DAC60 vs. Benchmark vs. PS Audio Link III

lpaudio2 · « **Reply #100 on:** 28 Apr 2008, 01:16 pm »

thanks! I would really appreciate pictures, it would save me a lot of time / frustration. I don't have my unit yet, I should have it later today (pending the brown truck man). Mine is supposed to have the "k" chips as its the pacific valve "modified" version, but I believe it still have the i/v flaw. I'll have to take a closer look when I get it.

regal · « **Reply #101 on:** 28 Apr 2008, 01:58 pm »

I have another mod for the advanced. It is possible to change the DF1704 to slow-rolloff. Steve N from emperical audio does this on his $4k DAC-60. You have to have a fine tip solder iron, or be willing to cut pin 27 from the ground pad. Then you solder a 30G wire to connect it to +5V. I haven't tried it yet, but this is probably a big reason the emperical audio version sounds so good. No I don't believe Jitter is audible , especially w/ a tube DAC.

lpaudio2 · « **Reply #102 on:** 28 Apr 2008, 02:44 pm »

sounds very interesting. I love the fact that there is so much potential with this unit.

Im going to start with throwing some JJ tubes in it, and hopefully do that i/v mod as that sounds the most promising thing to start off with. I think I may throw some clarity caps I have floating around in to replace the output. Ive had great results with the clarity cap s/a line in other gear.

Jon L · « **Reply #103 on:** 28 Apr 2008, 05:14 pm »

Quote from: lpaudio2 on 28 Apr 2008, 02:44 pm

Ive had great results with the clarity cap s/a line in other gear.

Really? My experience with Claritycap SA is not so positive. BTW, what's the stock cap value, and has anyone figured out what would be the minimum uF/voltage rating that would give good results? (Since good caps are so darn expensive).

markC · « **Reply #104 on:** 28 Apr 2008, 06:08 pm »

Stock value is 2.2 uf, according to the schematic. Mine had 2.7 polyester. I don't like polyester! Replaced them with 3.3 Sonicaps and later by-passed with .1 uf Sonicap Platinum. Much better; especially the upper end.

BobC · « **Reply #105 on:** 28 Apr 2008, 06:42 pm »

Not to hinder your conversation, but you guys are starting to make me think / feel that this unit requires modification to sound very good.

I know that is not your intent though.

markC · « **Reply #106 on:** 29 Apr 2008, 02:15 am »

As with any component in this arena that costs $500, there is room for improvement. It sounds decent stock, and if one were to just swap out the coupling caps for say Auri's or Sonics or the like, I think it is a very good deal with minimal alteration. In my journey so far, the greatest improvement has been the coupling caps, closely followed by the B+ power supply caps.

lpaudio2 · « **Reply #107 on:** 29 Apr 2008, 02:21 am »

Is this unit phase correct? It seems to me the phase is inverted (hitting invert on my bp-25) seems to snap things into focus... My amp and preamp are both phase correct.

markC · « **Reply #108 on:** 29 Apr 2008, 02:34 am »

What's a bp-25?

lpaudio2 · « **Reply #109 on:** 29 Apr 2008, 02:44 am »

bryston bp-25. its fully balanced and has a phase inversion switch. Very handy. Phase is hard to tell, now im seconding guessing, it'll take some more listening till I know. Of course some recordings are swapped anyway.

Interesting about the clarity-caps, they have great reviews just about everywhere, and my experience has always been positive, however I am curious what you hear, sometimes we make what seems to be a step forward only to find it was sideways..

Generally I find the SA very smooth, clean, if not a tad lean in the upper treble in absolute terms but they are one of the most reasonable caps and seem to be very good for the price.

markC · « **Reply #110 on:** 29 Apr 2008, 02:51 am »

So, we can assume that the Brown man arrived today? What mod level did you get from PV?

lpaudio2 · « **Reply #111 on:** 29 Apr 2008, 04:33 am »

the middle "modded" unit. I bought it used so I got a deal. The muting circuit was acting odd, it took like 2+ minutes to un-mute. After the first set of mods (SA caps) and replace that nasty stranded wire it stopped working totally. So I removed it. I don't hear any power on thumps, so Im probably just going to leave it off, I cant think of any real reason to add it back.

