Yamaha is not dedicated exclusively to the power amp business, but it doesn’t mean Yamaha is no power amp specialist. We have a history of more than 30 years of power amp development and manufacturing and some of our engineers are thinking of nothing but power amps, awake or asleep, rain or shine.
Please listen to some of the engineers involved in the new PC01N series and feel the hard work and professionalism they apply to their jobs.
Toshiro Mayuzumi
Mayuzumi joined Yamaha in 1975 and spent 12 years in the customer service department in Tokyo, where he mainly dealt with consumer audio products and had good experience with end-users. In 1987 he was reassigned to Pro Audio engineering and since then he has been engaged in the development of power amps and switching power supply units until today. He is now involved in a project to devise the next generation of high-powered power amps and power supply units.
Kazuhiko Nishizawa
Entering Yamaha in 1986, Nishizawa’s first assignment was mechanical design of consumer audio products. Back then he sometimes enjoyed building power amps for fun using parts that hadn’t been chosen for products due to high cost. In 1991 he was transferred to Pro Audio engineering and got involved in the design projects of multi-track recorders including MD recorders and AW4416. He is proud of having been part of the world’s first MD multi-track recorder, the MD4. Nishizawa is now developing analog mixers and power amps.
Takahiro Tashiro
Tashiro joined Yamaha and started his career as an electrical engineer of power amplifiers in 1985. Later he got involved in the development of powered mixers and then un-powered mixers as well. He sometimes visited China to look for low-cost but good quality parts. His current jobs include product planning of power amps, powered mixers, un-powered mixers and portable PA systems.
Takashi Handa
Handa joined Yamaha in 2003. In the PC01N series development he handled electrical and lead-free design.
Shinjiro Takeda
Taku Nishikori
Please summarize the background of the development.
Takeda: The PC series is a flagship series in our power amp line-up like PM series for mixers and we would like to keep improving its quality as long as we are in the power amp business, and since we came out with the PC00N series several years ago we’ve been conducting studies for further improvement. And we finally found a way to significantly improve sound quality and wanted to bring it into the market as soon as possible. That’s why we started PC01N series development.
You now have five models now instead of two. Why did you add three models to the previous PC00N series?
Takeda: PC01N’s target markets are live sound and installed sound sectors. Customers in the live sound business usually demand high power, so even the older PC00N amps probably meet most of their needs. In the installed sound sector, however, there are many types of projects and a huge variety of power settings are required depending on the speakers used, and a 2-model line is unable to cover some of the market needs. So this time we added a few models to fill the 200W - 700W range, which are very popular in this market.
Tashiro: Installation projects range from 100W to over-1kW. PC01N series covers 200W to 1kW and can take care of the demand from small to mid-sized projects. We are planning to introduce more models for this market to give the customer more options.
What has been changed from the previous series?
Takeda: We lowered the cut-off frequency of the HPF from 40Hz to 20Hz. The reason is a sound system involving PC series would usually use multi-purpose processors like DME24N/64N or speaker processors before power amps, and you can easily get HPF for speaker protection on those processors. We think what is expected from the HPF on PC series is to eliminate low-end frequency out of the audible range.
Tashiro: We also thought about matching it with the subwoofer we are developing now, which can reproduce frequencies down to 20Hz. One other thing to mention is these amps are lead-free and eco-friendly, complying with *RoHS, a new European directive for environmental protection.
*Restriction of the use of certain Hazardous Substances in Electrical and Electronic Equipment
Power amps are difficult to differentiate. What is the biggest appeal of this series? What are advantages over other amps?
Tashiro: The biggest advantage is the resolution of sound. It might be simple, but that’s one of the most important factors for power amps for commercial audio applications. We call the sound character of PC01N series “crystal sound”, because it is so transparent, so crystal-clear.
We have applied the “EEEngine” technology to get this crystal sound. This is Yamaha’s original technology for high efficiency and was developed to overcome the two biggest problems of the class D amp, that is, the non-linearity of frequency response and the low damping factor. Thanks to the “EEEngine”, PC01N amps have gotten the high efficiency of the class D amp as well as the linearity of the class AB amp at the same time.
This technology makes it possible to convey electric energy to speakers with a minimal loss, and that helps to greatly reduce the load on the power supply unit. It has the same effects on sound quality as using a large capacity power supply.
To sum up, super high resolution sound based on a super high efficiency technology is the biggest advantage of the PC01N series.
How was it received by evaluators?
Tashiro: The result was very interesting. At the evaluations, we had power amps from several manufacturers for reference. And most of the live sound engineers appreciated PC01N very much, while recording engineers chose other manufacturers’ amps.
