I think I've about hit my mod limits. Just finished the transistor mod, but too tired to tell if it was a major step up or not. The lower mids are fuller and music sounds almost a little slow, more natural but maybe too easygoing. Tomorrow I will do vref cap mod and then that will be it for the 1021.
Tips for anyone doing the transistor bc550/bc560 mod:
1. It's actually one of the easier mods to do because the parts being removed come off easily with heat from the soldering iron and from there you are just adding to the board not taking away.
2. I trimmed the transistor leads and soldered more flexible thin wire leads on the legs. This way I didn't have to worry as much about bending the legs in just the right way or breaking off pads since they are so stiff.
1. It's actually one of the easier mods to do because the parts being removed come off easily with heat from the soldering iron and from there you are just adding to the board not taking away.
2. I trimmed the transistor leads and soldered more flexible thin wire leads on the legs. This way I didn't have to worry as much about bending the legs in just the right way or breaking off pads since they are so stiff.
Attachments
Last edited:
Vref cap mod is a must with the transistor mod. You won't get full realization of the mod unless you dump a load of capacitance into vref.
You might want to do the mute mod after this as the mod bug doesn't stop once you fix one issue. There are many including myself that believe the jfets just being there *do* impact the overall sound quality.
There are also people like me who started out with v1 dam1021's without the muting jfets, and are used to them NOT being in the circuit....
*** Just be careful as the DC output on poweron/poweroff *will* destroy your amp and/or speakers ***
(in my case luckily it was just a softstart ptc I blew)
You might want to do the mute mod after this as the mod bug doesn't stop once you fix one issue. There are many including myself that believe the jfets just being there *do* impact the overall sound quality.
There are also people like me who started out with v1 dam1021's without the muting jfets, and are used to them NOT being in the circuit....
*** Just be careful as the DC output on poweron/poweroff *will* destroy your amp and/or speakers ***
(in my case luckily it was just a softstart ptc I blew)
Last edited:
I'll just have to live with the muting jfets. I've already messed up a dam1921 trying to mod it, which is why I pulled out my old 1021 to tweak some more. My modding skills are 'intermediate' level with SMTs. +/-5v and muting jfet mods are too risky for me. Gotta know my limits!
So far with each change in supply chain to the 1.2v there has been a significant impact on sound quality (though with this last configuration Windows decided to force an update right in the middle of testing, but I doubt the update impacted sound quality). With the Lifepo4 being used effectively as a capacitor, the SPDIF output has increased in bass impact, detail, and slightly lower noise. I now have both the 3.3v and 1.2v feeding off a Lifepo4 that is attached to a new LM317/LT3045 supply chain. I think the previous LM317 (which had a noisy led display)-->lt3045-->1.2v masked the impact of the vref cap mod. Now with the Lifepo4 added at the end, the 1021 is nice and punchy with strong dynamics.
The only question now is whether I want to use the one batter for both or add a second battery off the chain to feed just the 1.2v.
The only question now is whether I want to use the one batter for both or add a second battery off the chain to feed just the 1.2v.
I have got my DAM 1021 board and started assembling. One doubt / problem I find, that is when I measure J7 output after soldering, I get shorted alert with meter. I desoldered and checked by meter without any cable soldered , it is again signaling a short in all 4 connections. Is it a problem or it is ok. I have not connected with the power. I have thoroughly checked, no soldering is creating the short. Badly need your help, regards
Attachments
Last edited:
Muting jfets to gnd. jfets are normally on, so about 30 ohms shorting....
Finished with my 1021 after having it in storage for 2 years. Vref cap mods complete and BC550/560 done. Switched from SPDIF input back to USB/I2S powered with Lifepo4 (definitely better). Also came across a mod by Nige2000 to remove the resistor near the clock and use that to patch in clean 3.3v. Great mod! Easy to do and a real step up in resolution.
Thought about removing +/-5v regulators but doesn't sound it would make much difference unless I do the +/-4v vref mod. Too risky. Very happy with what I hear so far. Just need to decide if I need a small .1uf cap across clock since I am using Lifepo4 to power it now.
Thought about removing +/-5v regulators but doesn't sound it would make much difference unless I do the +/-4v vref mod. Too risky. Very happy with what I hear so far. Just need to decide if I need a small .1uf cap across clock since I am using Lifepo4 to power it now.
Attachments
Last edited:
Just for the sake of clarity, if an amp has DC blocking caps shouldn't that be enough to prevent damage if muting fets are removed?
Hi Greg, no I haven't. Too delicate an operation based on previous reports. Basically anything north of the Xilinx I'm not touching at this point. Though it's tempting to eventually add additional caps to the vref beneath the board for kicks.
I'd be up to removing the 5v regulators and patching in my power supply directly there but from what I've read it sounds like it wouldn't be worth it unless I go straight to removing Vref opamps/lifepo4, but not sure. Hard to tell how effective some of these mods have been for others when reading across 10,000+ posts on multiple forums!
To recap all my Rev3 mods (Pic below):
Removed buffer, output caps, added Paul's filters (2016)
Added 12,000uf Nichicon HE to Vref (hopefully not too low ESR)
BC550/60 Superreg Mod
Lifepo4 3.3v/1.2v in place of Regulators
Lifepo4 3.3v to clock
Removed Isolators
Attachments
Last edited: