Articles, Reviews and Measurements of Audio Products

SPL Volume8 Review

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This is a review and detailed measurements of the SPL Volume8 8-channel, balance volume control. It was kindly sent to me by a member and costs US $799.
SPL Volume8 Review 8 channel balanced volume control DAW.jpg

SPL nails the look and feel of this active unit. It is a substantial box but not too big. 8-gang volume control is custom made and muting is performed using a relay. Input/output is provided through DB-25 connectors so you need to buy those "pigtail" cables to go to and from XLR (or RCA):
SPL Volume8 Review Back panel 8 channel balanced volume control DAW.jpg

SPL Volume8 Measurements
I set the unit to max volume and tested channels 1 and 2:
SPL Volume8 Measurements 8 channel balanced volume control DAW.png

Distortion is quite low at -120 dB but I was disappointed to see power supply noise and harmonics bleeding into the unit. That sets the SINAD, i.e. dwarfs distortion as we can see in SNR measurements:
SPL Volume8 Measurements SNR 8 channel balanced volume control DAW.png

Frequency response is flat and extended which is nice:
SPL Volume8 Measurements Frequency Response 8 channel balanced volume control DAW.png

Not so nice is...

JBL A180 Tower Speaker Review

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This is a review and detailed measurements of the JBL Stage A180. I only paid $200 for the pair on sale including free shipping! Normal price I think is $400.
JBL A180 Review Tower Speaker Stereo.jpg

They were delivered via truck and are quite substantial as budget speakers go. I like the look of the white woofers. There are dual ports in the back.

This is a 2.5-way design with upper woofer playing to a higher frequency than the lower one.

Note: our company, Madrona Digital, carries Harman line (parent company of JBL). While we don't carry or sell JBL home speakers, I thought I mention this as any source of bias you want to read into my assessment.

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...

Earthquake XJ-300ST Stereo Amplifier Review

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This is a review and detailed measurements of the Earthquake XJ-300ST stereo amplifier. It was kindly donated by a member for testing. It costs US $462.83 from the company website.
Earthquake XJ-300ST Stereo Amplifier Review.jpg

I like the compact packaging and old school but solid feeling switchgear. Likewise, having a low-pass filter (no doubt to drive subs for which they are famous), filter corner frequency and phase come in handy. And of course the integrated volume control. Back panel is typical with the exception of crossing terminals (for bridging):
Earthquake XJ-300ST Stereo Amplifier Trigger subwoofer lowpass  Review.jpg

12 volt trigger is icing on the cake.

Unit runs is a "class J" amplifier and was cool and comfortable during testing.

Amplifier Measurements
Here is our usual dashboard:

Earthquake XJ-300ST Stereo Amplifier Measurements.png

We have massive mains spike which I could hardly reduce no matter what I did. I am assuming it is internal leakage. Can't figure out why one channel is so much more distorted than the...

Geshelli JNOG2 Review (Balanced DAC)

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This is a review and detailed measurements of the Geshelli Labs JNOG2 (J2) balanced stereo DAC. It was kindly drop shipped to me by a member and costs US $299.99.
Geshelli Labs JNOG2 J2 Review Balanced Stereo USB DAC.jpg

Strangely in this day and age, USB as an option ($50). The look is typical of Geshelli products with use of plexiglass. I am not a fond of the user interface with single input button that cycles through inputs with LEDs lighting up in different formation. There is no manual for the unit in the box and I could not find one online either. So just kept pressing the button until I saw signal out of it. Back panel is the same:
Geshelli Labs JNOG2 J2 Review Back Panel Balanced Stereo USB DAC.jpg

I could barely read the left/right indication on XLR connections. The S/PDIF jack is too close to Toslink for me to be able to connect both at once.

Geshelli J2 Measurements
I started...

GR Research LGK 2.0 Speaker Review (A Joke)

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This is a review and detailed measurements of the GR Research "Little Giant Killer" (LGK) 2.0 bookshelf speaker. It comes in various forms from a kit ($313) to fully finished pair ($1,038). Our DIY expert @Rick Sykora built my sample using the flatpack ($100):
Danny GR Research LGK Little Giant Killers 2.0 Review.jpg

Rick had to do the round over on the two edges per company recommendation as the flatpack is supplied with sharp edges. The build is superb and solid. Here is the back with the famous "tube connectors" and slot port:
Danny GR Research LGK Little Giant Killers 2.0 Tube Connectors Review.jpg

Internal structure is complex due to that port so unless you are a serious woodworker, you need to get the flatpack.

