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Old 5th February 2015, 10:08 AM   #1281
TNT is offline TNT  Sweden
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Quote:
Originally Posted by SebastianL View Post
Okay so here it is, .......
I think it would be god if you declared your signal chain used?

I do agree on one of your observations and that is the one about left/rigth focus. However, for me this was on multi-mic recording. On live acoustical events I didn't notice this but rather a deep stage with a lot of air - quite opposite of your findings - interesting.

I made an early declaration about my findings which I still stand by. I did not adress all aspects in that one and I'm still exploring/evaluating the product.

//
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Old 5th February 2015, 10:41 AM   #1282
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just curious to how you powered the dac?
i found ac powered to be a complete flop if were to match it against real high end dacs
Quote:
Originally Posted by SebastianL View Post

Most music sounds quite flat, the image is 2D, lacking depth and calmness. Not at all the 3D sensation or holographic image which are the trademarks of an R2R dac. There are however, a lot of details. But it doesn’t transcend into the sense of the acoustics of the recording room or the texture of the instruments or the sensation of space between the instruments.
i read this this morning and thought
thats exactly how to describe it
also glad that its not just me thinking this way

i strongly suspect some power supply upgrades and cap changes could turn it inside out
there seems to be very well detailed and i think its got a lot of potential with modding

curious to see what effect different filters will have

still lovin the project though
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Old 5th February 2015, 10:44 AM   #1283
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Quote:
Originally Posted by SebastianL View Post
I’m sorry to drop this bomb but my hopes are that we’ll all end up with a product that can really compete with the totalDac & MSB, for the benefit of all diy’ers who cannot afford a totalDac or the like - and enjoy tailormade electrical toys. Maybe there is a basis for doing some experimental modding on the existing dac or for Søren to work on a vers. 2?
The more honest opinions, the better! We all want to see the DAC become even better if possible. I hope more people will chime in with their impressions.
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Old 5th February 2015, 11:03 AM   #1284
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Quote:
Originally Posted by nige2000 View Post
just curious to how you powered the dac?
i found ac powered to be a complete flop if were to match it against real high end dacs

i read this this morning and thought
thats exactly how to describe it
also glad that its not just me thinking this way

i strongly suspect some power supply upgrades and cap changes could turn it inside out
there seems to be very well detailed and i think its got a lot of potential with modding

curious to see what effect different filters will have

still lovin the project though
I power the dac with AC. It's a Gerth Trafo 4815-2 which was suggested by someone earlier in this thread. One of the cheapest ones I could find, just to sort of get the project started. I too am keen on a battery solution.
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Old 5th February 2015, 11:04 AM   #1285
soekris is offline soekris  Denmark
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Quote:
Originally Posted by SebastianL View Post

....

Is it a bad dac then? No far from it. It just doesn't meet my expectations of an R2R-ladder dac. It’s at least on par with a lot of mid-priced commercial delta-sigma dacs.

Finally let me stress that I still highly value all the effort and hard work Søren has put into this project.
I still say thanks for your opinion, I welcome all opinions as long as they're well funded.... It's not like I expect everyone to just love the dam1021, it is quite demanding on the rest of the signal chain and people have different personal tastes.

And one place where there are plenty of space for improvements are the digital filters. Right now there are:

FIR1, upsampling from incoming sample rate to 352/384 Ksps in one step, with different filter lenght based on incoming sample rate. All FIR1 filters are basic Parks-McClellan "brickwall" types, designed with http://t-filter.appspot.com/fir/index.html, but still shorter than your regular DAC.

IIR, bank of 15 biquads operating at 352/384 Ksps, with one used for the CD de-emphasis filter, none otherwise used for the basic DAC.

FIR2, upsampling from 352/384 Ksps to 2.8/3.1 Msps, reasonable short and soft but still using same design as FIR1.

All filters are using 32 bit coefficients, with up to 67 bit MAC accumulator.

I'm not a believer in no filters (non oversampling), but also don't like the sharp "brickwall" filter types with the pre-ringing. The goal is to work towards filter types that remove just enough to not cause problems with aliasing. It's pretty easy with higher sampling rates, but is long and hard work and listening tests with 44.1 Ksps, which still are the sample rate mostly used....