The reason is obvious. The live sound engineers listened to the amps assuming how they would sound in their work environment such as the theaters or stadiums, but the recording engineers judged by how they sounded in that very room and whether they liked it or not. Power amps like PC01N series are not designed to listen to music at a relatively low volume in a certain listening position, like you listen to a CD at home, and there are fundamental differences in specifications from hi-fi amps. Live PA engineers know it too well. That’s why they appreciated PC01N amps. In the live sound applications where the sound has to be “magnified”, the resolution should be given a top priority. Personal preference doesn’t matter. In other words, you need to accurately reproduce the outline of “materials”, that is, each musical instrument and vocal before creating your preferred sound.
Now can you tell us the biggest issue in development?
Mayuzumi: As Tashiro-san mentioned, these are the first lead-free Yamaha power amps. And we had to change specifications and materials of many parts first.
Nishizawa: The highest hurdle for me was how we could achieve a supreme sound quality. We found mechanical parts have significant effects on sound character and so conducted a thorough analysis of the mechanical characteristics of each part. As a result, we learned the material and plating of the bottom chassis has much to do with the vibration decay and is deeply related to the results of the evaluations. We tried a variety of materials and platings to eliminate unnecessary vibrations that could degrade the sound quality. When the ideal sound, what we had been pursuing, came out of one of the prototypes, I felt really rewarded.
Mayuzumi: In the power amp development, sound quality is usually acceptable unless there are mistakes in design. What’s difficult and important is to go beyond that point, say, where and how. We started with looking for problems apparently insignificant but in reality very important to sound quality and then came up with a solution one by one.
PC9501N front
PC9501N rear
Why are these amps networkable? How do they work?
Takeda: As I said at the beginning, the primary targets of these amps are installed sound applications. In particular, PC01N’s major focus is on such applications as concert halls, theaters and churches, which are very demanding when it comes to sound quality. And such facilities usually have amp rooms located away from the control rooms. That’s why we made PC01N amps remote-controllable and monitorable using ACU16C (Amp Control Unit) and NHB32C (Network Hub). Also, in the stadiums where you need to put power amps in various places these remote control and monitoring functions should be very convenient.
Nishikori: Recently, two types of networking are in trend. One is audio networking like CobraNet and another is networking for remote control.
We’ve been studying remote control networking technologies for 10 years now and in fact applied such technologies to some of our products. For instance, we provided DME24N and 64N with an Ethernet port on the rear panel so they can be controlled through a TCP/IP network. And as Takeda-san said, power amps are demanded with networking too, so we made PC01N amps controllable. They’ve got a power current sensor, a thermal sensor and a CPU for control inside.
Frankly speaking, it was not as easy as we expected to build these remote control functions in power amps. Power amps are single function products by nature and priorities are usually given to sound quality, reliability, light weight, compactness, low power consumption, etc. Adding control functions to these brings you a lot of issues like how you secure space inside the chassis, how you reduce additional cost for additional parts, how you keep the noise low enough, etc. etc. We struggled to overcome these issues, but I believe we did it. Without affecting the sound quality, we gave them remote control capabilities.
The power amp market is very competitive with a lot of manufacturers. What are you doing to survive in this dog-eat-dog world?
Tashiro: It is very difficult to differentiate feature sets from others and the product value depends much on other factors such as reliability, sound quality, after-sales service, etc.
We are proud of a good reputation we have gained from the market for reliability and capability of service, but I think we should push it further and provide the market with more opportunities to listen to our amps. I would like more people to know the real value of PC01N amps.
We should also push forward our plan to make every product networkable from mixers to amps to speakers. Power amps should no longer be mere power amps, but components of a networked system.
Yamaha has quite a long history of power amp design and manufacturing. The first product dates back to the 70’s, if I remember correctly. What’s the most impressive model for you in such a long history?
Mayuzumi: Among recent ones, that’s PC9500N. At first we farmed out the development of its switching power supply unit but couldn’t get a satisfactory design from the contracted firm, so we had to bring it back in-house halfway through. When we achieved the continuous output of 3KW, I was really thrilled.
And among old ones, I cannot forget PC4002M. At that time, we didn’t need to think about cost because Japanese yen was pretty weak and we could do whatever we wanted. For instance, we mounted a copper plate on a PCB for the wiring of the output as well as the power supply.
Tashiro: For me, H7000 is the most memorable item. This is the first product with “EEEngine”.
With high efficiency power amps using the PWM (Pulse Width Modulation) technology, digital signals with high power current have to be converted back into audio signals through a coil. And this coil sometimes causes problems like deterioration of frequency response and distortion that never happens to class AB or class H amps, but we overcame such problems with the H series.
Lastly, can you tell me what’s tough being a power amp engineer?
Mayuzumi: As repeated in this interview a few times, product differentiation is not easy in power amps. It is really difficult to design a power amp with originality. Nevertheless, we are always expected to be original. That’s the toughest part of our job.
Thank you for your time today.
