Articles, Reviews and Measurements of Audio Products

This article is to explore how noise and distortion change through our system, and how different components can influence the final output.

<Note 1: This article assumes some knowledge of performance terms, what frequency response and harmonics are, and so forth. There are other articles, many of which are linked in my signature, that can provide the background for these terms.>

<Note 2: This article is very long. There are not any good shortcuts to understanding the problem and complexity of signal chain analyses. Trying to reduce years of education and practice into a few posts on the ‘net is challenging. I struggled for a while to decide what program(s) were appropriate – ADS, SPICE, Mathcad, Matlab, etc. – but chose Python since I need to improve my Python skills. This took several days to write as I was going through the Python/NumPy/SciPy learning curve along the way, then more days to create the examples and write the text. The advantage is that changes can be made quickly...

This is a review and detailed measurements of the thomann t.racks DSP four by four matrix DSP. It was kindly purchased new by a member and costs just US $99.

I really like the form factor here and inclusion of brackets for mounting in cars and such. Inclusion of balanced I/O is much appreciated:


Despite shipping to US, the 12 volt adapter has the round European plug so I had to use my lab AC generator to power it (it has a universal outlet). Fortunately it is a standard voltage so you can use your own or tap into the power in a car/boat.

I was annoyed that the software to control it only came on a mini CD. I had to power up an old PC to read it as I could not find any online sources for it. Once there, the interface is surprisingly rich and very responsive. Here is the...

This is a review and detailed measurements of the Superlux HD387 IEM. It was kindly purchased by a member in Europe and shipped to me. It costs US $15.90.


As you see, it has a two piece mount with the standard silicone tip and the spiral one to hold it steady. It comes with three sets of those (I have mixed and matched them and hence the color difference). It stayed in my ears and is more stable than just the silicone tip.

Superlux HD387 Measurements
As usual, we start with the frequency response measurement using GRAS system:


I thought the droop in low frequency should not be there and tried may techniques to improve seal but it never changed. There is not much compliance with our curve but a different reference may make that visual point better. For example if we shifted the graph up, then it may be compliant from a few hundred hertz to 3 or 4 kHz. And than have a massive boost in the 200 Hz...

This is a review and measurements of the JVC HA-SZ1000 closed back headphone. It is discontinued but I think it cost $399 when new. A member from Europe kindly donated it to me months ago:


It has a reputation of being for "bass heads."

The headband is quite bulky and stiff, putting fair bit of pressure on the pads.

JVC HA-SZ1000 Measurements
Let's start with our usual frequency response measurement:


Owner left a note for me in the box that said these were the worst headphones he has listened to. I will parallel that statement by saying this is the worst headphone I have measured! I fiddled with it hoping to get better response but above is the best. The bass it has is upper bass, not lower bass. Maybe they thought this is the "Beats" sound that people want? FYI I found one other measurement for it and it more or less correlated with this so it is not broken.

At this point, I thought I finish...

This is a review and detailed measurements of the NAD D 3045 integrated amplifier with DAC and HDMI ARC. It is on kind loan from a member and costs US $799.

As you see, the design follows the rest of the "D" series. As with them, the power button is an almost hidden touch area on top which I dislike. It is not very sensitive and requires messing to get it to activate. But then when you put your hand on top of it, it happily shuts of the unit. The volume control is rather stiff and slow to act. Same with the input selector.

What the D3045 loses on the interface, it gains back with rich set of interfaces for today's music listener (sans streaming):


Inclusion of HDMI ARC to receive digital audio from smart TV is rare and appreciated.

I was shocked to...

This is a review and detailed measurements of the WiiM Mini Wifi/Bluetooth streamer. It is on kind loan from a member and is on sale on Amazon for US $89.



As you can see the former factor is a "hockey puck." An included phone charger needs to be used to power the unit over USB-C. It did not work so when I used my computer USB port.

Initial setup is by connecting using Bluetooth and the available App. I connected using BT but the Android app would not see it. I had to shut off BT and turn it back on for it to recognize it. While this is disappointing, I have had similar issues with other streamers. Once there, the app was reliable and gave me the option of configuring Toslink output for bit exact and its maximum sample rate which I appreciated. It also updated the device on first connection.

WiiM Mini Measurements
My first tests were using Aiplay 2.0 as...

This is a review and detailed measurements of the Six Acoustics York moving magnet/moving coil stereo phono stage. It is on kind loan from a member and costs US $437.

I like the form factor and clean look of the unit. Nice to see a variable gain control as well. Back panel shows the usual connections:


There are loading selection from resistance to capacitance underneath (dip switches).

Six Acoustics York Measurements
Let's start with our MM mode using the default center gain level:



Like the absence of distortion spikes but noise level is high enough to place the unit below average compared to its rivals:


For MC, I lowered the gain to 60 dB:


I was impressed with the in-band flatness of the RIAA equalization:



Sadly there is no rumble filter so that extra...

This is a review and detailed measurements of the Technics SB-F1 mini vintage bookshelf speaker. It is on kind loan from a member:

SB-F1 was produced in Japan around 1978. It has a stout, diecast aluminum frame. I understand it was quite expensive for its time despite its diminutive size. I got a kick out of the circuit breaker in the back. Had forgotten about these back in the day:



Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable...

This is a review and detailed measurements of the Graham Slee Gram Amp 2 Communicator phono stage. It costs US $299.


The company gets the fonts right which look kind of classy. Otherwise, the case is ultra light which causes the unit to fall back under the weight of the cables. The edges of the front panel are also rather sharp. Back side shows this is as bare bones as a phono stage gets:

Naturally the unit is for Moving Magnet (MM) cartridges only.

Graham Slee Gram Amp 2 Communicator Measurements
As usual we start with our dashboard:


I was pleased with absence of distortion spikes and mains leakage. Not so impressive was the noise figure which sets SINAD below average:
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