Articles, Reviews and Measurements of Audio Products

STAX SR-5 (1975) Headphone Review

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SR-5_2.3.1.jpg

Measurement Conditions Explanation And Chart Interpretation Of Cuckoo Studio Review​


Welcome to Cuckoo Studio Review. I'm Anzol,this is a program dedicated to reviewing audio products from the perspective of a mixing engineer.
We've received the STAX SR-5 from Sandaimao. I'd like to thank him for his support of the channel.Let's take a look at how these headphones perform.

SR-5_2.2.1.jpg


The STAX SR-5 was released in 1975, nearly half a century ago. Those familiar with the brand might know that the SR-1 was their inaugural model in 1960, and while the subsequent SR-2 and SR-3 had detail changes, They retained the vintage "big scissor" headband design. The most significant change in the SR-5, based on the SR-3, is here: the...

3e Audio TPA3255 Amplifier Kit 480-1-29A Review

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This is a review and detailed measurements of the 3e Audio 480-1-29A, TPA3255 based class D amplifier module. It was sent to me by the company in a reference design for ease of testing:
3e audio TPA3255 Amplifier Review 480-1-29A Mono Class D.jpg

The module is the PCB to the right and costs US 89.99 from company Aliexpress store. This is the mono version (I reviewed the stereo version earlier). The differentiation is pulling the required class D filter into the amplifier feedback loop (PFFB) and with it, essentially eliminate the effect of speaker load on frequency response. Low cost implementations lack this which can make the tonality somewhat variable. Other optimizations are done to extract better performance out of the TI TPA3255 class D amplifier module.

When swapping the stereo module for mono above, I was...

AES Paper Presentation on DAC Measurements (Video)

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As some of you know, I presented a paper at this years Audio Engineering Society on measuring over 450 DACs. All the tests were detailed in the paper together with motivations and learnings from the multi-year project. The paper is only available for a fee (link below). AES asked for a short presentation at the conference itself. In this video, I go through that presentation with more detail than I intended to cover at the conference. This way, you get a bit more flavor of what I had written in the paper.


Here is the link to the paper and where you can download it: https://www.aes.org/e-lib/browse.cfm?elib=22278

It is free for members and costs $33 otherwise.

WiiM Pro Plus Streamer Review

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This is a review and detailed measurements of the WiiM Pro Plus streamer, DAC and preamplifier with Bluetooth support. It was sent to me by the company and costs US $219.
WiiM Pro Plus streamer airplay wifi chromecast roon pramp review.jpg

While the case is plastic, it still "looks the part" as the Brits would say relative to other more famous brands of streamers. I was pleasantly surprised to see support for analog input:
WiiM Pro Plus streamer airplay wifi chromecast roon pramp back panel toslink in out review.jpg


There is both Toslink in and out and even trigger support (for automation/turning on downstream devices). As usual, you need to download an App to get access to full set of functionality. Upon running said app, I was once again pleasantly surprised in it instantly finding the streamer. It asked me if I wanted to upgrade and I said yes. It took about 6 minutes which was rather long...

7Hz Salnotes Zero IEM Review

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This is a review, listening tests and detailed measurements of the 7Hz Salnotes Zero IEM. It was kindly donated by a member and costs US $22 ($20 on Amazon now).
7Hz Salnotes Zero IEM budget cheap good Dynamic Driver in-Ear Earphone IEM review.jpg

The molded plastic looks cheep and the left and right markings barely visible. The included tip was extra soft/thin which may be a good thing for comfort but made for very difficult measurements. You could easily deform it to the point of it blocking most of the sound in the fixture. When I wore them on my ear though, the fit was excellent and with their light weight, I could barely feel them.

7Hz Salnotes Zero Measurements
Per above, I had a heck of a time measuring these IEMs but as if by magic, I toughed the off channel once and it created perfect fit and alignment with the other channel:

[ATTACH type="full" alt="7Hz Salnotes Zero IEM budget frequency response...

3e audio TPA3255 260-2-29A Amplifier Review

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This is a review and detailed measurements of the 3e audio 260-2-29A TPA3255 chip based stereo amplifier. It was sent to me by the company as a complete unit even though they only sell the amplifier modules.
3e audio TPA3255 stereo amplifier kit class d PFFB review.jpg

As you see, it is a generic box which is something you can easily build yourself. I don't know what power supply is in there. Will fill in when I know. Cost is US $109 for the stereo amplifier module.