I intend to procure some commercial filter design tools, but are also very interested in people with more experience in filter design, the filter work with dam1021 is a first for me.... I do have the filters tools and will release them soon, just need to make the docs.
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Old 5th February 2015, 11:05 AM   #1286
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Quote:
Originally Posted by jamesblonde View Post
The more honest opinions, the better! We all want to see the DAC become even better if possible. I hope more people will chime in with their impressions.
My view exactly! Glad you understood
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Old 5th February 2015, 11:09 AM   #1287
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I still wonder how many people in here have ever experienced a real discreet r2r dac like the totalDAC? (not just r2r chip dacs like AD1865 and PCM1704)
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Old 5th February 2015, 11:16 AM   #1288
pos is online now pos  Europe
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Quote:
Originally Posted by soekris View Post
FIR1, upsampling from incoming sample rate to 352/384 Ksps in one step, with different filter lenght based on incoming sample rate. All FIR1 filters are basic Parks-McClellan "brickwall" types, designed with TFilter - Free online FIR filter design, but still shorter than your regular DAC.
Hello Søren,

You can try rePhase to generate the FIR.
It will let you specify any sampling rate (the drop down menu only shows common values, but it can be manually edited) and configure any type of filter (brickwall, LR or arbitrary slope, linear or minimum phase to avoid preringing, etc.) and let you see what you can get at the end for a given number of taps and windowing algorithm.
There is no manual (yet ) but I would be glad to help if something is unclear or if you need specific functionalities.
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Old 5th February 2015, 12:05 PM   #1289
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Quote:
Originally Posted by SebastianL View Post
I power the dac with AC. It's a Gerth Trafo 4815-2 which was suggested by someone earlier in this thread. One of the cheapest ones I could find, just to sort of get the project started. I too am keen on a battery solution.

I used lifepo4 power last night 8 0 -8 v
it was a very good improvement over ac which I had in previous
but still lacking the depth, calm, acoustic positioning a sense of time and space that can be achieved with excellent power supplies

sebastian how does it compare to other r2r dacs in regards detail ?
my impression is that it very well could be better than any sigma delta I've heard detail wise
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Old 5th February 2015, 12:21 PM   #1290
Eldam is offline Eldam  France
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Quote:
Originally Posted by nige2000 View Post
just curious to how you powered the dac?
i found ac powered to be a complete flop if were to match it against real high end dacs

i read this this morning and thought
thats exactly how to describe it
also glad that its not just me thinking this way

i strongly suspect some power supply upgrades and cap changes could turn it inside out
there seems to be very well detailed and i think its got a lot of potential with modding

curious to see what effect different filters will have

still lovin the project though
Can someone draw a rapid shematic on how to get +/- 12 VDC from a 9V/30VA RCore please . I have one on hands ! (measured 10 V unloaded on the two secondary windings !

I can testimonie as my DAM1021 is running with a 7W/15VA torroid and I share some of the conlusions with Sebastian ! IHMO there is a hole in the mids but it doesn't lake of bass : just a subjective lacke of mid-bass and life whic can be resolved with EQ. I didn't try the SE Buffer side (just the unbuffered SE) but plan to do it today with the input of Spzzzzkt member above ! My Pre is 47 k ohms at the input and the amp is 100 k ohms input (and believe me : don't lacke of life and bass : Chord SPM 1000 B, modulatios links are Oyaide Across 750)

I will testimonie after using the R-core if someone helps me with a shematic !

I have some 16V 2200 Panasonic FM & FR and some Schottky diodes ! From almost the beginning I was in for vias to swap the mains caps to test some alternatives, I would like to see how a serie diodes bridge can mix with the existing one ! Because the single 860 uF negative rail : does a DC Pi filter have to go not further than this value for the first cap after the rectifier diodes ? So something like : 860 uF -> resistor for Pi filter and to get a lower VDC -> 860 uF to 2200 uF then connecting to the DAC PS plug ?

Last edited by Eldam; 5th February 2015 at 12:35 PM.
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