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Review and Measurements of Lounge LCR MKIII Phono Amp

amirm

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#1
This is a review and detailed measurements of the Lounge Audio LCR MKIII Phono stage (amplifier). It is on kind loan from a member. The LCR MKIII costs $300 from the manufacturer direct.

The LCR MKIII is a very simple, typical DIY box:
Lounge Audio LCR MKIII Phono Preamp Audio Review.jpg

A touch of class is intended to be provided by that lexan sheet with blue LED. It doesn't do much for me especially since the lighting is not uniform.

The back panel is simple too:

Lounge Audio LCR MKIII Phono Preamp Back Panel Audio Review.jpg
Since this is a moving magnet only phono amplifier there are no switches or controls. We have our simple RCA in and out plus a ground lug. Power is provided through an external AC adapter which is not a bad idea to keep mains inductance from the transformer leaking into sensitive amplifier stage.

As the name technically implies, this phono amplifier sets itself apart from others by using an inductor ("L") to implement RIAA equalization instead of just using capacitors. In an ideal world, there is no difference between implementing a set of filters using inductors, and resistors and capacitors and resistors. The world is not ideal though. Inductors can have capacitance that causes self-resonance which creates its own problems. And as a rule, there are a lot more variations in inductor ratings than there are in capacitors. Company doesn't explain why using an inductor is any better other than it subjectively sounds more real. Some justification I have heard is that early mastering of LPs may have used inductors for its reverse RIAA equalization. Anyone can verify this? Regardless, who knows what their curve was as to try to match it inversely.

Measurements
The company rates the specifications at 0.7 volt output but my testing standard is 1 volt so let's go with that:

Lounge Audio LCR MKIII Phono Preamp Audio Measurements.png


I like the extremely good match between channels as far as output levels. Distortion rating is quite poor though and is worse than the spec. Company says the distortion is dominated by 2nd and 4th harmonics:

1554660372852.png


As is clear from the FFT, the dominant distortion is 3rd harmonic. Its level is so high that it dwarfs any noise and sets the SINAD at its value of about 53 dB. This is how the LCR MKIII rates then:
Best Phono Preamplifiers 2019.png


Not a good place to land for a solid state amplifier and price point.

From countless previous listening tests of amplifiers with this much distortion products I expect some distortion of high frequencies together with lack of detail as the low frequency harmonic distortion stomps on the low level detail in higher frequencies. When music gets busy/complex, I suspect it will be less satisfying as the distortions pile on top of each other, reducing instrument separation.

Signal to noise ratio beats the spec by a bit:

Lounge Audio LCR MKIII Phono Preamp Audio Signal to Noise Ratio Measurements.png


At 74 dB, it is much better than 53 dB for distortion and hence the reason I predicted noise is not the contributing factor here.

The spectrum of noise simply shows mains hum and buzz:
Lounge Audio LCR MKIII Phono Preamp Noise Spectrum Audio Measurements.png


I tried different grounding methods and all made the results considerably worse. The best case was the floating input and outputs of my Audio Precision analyzer. Your results then may be worse since your audio gear is most likely grounded to mains. Balanced output is such a necessity in phono amplifiers.

Worst news was waiting for us in the form of frequency response:
Lounge Audio LCR MKIII Phono Preamp Frequency Response Audio Measurements.png


This is supposed to be flat which of course it is not. Deviation from peak at low frequencies to dip in low high frequencies is about 2.4 dB. I don't know about the merit of boosting low frequencies like this in LP format. Seems to me it would magnify rumble and such.

The dip at the end is likely due to self resonance of the inductor which creates a dip at that frequency. The design should have worked to use an inductor that pushes that farther out from audible band.

THD+N versus frequency reveals high levels of distortion in low frequencies:
Lounge Audio LCR MKIII Phono Preamp THD versus Frequency Audio Measurements.png


THD+N versus level shows good headroom, with the unit providing almost 10 volts before clipping:
Lounge Audio LCR MKIII Phono Preamp THD+N versus Level Audio Measurements.png


Conclusions
Audio is a crowded market so I can see from marketing point of view one would want to use a different circuit design to stand out. That is fine as long as performance is not compromised. Nothing like reinventing the wheel but then making it less round! LP format has enough variability to not have to pile on that the frequency response that we see. And of course all that distortion that cannot be musical no matter how much the marketing message pushes that message. Distortion adds artificial components not in the music which will mask detail and cause harshness in highs if audible.

Needless to say, I can't recommend the Lounge Audio LCR MKIII. There are much better alternatives such as Cambridge Audio Duo.

EDIT: the designer was kind enough to join the forum and comment on the review. Please see: https://www.audiosciencereview.com/...f-lounge-lcr-mkiii-phono-amp.7244/post-166744

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amirm

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#2
When I do reviews, I usually go out there and search others to see what they say. I ran into two review of Lounge LCR MK III with completely opposing view. Here is the first one. NOTE: level is too high initially so set the volume low:



Who do you believe? I put my money on the first guy. :)
 

daftcombo

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#3
Good work Amir.
Can you listen to a few records and give us your impression?
 

bunkbail

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#6
When I do reviews, I usually go out there and search others to see what they say. I ran into two review of Lounge LCR MK III with completely opposing view. Here is the first one. NOTE: level is too high initially so set the volume low:



Who do you believe? I put my money on the first guy. :)
Damn, the first guy is a savage!
 

restorer-john

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#7
It's MM, so at minimum, you should be measuring input impedance.

/broken record
And overload in mV/dB...

/scratched CD

:)

(I can work back from the gain at ~X115.5 (41dB) and the clipping plot at ~9.5V to give an an overload of approx 82.3mV)

Maybe put the gain in dB window on the dashboard view instead of the 1KHz frequency counter? (we know it's 1Khz)
 
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TimW

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#8
Why isn't this review showing up on the reviews page?

Edit: Nice that was quick.
 
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amirm

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#9
Why isn't this review showing up on the reviews page?

Edit: Nice that was quick.
Thanks. I was rushing out the door and forgot to post it there.
 

amirm

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#10
Maybe put the gain in dB window on the dashboard view instead of the 1KHz frequency counter? (we know it's 1Khz)
I had the gain below that but AP software doesn't remember the application size in templates so didn't show it and I didn't catch it.

I can knock out 1 Khz measurement but then I worry about someone asking what test frequency was used.
 

amirm

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#17
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#18
Needless to say, I can't recommend the Lounge Audio LCR MKIII. There are much better alternatives such as Cambridge Audio Duo.
I know that Schiit products have mostly measured poorly, and I'm certainly not a Schiit fanboy, but I thought it might be interesting if Amir could test the Schiit Mani phone preamp to see how it compares to the Cambridge Audio Duo (or Solo).

The Mani has been highly praised by a ton of folks on the internets, but I've never seen any performance measurements. It would be interesting to see if the Mani's measurements live up to its subjective praise.
 
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#19
The FR curve almost looks like something you would see on a cartridge, since most cartridges are not 100% flat. I nearly bought one of these at some point, kind of glad I didn't.
 
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#20
I know that Schiit products have mostly measured poorly, and I'm certainly not a Schiit fanboy, but I thought it might be interesting if Amir could test the Schiit Mani phone preamp to see how it compares to the Cambridge Audio Duo (or Solo).

The Mani has been highly praised by a ton of folks on the internets, but I've never seen any performance measurements. It would be interesting to see if the Mani's measurements live up to its subjective praise.
When I had a Mani, there was a fair bit of audible noise as well as RFI. Would be interesting to see if that shows up with Amir's measurements.
 
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