[jenhwa]

AD823 has a very nice detail and airy
OPA627 is warm and has more bass
i currently run opa627 in sides and ad823 in center

the opa627 is more musical/lively when biased to class A(5-10mA)
solder a resistor from -Vs(pin4) to output(pin6)
resister values
1.5kohm 10mA(for risk takers)
1.8kohm 8.3mA
2.2kohm 6.8mA

also try 2 TDK ferrites(more detailed bass)
one on the power supply cables to the clock and the dac
one on the power supply cables from the transformer to the regulator

replace the dac output wires with 7N OCC copper wires
improves the sound stage/detail/warmer/fatter

 

[yo2tup2]

nice

 

[TigzStudio]

looks like u removed your XLR's and associated cables?..


also looks like u got some new rca-outs too?

what else did you do?


Im going to try some pure silver wire instead of the 7n occ (from homegrown audio)

 

[jenhwa]

yupe that's all ...

unplugging the headamp opened up the soundstage

unplugging the xlr slightly less noise

the rest is just the standard psu and clock upgrade

 

[HumanMedia]

Quote:

Originally Posted by jenhwa AD823 has a very nice detail and airy OPA627 is warm and has more bass i currently run opa627 in sides and ad823 in center the opa627 is more musical/lively when biased to class A(5-10mA) solder a resistor from -Vs(pin4) to output(pin6) resister values 1.5kohm 10mA(for risk takers) 1.8kohm 8.3mA 2.2kohm 6.8mA also try 2 TDK ferrites(more detailed bass) one on the power supply cables to the clock and the dac one on the power supply cables from the transformer to the regulator replace the dac output wires with 7N OCC copper wires improves the sound stage/detail/warmer/fatter

huge thanks jenhwa!

Im going to follow your lead and keep tweaking. I will try the 823's.
I was wondering if anyone had the 627 in Class A mode. I thought that you needed the metal can version for this for heat reasons?

 

[HumanMedia]

For biasing the 627 into Class A, are your sure its pin 4 to 6? or is it pin 4 to 7?

 

[TigzStudio]

Quote:

Originally Posted by jenhwa AD823 has a very nice detail and airy OPA627 is warm and has more bass i currently run opa627 in sides and ad823 in center the opa627 is more musical/lively when biased to class A(5-10mA) solder a resistor from -Vs(pin4) to output(pin6) resister values 1.5kohm 10mA(for risk takers) 1.8kohm 8.3mA 2.2kohm 6.8mA also try 2 TDK ferrites(more detailed bass) one on the power supply cables to the clock and the dac one on the power supply cables from the transformer to the regulator replace the dac output wires with 7N OCC copper wires improves the sound stage/detail/warmer/fatter

how did you get such thick wire soldered to the bottom of the pcb???

and not get it to pop off?

did you use a glob of soldeR?

or do u have it hooked up some other way? (like where the white socketed part is on top)

I notice the stock rca are gone and looks like 2 wire for each rca (1 ground 1 live on each)?

is this correct?

also looks like you pulled some other socketed parts off and just directly solder the wire?

 

[jenhwa]

for bias to class A, pin 4 to pin 6, tried and tested

the wire i used is solid core, i desoldered the white connector,

plugged the wire through the pcb and soldered them

the default wire eddie used really sux, this should be the first tweak.

solid core wire is fast and has no skin effect, it took 2 days to burn in.

 

[JJ15k]

What is the deal with the skin effect? How does it degrade sound?
and if there is no skin effect what s the point of using
"solid core" since only the surface of the metal would be useful?

 

[jenhwa]

skin effect is the reason solid core cables sound better then multistrand ones of the same material

the signal experiences some loss everytime it jumps from strand to strand

but solid core wire is not exactly plyable and a real pain to work with.

well if you want to nitpick, my bad, the correct wording is to reduce skin effect.

Quote:

Originally Posted by JJ15k What is the deal with the skin effect? How does it degrade sound? and if there is no skin effect what s the point of using "solid core" since only the surface of the metal would be useful?

 

[goto2003]

I have to agree that the wire btween DAC PCB and RCA sucks

I used Canare as a replacement and like the sound more. RCA jacks suck even deeper. Finds some with good quality to replace them.

 

[JJ15k]

I didn t mean to nitpick :d

 

[yo2tup2]

isn't the stock wire soldcore? it seems pretty stiff to me.

 

[TigzStudio]

Anyone know a good spot for some cheap blackgates? hehe..

Also which ones would be the most important to replace on the unit?


i know they have to be 2200uf 25v, could the 25v be higher like 63v or something ? or is this not possible?


http://www.mouser.com/index.cfm?&han...&N=0&crc=false

would any of the Vishay in the above link be good?

what type of capacitor is needed for the main blue board, power board?

do we need Radial Electrolytic Capacitor's?

 

[RogerWilco]

I had also planned on changing the wire out.My choice was going to be small silver ribbon cable.If i can find any?

If you are not using the xlr and headamp i would unplug it.I also unplugged the front light.Opamp AD 712 JN i have had some great results with.Very clean high resolution.

As for bias to class A,this is interesting,but do remember before you guys go soldering there are no more 1.2--1.3 boards Available so be carefull.