[Epoch]

I have owned my C2 for a few months and it has an ALPS pot on it as well.  I am curious as to how different the C2.1 sounds compared to the C2 and if I could swap out all of the caps myself or if there was a change on the PCB.  I should ask Kingwa.

 

[Pacha]

 
Quote:

I have the C-2 (just took ownership of it on Friday).  The ALPS 27 pot was installed on my version so I guess I got a transitional model
 
Quote:

Audio-gd is to release a C-2.1 with upgraded caps, and with adjustment to sound more neutral :
 
http://www.audio-gd.com/Pro/Headphoneamp/C-2new/C2.1EN.htm

 
The differences don't remain in the volume pot if I'm correct but only on the capacitors soldered to the motherboard.

 

[Epoch]

I emailed Kingwa, the main difference is the capacitors on the PCB.  Its more than just a change of brand, there are capacitance value changes as well.  I plan on doing that some time next month.

 

[Pacha]

You mean swapping all the caps yourself? Do you plan to put the same as he does on the C-2.1 or others?

 

[MasZakrY]

I swapped out the OPA604's for LT1028ACN8's.  I do believe it's worth the switch over if you use the c-2 with RCA sources.  With these op-amps, it brings the RCA input's overall sound to almost ACSS quality.  A/B'ing them back and forth, I can hardly tell which is which. 

 

[Epoch]

Yes, I mean swapping the capacitors myself with the same value that is used on the C-2.1.

 

[Pacha]

Ok. Please let us know how it sounds when you have replaced the caps. I wonder what could be expected in regards of the said "more neutral sound" improvements.

 

[notThinking]

Quote:

I emailed Kingwa, the main difference is the capacitors on the PCB.  Its more than just a change of brand, there are capacitance value changes as well.  I plan on doing that some time next month.

Did he share value changes also? I'm wondering if he would sell those of us that are able to replace them our self an upgrade kit?
Mine are dated 2010-11 and have the ALPS 27. But sadly with an value that are less useful for me. Way to much gain (stock). I plan to parallel the pot with two 6k8 resistors so that I can turn the control past 9 o'clock without ear bleed.

 

[Epoch]

Yes he shared the values that were changed.  Its a lot of capacitors to change though.  Unless you are very comfortable desoldering and replacing them all I don't know if you want to do it.  Kingwa pointed out that there is a risk of cracking the PCB if you don't do a good job of desoldering and replacing the capacitors.

 

[leeperry]

 

I swapped out the OPA604's for LT1028ACN8's.  I do believe it's worth the switch over if you use the c-2 with RCA sources.  With these op-amps, it brings the RCA input's overall sound to almost ACSS quality.  A/B'ing them back and forth, I can hardly tell which is which. 

Oh yah, LT1028AC can easily turn its listeners into instant mental slaves...I wouldn't mind a good DAC to host it, but the damn thing is not unity gain stable and has been known to be pretty cranky...clearly not your average roller

 
I know it does wonders in the FUN, though...but A-GD have so many DAC's that I wouldn't know which one to try.

 

[notThinking]

Thanks!
 
mmm.... that sounds more like the penny counter has taken the better of him.
Using one brand all over the place makes for larger volumes and better deals.
If we brake it down to new values how many caps are we talking then?
 
Quote:

Yes he shared the values that were changed.  Its a lot of capacitors to change though.  Unless you are very comfortable desoldering and replacing them all I don't know if you want to do it.  Kingwa pointed out that there is a risk of cracking the PCB if you don't do a good job of desoldering and replacing the capacitors.

 

[Black Stuart]

not Thinking,
 
why not shunt the pot, or is that what you meant.
 
Shunting normally means using resistors with 90% of the pot value, that way you get a drop of 6% but if you want a bigger drop just adapt the values to suit. Use cheap resistors first to establish what value you want and then use  whatever floats your boat. I'm sold on naked Vishays but years ago on another forum a lot found that Maplins bog standard 2 W metal fims worked very well with Alps pots.
 
Or if you want to upgrade the pot take a look at www.thel.de  they do 2 pots @ €30 and €89 - I  may splash out on the more expensive for my new Bada hybrid power amp.

