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Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 KHz

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matt_garman

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Joined 2008
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lduarte1973 said:
my bad sorry , stereo 3 way system , bass mid treble x 2 - 6 channels , not 6 dacs :) , i own a minidsp 4 x 10 and a nanodigi
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You could get that with three dam1021 boards. Just need to wire up the i2s in parallel. Though, you might need some kind of buffer for the i2s signal to ensure signal lock for all three cards.

Not cheap, but doable :)
 
TNT

TNT

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Joined 2003
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Do it with toslink and active splitters instead. It works well - I have tested with 2 boards - it works well. The onboard re-clocker fixes jitter and you get galvanic isolation as an extra bonus. You could also use the smaller 1121 board. Its cheaper and actually I think better sounding. I own also a 1021.

//
 
M

matt_garman

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Joined 2008
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The manual states the dam1021's positive rail pulls 0.18 A at 10V, and says "the current is almost independent of voltage". I am running a dual-mono setup, meaning two boards ought to pull 0.36A on the positive rail.

I'm using a +/-12 VDC regulated supply to the dam1021. (Specifically, one of these DIYINHK LT3042 power supplies.)

So far I've been using a transformer with dual 15V 1A secondaries. Plenty of power.

Now I'd like to switch to a transformer with dual 15V 0.5A amp secondaries. Obviously 0.5A is greater than the required 0.36A, but this power supply certainly isn't 100% efficient. Anyone have any thoughts on whether or not this transformer can supply enough current? My gut says I might be cutting it too close, but I thought I'd ask anyway...

Thanks!
 
R

RollE2k

Member
Joined 2007
matt: since you will be using 15VAC secondaries i'm quite certain it will work - but if you are looking for a small 15VA transformer a 2x12v (0.625A) would be a better choice... you will also burn less heat in the power supply, so that is another plus. 12VAC secondaries will not have any trouble giving 12VDC output on that regulator.
 
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soekris

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Joined 2009
soekris.dk
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alecm said:
Soren,
1121 has external master clock connection.
Is it possible (in theory) to connect 2 oscillators with fixed frequency(crystek 22/24, 44/48 or whatever) based on I2C flow analyzing?
Or 1121 should be fed a range(set) of frequencies?
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The dam1121 firmware is expecting programmable oscillators, use them for the digital PLL / FIFO, it won't work without. If you worry about the Si514 is too noisy, get a 0.01% board (with the Si570). But a R-2R DAC is much less sensitive to clock jitter than a DS DAC anyway....
 
M

matt_garman

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Joined 2008
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RollE2k said:
matt: since you will be using 15VAC secondaries i'm quite certain it will work - but if you are looking for a small 15VA transformer a 2x12v (0.625A) would be a better choice... you will also burn less heat in the power supply, so that is another plus. 12VAC secondaries will not have any trouble giving 12VDC output on that regulator.
Click to expand...

soekris said:
Fyi, the dam1021 actually works best with 9V DC in, there is no advantages of higher input voltage, just more heat....
Click to expand...

Thank you both, very helpful! Will modify things a bit: I ordered another transformer with 12V/0.6A secondaries, and with that I'll drop the regulator voltage down to +/- 9VDC. Less heat and a bit more current available.
 
S

soekris

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Joined 2009
soekris.dk
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I'm actually trying to write something for my website about the advantages of the R-2R sign magnitude DAC, as not many people seems to get the advantages, some even still insist the a 28 bit R-2R sign magnitude DAC with 0.01% resistors is only a 13 bit DAC....

So I need a way to explain the advantage, without it being too technical or too simplified.... Any ideas or pointers ?
 
R

RollE2k

Member
Joined 2007
matt_garman said:
Thank you both, very helpful! Will modify things a bit: I ordered another transformer with 12V/0.6A secondaries, and with that I'll drop the regulator voltage down to +/- 9VDC. Less heat and a bit more current available.
Click to expand...

Matt: if you are going to regulate down to 9VDC with the diyinhk supply, then go for a 9v transformer, if you are thinking about it, rectified it will give you 9 x 1.414 = ~12.7v, minus rectifier = ~11.3v.. so you still have quite good headroom... and since you would go down in voltage you get 0.83A secondaries, which will mean you have even better current headroom, and even less heat. Transformer will also run cooler.
 
markusA

markusA

Member
Joined 2009
Pardon a trivial question. The RAW SE (J7) output is listed as 1.4V Rms, does that mean 4Vpp or 2Vpp?
Afaik normal reference levels are 0dBV (or -10dBV) for consumer equipment and +4dBu for pro equipment. 0dBV being 1Vrms and +4dBu being 1.228Vrms.
Now, 1.414Vpk is 0dBV.
So either it's not conforming to any standard, there is a typo or I'm missing something obvious?
 
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Dimdim

Member
Joined 2008
RAW SE is 1.4VRMS = ~4Vp-p

Regarding the "normal reference levels", there really isn't a standard per se.

Most DACs and CD players output 2VRMS..

Btw, the DAM's SE output of 1.4VRMS goes to ~1VRMS once we load a filter that has 3dbs of headroom (we should be using such filters IMHO..).
 
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