Here are the details on the RWAK240 / RWAK240+ modifications:RWAK240
When comparing the headphone output (both the SE and BAL outputs) of the AK240 to some of the best dedicated, portable headphone amplifiers, it becomes apparent that the AK240 lacks in bass impact and extension. While the AK240 bass is nimble, it is missing foundation and authority when called upon, especially with lower impedance headphones. There is also some missing body. The main reason for this has nothing to do with output voltage swing or output impedance. It entirely has to do with the fact that the power supply rails for the headphone output stages are quite low on reservoir capacitance
, so they have a hard time delivering the needed instantaneous current that high end, dedicated portable amplifiers can deliver. Inside the AK240, space is at a premium and there isn’t the room for a respectable amount of power supply rail capacitance if it is to be installed on the board as needed for machine assembly. Fortunately, there IS a way to hard-wire increased capacitance directly to the rails of the output stage FETs by way of the modification process, and this is exactly what is done:Modification:
2,000uF of super-low ESR power supply rail capacitance is hard-wired directly to the headphone output stages.Result:
With this modification installed, the AK240 delivers the bass weight and scale that is now on par with high-end portable headphone amplifiers. It extends deeper, hits harder when called upon, and is tighter and more responsive throughout the entire volume range – but is most welcomed at medium to higher listening levels where more instantaneous current is required (especially with lower impedance headphones). This modification also helps add more depth so certain recordings.Another area where the AK240 headphone outputs can be improved upon is in both the midrange and top-end.
While it does a good job at keeping things neutral, the tends to sound a little dry at times – siding towards being more analytical instead of delivering the right amount of richness and musicality that makes you want to listen longer and longer. While not
“hard” or “digital” sounding in its stock form, there is still a certain lack of emotion in the midrange, and lack of naturalness in the top-end that is so important for taking this DAP’s sonic performance to the highest level possible. After much experimentation, a solution was put in place to improve both SE and BAL headphone outputs equally:Modification:
Pure Class-A biasing of the headphone input stages via an installed JFET cascaded constant current source (CCCS). The JFET CCCS’s are bench-tested and matched to be better than +/- 0.5% tolerance.Result:
This greatly improves the midrange by making it sound more seductive and natural, and does not harm the transparency and micro detail retrieval of the stock player. Treble becomes very open, extended and effortless sounding – and these improvements, along with the improvements to the bass response (mentioned above) work together to elevate the AK240’s SE and BAL headphone output performance to a level that is competitive with some of the best source + portable amp pairings! Availability and Lead-Time:
We are accepting AK240 players for the RWAK240 modification service starting 4/21. Lead-time is within 2-weeks from receiving your AK240. Price:
$495 + return shipping ($15 inside the USA, $55 outside the USA).Payment:
Please paypal directly to: email@example.com
until we set up an RWAK240 page on our website that adds a shopping cart interface.
Be sure to confirm your email return shipping address is added to the "notes" section of the payment.RWAK240+
- Includes the AK240 modification listed above
- Adds either a SE (3.5mm TRS jack) OR BAL (3.5mm, TRRS jack) true line output jack. You select the line-out that you prefer.
The location is on the angled surface above the volume wheel. Some machining of the enclosure internally is needed to take place (Very carefully!) to remove aluminum so we can fit the 3.5mm TRS or TRRS jack inside, along with drilling the hole on the angled surface to panel-mount the jack. This is hard-wired from the output stage of the d/a converters, and completely bypasses the stock headphone output stages and gives you the cleanest possible line-out signal to feed an external portable amplifier.
NOTE: You will still need to set the volume wheel to MAX in order to get full output voltage (no digital attenuation) from the d/a converters.Availability and Lead-Time:
We are accepting AK240 players for the RWAK240+ modification service starting 4/21. Lead-time is within 2-weeks from receiving your AK240. Price:
$795 + return shipping ($15 inside the USA, $55 outside the USA).Payment:
Please paypal directly to: firstname.lastname@example.org
until we set up an RWAK240+ page on our website that adds a shopping cart interface.
Be sure to confirm your email return shipping address is added to the "notes" section of the payment.
We also plan to offer new, fully modified RWAK240 and RWAK240+ players.
RWAK240 player: $2995 + shipping ($15 inside the USA, $55 outside the USA).
RWAK240+ player: $3295 + shipping ($15 inside the USA, $55 outside the USA).NOTES:
- Website for AK240 mods and players will be added soon to: http://redwineaudio.com/mods
- As with all our modified products, we do not offer a return policy. See: http://redwineaudio.com/about/terms-and-conditions
- Just like the AK100/120 modifications, we warranty the RWAK240 for as long as you own it (applies only for the original owner). Note - This excludes any issues unrelated to the modification, such as the battery, LCD, etc., but we still try to offer prompt repair service for such non-warranty items. Price depends on nature of repair.
- All stock functionality does NOT change with the RWAK240 or RWAK240+ ... these are only sonic improvements and not firmware related.
Thank you for all your interest and support!