Articles, Reviews and Measurements of Audio Products

This is a review and detailed measurements of the NAD PP2e phono stage/preamplifier. It is on kind loan from a member and costs US $219 (on sale for $197).

As you see, there is not much to the box or the front panel. It only has a power button. The back side exposes the control for moving magnet vs moving coil cartridge input:

The externa dc power supply is rated at 24 volts @100 ma.

NAD PP 2e Measurements
Let's start with moving magnet input:

The major contributor to low SINAD is 120 Hz and harmonics which is from the power supply. I wanted to test with my lab supply but it uses a very uncommon connector so could not. Going...

This is a review, listening tests, EQ and detailed measurements of JBL 4312M II 3-way compact studio monitor (passive speaker). It is on kind loan from a member and I think costs US $1,000 for a pair.

Without its ordinary looking grill, the 4312M II definitely has that vintage vibe but with added "beauty" of that white woofer. Those were the days where drivers were positioned to look good. Speaker is a bit heavy for its compact size, which imparts a feeling of quality which its standard box does not impart. Here is the back side:


What did the originals have? Screw terminals?

Let's measure it to see if these old ideas of speaker design were any good and whether if any faults have been remedied.

Note: I am the founder of Madrona Digital, a company that specializes in custom installs...

This is a review and detailed measurements of the MT-ViKI MT-431AV 4-way audio and composite video passive switch. It is on kind loan from a member and costs US $11 on Amazon:

I wouldn't be able to give you time of day for $11 (including shipping no less!) yet we have a metal box here with four nice/solid feeling selector switches. Back panel brings back horrible memories though:

Composite video! Man, those were the days of horrible picture quality with color decoder errors and lousy resolution. I assume no one uses the video feature in this day and age so let's quickly test the rca switching capability.

Audio Switcher Measurements
Let's start by measuring the performance of the Audio Precision APx555 while looping back internally with 2 volts out:

Immeasurable distortion and SINAD limited by noise. Let's now route the signal through a 6 foot switch to the...

I'm presenting a review of the Wharfedale Diamond Series Center, specifically the 12.C.
Personally, I find this series to offer excellent finish quality for its price range.
Let's delve into its performance!

Impedance



The speakers show stable performance even with increased output signals.(0.1 V to 2.83 V)
I believe this is a common feature of speakers with good fundamentals.
However, there's a slight resonance at around 300Hz.

Frequency Response


The tonal balance across the full spectrum is fairly decent.
Distortion is noticeable around 3~5kHz.
The lower limit of the bass is approximately 82.3 Hz (-6dB), and there's a gentle decline at -12dB/oct starting from around 120Hz.

Nearfield Measurement


The measurements looks clean without unnecessary complications, but the...

This is a review and detailed measurements of Arylic BP50 preamp with internal DAC, phono stage, HDMI ARC and Bluetooth. It was kindly drop shipped to me by a member and costs US $99.

Front panel doesn't hint at the immense amount of functionality BP50 provides. You get that from the back side:

This thing has every in and out you can imagine! It even comes with a remote, making it one of the most ideal preamplifiers there is as far as connectivity in modern era. How well does it work though? Let's measure:

Arylic BP50 Preamplifier Measurements
Let's start with the DAC measurements:

I kind of expected this level of performance and that is what we get. I didn't put it in my ranking table but would be in the "fair" category. Distortion is a problem as is noise to some extent:



Since there is digital out, let's see if that gives...

This is a review and detailed measurements of the Juson Audio JTA35 stereo hybrid tube amplifier including DAC, Bluetooth, Phono input and headphone out. It was sent to me by the company and costs US $180.

As if all that functionality was not enough, we even have a pretty VU meter! And oh, motorized volume control remote control too!

There is even subwoofer out!

Overall build feels good and polished. Speaker terminals are oversized for class (good) and we even have built-in power supply. Let's see how it measures.

Juson Audio JTA35 Measurements
Let's start with the power amplifier:
[ATTACH type="full" alt="Juson Audio JTA35 Tube Stereo Amplifier DAC Headphone Amplifier...

I was looking for a compact audio interface with one mic preamp with software-controlled gain and a balanced stereo output for live shows.
The ESI Maya22 seemed to match my needs pretty spot on, at least I couldn't find anything smaller that fit the bill, so I ordered it and sure enough it showed up at my doorstep today.
As you'll see further into the review, the interface has some fundamental flaws which made me return it. Sadly I had forgotten to take a picture of the unit, so the stock image from the ESI website will have to do:



For the measurements I used a Topping EX5 as signal generator and the Cosmos ADC as input device.
Let's kick things off with the DAC part:

80,5dB SINAD:

Ouch... That's a rough start. At 0dBFS it produced 3,6Vrms unloaded, which dropped to about 2,3V being connected to the low-impedance Cosmos ADC.
-1dBFS (the level of this...

POLL IS NOW CLOSED (thread remains open for analysis and comments)...

This is an updated follow-up poll to my September 2022 one. Was asked to see whether much has changed since then. Also deleted the active or passive options to simplify the poll.

As mentioned previously, the forum software limits the number of choices to 10. A final edit glitch also limited my ability to modify the responses without deleting the entire poll. So, the last couple of responses are out of order.

Thanks for your participation!

P.S.
Casting an intentionally inclusive net, wanted to include home theater and home theaters that are used for music listening. So, if you feel you are limiting your response, you likely should choose the Multiple systems option. For example, I have Amazon Echo speakers, a stereo system and a home theater. Which I listen to primarily is more a matter of convenience, so I fit the Multiple Systems case even though I barely use the home theater for video anymore...

This is a review and detailed measurements of the miniDSP 2x4 HD as is, and as modified by German company sweetspot-audio. Later version was kindly provided by a member and costs US $191 (EUR 175) on top of the cost of the 2x4 HD ($225).

As you see, the main indication that the 2x4HD has been modified is their sticker. This is what the company says they modified:

Scope of modification:

• Improvement 12v DC input voltage
• Improvement entrance level
• Improvement output stage
• Replacement of all operational amplifiers
• RFI measures
• Reducing the noise floor
• Distortion Reduction (THD)

Total changes: 21

The 2x4 HD was one of the earliest measurements I had made with my older analyzer. So let's first update that with a handful of new...

This is a review and detailed measurements of the Human Speakers 81 dk. It is on kind loan from a member and costs US $1,270 (kit or finished?).

Everything from the grill to lacquer finish looks gorgeous. Like the hand written notes on the back (and very recent production date):


The grill was stiff and hard to remove so I left it in place. As usual, measurements are performed using Klippel Near-field scanner. I roughly identified center of tweeter through the grill and set it as the acoustic axis.

Company hand builds/modifies its own drivers.

If you are not familiar with my tests, I highly recommend that you watch my video on understanding speaker measurements.

Human Speakers 81 dk Measurements
Let's start with our frequency response measurements:

Ouch. We clearly have design issues around the...