Articles, Reviews and Measurements of Audio Products

How good is bad? (Raspberry Pi 4B headphone output DAC review)

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RPI4B Headphone out.png


Hi, Guys!

A short intro:
I have been following ASR for last 4 years, since friend of mine showed this forum and somewhat initiated my journey in all-things-related-to-audio. 1 month ago, I decided to buy TOPPING E2X2 audio interface due to its quite good ADC (up to 110 SINAD) to make some basic, practical measurements. (More info on E2X2: https://www.audiosciencereview.com/...ds/topping-e2x2-audio-interface-review.49127/)

First “gadget” I decided to test is built-in 3.5 mm (headphone) output of Raspberry Pi (RPI) 4B when used as a DAC.
If you are rolling your eyes already, hear me out.

My motivation is simple – I couldn’t find detailed measurements of it. Since RPI streamers + DACs are still quite popular, in any audio forum a natural suggestion to newcomers planning such system will be to use dedicated I2S (usually hat) DAC or USB DAC, because audio from RPI headphone output is bad...

JBL Conceal C83 Invisible Speaker Review

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This is a review and detailed measurements of the JBL Conceal C83 "invisible" speaker. It is on kind loan from a member and costs US $1,100.
JBL Conceal C83 Invisible Speaker Home Theater Review.jpg

As the name indicates, this is basically a flat surface that you cut out in the wall and "tape and mud" the edges. Once painted, it can be made to look just like the rest of the wall and hence "disappear." In the inset, I am showing the stock photo from JBL showing a center woofer and dual higher frequency transducers. All work to excite the front panel.

These type of speakers are high desirable in higher-end stereo, ambient and home theater applications where you want a completely hidden audio system. They require careful project management with the builder/trades to make sure accommodations are made for them during the construction phase of the house. It is highly advised to use appropriate limiter/protections in the amplifier driving...

Fosi Audio SK02 DAC & HP Amp Review

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This is a review, listening tests, and detailed measurements of Fosi Audio SK02 USB powered DAC and balanced headphone amplifier. It was sent to me by the company and costs US $99.99 (€99.00).
Fosi Audio SK02 Desktop DAC Headphone Amp balanced review.jpg

The SK02 is excellently designed. Having it horizontal gives comfortable access to the rotary volume control. I was going to complain about it not showing the current level but then noticed an LED which blinks with music signal and becomes brighter at higher volumes. Brilliant! The rest of the LEDs provide the exact kind of information you want to know about the status of the device and the format of the incoming signal. Again, wonderful. The gain button is right there to nicely control that setting. And mode selects between Toslink optical and USB-C inputs:

Fosi Audio SK02 Desktop DAC Headphone Amp balanced usb powered review.jpg


This is as ideal of a design as one can imagine for a compact dac and headphone amplifier.

Fosi Audio SK02 DAC Measurements
I started with balanced HP output...

AIYIMA A70 Stereo Amplifier Review

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This is a review and detailed measurements of the AIYIMA A70 stereo class D amplifier. It was sent to me by the company and costs US $190 with 48v @ 5 amp supply. As tested with 48v 10amp GaN supply, it costs US $220.
AIYIMA A70 Class D Stereo Amplifier with PFFB balanced Review.jpg

As you see, the A70 comes in vertical desktop configuration. Controls are easy: push the button for power up and again to cycle between XLR and RCA inputs. Hold it for a few seconds and it goes into standby. Back panel shows nice inclusion of balanced XLR inputs:
AIYIMA A70 Class D Stereo Amplifier with PFFB balanced back panel GAN power Supply Review.jpg

Yes, that 10 amp brick is the mother of all external power supplies! :) At 480 watts, any heat dissipation would be challenging given the sealed box. Use of GaN transistors seems to have enabled high efficiency as it hardly warmed up during the testing. The amp's...

Bricasti M1SE Stereo DAC Review

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This is a review and detailed measurements of the Bricasti Audio M1SE balanced stereo DAC. It is on kind loan from a member and costs US $10,000:
Bricasti M1SE high-end balanced stereo DAC Review.jpg

The indication says M1 but owner tells me it has the "SE" upgrade. I have been a fan of the industrial design of Bricasti audio products since I first saw them. They remind me of Mark Levinson designs (I believe the industrial designer is the same). While a bit old fashioned with that dot matrix display, it still screams "high-end" to me. The interface is easy to navigate by pushing a button and then selecting things.

The box itself is very heavy and dense. It has an independent linear power supply for each channel which likely is responsible for much of that. It uses an Analog Devices DAC combined with external filtering.

