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- Idea & Design by Wim.
Project design goals are: hybrid design, low cost, good specs, good sound and reliability.
This design is published in the September 2006 issue of AudioXpress. Down here an overview of downloadable files. Please do respect the copyright issue.
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A Professional made Circuit Board for the power current stage is available, please check this page. |
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AudioXpress readers who are interested in the layout as mentioned in the article may click here. |
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Nishiki Hybrid Amp as PDF file [1.262 KB]
, original document prepared by the author |
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The Nishiki design and publication is as is. Circuitboards and additional info regarding the AudioXpress article are available. In addition to the Nishiki design the Mugen Hybrid Amp is added to the website, this design is based on the oroginal Nishiki Amp. It offers a complete main amplifier, this with a different driver but uses the same quasi-complementary outputstage with a small update. It shows no improved in sound, it sounds different though, and it is made in such way to achieve more power, lower distortion and even easier to make. Driver and power section as powersupply are using circuitboards.
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I fired up the Nishiki modules today. I'm impressed, darn impressed. To be honest I had my doubts as to the DC offset tracking and the bias control. The modules ran smoothly after setting the DC offset and bias. I ran them up on a load and there was no bias run away, no nasty oscillation, no glitches on the scope just a pure clean sine wave.
After being satisfied that they were going to run without any problems I hooked them up to my speakers without the aid of the Velleman speaker protection kit I purchased.
I am still shaking my head wondering how these little modules can sound so clean and clear. They seem to have the good qualities of the tube line stage and the clarity and quickness of a real good soild state amp. They have nice bass and a smooth liquid mid and high frequency.
As one could expect these modules are going to need a hefty signal so I would not be afraid to hook them up to a line stage with a LOT of gain. I ran them with my Aikido 6Au6/5687 line stage without any glitches, noise, or problems. I can hardly wait until I try Wim's new line stages with it.
Bottom line..... are they worth buying?
With out a doubt they are well worth the money and effort. They provide a real nice reproduction of the material presented to them without coloration. I have listened to other hybrid amps and NONE have come close to this one. A well engineered product that I can recommend without second thoughts.
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I tested the amplifier probably under the most unfavorable conditions because it had no fancy power supply but one borrowed from a piece of commercial audio gear. I ran the amplifier with an unregulated supply of plus and minus 40 volts with 9,000 mfd filter caps with no by passes and nothing fancy added. The amplifier was put together with all the parts as stated by Wim in order to give a fair idea as to the performance of the amplifier. The amplifier was biased at 33mv across R14 per the instructions. There might be some to be gained by setting the bias a little stronger but then again one needs to think along the lines of product life as well. I will also say I ran the amps with less than stated bias and they still sounded sweet.
I believe that Wim has done his home work and has presented a good viable product well worth your consideration. I will also point out that one should purchase GOOD quality pots instead of the cheap ones I threw in there and they won't have to be replaced like I did mine.
There is only one Quasi-complementary amplifier I have ever liked before this amp and that was an ALtec 9440.
Note* I used the 2SC5200's for outputs and the 2SC2073 and 2SA940 for drivers and the BD679 bias transistor.
I will also mention that I am not affiliated with Wim in any manor nor am I receiving any consideration for my report on this amplifier. I am giving it a fair trial as I would with anything that was sitting before me.
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