 

[Tom W]

Finally got around to making some  digital cables to use between my 63KI and my recently bought s/hand DAC 19. I use a shunted pot in my Bada h/amp and was shocked at the o/put level of the DAC 19. Because I lose about 6dB by using the shunt, I normally have volume at between 10.30 - 1.30 but now I can't go above 9. I don't believe the problem lies with the 63KI which has a nominal 2V o/put.
 
It's not possible at the moment to download manuals from the Audio-GD site - does anyone know what this DAC's o/put is?
 
For all those who use  ACSS - why does Kingwa use these crap connectors - they are simply not nec. Take a look inside - the chassis connectors for both ACSS and digital have only one difference between them and a standard RCA chassis plug - the removal of the Teflon washer decoupling the connectors from the metal chassis. This simply means that both ACSS and digital are grounded twice - once on the PCB and again to the chassis.
 
So, if you must use connectors, choose RCAs that float your boat and just remove the Teflon insulating washer - solder a piece of wire (your choice) from the earthing lug to the PCB earth - now you can experiment to your hearts content to find the best ACSS sound.
 
However if your smart you won't use any plugs at all - remember the best plug is no plug at all, just solder from DAC PCB to C2 PCB. To facilitate wiring experiments use a piece of right angled copper wire as a PCB pin (they are crap and best avoided).
 
As to DAC 19's sound - I use the digital connection and in this respect, the sound is hugely dependant on the digital cable - use the wrong type and it quite frankly is poor but with the right kind of d/cable it is very good indeed. Mid's are very good and bass goes deep but lacks real detail. Using only one make of electrolytics seems to be a Chinese thing. I think that working on mods around the analogue sections will reap real benefits.
 
Looking to find good caps for the PSU - never heard of Nover - low ESR is only one part of the equation with PSU caps - shame I can't use my stash of Philips LL (create air and just a hint of warmth) Nichicons may lack body - anyone else got thoughts on mods for this DAC?

I was reading an article about digital cable length with regards to reflections, timing errors, etc and thought I'd like to give it a try.
 
I wasn't quite sure if I wanted or needed another digital cable so I picked up a cheap RCA-RCA connector to join the two digital cables I already had together. I've been busy since I made the change and have minimal listening time. In addition I've been listening to some well recorded classical music so I didn't notice much (if any) improvement.
 
This weekend I spent some time listening to some older rock and was astonished by the difference. Before the change there wasn't much difference between the RCA coax and the optical connections (the optical connection sounded slightly smoother). After the change there was a slight improvement in sound-stage and a large improvement in the bass region (confirmed by switching between the coax and optical connections). After the change the bass sounded much, much clearer and had more of the overtones that you normally hear when you're listening to an actual bass stack. This was very apparent listening to the Beatles's Abbey Road CD.
 
BTW the two cables I used were mis-matched. One was a BJC Belden (2') and the Other was a BJC Canare (3'). Source is an inexpensive Sony DVD Player. The two cables combined sounded much cleaner than either cable individually. 
 
Black Stuart,
 
What digital cable(s) do you think sound good with the DAC19-DSP?  If you have the material on hand, can you make up a 2 meter cable for testing and report your findings?
 

 

[Pacha]

Did you try, if that's possible in your rig, to use the RCA-RCA adapter directly between interface/transport and your DAC?
That's the way I went since a while and I'm pretty satisfied with the results.

 

[Black Stuart]

Hi Tom W,
I've had a nerve/arm muscle problem for a couple of weeks so hav'nt done any practical stuff at all.
 
I'm wondering if the reason the two cables sound better than seperately is because the RCA connectors in some way stopped any reflections from travelling the length of the combined cables. I'm betting that you may have read J.kenny's excellant input on digital cables on tweakfi?
 
It does seem important that a digital cable is a true 75 Ohm. It may also be good to use BNC connectors and as John said with built in attenuators - at $12 a pop that's not a big outlay. This set me thinking that as I cannot easily remove the rather complicated plug chassis arrangements in the 63 KI, I could none the less use a resistor in series going into the DAC19.
 
And finally I may get around to measuring the o/puts in the DAC19 to establish exactly what the o/put voltages are.
 
As to using a 2 M cable I would personally find that very hard to use with my system layout, meaning very long i/cs from Dac to h/amp.
 
What I shall try just for the craic is connecting the ACSS connection to my hybrid h/amp - quien saves.