experience. 

To use Super X-Fi, you need to download the SXFI App on your phone, create an account and start the process of head and ear mapping. This involves using your phone camera to take pictures of your face and ears. 



The personalised settings are then downloaded into a SXFI certified headphone, like the SXFI Gamer.

The package includes the headphone set, the detachable CommanderMic, and both a USB C and 3.5 mm audio cable. A USB-C to USB adapter is thoughtfully provided in case your computer only has normal USB ports.

The 3.5mm audio cable looks like any stock cable, while the USB C cable is Kevlar jacketed which should provide long and reliable use. The USB cable is unfortunately very sensitive to microphonics and friction between the cable and your clothes will be picked up and annoyingly amplified.  

The headset comes with large and heavily padded over-ear pads which are mounted in a plastic frame that allows a small amount of swivel. Combined with the low-pressure headband, the SXFI Gamer is very comfortable to wear for extended periods of time. Noise isolation is also decent, with both little noise making it through, or being leaked out. The headband also has a numbered scale to make adjustments both easy and repeatable - something I wished that other manufacturers would do. Both headphone cups are equipped with an RGB ring. This is tastefully done, and you end up looking like a serious gamer rather than out-of-control Christmas tree lights.




Downloading the SXFI Control program on either your PC or Mac will allow you to adjust the EQ on your headphone, as well as customise the RGB rings on your headphone. You can also adjust between 2 channel mode and 5.1 or 7.1 modes, and other settings like the microphone and headset volume.




A variety of controls are placed on the left side of the headphone - a mic mute button, a volume control wheel, and buttons to toggle Super X-Fi and the RGB light mode (on, off, or a cycle mode).

The CommanderMic is equipped with active noise cancellation to suppress ambient noise. A red LED is placed at the microphone inlet so positioning is easy. The LED flashes when the microphone is muted, which is a nice touch.

I used the SXFI Gamer via USB on both a Windows 10 and macOS Catalina computer without any issues. I also did some testing via the 3.5mm jack on a variety of mobile phones and DAPs. 

Sound Quality  

Tonally, these headphones are close to neutral with good levels of detail. The 50mm drivers impart a solid and hefty feel to bass lines. However, the SXFI Gamer avoids the thick and heavy handed approach, so you will not get overblown or exaggerated bass. Bass is tight and tuneful, and powerful when the source material dictates it. If you like a bass-heavy presentation, you can always fix that through the EQ function.

Vocals are reproduced clearly and with minimal amount of grain. High frequencies have sparkle and extension, and cymbals have a crisp and clear response. There is a hint of splash and confusion during heavy mixes, but this is to be expected given the modest price of the SXFI Gamer. Sonics wise, these headphones perform way above the competition in the same price bracket.

Depressing the SXFI button toggles between the normal, Super X-Fi and Battle Mode. I found the Super X-Fi mode to work best on 5.1 and 7.1 material. At its best, this imparted a spacious and more speaker-like experience. However on 2 channel material, the effect is somewhat unnatural and hollow. Similarly, Battle Mode did its job on first-person shooters by altering the frequency curve to accentuate footsteps and suppressing the rest of the audio-band. While you can hear your enemies better, this came at the expense of an unnatural tone that made the experience less immersive and realistic. 

The surprise star of the show is the CommanderMic. The microphone is very clear and the software does a decent job of suppressing ambient noise. However, the microphone is highly directional and has to be pointed directly at your mouth for best results. I often preferred using these headphones for conference calls over my professional headsets from big-name manufacturers. 

The SXFI Gamer sounds almost identical using the 3.5mm cable, with results varying only slightly depending on the equipment used. These headphones are easy to drive and sound comfortable powered through a mobile phone jack. However, you will lose a lot of functionality as none of the buttons nor sound modes will work. Nevertheless this is a good option so that you can take the SXFI Gamer on a business trip and use them on the road or airplane with your mobile phone or DAP.

Conclusion

Equally comfortable doing multiple duties as a gaming or office headset, or music listening for the audiophile on a budget, the SXFI Gamer offers outstanding value at its recommended retail price of S$ 179. 

At the time of writing, they are being offered at a discounted price of S$89 which makes this an absolute no brainer - Best Buy. 


Creative SXFI Gamer USB-C Gaming Headset

Specifications

Audio Processing
Super X-Fi
Interface
USB, 3.5 mm Stereo Input
Weight

With Mic 349g (12.31 oz), Without Mic 336g (11.85 oz)
Frequency Response
20–20,000 Hz
Microphone
Frequency Response: 100–16,000 Hz
Sensitivity: - 42 dBV / Pa

Price : S$ 179

http://sg.creative.com/