Articles, Reviews and Measurements of Audio Products

ifi Zen Air Phono Review

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This is a review and detailed measurements of the ifi Zen Air Phono stage with moving coil and moving magnet support. It is on kind loan from a member and costs US $99.
ifi zen air phono review MM MC pre-amp stage budget.jpg

This is the first ifi product I have seen in this casing which is made out of plastic. It is textured and actually feels more luxurious and modern than the metal version. Due to black color, the white labels are easier to read as well. Cheaper, nicer and better, what could be better? :)

Power is provided from USB to barrel connector. There is a power supply but I don't knew if it is the original or not:
ifi zen air phono review MM MC pre-amp USB stage budget.jpg

ifi Zen Air Phono Measurements
Let's start with our dashboard in moving magnet gain setting:
ifi zen air phono measurements MM input.png

Nice and clean frequency spectrum. Noise is rather high though resulting in slightly below average ranking:
best budget phono stage review.png

Dropping input to 0.5mv and switching to Moving Coil, I was...

The REAL Problem of March Audio's Sointuva WG (Review, Measurements and Reinforcements with Klippel device)

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I am not good at English. Therefore, this post was written with the translation help of many people in Korea. I am very grateful to them.

I am an audiophile publishing speaker reviews to audio communities. Currently, I am using Klippel Distortion Analyzer 2, Earthworks M30 mic, and a DIYed turntable to measure directivity(quasi-anechoic measurement) and nonlinear distortion for my reviews.

I’ve recently reviewed March Audio Sointuva WG and I’d like to report some problems I found and share some thoughts here, although I am not a native speaker of English.


In a nutshell,

1. The Sointuva WG I received turned out to have rather high levels of THD at 85dB SPL. Also, the distortion rate was lower at 95dB SPL than it was at 85dB SPL, unlike any other typical speakers in which nonlinear distortion increases proportionally as output dB increases...

ifi Zen Phono Review (phono stage)

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This is a review and detailed measurements of the ifi Zen Phono pre-amp. It is on kind loan from a member and costs US $199.
ifi zen phono review balanced stage MM MC.jpg

As you can see, it comes in a similar case to other (newer) ifi line. And as with those, the white labels are not legible in all but one or two angles. The left switch is power which has a delay in it (?). The right switch is a sub-sonic filter. The four dots are LED indicators for the four separate gain settings which you can select in the back:

ifi zen phono review balanced stage back panel MM MC.jpg

Power is provided by an ordinary (non-ifi) 5 volt supply. Internally this is stepped up using a very high frequency switching regulator (running at 1.5 MHz). This should do away with mains spikes we see in many phono stages.

An unusual output is the 4.4 mm penticon balanced output. This is a very unusual connector for anything but headphones. It is nice to see it though if it provides a benefit in the form of cutting out ground loops...

Naim Uniti Atom Review (Streamer & Amp)

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This is a review and detailed measurements of the Naim Uniti Atom streamer, DAC and integrated amplifier. It is on kind loan from a member and costs US $3,799.
Naim Unity Atom Review integrated digital analog streamer amplifier.jpg

The overall industry design is attractive and has a high-end look to it. Alas, every part of the unit has an ultra sharp edge from heatsinks to edges of the plexiglass (?) front panel. It is a heavy box which makes you really feel those sharp edges as if they are going to tear into your skin. It was unpleasant every time I had to move or rotate the unit.

The front panel is large and sharp which I like. Alas, and strangely so, it is not a touch screen. In this day and age and at this price, a touchscreen is a requirement in my opinion. A very large rotary control managed the volume. It seem to have some kind of acceleration but wasn't very intuitive.

Here is the back panel:
[ATTACH type="full" alt="Naim...

Grimani Systems Rixos-L Review (Active DSP Speaker)

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This is a review and detailed measurements of the Grimani Systems Rixos-L active DSP speaker. It was sent to me by the company and costs about USD $8,200.
Grimanisystems RIXOS-L CEA2034 Review home theater active speaker.jpg

Speaker is designed to go into the walls or mounted on them and then covered by a screen for home theater applications. The former is aided with a depth of just 6 inches. Each speaker is manufactured in US and can have its termination customized for each use (my sample had a "pigtail").

Configuration is 2.5 way (one woofer playing to higher frequency) and actively driven through a four-channel compact DSP amplifier from Italian company, Powersoft (Mezzo 604A):

Grimanisystems RIXOS-L powersoft mezzo four channel amplifier.jpg

Grimanisystems RIXOS-L powersoft mezzo 604A four channel amplifier.jpg

Typical of products in custom...

Topping D90LE - "Valve" and "Transistor" effects measurements

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I've performed a few quick measurements with the Topping D90LE

DAC 5V at Max level (USB in, 48kHz, Right Channel)
(ADC: E1DA ADC 4.5V Mono, measured with Virtins Multi Instrument 3.9.6)

"Standard" mode


In "Valve" mode
We see a big 2nd harmonic peak (0.32%), with a more limited 3rd harmonic (0.001%)


In "Transistor" mode
We see a limited 2nd harmonic peak (0.03%), with 3rd harmonic 10 times below (0.003%) - but 3 times higher than in the "Valve" mode.


NB: I can't get more than around 122 dB SINAD.
This is most probably due in part to the low impedance of the E1DA ADC (especially in Mono mode): the output of the D90LE peaks around 4.5Vrms in 5V mode under such a heavy load (around 850 ohm). Or we just reach the limits of the E1DA ADC.
My cabling may also count for a few...

Topping A90 Discrete Review (Headphone Amp & Preamp)

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This is a review and detailed measurements of the new Topping A90 Discrete balanced preamplifier and headphone amplifier. It was sent to me by the company and costs US $599.

Topping A90 Discrete Review Headphone Amp Preamplifier Balanced.jpg

Announcement was supposed to be a few hours from now but one of the distributor already released it so here we go. As you can tell, there is a new design in the form of those pin-hole LEDs which I find quite elegant. Inside there is stepped relay for volume control. Of course as the name indicates, this design uses discrete transistors rather than op-amps. 39 transistors are used to accomplish that task in each module. Will performance be as good as op-amps? And is there an advantage? We will find out in the measurement section. Here is the back panel:

Topping A90 Discrete Review back panel Headphone Amp Preamplifier Balanced.jpg

I was pleasantly...

Nectar Hive Review (Electrostatic Headphones)

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This is a review and detailed measurements of the electrostatic Nectar Hive headphone. It is on kind loan from a member and costs US $600 (seems to be replaced with HiveX).
Nectar Hive Review Electrostatic Headphone Stax.jpg

The headphone as tested came with the upgraded sheepskin pads. I am told the company has moved away from the stock pad that is supplied with these anyway. Four small Velcros hold the pad which I found insufficient as it was easy to pull the pad off. The build feels somewhat plasticky and creeks a bit. Fit is very different than my Stax headphones and is tight around my ears.

Electrostatic headphones require special amplifier with high voltage bias feed. I went into my bin of Stax headphone amps I have and selected the SRM-313 which is transistor based (to avoid issues with aging tubes in my other ones). The testing you see is the combination of these two working together.

Note: The measurements you are about to see are made using a...

GR Research LGK 2.0 Kit Speaker Review (video)

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Video review of my recently tested GR Research LGK 2.0 DIY Kit speaker. There is bonus content here including recording of the sound coming out of the speaker and some additional graphs (which were also added to the text review):

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