Articles, Reviews and Measurements of Audio Products

Ascend Sierra-1 V2 Speaker Review

  • 122
  • 20
This is a review, listening tests, EQ and detailed measurements of the Ascend Acoustics Sierra-1 V2 bookshelf speaker. It is on kind loan from a member and costs US $16,48 for a pair.
Ascend Acoustics Sierra-1 V2 Speaker Anechoic CEA2034 Speaker Review.jpg

The finish is nice enough. The cabinet feels quite heavy for its size and especially in the front indicating beefy low frequency woofer. I do wish the grill was magnetic though rather than plastic tabs that are more delicate. I did my testing without it and would have been nice to not see those holes.

Back panel put a big smile on my face:
Ascend Acoustics Sierra-1 V2 Speaker Anechoic CEA2034 Speaker Klippel NFS Optimized back panel...jpg

See the "NFS Optimized" tag! A couple of years ago I tested an Ascend speaker and found the performance wanting. Needless to say, the company owner/designer, Dave, was not happy. But instead of taking his anger on me, he reached out to Klippel to learn more about the Near-field Scanner I had used to test his speaker. He quickly ordered one and started to revamp his speaker designs...

KEF R11 Meta Tower Speaker Review

  • 32,939
  • 234
This is a review, listening tests, EQ and detailed measurements of the KEF R11 Meta floorstanding speaker. It was sent to me by the company and costs US $3250 each.
KEF R11 Meta Floorstanding Tower Stereo Speaker Review.jpg

The R11 Meta is gorgeous looking with high gloss finish and cabinet that has been shrunk as much as possible to basically hug the drivers. The coax center driver is the star of the show carrying most of the audible band from 200 Hz up (see measurement below). I was impressed with the engineering that went into binding terminal of all things:
KEF R11 Meta Floorstanding Tower Stereo Speaker binding posts Review.jpg


With a turn of a knob, you connect the bass to the coaxial and vice versa! No jumpers here. Even the cardboard that the speaker came in has clever features like plastic that you pinch and it releases the sides of the box so you can get it out easier. First class...

Chapeau ou non? (PCM5102MK non-HAT DAC review)

  • 8,874
  • 39
Cover.png

Hi, Guys!

Use of French in the title is not arbitrary. :)

Chapeau ou non? literally translates to: “Hat or not?”. However, chapeau is also frequently used as expression of admiration, approval, respect and is short for chapeau bas (literally “hat down”) in a same sense as in English “I take my hat off”, “well done” or just doing the hat tip gesture. (https://www.oed.com/dictionary/chapeau_n?tl=true)

If Chapeau ou non? in common language translates to: “Well done or not?”, why bother with French?

In this review I will take a closer look to a small DAC board that has printed PCM5102MK on it and I will refer to it as that (+ v2.0). As name suggests, it uses TI PCM5102A DAC chip. Usually, it can be found in entry-level Raspberry Pi’s (RPIs) Hardware-Attached-on-Top (or HAT for short) DAC designs.

However, PCM5102MK reviewed here is not a HAT.

I hope by now you start to appreciate...

Down4Sound JP95 Car Amplifier Review

  • 9,457
  • 54
This is a review and detailed measurements of the Down4Sound JP95 4/1 channel car audio amplifier. It is on kind loan from a member and is on sale for $250.
Down4Sound JP95  5 Channel Amplifier Car Audio Amplifier Review.jpg

This is a massive amplifier with incredibly beefy terminals and many features. I am shocked that it sells for just $250.

I configured the amplifier for 4 channel use and defeated all the filters I could. Alas, it seems the main channels always have a high pass with a minimum of 20 Hz (see measurements). Testing is focused on Channels 1 and 2.

Power was provided by a custom Lithium back with capacity of 300 amp hour and peak current above that. Lab supply was used to augment the battery bank as needed (I checked and it had little impact on measurements).

Down4Sound JP95 Amplifier Measurements
As usual, we start with our 5 watts test into 4 ohm load:
Down4Sound JP95  5 Channel Amplifier Car Audio Amplifier Measurement.png


Distortion is actually kind of reasonable at -92 dB. It is the noise that is the problem...

Akitika GT-108 Stereo Amplifier Kit Review

  • 19,513
  • 140
This is a review and detailed measurements of the Akitika stereo amplifier kit. It was purchased preassembled by a member and kindly sent to me.
Akitika GT-108 stereo amplifier kit review.jpg

As you see, the case is rather simple but for a kit, it is not bad. That large power switch is reassuring, giving you the feeling that it could switch a lot of "gigawatts." :D
Akitika GT-108 stereo amplifier kit back panel review.jpg

We can excuse the lack of serial number. :)

The unit is rather heavy which I imagine is due to power transformer. Company notes says the kit originally was based on a TI IC but that was hard to get so they switched to a discrete design. Manual is very comprehensive. There are a ton of parts in there so you better have lots of patience to assemble it!

Akitika GT-108 Amplifier Measurements
As usual we start with our dashboard:
[ATTACH type="full" alt="Akitika GT-108...

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

  • 13,559
  • 43
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

  • 11,460
  • 64
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

  • 21,173
  • 113
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

  • 57,502
  • 328
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

  • 34,092
  • 322
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...
Top Bottom