Back side of the reference design:
3e audio TPA3255 stereo amplifier kit class d PFFB complete amplifier review.jpg

The differentiation here is implementation of "PFFB" which stands for post-filter feedback design. Without this, the required output filter will interact with speaker load, varying the frequency response of the amplifier. High cost amplifiers from likes of Hypex and Purifi have this but budget amplifiers usually do...

McIntosh MC 427 Amplifier Review

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This is a review and detailed measurements of the McIntosh MC 427 (MC427) stereo car audio amplifier. It is on kind loan from a member. It has been discontinued but used ones go for about US $500.
McIntosh MC 427 MC427 stereo 2ch high-end car audio amplifier review.jpg

Not much to distinguish the amplifier from other car amps other than the bright blue logo. Unlike all the others I have tested though, this one is class AB, not Class D.

There are two small fans which I don't like to see. Fortunately in use the amp ran very cool, barely getting warm and I don't think the fans ever came on.

McIntosh MC427 Amplifier Measurement
As usual we start with our dashboard of 5 watts into 4 ohm load:
McIntosh MC 427 MC427 stereo 2ch high-end car audio amplifier measurement.png

Are you seeing what I am seeing? Distortion product at nearly -120 dB??? And in a car amp? Incredible. SINAD is noise...

D'AMORE E660.5 Car Amplifier Review

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This is a review and detailed measurements of the D'Amore E660.5 5-channel automotive amplifier. It is on kind loan from a member and costs US $299.
D'Amore E660.5 car audio amplifier multichannel review.jpg

The E660.5 seems well built and as you can see, is in a rather large enclosure. I suspect that will let it run cool. In testing it did not even get warm. Power terminals are designed well with angled hex screws that bite wires quite well.

Company designer used to be at Fostex and currently builds a line of test instruments for automotive amplifiers so I expect good performance.

Note that my instrumentation is limited to 2 channels and that is what I tested. Power source is a custom Lithium battery bank with 100 Ah capacity (instantaneous power of hundred of amps). I was charging the bank as I was testing the amp so you will see rising voltage notations in the testing (ranging from 13.4 to 13.8 volts).

Note 2: I thought the amp...

VMV D2R Stereo DAC Review

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This is a review and detailed measurements of the (SMSL) VMV D2R stereo balanced USB DAC with Bluetooth. It was sent to me by the company and costs US $999.
SMSL VMV D2R Balanced Stereo USB DAC XLR review.jpg

The DAC is quite heavy for its size and has pretty stout construction. User interface is similar to other SMSL products. A higher-end metal remote is provided:
SMSL VMV D2R Balanced Stereo USB DAC XLR back panel remote review.jpg

Alas, no coin cell battery was included so I used the front panel for configuration of the DAC.

The DAC design is different than many other in that it uses a DAC IC from Rohm (BD34301EKV) instead of the usual ESS and AKM. Let's see how it performs.

If you are new to DAC measurements, be sure to watch my tutorial video.

VMV D2R DAC Measurements
Let's start with balanced output and use the default -2 dB on the volume control which generates our nominal 4 volts:
SMSL VMV D2R Balanced Stereo USB DAC XLR Measurement.png

Noise performance is excellent...

Hidizs MP145 IEM Review

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This is a review, listening tests, EQ and detailed measurements of the Hidizs MP145. It was sent to me by the company and costs US $150.
HIDIZS MP145 IEM review.jpg

The immediate impression of the shells is one of jewelry with its machined aluminum case. As you see, the included cable has 4.4mm balanced connection even though it doesn't need that (plenty sensitive to work fine with 3.5 mm unbalanced). Included in the case are three tip variants and nozzles (latter not shown):
HIDIZS MP145 IEM tips.jpg

As is typical, medium size tips match my GRAS 45CA measurement artificial ears best. But for listening, I have to go one size larger. I started with balanced tips but then tried to measure with the other tips. I found the process of swapping tips very difficult. The nozzle is large and the tips barely fit it. Good news is that once you get them on there, they going to stay. With some other IEMs...
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