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Review and Measurements of Lounge LCR MKIII Phono Amp

SIY

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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.

In this case, it was suggested to me that the response might also be level-dependent because of the inductor. That would be interesting to explore- but of course, with an MM, the input impedance will often have a similarly large effect.
 
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amirm

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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).
Agree it is good to measure the Mani. I just ordered one. :)
 

watchnerd

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@amirm what's the best case SINAD for LP? I know you state CD quality is 96db or so.

The best turntables have SNR rates of 78-86 dB, but the best LPs is capable is usually listed as 78-84 (13-14 bits equivalent) dynamic range.

So combined, call it high seventies to mid eighties.
 

Lounge Audio

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Hi Amirm,

This is great! I’ll tell you what! Have that unit you tested sent to me and I will upgrade it to nearly an LCR Gold sans the volume control and headphone jack. Then you can test it. The numbers you get will probably be worse than you posted. But then, promise me you will actually listen to the unit with a real turntable. Don’t cheat by using a digital source pumped through a reverse RIAA circuit. The source has to be a real cartridge with that little rock dragging across the vinyl.

Up for it?

I don’t design for numbers from a machine but it is always nice to know just for a benchmark. I did work at Alesis Studio Electronics all through the 90’s. That place lived and died by 16 bit digital audio and test and measurement so I know plenty about these rigors.

In regard to your measured adherence to the RIAA curve, I have been including trimpots for HF boost and LF cut. One of the reasons for this is so I can boost 20kz by 2db. This boost level came about by customer feedback. So now the measured RIAA response is even less clean looking.

My primary design goal is details like frequency extension, dynamics, depth (vertical, horizontal, lateral). So far, since 2011 when I started to sell my preamps, a machine has never purchased a unit from me. But, vinyl listeners do and most care about these details of sound more than a measurement number.

By the way, I think it would only be fair if you make my response a sticky post so that whoever stumbles upon this thread can read both aspects of this easily.

Robert Morin
Lounge Audio
www.loungeaudio.com
 
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amirm

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Hi Amirm,

This is great! I’ll tell you what! Have that unit you tested sent to me and I will upgrade it to nearly an LCR Gold sans the volume control and headphone jack. Then you can test it. The numbers you get will probably be worse than you posted. But then, promise me you will actually listen to the unit with a real turntable. Don’t cheat by using a digital source pumped through a reverse RIAA circuit. The source has to be a real cartridge with that little rock dragging across the vinyl.
Hello Robert. Welcome to the forum. As requested, I linked to your post in the original review for viewers to read.

As to making the change, the unit is not mine so I can't send it in. I will pass on the comment to the owner to see if he is interested.

That aside, I am sure there are plenty of people who can give opinions of said rock dragging across the vinyl using your amplifier. The issue with them all is that there is no way to verify what they are saying is correct, or even duplicate their experience. The data I provide doesn't have those issues. Owners can combine the two and make more informed purchase decisions.
 

patient_ot

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I think what's happening here is that audiophiles, vinyl freaks, etc. are not all shopping for the same things and you have a company that is simply responding to market demand. I do think that companies making equipment that has a tuned/tailored response curve ought to be up front about it, just as companies making equipment with the goal of being flat/accurate should do the same. FWIW I nearly bought one of these and Lounge was up front with me re: their RIAA correction curve not being the most accurate one when I asked about it. I did not ask for FR measurements, but it's good to see them here.

In the end, I think this is not a product for me personally, but it's obviously a product for someone as many have been sold.

To me there is enough sonic coloration in cartridge FR across models and brands that I don't really want to add to it by plugging one into a highly colored phono preamp. I'd rather the phono preamp be relatively flat and then I can tweak the sound if necessary using other methods (e.g. loading plugs, tone controls, etc.).
 

SIY

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To me there is enough sonic coloration in cartridge FR across models and brands that I don't really want to add to it by plugging one into a highly colored phono preamp. I'd rather the phono preamp be relatively flat and then I can tweak the sound if necessary using other methods (e.g. loading plugs, tone controls, etc.).

Of course, the other end of this is that the input impedance will also cause response changes, and those may or may not be complementary to the RIAA network errors. Ditto noise performance, which to be meaningful, must be measured with a cartridge as a source, not just shorted input. In this, I am in agreement with Robert and rare disagreement with Amir.

I am curious about the idea of frequency response changes as a function of level, but until I have one of these on hand, I can only speculate. And I suspect that Lounge won't be sending me a unit for review...:cool:
 

patient_ot

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Of course, the other end of this is that the input impedance will also cause response changes, and those may or may not be complementary to the RIAA network errors. Ditto noise performance, which to be meaningful, must be measured with a cartridge as a source, not just shorted input. In this, I am in agreement with Robert and rare disagreement with Amir.

I am curious about the idea of frequency response changes as a function of level, but until I have one of these on hand, I can only speculate. And I suspect that Lounge won't be sending me a unit for review...:cool:


Have you looked at Miller Audio Research's measurements of phono stages? I'm not a measurement expert but they have some very interesting measurements. Sadly the data is old and they haven't had a new measurement since 2014. But they are interesting to look at.
 

SIY

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Have you looked at Miller Audio Research's measurements of phono stages? I'm not a measurement expert but they have some very interesting measurements. Sadly the data is old and they haven't had a new measurement since 2014. But they are interesting to look at.

I grabbed one at random and didn't see a lot of the things that I think are critical.

@JPJ is sending me a Puffin stage to measure so that I can do a demo of what I think is the right way to characterize a phono stage by measurement.
 

patient_ot

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I grabbed one at random and didn't see a lot of the things that I think are critical.

@JPJ is sending me a Puffin stage to measure so that I can do a demo of what I think is the right way to characterize a phono stage by measurement.

If you do end up trying to test with a cartridge, I would suggest putting some higher output cartridges and hotly cut records through it and see how it fares. I had an otherwise good sounding phono preamp that completely fell apart on this score, which is why I ended up selling it.
 

SIY

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IMO, that's more a test of the cartridge and record than the preamp. But I hope you'll like the approach I take.
 

patient_ot

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IMO, that's more a test of the cartridge and record than the preamp. But I hope you'll like the approach I take.

Yes and no. If the preamp distorts when being pushed with a hot cart and hot record, it means the overload margin is weak.

Interested to see what your approach is like when you get the Puffin.
 

SIY

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But of course, you can measure overload margin as a function of frequency. It's just that hardly anyone does so.
 

watchnerd

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To me there is enough sonic coloration in cartridge FR across models and brands that I don't really want to add to it by plugging one into a highly colored phono preamp. I'd rather the phono preamp be relatively flat and then I can tweak the sound if necessary using other methods (e.g. loading plugs, tone controls, etc.).

Ditto, vinyl is already finnicky enough, which is why I used a DSP-based phono stage:

It measures great, has superbly low noise, and I can not only load different LP EQ curves, but I can adjust loading via software, too.
 
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amirm

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Ditto noise performance, which to be meaningful, must be measured with a cartridge as a source, not just shorted input.
I don't test with inputs shorted. Output impedance is 20 ohm in the generator. Yes, still low but is not a short. :)
 

SIY

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I don't test with inputs shorted. Output impedance is 20 ohm in the generator. Yes, still low but is not a short. :)

Close enough.:D And with well-designed FET or tube stages, that will often be adequate. With bipolar or less-well-designed FET or tube stages, the number will be misleadingly good.
 

SIY

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As long as it's better than the thermal noise of the cartridge, it's good enough. But that assumes you get an accurate measurement which takes into account current noise.
 
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