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Gamma-2 (γ2) DAC Thread

Mar 11, 2010 at 9:22 AM Post #1,621 of 2,154
Quote:

Originally Posted by thoppa /img/forum/go_quote.gif
Actually you are right. I just realised my business email address just gets me free shipping.


Yes, thanks for saying so...I wasn't just talking out of my butt in an effort to rationalize bad behavior. They literally do not seem to care if you are a business, and for all appearances an enthusiast like me is welcome to order samples.
 
Mar 11, 2010 at 7:17 PM Post #1,623 of 2,154
Beefy, I remind you that I did not actually use the program, I bought the part. I haven't sampled in over two years.

Reread my post #1612 - this issue, and marketing in general, are far more complex than you allow. Besides, this is quite a small, dumb thing to get so puritanically, morally indignant about (assuming it is "wrong" as you think it is). But if you want to think I'm The Great Satan for considering sampling a $3 part that's hard to find, go ahead.

Either way, I'm pretty excited because my package arrived today from Mr. Ti Kan, and the building of the y2 will commence in earnest this evening. !!!
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Mar 12, 2010 at 4:09 AM Post #1,625 of 2,154
Quote:

Originally Posted by mace1337 /img/forum/go_quote.gif
Guys, please, just stop.

Continue the argument in PM's or something but keep this topic clean please, nobody cares about your disagreements.


I disagree.....I like reading poor-man's rhetoric online ;-) It certainly is a nice break from reading datasheets to find a sot-23 ldo with less than 30uV noise and better than 60dB PSRRrrrrrrraahhhhhzzzzzzzz
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If anyone does know who makes a 3.3v ultra-low-noise (10uV ?) and good line/load reg and psrr ldo for the y2, please let me know. [/size]

I found a 7812A that does this (not ldo though of course ; Farnell 1087090) for the Mini3 so I'm sure such a thing must exist. BTW I also found that (some?) ldo's don't seem to work in the Mini3 - both lm2940 and lm2937 seem to give 13.2V in the Mini3 circuit.
 
Mar 12, 2010 at 4:51 AM Post #1,627 of 2,154
Actually, although I'd prefer the same package, I'm starting to think this isn't possible. So maybe a to92 and I'll bend the legs or something and use the appropriate pads on the board to connect it. Just as long as it isn't smaller....do you know any awesome 3.3V regs ? I hope so....thank you !

EDIT: I think I found one - LT1761 - but it is 100mA and I'm not sure it'll be stable with the Oscon cap on the output. Noise is 20uV. Any thoughts anyone ?

http://hk.farnell.com/linear-technol...3-5/dp/1663779

Ti also do the REG113 which seems to have slightly lower noise - is this a suitable substitute ?
 
Mar 12, 2010 at 3:36 PM Post #1,628 of 2,154
TEXAS INSTRUMENTS - REG113NA-3.3/250G4

The datasheet says that with an a 10uF output cap, a 10nF noise reduction cap on pin 4 to earth and a 100nF cap on the input will give less than 7uV noise. With just the nr cap it is about 27uV. It says it is stable with no or almost any output cap up to 10uF or more. The dropout is fine (max 400mV) for a 4.5v to 3.3v drop. It'll handle 400mA. Ripple rejection at 120Hz is 65dB but that has dropped to 30dB for 100kHz to 1Mhz. Line and load regulation seem to be 1%.

So it seems this is an upgrade for the TPS 3.3v reg. Any thoughts anyone ?
 
Mar 12, 2010 at 3:57 PM Post #1,629 of 2,154
thoppa, looks like the LT1761 might have a compatibility problem. Pin 4 (BYPASS) according to its datasheet should have a capacitor going to OUTPUT, rather than to ground like the TPS793xx or LP2985-xx. I don't know if it would still perform the same if you simply dropped one in as a replacement. Even though the noise spec is lower than TPS793xx, I don't think it's significant enough to matter in the end (keep in mind that the noise spec may also not be directly comparable between parts from different manufacturers due to differing measurement methodology).

The REG113 seems like it would work, but here the noise difference against TPS793xx is even smaller.

I have tested neither of these so if you want to try them, you're on your own.
 
Mar 12, 2010 at 5:27 PM Post #1,631 of 2,154
Quote:

Originally Posted by amb /img/forum/go_quote.gif
The REG113 seems like it would work, but here the noise difference against TPS793xx is even smaller.

I have tested neither of these so if you want to try them, you're on your own.


Hi,

Thanks for the reply !

It seems the Reg113na is a slight improvement over the TPS and pin and cap compatible so I'll give it a try. I'll try it in the y1 dac board first - the CS8416 reciever datasheet says noise on the power line affects jitter so I hope slightly lower noise will improve the definition slightly. I realise it might not be audible but it's worth a try.

I noticed that you changed the PLL filter on the CS8416 - I assume this was because the y1 is limited to 96Khz so the filter can be adjusted ? If I was only going to run 44.1Khz into the y1 dac board, could I adjust the filter to further improve performance ? I doubt I will; I'm just curious !

Thanks very much for you help.
 
Mar 12, 2010 at 5:28 PM Post #1,632 of 2,154
Probably more for my edification then anything practical but i'm curious about balanced output. Doing some research into "hacking" balanced outs into the y2.

Can I wire L+/L- and R+/R- test points into a TP IVY III + PS and get balanced outputs?

Is there an easier way of getting balanced outputs with all the benefits of the y2's analog output stage?

I know MisterX mentioned something about replacing the RCA's with mini's then getting mini to XLR converters. Can someone please go into a little more detail on this?
 
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