I’ve been modifying audio gear for clients in Thailand for many years as a hobby. I figured I should share my research in Fidelizer website from now on so I’ll start the first one with Cowon Plenue 1. I’ll write my past projects in future when I have time.
I received Cowon Plenue 1 from my client for about a month now. He said it sounds quite bland and narrow requiring EQ to make it Plenue more juicy. Now it’s time for Plenue 1 to shine after modifying a few DX200 and X5iii with Fidelizer Ultimate Mod.
Cowon Plenue 1 has quite interesting digital audio implementation. It uses Burrbrown PCM1792A DAC chipset with Wolfson WM8998 audio hub for interface. Before we continue with analog stage implementation, let’s see how PCM1792A works.
As you can see, PCM1792A has balanced output configuration requiring I/V stage for output stage. From our inspection, we found 3 x OPA1612 op amp doing the following jobs.
2 x OPA1612: I/V and LPF stage
1 x OPA1612: Output and buffer stage
The I/V stage will have two small pot for each channel to adjust voltage output. I thought about calibrating voltage output too as I did before with FX-Audio DAC-X6 DAC but the board was put behind display panel so I can’t do measurements during operation, let alone listening.
So I decided to use different opamps with similar specifications from different models instead. Output and buffer stage can be replaced with more powerful ones but I’ll pick ones that won’t draw too much current and retain similar sound signature.
I also thought about upgrading capacitors too but it needs to be very thin so I’ll look around for a while and see if I can find better capacitors to upgrade. I’ll upgrade battery wiring with high quality ones that should keep Cowon sound signature with other internal tweaks.
I thought using dedicated audio hub WM8998 with separated clock will have potentials for upgrading clock modules inside but it doesn’t look like I can find any information about its frequency like I did on Oppo UDP-205 recently (Will post about that later).
I think I can modify Cowon Plenue 1 DAP up to Signature level if I can find any worthwhile parts for additional improvements. For Reference level, I think upgrading opamps alone would be suffice for important parts. He should be happy without having to keep changing EQ now.