Sounds much clearer in the mids now. Cant wait for my JJ tubes to come in!

Id love to do that i/v mod, but im still sorta at a loss for where to go. Im a relative novice, but I would like to learn!

regal · « **Reply #112 on:** 29 Apr 2008, 12:24 pm »

COUPLING CAPS

Coupling cap sizing, F is the -3db point, you want <3hz because of phasing issues up 10x the -3db point.

F = 1/(2 * pi * C * R)

So C= 1/(2*pi*F*R)

R is the input impedance of your amp or preamp whatever is next. Typical is 50K.

C= 1/(2*pi*3*50,000) = 1 uF

So if you want to save a buck and you are sure your next stage has an input impedance greater than 50K a 1 uF cap will be fine.

markC · « **Reply #113 on:** 29 Apr 2008, 06:22 pm »

Quote from: lpaudio2 on 29 Apr 2008, 04:33 am

the middle "modded" unit. I bought it used so I got a deal. The muting circuit was acting odd, it took like 2+ minutes to un-mute. After the first set of mods (SA caps) and replace that nasty stranded wire it stopped working totally. So I removed it. I don't hear any power on thumps, so Im probably just going to leave it off, I cant think of any real reason to add it back.

Sounds much clearer in the mids now. Cant wait for my JJ tubes to come in!

Id love to do that i/v mod, but im still sorta at a loss for where to go. Im a relative novice, but I would like to learn!

If you look at the pic I posted, (on page 10, I think), and follow Regal's instruction, you should be able to do it.
The resisters in question are R9 & R10, (on the outsides of the tubes), R5 & R7, (in front of the tubes), and R6 & R12, (between the tubes).

lpaudio2 · « **Reply #114 on:** 29 Apr 2008, 07:53 pm »

Ok I think I am following better now. So to do the bypass mod, looking at regals schematic posted,

do r5 and r7 on the lite unit correspond to r4 on regals?

Im still having trouble seeing how the rest of the lite part numbers line up with regals schematic posted. Are L1 the coils currently there just being replaced?

Jon L · « **Reply #115 on:** 29 Apr 2008, 08:45 pm »

Quote from: lpaudio2 on 29 Apr 2008, 02:44 am

Interesting about the clarity-caps, they have great reviews just about everywhere, and my experience has always been positive, however I am curious what you hear, sometimes we make what seems to be a step forward only to find it was sideways..

It *is* a good cap, especially for the price. Among low-cost caps, I can highly recommend the Mundorf Zn tin-foil/poly cap; it is unambiguously in a different class from Clarity SA yet still very affordable. My other capacitor ramblings can be found here:
http://www.head-fi.org/forums/f21/orgy-capacitors-cap-thread-284863/

markC · « **Reply #116 on:** 29 Apr 2008, 09:25 pm »

Don't follow the schematic to correspond with the Dac-60 . Regal's schematic is a simulation with it's own numbers. Follow his parts list ommiting the inductors and MKP capacitors, (unless your doing the filter mod as well).

lpaudio2 · « **Reply #117 on:** 30 Apr 2008, 01:40 am »

Ok I think I got it. Im slowly comprehending this. THanks for taking the time to explain this so I can understand! I really really do appreciate it.

r10, and r12, I am adding a 1000uf bypass cap over the resistor
replacing the 220ohm resistors on the output of the dac chips with the 100ohm

thats it?

markC · « **Reply #118 on:** 30 Apr 2008, 01:53 am »

R10, R12, R6 & R9 your replacing with 330 ohm. R10 & R12 get the bypass caps. R5 & R7 get replaced with 100 ohms.
This is not my advise, this is how I interpret Regal's suggestion.

lpaudio2 · « **Reply #119 on:** 30 Apr 2008, 02:05 am »

regal. can you chime in is this right? This is EXACTLY what I need to figure out what goes where.