The main driver is a tiny "full range" 3 inch unit. This allowed...

Sennheiser HD660S Review (Headphone)

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This is a review and detailed measurements of the Sennheiser HD660 S open-back headphone. It is on kind loan from a member and costs US $400.
SENNHEISER HD 660 S  HiRes Audiophile Open Back Headphone Review.jpg

You would be hard pressed telling it apart from the similarly numbered Sennheiser headphones which is not a bad thing.

Note: The measurements you are about to see are made using a standardized Gras 45C. Headphone measurements by definition are approximate and variable so don't be surprised if other measurements even if performed with the same fixtures as mine, differ in end results. Protocols vary such as headband pressure and averaging (which I don't do). As you will see, I confirm the approximate accuracy of the measurements using Equalization and listening tests. Ultimately headphone measurements are less exact than speakers mostly in bass and above a few...

Cambridge Audio CXA81 Review (Sample 2)

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This is a follow up to my first test of the Cambridge Audio CXA81. Results there showed fair bit of noise which was uncharacteristic of other products I have tested from the company. There were a lot of speculation as to the source of the problem but no data to back any. Fortunately company CEO was kind enough to contact me about a week later expressing surprised at my results. I asked them if they have measurements that are better. After some investigation, they said that they could replicate my results at their China manufacturing facility but not their R&D lab. I expressed that I no longer had the unit so there was not any work I could do to get to the bottom of this. I was offered a new unit and offer for payment to test again. I accepted the second unit but turn down the offer of payment.

In the communication, I was asked (as some members had also suggested) whether I lifted the USB ground using the switch in the back. I had not and ran those tests on the second unit...

Lynx Aurora 8 Review (8-channel DAC/ADC)

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This is a review and measurements of the discontinued Lynx Aurora 8 audio interface (DAC & ADC). I am told you can find them used for $700 although the price I see on ebay is $1000.
Lynx Aurora 8 Review External Interface AES DAC ADC.jpg

The owner wants to know if this can be competitive with modern 8-channel DACs so that is the functionality I focused on. Back panel has DB25 which means you have to also make or buy pigtails to XLR connectors:
Lynx Aurora 8 Review Back Panel DB25 External Interface AES DAC ADC.jpg

These cables are quite thick although the ones the member send me are surprisingly supple. While you can add a USB input card to it, as you see this one doesn't have one so I tested using AES output of my analyzer. That output is stereo only so you are only going to see channels 1 & 2 in the measurements.

Lynx Aurora 8 Measurements
Full output level is a healthy 8 volts so I knocked the digital input by 6 dBFS to get our nominal 4 volt out:
Lynx Aurora 8 Measurements External Interface AES DAC ADC.png

While I am not happy with the shape...

Soundstream RN4.1400D Rubicon Nano Review (Car Amp)

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This is a review and detailed measurements of the Soundstream RN4.1400D Rubicon Nano four channel car power amplifier. It is on kind loan from a member and costs US $150.
Soundstream RN4.1400D  Rubicon Nanon Review  four channel car audio amplifier.jpg

I could not believe the price of this unit given the exceptionally nice fit and finish of this amplifier. It is also extremely heavy and dense for its size. The terminals while using Philips screws were actually much nicer and easier to tighten than typical hex drivers.

Soundstream RN4.1400D  Rubicon Nanon Review Wiring Terminal auto four channel car audio amplif...jpg

You have the usual controls. I tested the unit in flat EQ setting and focused on only left and right channels.

Idle current draw as about 0.8 amps. During the testing the unit remained almost at room temperature, backing companies claims of high efficiency.

Soundstream RN4.1400D Rubicon Nano Measurements
This amp gave me a lot of difficulty in measuring it due to mains intrusion:
Soundstream RN4.1400D Measurements four channel car audio amplifier.png

Power was provided by 300 amp/hr Lithium...
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