National Semiconductor audio sound room
I was over at National Semiconductor Tuesday to hear about their new ultra-performance audio chips and have a listen in their upgraded sound room. Mark Brasfield, a buddy I knew from my days at the National amplifier group was rightfully proud of the great sound of the room that he helped perfect. My tube-nut buddies all knew of Mark’s previous company—MSB Technology. He designed D to A converters that take SPDIF and give out sweet sweet analog. The parts National just announced build on the two previous ultra-performance parts they have released, the LM4562 dual op-amp and the LM4702 power amp transistor driver IC. The new amplifiers are now available as singles (LME49710) and quads (LME49740) as well as the LME49720 dual that is the same die as the LM4562. They also spun a LME49860 dual that is a 44-volt version of the 49720. They are getting a lot of interests from industrial customers since a good audio op-amp is also a good medium speed op-amp. The 0.00003% distortion gets people’s attention. Yes, four zeros, and that is driving 600 ohm loads.
National also released the 200-volt LME49810 power driver IC. This starts with the LM4702 that so impressed my buddy Bob Pease only they added Baker Clamps so your amp will come out of saturation at the rail much nicer. This is a mono chip whereas the LM4702 was a dual. Also the 49810 has 50 mA of drive current instead of 5 like the 4702 so you can drive larger output transistors.
I thought you might like to see the fact-sheet National gave me about their sound room:
Sound Room Fact Sheet
National Semiconductor’s dedicated sound room boasts a floating floor, with built in high-, mid- and low-frequency diffusers and selected tube traps. The sound room uses state-of-the-art audiophile equipment based on National’s high-performance audio technology. National audio IC technology is employed in the digital-to-analog converter and preamp as well as the two mono-block power amplifiers that drive the Wilson Watt-Puppy speakers.
A digital transport (DVD/CD player) plugs into National’s digital-to-analog converter (DAC) and preamp via a Sony/Philips-Digital Interface Format (S/P-DIF) connector cable. The pre-amp plugs into two mono-block power amplifiers, which drive the Wilson Watt-Puppy left and right speakers.
National Analog Audio ICs Inside
The DAC and pre-amp use National analog ICs for the signal-path and power supply: Several soon-to-be-released National current feedback audio op amps are inside the DAC signal-path (four in the left-channel, and four in the right-channel). National’s multiple award-winning LM4562 audio op amp is inside the power supply regulators, which connect to National’s soon to be released headphone-buffer current driver. The two mono-block power amplifiers each employ National’s LME49810 audio power amplifier driver’s for driving the left and right Wilson Watt-Puppy speakers.
Sound Room Demo: Music Selections
1. All-Star Percussion Ensemble: Listen for high-frequency definition and sound-stage depth/imaging.
2. Duets – Jennifer Warnes: Listen for vocal presence, proper syblance and phase coherency.
3. Duets – Violin: Listen for presence, depth of sound stage and harmonic structure.
4. Monty Alexander Live Jazz Piano: Listen for live sound; “close your eyes and you’re there.”
5. Harry James Big Band: Listen for separation between instruments, sound staging and attack (dynamic range and contrast).
6. Drum Solo: Listen for percussive attack (dynamic range and contrast).
Sound Room Creator
Mark Brasfield created the current version of National’s Audio Sound Room. He is a principal audio applications engineer with more than 30 years of industry experience. Before joining National in 1999, Brasfield served as chief engineer at Eiger Systems (analog and digital audio circuits), Yes! Entertainment (video and RF circuits) and MSB Technology (consumer and professional audio and video products). Before that, he worked as a senior engineer with the Bear Group (biometrics and security systems) and as a development engineer within SRI International’s Advanced Technology Division. Brasfield’s background also includes Dolby Labs where he designed, built and debugged prototype noise reduction circuits.
I took along my Phillips disk of Vivaldi and was very impressed by the sound. The sound room allows you to hear the improvement in fidelity offered by National’s new chips. National got rightly famous making their Overture line of audio parts years ago. Then they spent a decade making linear and class-D Boomer chips aimed at cell phones and portables. Now they are becoming a major player in ultra-high performance audio. After seeing how good my 45 inch Sharp LCD TV looks I am sure people will want a high-quality audio experience to go along with it. The class-D chips that many people are putting in the panels sound good, but for the ultimate sound you can’t beat this linear stuff.