I thought you sold your MK1 in November.
Yes, owned 3 pcs MK1 so far, the APS version sold, and base version with Vocm+XS4400 sold.
Current version 2008 built with XS4400+external dc psu, this my favourite that I will not touch.
To implement any chances, like adding this new APS Vocm pcb, I will buy a used MKI, get the work done and I don,t enjoy then re-sale.
Thank you.
This appears to be the latest version, I will have try it to find out.
How many pcb units for a MK1?
Is this install only done by APS or can it be done at a local shop with APS instructions for those who are not in the USA?
One of these is used for each channel (so two required). APS’s website indicates that they are willing to sell these separately if they will be installed by a qualified technician.
I implemented two versions of an active Vocm buffer using a form factor similar to APS’s. This allows the buffer to be connected directly to the pads that are currently used for the resistor divider. As with APS’s approach, all the R5 & R6 resistors will be removed, and one of these will be installed for each channel.
The board on the left uses a design similar to APS with a resistor divider between the positive rail and ground to set the Vocm voltage. I’ve left room for additional resistors to adjust the voltage if necessary. This is filtered with a small X7R capacitor before feeding the op amp (LT6202) driver.
The board on the right uses a REF50xx voltage reference to set the voltage. My current boards are populated with the REF5045 which sets Vocm at 4.5V (I am planning to replace the AD8132 op amps with the AD8139 and increase the voltage to 9V), but I may need to swap parts to reduce the voltage.
It will be a little while before I can test these since I’m trying to finish up some other projects before I dive into the DAC.
If your Vocm buffer works as well as APS does then you are in for a treat.
I believe this resulted in one of the most significant enhancements in sound quality for these DACs. The midrange to low bass has been enhanced. The bass feels more integrated into the music and is considerably tighter. The entire presentation is significantly more coherent and clearer. It’s as if a coating of mud has been taken away.
The Modified LESSP MK1 had superior sound compared to the modified MK2. It now sounds far superior to the modified MK2 and will challenge the new PMG DAC effectively. Just a few seconds of listening is enough to notice the difference.
Good to hear. I’m looking forward to working on the DAC and hearing how much it can be improved.
Did the Vocm buffer just recently get introduced, or was it part of the original Limited Edition Signature Series PLUS upgrade?
This is new. A few of us have beta tested these last month and they are available now at APS. According to their website they are implementing these now as part of the Limited Edition Signature Series Plus.
Has anyone else experienced these new Vocm buffers besides the beta testers?
Glad I didn’t send my DSD MkI in a month ago for the latest upgrades, I’d be sending it back again.
Sometimes procrastination pays off.
Welcome to high end audio and the need to have the best.
Taken directly from APS website:
“This continual research and development by APS demonstrate their commitment to refining and enhancing the DAC experience. While some may feel disappointed at not receiving this new upgrade earlier, the ongoing advancements highlight the brand’s dedication to excellence and innovation in digital audio technology.”
I just received a LESSP yesterday with the new VOCM mod. I have a LESSP with the old mod that I purchased in February of this year for comparison. Right out of the box the new LESSP presents a tighter, deeper bass. The overall sound stage seems to have more clarity. The difference is significant to me and I am very happy with the unit.
That’s great that you have both units to compare, the old Vocm mod DAC and the new Vocm buffer DAC. I had mine upgraded and couldn’t do a direct comparison however I knew right away the new upgrade was far superior sounding.
Congrats on your new LESSP. Welcome to the club.
I think APS will take care of that previously purchased DAC and give you a big discount on the new Vocm mod upgrade.
Nice job!
Has anyone tried running the LESSP DSD MkI DAC with the new VCOM buffers directly into an amp without a pre amp?
I’m just wondering with all these improvements to the DSD MkI, if it may sound better if run directly vs using a pre amp like the BHK?
Makes sense since none of the upgrades change the fact the DSD MkI uses a digital volume control.
After much hemming and hawing I finally pulled the trigger to update my DSD MkI with the latest APS improvements. The unit has been shipped and should arrive this Fri.
The main reason for my hesitation was, is investing in an older DAC once again, had the rev 1 transformer and VCOM upgrade done in 23, a wise decision, vs purchasing a newer DAC along with all the new advances in technology?
Can’t really answer that question yet because I haven’t actually listened to any newer DAC’s, nor have I heard the latest upgraded DSD MkI DAC. But being so satisfied with the first go around of improvements by APS, another reason why I wasn’t in a hurry to upgrade again, I trusted these latest upgrades should push the envelope even further, on a DAC I was happy to live with, and at much more affordable price vs purchasing a new DAC.