193L in a Modded DAC-AH..

[lucpes]

Just my 2c - most times, mains filtering using a cheap common-mode choke with 2 polypropylene capacitors forming a PI-filter (low value, say 0.047uf) helps a lot on digital and/or line-level applications.

[Puffin]

I am thinking of changing the op-amps in my Dac Ah. Are the stock ones fitted in the factory single or dual op-amps ?

[lucpes]

Originally posted by Puffin
I am thinking of changing the op-amps in my Dac Ah. Are the stock ones fitted in the factory single or dual op-amps ?

Single opamp. At least in mine it's the OPA602, which has a similar sonic signature to the highly regarded OPA627. Taking into account the fact that OPA602 is better at driving capacitive loads than the OPA627 I would leave those in place as they are. Better change the output capacitors, that's where most of the sound quality is lost in the first place.

[singleended40]

I have tried to replace the output caps with two 100K resistors. The sound was better than the stock unit but compared with bypassing the whole buffer stage(opamps) I think it is much better way since the more simple circuit makes the better sound.

[Puffin]

The stock op-amps in my dac are not BB's and are some obscure make and number.

[singleended40]

Originally posted by Puffin
The stock op-amps in my dac are not BB's and are some obscure make and number.

Hi Puffin,

I think you do not want to waste your money to purchase the BB Opamps 627BP (the best opamps sofar) and also two coupling caps and two resistors 100K @ output stage. Like I mentioned before the best way to mod is two(2) Auricaps 2.2uF/200V @ output stage by bypassing the buffer stage, two Auricaps 0.47uF/600V and Hammond choke 193L @PS and IEC. The sound in my system right now is getting better and better. Good luck.

Tan.

[Puffin]

Tan. Thanks for your reply. There was a long thread on the headfi forum about modding the DacAh. Is the modification you are talking about the "passive" mod whereby the active stage (the op-amps) are by-passed ?

[singleended40]

Puffin,

I have tried other headfi mod version and that version did not sound good enough to me as this mod version of JANDG in this page. You might email him some more details about it. JANDG is a nice and knowledgeable gentleman and will answer any questions right away.

I have modded my DAC AH with his version and had tried NOS caps as Gudeman, Sprague Vit. Q and Westcap caps. The oilers give you a nice soft musical sound but not as good as Auricaps as metallized polypropylene caps, which have more details, real open-up musical and more energetic -I mean strong punchy- sound (in the third day caps breaking-in usually 100 to 200 hours and a week 193L choke break-in too). I also replaced Furutech IEC and two Sprague Vitamin Q 0.0015uF/100VDC @ C1 and C2 where two blue square caps were.

Besides this is not a passive mod @PS (as I understand using battery) and I use a DIY PC. Trust me battery PS is very quiet but you can not listen your music continuously unless you are using a huge battery or an expensive Odyssey or Optima battery (range of USD$150-$300).

Good luck on your mod but you will absolutly satisfy with the result.

Tan

[nicoch58]

hello all, look this mod

http://www.audiodesignguide.com/Head...one_opamp.html

[vvs_75]

C1 & C2 are .001uf Mundorf silver supreme's & the outputs by-pass caps are 2.2uf 450v Auricaps.. There is 2-.47uf 600v Auricaps across mains, as well as a Hammond 193L, I did lots lof listeniing with differant configuration on the power & this I like & have no want to change.. Acyually haven't even touched the DAC in a long while because it just makes me happy now, with all types of music. J & G

Hi J & G!

I wante to order parts to make 193L mode to my DAC-Ah and I am wondering if you remember why you chose 0.001uF replacement for C1 & C2 caps?

I checked the schematic and the C1, C2 caps are 103nF which is about 0,103uF. Are there any sonic benefits of chosen 0.001uF capacitors?

Also I found that the H version of 193 choke have almost the same spec. except it can take 600VDC compare to 800VDC on 193L. But it�fs cheaper and twice smaller!

Can I use 193H choke? What do you think?

Thank you for you time! I am really appreciating you help!!!