My Audio Projects

I have after a long silence completely updated my Audio Projects pages. (I preserved the old page just in case.)

It's been a long time since these pages were last updated. I have been neglecting my web site for several years, since I have been quite busy with my consulting job.

However, I have not abandoned the audio design, far from it. For the past three years I have been brewing a revolutionary new amplifier concept that will eclipse anything else I have achieved in audio amplification. The scheme is not quite completed yet, but the first three prototypes have shown the enormous potential of the new concept.

1. JT-ADC No. 1 (24-bit 192kHz A/D Converter)


Disappointed in the sound quality of the sound card input in your PC? This little device offers premium quality digitizing of any analog signal source.

2. MÖKÄ (Preliminary)


This is the project I have spent my sparse spare time during the past three years.

For ten years, I have been building, studying and researching tube audio. Mökä is the result of all my knowledge and experience in the art of amp building. It would not have been possible without the help of my two golden-eared friends, who I could depend on when judging whether a modification was an improvement or not.


Status: READY

Since it became evident that 24-bit digital system shall not be here any time soon, I have turned more and more back to my vinyls. My trusted Daniel preamp includes a tube-based RIAA interface, which I have used for the last 10 years. While the rest of the system has been dramatically improved by Mökä, the vinyl reproduction started to sound a bit soft. Consequently, I designed a high performance solid-state RIAA interface.

4. JT-DAC No. 3

Status: ready, PCB available

Lately, many people have been asking if I have any plans to upgrade JT-DAC to support 24 bits of data and 96 kHz sample rate. My answer has been: probably, eventually. At the moment, I see no reason to upgrade. Frankly, I myself am very frustrated to the slow progress of the new digital audio standard, so much so that I have refocused to my vinyls and new generation of tube amps.

As soon as I see that reasonably priced 24-bit/96kHz records will be commercially available (if ever), I will no doubt design JT-DAC No.4. The major change will be to get rid of the AD1890. The jitter is even more issue with 96kHz sampling, and I have plans to make jitter reduction with PLL, buffer memory and VCXO. But until that I will concentrate my efforts to DHTSE and DHTPP amplifiers.

It seems that the present 16-bit CD will be around for along time. It makes sense to me to build a high-quality system for them and not to wait for something better in the (near or distant) future.

5. Tube DAC Tubed DAC Output Stage

Status: READY (PCB available)

An optional output stage for JT-DAC No.3 or any other current output DAC.



6. OTL power amp


This project is currently terminated: MÖKÄ beats any OTL in every respect!



© Jukka Tolonen, 2001-2003

Comments, questions and feedback are highly appreciated:

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This page was last modified on 01.06.2003.