Lector Strumenti Audio Digitube S-192 D/A converter Specifications

Sidebar 1: Specifications

Description: Single-box digital-to-analog converter. Tube complement: two ECC81/12AX7. Digital inputs: USB Type B, S/PDIF (RCA, BNC, TosLink), AES/EBU (XLR). Analog outputs: one pair RCAs. Sample rates supported: 44.1, 48, 88.2, 96, 176.4, 192kHz (S/PDIF, AES/EBU), plus 384kHz (USB). Bit depths supported: 16 and 24 (S/PDIF and AES/EBU); 32 bits (USB). Maximum output voltage: 2.5V. Frequency response: 15Hz–192kHz, ±1dB "at hi-rez input 192kHz." Output impedance: 250 ohms. Signal/noise: 100dB, A-weighted. THD: <0.1%. Interface jitter: 20ps.
Dimensions: 16.9" (430mm) W by 4.75" (121mm) H by 11.7" (300mm) D. Weight: 17.6 lbs (8kg) net, 22 lbs (10kg) shipping.
Serial number of unit reviewed: 58592K12.
Price: $3595. Approximate number of dealers: 5.
Manufacturer: Lector Strumenti Audio, Via Verdi 35, I-27010 Albuzzano PV, Italy. Tel: (39) (0382) 484165. Fax: (39) (0382) 481021. Web: www.lector-audio.com. US distributor: Hudson Audio Imports, 143 Bergenline Avenue, Closter, NJ 07624. Tel: (201) 768-6986. Web: www.hudsonaudioimports.com.

COMPANY INFO
Lector Strumenti Audio
US distributor: Hudson Audio Imports
143 Bergenline Avenue
Closter, NJ 07624
(201) 768-6986
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COMMENTS
remlab's picture

What does this mean? That the "absolute sound" of a component is all that matters? Horrid measurements have no effect on what some of the best ears in the business can perceive? Yikes!

1audio's picture

I think something is misconfigured. I have never seen or measured an AKM device that was so far from correct operation. You can see measured results for the chip here: http://www.akm.com/akm/en/file/ev-board-manual/AK4397EQ.pdf Everything indicates a problem with the board or with the specific device.

Is it possible that the analog electronics could be the cause of the non-linearity? It seems unlikely but getting the digital side so misconfigured and still working is not easy.

Obviously non-linearity at -90 dB doesn't scream at reviewers saying "I sound bad!" but MP3's demonstrated how much audio can be removed and still have "decent" audio.

Kal Rubinson's picture

FWIW, in the "Manufacturers' Comments" section, Lector Strumenti's US representative states that the designer "deliberately sacrifices measured performance to achieve his design objectives, the most obvious one being superior musicality" and seems not to think that the measurements are unexpected.

Archimago's picture

I read the comment. Looks like a well written manufacturer damage control comment that just regurgitates a number of adjectives from the subjective review (which more likely demonstrates hearing limitations).

Good for John Atkinson to say it as it is. A device that costs a significant chunk of change, that's marketed with big numbers (ooohhh "32 bit DAC from AKM" as seen on the web site, capable of 192kHz and 384kHz) but in reality you'd be wasting dollars feeding this baby >16-bit audio data.

It'd be a shame to think that "musicality" is achieved by sacrificing dynamic range.

remlab's picture

..is that in order to make a digital product sound good, you need someone incompetent to design it. Sign me up!

corrective_unconscious's picture

Damage control is not to double down on a bad result. Damage control is normally to attack the measurer or to "discover" on its return that the unit was broken somewhere along the line. Or to announce revisions to the product "since" the review.

This manufacturer has a far more interesting response than damage control.

qwerty's picture

graph 12 is for sony?
Fig.12 Sony HAP-Z1ES, high-resolution jitter spectrum of analog output signal, 11.025kHz at –6dBFS, sampled at 44.1kHz with LSB toggled at 229Hz: 16-bit internal data (left channel blue, right red). Center frequency of trace, 11.025kHz; frequency range, ±3.5kHz.

and comment is wrong?
maybe this measurement are all fake!
manufacture web site say: setup the dac in service mode for measurement !

John Atkinson's picture
qwerty wrote:
graph 12 is for sony?

That's correct and fig.8 is for the MSB Analog DAC. Both are examples of what the measured performance on these tests should look like.

qwerty wrote:
maybe this measurement are all fake!

No, they are not fake. The manufacturer stated that the measurements correctly characterized the product in his published comment.

qwerty wrote:
manufacture web site say: setup the dac in service mode for measurement !

As the reviewer didn't audition the Lector DAC in "service mode," I didn't feel that to be relevant.

John Atkinson
Editor, Stereophile

corrective_unconscious's picture

I think as a matter of testing protocol it would have been better to additionally do the measurements and do some listening in service mode.

For the measurements then we could at least have an inkling whether the manufacturer is even capable of designing gear which will measure conventionally, a pretty important piece of data. Then listening to service mode would possibly indicate whether the manufacturer's choice of poorly measuring configurations actually yielded some audible benefit...in one person's system, at least.

I understand then in terms of workload it's like doing two reviews, though, but I'd be really curious about all this.

(Also, as an aside, in my quite old Camino trying to preview and edit my post twice before hitting "save" results in my getting trapped in an endless loop always returning me to preview mode...even when I do eventually hit "save." Either that or I will have double posted, as happened sometimes with the old messaging system here.)

qwerty's picture

service mode is for measure test non for listening.
feedback email with manufacture, without service mode setup internnally switch the dac stay in soft mute condition, so the measure are wrong

corrective_unconscious's picture

A claim to be tested as is any other claim about specs from...whom? A manufacturer?

Speaker companies say their speakers have a certain efficiency; then the efficiency of the speakers gets tested.

One mode allegedly measures well. We don't know that. It wasn't tested.

Not too difficult.

SNI's picture

You write that the Lector uses 32 bit AK4397 DAC chips.
AK4397 is a 24 bit DAC chip which is obsolete.
If it is in fact a 32 bit chip, then it must be AK4399, which I think is also obsolede by now.
You also describe that the I/V conversion is done discretely with use of only resistors.
This cannot be true, as both AK4397 and AK4399 are both U (voltage) out converters, which in general do not require I/V conversion at all.
Anyways I cannot believe that sound would not be bettered, if the measurable components were optimized.

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