and the newer stock units come with 6v regs... so you need to change the regs or the resistors. or both if you want boutique resistors. read through this thread and the thread i referenced and you'll be set as far as mods go. edit: typos... too much scotch

i think i used 4.7uf auricaps and 270ohm rikens. also swapped in 8v regulators.... essential reading here

i'm using vista with hagusb. works well with vista standard usb-audio driver... 16/44.1 output (bit-perfect?) without asio4all. sound is just as good as xp with asio4all. now i'm just waiting for a new version of foobar that will support the vista audio "exclusive mode".

Quote: Originally Posted by revo_909 i don't know if it makes any impact on sound, but definately there's less voltage drift on the DAC chip. with original trimpot i got around 0.5V variance with bourns trimpot it's around 0.1V variance. this is between the forst time i turned it on and...

i notice that many of you have replaced the trimpot with a bourns model. what is the model number of the best part? it seems that there are a few over at digikey that might work... thanks

hi all. i'm wondering if anybody knows the optimal values (approximate) for the Vref and I/V resistors in the dac-ah, for both 6V and 8V. thanks. EDIT sorry. just found this thread with all the answers.

from jim hagerman, designer, over at audiocircles... Quote: Clearly you don't want the raw power line from the computer to directly drive the circuits. And that's why I use special filtering prior to the linear regulators, to reduce the effects of such noise. Then I add extra wideband...

file this under thoughts... i have an m-audio firewire, similar to the usb edition, i believe. sounds good with a modded dac-ah and tube amplifier. hagusb is capable of dealing with only 16 bits. not an issue if you will be playing lossless files (like FLAC), but means you may get less...

hmmm... my dac-ah worked ok after doing the bypass, and i did not take out the opamps.

Quote: Originally Posted by Samgotit reclocking and stacking 8 more DACS wha?? can you seriously just start stacking up more dac chips in this design? i know that in the dddac1543 mk2, you can have multiples of 12 dac chips. man that would be sweet. and what is this about...

kewl!!! was it easy to put in the new regulators?

and with a 6V supply, for the sake of completeness.... 6V-1.2V-1.8V = 3V peak-peak 3V/(2.3e-3*8) = 163 ohms I/V 1.8V + (3V/2) = 3.3V midpoint 3.3V/163 ohms = 0.0202A = 20.2mA 20.2mA "plus our 1.15mA DAC digital silence current" = 21.35mA 21.35mA/2 = 10.68mA = 0.01068A 2.2V/0.01068A =...

i'll take a stab at the ref resistor for an 8V supply... Quote: Now Vref is fixed at nominal 2.2V... Our output Voltage swing can now be 1.8V to 8.6V - 1.2V = 7.4V or 5.6V peak-peak (2V RMS). Our full scale current is still only 2.3mA, so our I/V resistors become 5.6V/2.3mA=2.43k NPV...

Quote: Originally Posted by Samgotit 3V/(2.3e-3*8) = 163 ohms here's a question to show my utter lack of understanding of electrical systems... why is it (2.3e-3*8) instead of just (2.3*8)? and another question about the following.... Quote: To get the output to the new...

you can get fanless external usb enclosures at newegg...

my query to diyshop... Quote: i bought a dac-ah from you a while ago. i've been doing some slight mods, and i noticed that the voltage supplied to the dacs from the regulators is only 6v (measured between pins 4 and 5 on any 1543 chip). isn't it supposed to be 8v? why is it lower and...

i had 2 of the seagate 7200.7 200gb drives. when soft mounted in a tower case (with very quiet case fan and power supply), they were not audible unless i would put my ear to the case. when i moved these drives out of the case into external enclosures, a specific seagate "feature" drove me crazy...

Quote: Originally Posted by Samgotit LM7808? What will voltage do for sound quality? That is the question. +2V or not +2V... that is the question.

... and here's a picture of the new caps in the c28 and c37 positions. like i said, it's tough for me to judge this one. i'm using my old yamaha amp (decent solid state) while my tad-60 (awesome tube amp ) is out of commission. listening to some thievery corporation -- bass seems tighter...

mystery solved! i wonder why diyclub used 7806's instead of the 7808's in the schematic... cost cutting or "better" sound? in any case, 6 volts is certainly within the specs for supply voltage to the 1543's (5v typical and 8v max). does anyone think it would be worthwhile to swap out the...

Quote: Originally Posted by Samgotit They are completly blocked and I can't read them from any angle. i should be able to read the writing on the regulators when i take out c28 and c37 later tonight. i'll let you know what i find...

can someone point me to the place in the schematic where it says specifically that the supply voltage should be 8v?

sam- those resistors are still in the signal path, immediately before the bypass coupling caps. and thanks for the info on the rectifiers. when i read it the first time, i thought he said he replaced the "regulators"... but of course i was wrong. Quote: And the verdict is...

Quote: First thing to go were the three rectifier modules, these I replaced with BYV26E ultra fast diodes. The next items were the two small digital input caps, these I replaced with RTX MIT film caps and this was followed by removing the two 390R feedback resistors and replacing them with...

ami doing this correctly to get the right voltage after the regulators? (see picture attached) meter is set to "200 DCV"...