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Inter.View with Norbert Lehmann, Owner and designer of Lehmann Audio (Entec) HiFi products

by Lucio Cadeddu

[Italian version]

LC >
May you tell our readers how did you get involved in HiFi (first) and in equipment design (later)?

NL >
When I grew up there was no question that anyone had to own a stereo setup. I bought my first stereo setup when I was fourteen years old. It was a stereo center by Rank Arena, a name I never heard before, consisting of a Lenco (!) tuntable, a built in tuner and a built in power amplifier. I also bought cheap three way loudspeakers "120W true RMS power with original Pioneer chassis".
I was absolutely in heaven! Before that I had owned just a small compact cassette recorder and taped some radio broadcasts with this unit holding the microphone in front of a loudspeaker at the radio. You can estimate the difference even if you do not know the exact hardware setup ;-)

Some years and some system upgrades later, when I already became a student, I borrowed an integrated, cheap Rotel amp and made an audition in a hifi shop. The "sparring partner" was the A1 by Musical Fidelity. I am a fan of single system comparison now but at that time we first listened to the A1 and then changed the cabling to the Rotel.
It seemed as if the same musicians who had been playing with great fun and maximum power before just went sleeping. That was the very moment when I really got caught by the virus of high-fidelitis.

The next step was a seminar held regularly by Prof. Matthes in Duesseldorf. He is now president of the Tonmeisterschule in Berlin. He does all the recordings with the Alban Berg Quartett. During one of those lessons he first demonstrated a vinyl lp. There was no high-end setup, just a Thorens turntable, small Ortofon cartridge and the phono input of an integrated amplifier.
Then he took the cd made of the same recording and switched to the cd player. We all wanted to rather turn the music off at that moment. Before that I had believed that the new medium cd is by far superior to the lp.

I came into electronic design because we could not afford an expensive mixing console or microphone preamp. So we built our own equipment. We compared circuits and exchanged experiences. This time was very important for me. Then I found out that it might be possible to get some money ot of these devices and tried to improve designs and sell them. I got custom orders for balacing amplifiers, phonostages, microphone preamps and ms decoding circuits.

LC >
May you briefly tell us something about the HiFi and hi-end scene in Germany?

NL >
I fear I do not have to contribute much at the actual time. I am still a newbie in that circle. I just looked at devices during the past years and have got the impression the the hifi scene became quite vivid with some really hot gadgets out there. The units are getting better, serious circuit design survives the hype oriented stuff.
Believe it or not: I visited the Frankfurt show for the first time this year - as a visitor. What I feel is that customers in Germany cling to big names. When you are new to the scene it is very hard. You need very good dealers with a huge amount of knowledge and authority and customers who trust in their dealer's qualities if you want to get into this market.
What I also notice is that some of the manufacturers realized the possibilities of the internet but it is not taken too seriously by most of the dealers. I hope this changes. All this are only very personal impressions.

LC >
You started your carreer designing phono preamps, so I understand you DO love vinyl. Which are, according to you, the main pluses of a fully analogue reproduction?

NL >
Just a slight correction: Before I built "real" hifi electronics I built some microphones with electret capsules and a circuit for battery power and another version for connecting professional phantom power.
They were quite popular among students and some professional musicians around Duesseldorf where I studied audio engineering. I even got a review in a musicians magazine called "Musiker" in 1989.
The first thing I built then was still not a phonostage but a balancing amplifier to connect an unbalanced stereo output to a balanced input. Then came the phonostages.
But back to your question: I know that you are "quite" familiar with mathematics.
The main problem in digital sound reproduction (and recording) is that you only have samples (time discrete) and even have to decide which value of the signal you take (value discrete). The analog signal consists always of all components of the signal all the time (time continous) and with no restrictions by quantisation (value continous). To say it more explicitly: digital sound recording and reproduction means always data reduction compared to the analog original.
Nevertheless I am of the opinion that digital technology has made several big leaps in the right direction. I can mostly live with the status quo.

LC >
You design a D/A converter too. May you explain us some of the main ideas behind a good D/A converter?
According to you, which is the weakest spot of a CD player, the transport or the D/A converter?

NL >
A good, clean pcb layout is essential for a good result. And I found that good analog stages, especially the output stage and a good power supply are always crucial for the sonic quality of a D/A-converter and sometimes contributing more to the final sonic result than the converter chip itself.
Regarding the cd-players I believe in the "quality of the source" importance. So to me the transport is more important. Mistakes in the mechanical construction of the transport show more effect than problems with the built in dac.
This is one of the reasons why I did not try to build a cd-player yet. I just found no time to learn enough about the mechanical constructions regarding the transport until now.

LC >
Lehmann Audio (previously Entec) products aim to the best quality without being extremely expensive. Where can a designer save something in order to keep the quality/price ratio of his designs high?

NL >
Mechanics, mechanics and mechanics. Of course you can always have a look if certain components could be replaced by cheaper ones. But as long as you do not take extremely expensive special electronic components, mechanics contribute the highest money saving potential.
BTW: I would never claim to build the best electronics available. I am just a music loving audio engineer who tries his best to get some people involved into listening to the music.
If I would have to spend money and would have to decide between hifi-electronics (hardware) and music (software) I most probably would spend the money on music - a certain sound quality of the reproduction system as precondition.

LC >
Your products are solid state designs. Which is your point of view regarding tubes?

NL >
I know some people who like tubes. That's it. To be serious again: there is so much out there I would have to learn, but I guess I would prefer getting involved into dsp programming rather than building tube amplifiers.
You can do so much with these little chips just think of all the different filter setups in a cd player. And when you are not satisfied you can just release a new software version. But at the moment I think that dsp's are more essential for professional studio equipment developers in the field of digital mixing consoles and effect processors.
For "standard" two channel hifi sound reproduction I can actually live without them. Anyway I would prefer to get involved in modern technologies. It is nearer to where I stand personally.

LC >
Do you have any new design on your desk? May you reveal something as a "premiere" for our readers?

NL >
Oh I hope so. I have my 10 years anniversary this year. I could imagine doing something special - maybe only to prove that I can build some more expensive, better looking devices too ;-) I promise to keep you posted.

Courtesy Norbert Lehmann for TNT.

Copyright © 1998 Lucio Cadeddu

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