Kompakt II DAC
Update -Finally after lots of development and testing I have a brand new DAC based on the premium AKM chip, the AK 4497S.
This is their premium single DAC chip & it was the previous version, the AK4497 that my Gross DAC was based on.
The AK4497S is a more recent improved version.
The design presented here is using the chip running in hardware mode, which keeps things more simple but still extracting the maximum sound quality out of the chip.
It is PCM only with compatibility up to 32 bit & 384K sample rate.
The design is very basic, but aimed at extracting the maximum sound quality.
This is a voltage output DAC so suits transformer output really well and that's what I decided to use.
The first prototype used the superb Jensen output transformers. and this was my reference.
The challenge was to find a reasonable price transformer that gave similar performance, and after a lot of testing, I have definitely achieved that.
In fact, the final design using a compact permalloy transformer gave incredibly close sonic results to the Jensen's.
In AB comparisons, I was struggling to hear a difference, but after lots of testing I concluded that the Jensens were maybe a smidgen smoother.
Measuring the output with instruments, they both measured identical with a perfect 20Hz to 20KHz response.
I will be offering the Jensens as an option, but they are very costly these days, so will add $250 to the price of the DAC.
The US triad transformers (yellow in photo) we're also excellent. but I felt the Perma alloy were a fraction better.
Sound quality.
Obviously, I'm totally biased, but the sound totally blew me away.
I'd go as far as saying IMHO that this is the best sounding DAC I've built so far bar the PCM1704K NOS version.
I've been designing DAC's for about sixteen years, so I applied all the tricks of the trade I've learnt during that time to this design.
Also as this is a single rail design it is possible to power it with a 12v DC low noise linear power (eg Kraftwerk II) which will slightly improve the sound again.
A few standouts would be.
Running the AK4497S in heavy duty mode, this improves the driving ability of the DAC chip into the transformers.
Ultra low noise RF grade regulators for the digital supplies to the DAC chip.
Japanese linear style regulators for the critical analogue supplies.
US Wonder Solder for the DAC chip and surrounding components.
All the electronic components are handpicked for the best sonic quality.
eg Japanese Nichicon audio grade capacitors and Koa resistors.
To keep the cost down and save the delays and expense of a retooled case, I'm using the standard Kompakt II design.
What this means is that the filters and XLR or RCA outputs are selected by a simple internal jumper setting.
This is not a big deal, as this is usually a set and forget option anyway.
Cost
I've kept the price the same as the original Kompakt I DAC at $1500 however, this one is a huge sonic improvement.
There will be an option using the Jensen Transformers at $1750 but I really wouldn't recommend it, as it is only a very minor improvement.
Features
Fully imported custom Japanese made solid aluminum case. The case is a high quality 2.5mm thick "clam shell" style with fully machined front and back panels with a satin black finish.
Dimensions - 160 mm Wide 55 mm High 240 mm Deep. Shipping weight 2.2 Kilo grams
A highly improved multiple on-board power supplies providing excellent isolation from mains power noise. Functionally this improvement is equivalent to running the DAC from a low noise external linear power supply.
Nichicon premium for audio capacitors.
Sample rate - 32 bit PCM up to 384K via all inputs
Outputs XLR balanced or RCA - Selectable via internal jumpers
Includes Express Post shipping and two year parts and labour warranty.
Contains: Kompakt DAC and EI core 9v 2A external transformer.