Another interesting r2r dac

[nige2000]

build two
reclocked the shit out of it
much more detailed sound



seem to have a bit of static or something funny, like a distorted sound shadow its barely noticeable but sometimes audible at low volumes
doubt its anything to do with my mods... hmmn is that a nos thing?
other than that it sounds great

[rickmcinnis]

Normally, someone saying they had "______ the shit out of" something is nonsensical (but we all say it without thinking about how silly it is) but in this case it (I suspect) a statement of fact. Getting the shit out of our systems is the goal.

Hoping you find the time to show the slow chirren in the audience how to do this. I know you have thrown us a few drawings that make sense to those who already know what you are doing! Something that makes it clear to those who don't.

Maybe about the time abraxalito reveals his buffer ...

Take care,

[abraxalito]

Here's my suggestion for a buffer (i.e. unity gain stage) to drive the cable.

TirNabuffer.png (9.79 KiB) Viewed 2586 times

[rickmcinnis]

Thanks, abraxalito.

Is there some kind of selection one must make for the transistors?

Is there an available transformer you can recommend?

On another subject that applies to both SOEKRIS and AUDIO-GD DACs - I had removed the ceramic low pass cap on the SOEKRIOS board but kept thinking of how SOEKRIS thought that was a terrible idea.

I had long ago purchased some Russian teflon caps of 1400pF to use in place. I thought I should hear what they do. I cannot remember how I picked this value - I have no idea how close it is to the original value.

In my system it makes a tremendous difference. I installed them across my output cable since they are too big for the board.

Certainly a modest amount of filtering but there is a gain in quality. I could not go back to no filter. I am sure there could be better values and I will try them.

In my system there is no question a low pass filter sounds better with the SOEKRIS and I suspect the AUDIO-GD would benefit, too.

[nige2000]

Here's my suggestion for a buffer (i.e. unity gain stage) to drive the cable.


TirNabuffer.png

recommendation for cap types?
not with you with the transformer? can u elaborate ratio etc?
what voltage in and out is

[abraxalito]

Is there some kind of selection one must make for the transistors?

Nope, just pull them off the reel.

Is there an available transformer you can recommend?

None I have experience of no as I always make my own. If you're up for making your own something about EE25 sized should work fine. If you want to buy one I'll dig out one or two Taobao links as the guys on a classD thread found some promising ones.

On another subject that applies to both SOEKRIS and AUDIO-GD DACs - I had removed the ceramic low pass cap on the SOEKRIOS board but kept thinking of how SOEKRIS thought that was a terrible idea.

Where on the schematic is this cap? Just because Soekris thinks its bad is far from a guarantee that its bad for SQ, sometimes quite the opposite is true - what he things is a really bad idea turns out to be an improvement for SQ. Despite all the feedback he's received from tweakers he still thinks like a typical engineer.

Certainly a modest amount of filtering but there is a gain in quality. I could not go back to no filter. I am sure there could be better values and I will try them.

With a transformer you make yourself there's the opportunity to load it with the correct capacitance and use its leakage inductance to form a 2nd order low-pass filter. With off-the-shelf trafos you'll have no idea what the leakage inductance is as its rarely specified in DSs.

In my system there is no question a low pass filter sounds better with the SOEKRIS and I suspect the AUDIO-GD would benefit, too.

Yep, I've found similarly.

[abraxalito]

recommendation for cap types?

The input cap is best an NP0 1206. That's what I use anyway. The rest are electrolytics and I'm not fussy about those in signal circuits (power supplies is another matter though).

not with you with the transformer? can u elaborate ratio etc?
what voltage in and out is

The transformer is really up to you for the ratio you need. It needs to match the maximum output of the DAC to the maximum input of the amp. I'm assuming you're still using the TVC on the output of the amp.

[rickmcinnis]

Abraxalito,

You are a true iconoclast! You and SOEKRIS agree on ceramic caps! I guess I show my age when I cringe at the thought of my audio signal passing through, or even near, a ceramic cap. Admittedly, I have never actually listened to a good ceramic cap in isolation so I have no real idea of what they do to the sound. I know I should.

Usually guys that like transformers are not the same one's who use ceramic caps. I do appreciate the singularity of your audio vision. It speaks of one who thinks for themselves, as if anyone here or at DIYAudio ever had any doubts about that.

Have to say SOEKRIS is right about the low pass cap. I could never return to not using one. Listening fatigue has been abated. I wondered why I did not want to listen longer after dinner. The last couple of nights I have had to make myself go to bed. Worth a try for those SOEKRIS DACs that have had the standard ceramic cap removed.

Neat that you do not have to do circus tricks for the transistors. If you come across a suitable transformer, please let me know. I have never wound one myself and figure the cost to DIY would exceed the cost of getting one already made.

My DAC is supposed to be delivered today. Wish I had got some of his CLASS A power supplies just to see what they are. I feel sure they are shunt regs but wold still like to see.

This AUDIO-GD fellow seems like the real thing. Certainly cannot call him a copy cat. I wonder if I should have got the complete DAC just to see how he does things?

[wushuliu]

Abraxalito,

You are a true iconoclast! You and SOEKRIS agree on ceramic caps! I guess I show my age when I cringe at the thought of my audio signal passing through, or even near, a ceramic cap. Admittedly, I have never actually listened to a good ceramic cap in isolation so I have no real idea of what they do to the sound. I know I should.

Usually guys that like transformers are not the same one's who use ceramic caps. I do appreciate the singularity of your audio vision. It speaks of one who thinks for themselves, as if anyone here or at DIYAudio ever had any doubts about that.

Have to say SOEKRIS is right about the low pass cap. I could never return to not using one. Listening fatigue has been abated. I wondered why I did not want to listen longer after dinner. The last couple of nights I have had to make myself go to bed. Worth a try for those SOEKRIS DACs that have had the standard ceramic cap removed.

Neat that you do not have to do circus tricks for the transistors. If you come across a suitable transformer, please let me know. I have never wound one myself and figure the cost to DIY would exceed the cost of getting one already made.

My DAC is supposed to be delivered today. Wish I had got some of his CLASS A power supplies just to see what they are. I feel sure they are shunt regs but wold still like to see.

This AUDIO-GD fellow seems like the real thing. Certainly cannot call him a copy cat. I wonder if I should have got the complete DAC just to see how he does things?

I removed the ceramic caps and actually prefer the sound without them, although yes it still sounds very good with other caps. But then I do not use the NOS filter with the soekris. IIRC the NOS filter plus no caps = bad idea.

I had an audio-gd DAC a long while back. One of the wolfson chip versions. My overall feeling was that it was nice and clean but somewhat 'flat' in presentation. I have read this elsewhere too. Like maybe his output filter takes a little of the life out. Beautiful pieces of kit on the inside though.

[rickmcinnis]

It certainly looks like beautiful construction from the photographs.

I had removed the ceramic low pass cap when we were all nigel-izing our SOEKRISs.

I do use the NOS filter, only, so that could explain what I am hearing.

Which filter do you use most often, wushulu?

Got my boards in today.

Wondering if, as with the SOEKRIS board, if I should remove all electrolytic capacitors (except the one I assume for the 1.8 volt regulator)? Nice that with this board you can put them back in easily if you need to. Have never seen this brand of cap before. One wonders if it is total junk or some magical electrolytic the Chinese audio folks have kept for themselves?

Should be a simple install. I think I will get a fresh pair of batteries for this project. One wonders how long our batteries last in the Keny scheme? Guess I should keep the SOEKRIS as is until I know which one will be part of my digital player.

Last thing, I wonder if it makes funny noises if you attempt to remove/replace the polarity jumper while playing?