Hello!
I'm a audiophile with very limited knowledge about electronics, but I want to improve this DAC further, it's my first DIYish project like this.
It started with me needing a DAC but not having thousands to spend after a system upgrade and other things.
Bought this thing, changed the standard opamps (all were opa2604) with opa1612 on LPF and Muses8920 on I/V and liked the sound, so I did more, every time was an improvement but now I've came to a stop, and I need help to go on. The purpose is to make a "better" (whatever that means for everyone) DAC (hopefully) than the Denafrips Pontus II with less sugar. Right now I'm at around 900E with it. I'm also curious how far can this DAC go, how good can it can be with mods.
I removed all the iron connectors, fuse delete, IEC (from VBS Audio) and XLR (Neutrik NC3MD-LX-B) replaced and also solid copper wire from VBS Audio where I could install it.
On the I/V stage I have Muses01 that's a bit muddy, although more audiophile sounding than the Muses8920 that's a bit cleaner but boring and has a smaller soundstage.
Those differences between the muses opas in the I/V were very easy to hear after installing Sparkos SS2590 on LPF, that I want to keep there. Sparkos made the scene holographic sounding and are very clean and revealing, with great separation and details. But sadly also a bit thin, a little flat and light in the bass region - would like to fix this.
The DAC uses 4x dual opamps for the I/V stage and 2 dual on LPF, also 1 for SE output but at least for now, I only care about the balanced output.
Other than trying other opamps like the opa1612 on the I/V stage (any other recommendations for a clean sound but also strong bass?) what more can I do to it? Change some caps? I also had a thought about making a external PSU for it, but I think it's very complicated and risky to make holes in the PCB to connect wires and such, so maybe improve the existing one somehow?
More info on the DAC here, like clock and other chips used https://www.head-fi.org/threads/review-firestone-audio-tobby-dac.664270/
Maybe some photos with it will help.
If it matters, the rest of the system is iFi streamer (plan to upgrade to a Eversolo or whatever sounds better on the cheap), Luxman L-507Z and ProAc D30R. And different good cables, also separate power line to a dedicated DIY passive ac distributor, etc.
I'm a audiophile with very limited knowledge about electronics, but I want to improve this DAC further, it's my first DIYish project like this.
It started with me needing a DAC but not having thousands to spend after a system upgrade and other things.
Bought this thing, changed the standard opamps (all were opa2604) with opa1612 on LPF and Muses8920 on I/V and liked the sound, so I did more, every time was an improvement but now I've came to a stop, and I need help to go on. The purpose is to make a "better" (whatever that means for everyone) DAC (hopefully) than the Denafrips Pontus II with less sugar. Right now I'm at around 900E with it. I'm also curious how far can this DAC go, how good can it can be with mods.
I removed all the iron connectors, fuse delete, IEC (from VBS Audio) and XLR (Neutrik NC3MD-LX-B) replaced and also solid copper wire from VBS Audio where I could install it.
On the I/V stage I have Muses01 that's a bit muddy, although more audiophile sounding than the Muses8920 that's a bit cleaner but boring and has a smaller soundstage.
Those differences between the muses opas in the I/V were very easy to hear after installing Sparkos SS2590 on LPF, that I want to keep there. Sparkos made the scene holographic sounding and are very clean and revealing, with great separation and details. But sadly also a bit thin, a little flat and light in the bass region - would like to fix this.
The DAC uses 4x dual opamps for the I/V stage and 2 dual on LPF, also 1 for SE output but at least for now, I only care about the balanced output.
Other than trying other opamps like the opa1612 on the I/V stage (any other recommendations for a clean sound but also strong bass?) what more can I do to it? Change some caps? I also had a thought about making a external PSU for it, but I think it's very complicated and risky to make holes in the PCB to connect wires and such, so maybe improve the existing one somehow?
More info on the DAC here, like clock and other chips used https://www.head-fi.org/threads/review-firestone-audio-tobby-dac.664270/
Maybe some photos with it will help.
If it matters, the rest of the system is iFi streamer (plan to upgrade to a Eversolo or whatever sounds better on the cheap), Luxman L-507Z and ProAc D30R. And different good cables, also separate power line to a dedicated DIY passive ac distributor, etc.
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You've taken out the OPA2604s which are JFET input opamps and substituted bipolar input discrete opamps. The loss of bass might be due to extra LF noise being introduced by this change. While Sparkos is open about the input stage voltage noise performance (1.5nV/rtHz) they're staying completely mum about the input stage current noise. The resistors around the LPF stage probably should be reduced to get better noise performance, they look to be MELF type and the values are likely 5k-10k which would be compatible with JFET opamps but less so with the BJT input stage of the Sparkos's.
From a look at the pics on the HeadFi thread, the relevant Rs on one channel look to be R42,R43,R51,R52. It shouldn't be too difficult to figure out those on the other channel as the components on the board are largely symmetrically placed. C116,C117 would also need increasing in value to preserve the filter time constants.
Thank you for the advice. Doesn't look like a job for me, don't know what values they would have to be, while also being safe, etc. I will show this to my trusted electronics pal.
What would be a very good opamp in 2023 on the I/V stage for a PCM 1794? The opa1612 already has a few years. And do the modifications for Sparkos (on the LPF) should also be made on the I/V stage for let's say a opa1612 or recommended/similar?
Could the internal PSU be upgraded as well? Other capacitors, or something more complex?
At this point I'm asking for ideas (at least for inspiration) to show they guy I will go to with the DAC so he can modify it.
Thanks!
What would be a very good opamp in 2023 on the I/V stage for a PCM 1794? The opa1612 already has a few years. And do the modifications for Sparkos (on the LPF) should also be made on the I/V stage for let's say a opa1612 or recommended/similar?
Could the internal PSU be upgraded as well? Other capacitors, or something more complex?
At this point I'm asking for ideas (at least for inspiration) to show they guy I will go to with the DAC so he can modify it.
Thanks!
It’s very difficult to recommend technical alterations for audio gear which will deliver specific changes to the subjective sound character. You really are in a trial and error activity there. Lacking expert understanding of the circuit design and elements, hobbyists can easily spend many, many hours of circuit tinkering in looking for the exact sound character they hope to find. DAC boxes can be particularly problematic in that regard, because they typically feature so many circuit sub-systems. With your admitted lack of expertise in electronics, I think all that you can do is either continue substituting circuit components and listening to the result, as you’ve been doing, or acquire a new DAC box which already exhibits the sound character which you seek.