Here is the back panel:
Bricasti M1SE high-end balanced stereo DAC back panel toslink AES EBU Review.jpg

Nice to see S/PDIF provided both as RCA and BNC.

Bricasti M1 SE DAC Measurements
Let's start with our usual...

Tanchjim Origin IEM Review

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This is a review, detailed measurements and listening tests of Tanchjim Origin IEM. It was sent to me by the company and costs US $260.
Tanchjim origin stock nozzle IEM In-Ear Monitor Review.jpg

Everything from packaging and look and feel of the Origin is a huge step up from the budget IEMs we have tested in the past. The ear pieces themselves feel like solid metal and have high polish. Despite the extra weight, I had no trouble keeping them in my ear (stationary position). The cord is soft and seemed to be tangle free. Even the act of inserting the cables into the IEM felt good without excessive force and a final feeling of it being properly seated.

Two versions of the tips are provided. One said better bass and another, better treble. I chose the former for testing.

Three sets of nozzles are provided. There is no documentation on what the difference is. I measured all three (see below).

Company touts low distortion and compliance with their target:
Tanchjim origin stock nozzle IEM In-Ear Monitor Stock Tuning.png


It is...

Yamaha R-S202 Receiver Review

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This is a review and detailed measurements of the Yamaha R-S202 Receiver (tuner plus stereo amplifier) with Bluetooth. Money was kindly donated by a member for me to purchase it new for $200 from Amazon.
Yamaha R-S202 Natural Sound Stereo Receiver Amplifier Review.jpg

The R-S202 harkens back to the old days of receivers being the most popular way to play your content with inclusion of AM/FM receiver and preamplifier to select among your inputs. Alas, the volume control is the new incarnation with poor/stiff feeling but otherwise, a lot is familiar including bass and treble controls (which used to be knobs but now up and down buttons). The back really brings back old memories:
Yamaha R-S202 Natural Sound Stereo Receiver Amplifier remote control Review.jpg

I hated those spring speaker terminals then and now. They don't allow thick wires to be inserted and you never know how far you have pushed them looking from above. I know every cent needed to be saved here but are these really cheaper than standard binding posts??? Another factor is the attached cord...

Mytek Brooklyn Bridge II Streamer Review

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This is a review and detailed measurements of the Mytek Brooklyn Bridge II Roon Core, streamer, phono stage and analog preamplifier. It is on kind loan from a member and costs US $4999.
Mytek Bridge II Roon Core DAC Streamer USB balanced phono stage review.jpg

I really like the industrial design of the Mytek. It elevates the standard form factor of desktop DACs with that tasteful texturing on front and top. The box is quite heavy for its size. It houses an Intel i5 CPU based single board computer running Roon Core image. I think I read it uses linear power supply which would explain its weight. There are no fans which is very nice when so much functionality is stuffed in this little box. Back panel shows surprisingly complete functionality which even includes a phono preamplifier:
Mytek Bridge II Roon Core DAC Streamer USB balanced phono stage back panel review.jpg

The labels are a bit hard to read but not a big deal. Connectors as you see are very good quality.

Back to the front, the touchscreen is reasonably responsible as to not be annoying but don't mistake it...

Lehmannaudio Decade Phono Stage Review

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This is a review and detailed measurements of the Lehmann audio (one word?) Decade Moving Coil and Moving Magnet phono preamplifier. It is on kind loan from a member and costs US $2099.
Lehmann audio Phono stage preamp low gain MC Review.jpg

As you see, it comes in two boxes with the one on the left being the power supply and on the right, the preamp. A high pass filter is provided as well as four gain settings. The two boxes are interconnected using a 4-pin XLR connector:
Lehmann audio Phono stage preamp low gain back panel power supply Review.jpg

I was disappointed to not see labels on the RCA connector. They are under the unit as well as switches to select loading. Otherwise, the two box solution looks nice.

The Decade is the mid-level unit and I think came out some 10 years ago but still being manufactured.

Lehmannaudio Decade Measurements
I measured the Decade in three gain...

Moondrop May USB-C Headphones Review

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Hello! This is a review and measurements of the new Moondrop May headphones. This is my personal pair and it costs US $65.

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I have been browsing ASR for a while now, but I have never posted anything here. I decided to write my very first review on this budget friendly USB-C DAC and headphone combo, as I am intrigued by the new wave of these DSP enabled headphones. This review will cover both the electrical performance of the DAC and the acoustic performance of the headphones driven passively.

Packaging and Physical Characteristics

I have to say I especially liked the box art on this product. Just look at the details here.

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The suit of clubs motif is because this suit is called Meihua(梅花) in Chinese, which directly translates to plum blossom. The name of the product, May(梅), translates to plum.

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Here is the information on...
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