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Review of the Audio-gd DAC-19 DSP & C2 amp - The ACSS connection - Page 8

post #106 of 981

I've been thinking about the stepped attenuator and the C-2. Could it be that the unconventional use of the pot would somehow prevent the use of a stepped attenuator with the C-2? And even if it doesn't, are there more things to consider than with the C-2C mod? For instance, the popping noises, which to my understanding are the result of unattenuated signal being let through the attenuator in between the steps. Not a huge problem with the C-2C, but how about with a variable gain amp with such a high max gain as the C-2?

post #107 of 981

 

Quote:
Originally Posted by Newk Yuler View Post

Quote:

 

Did you email Kingwa about it?  I imagine he would be able to say right off if it was the pot.

 

I don't have a C2 yet but it's on the way.  If you think it's the volume pot why not replace it?  As I understand it, the pot is dialing resistance for gain reduction to follow instead of acting as a typical signal-through-the-pot volume control.  It may be something else is out of whack, but if it is the pot, that's not so big a deal to fix yourself if you have half decent soldering skill.  If you don't you may know someone that does.  If you can't see numbers on the pot, remove the knob and remove the pot from the panel but don't cut wires, look at the numbers, find it on the net at Newark or Digikey, or wherever.  If Kingwa says it could be the pot it's well worth the effort.  He could tell you the make and model of the pot.  Maybe he'll send you another pot.  It would sure beat mailing the C2 back to China.

Not yet, as I would have rather wanted to hear if members here with the same pots and same unit have imbalance around the same level or if it's just my unit were the leftie dominates considerably at the lower end spectrum.

 

I don't have almost any experience with soldering though, and sending unit all the way back to China would be futile due to postage and custom costs.

 

Well, could ask him about the issue neverthless.

 

Quote:
Originally Posted by noinimod View Post

Nope, the volume pot itself probably has issues. And you can't fix it - the only way would be to replace it. Strangely enough, kingwa used to offer a stepped attenuator with almost perfect channel balance at all volume levels with the c2c i think, but because of the popping noises when changing volume, people complained and so he reverted back to using the normal pots. He does, however, still keep stepped attenuators in stock so you might want to check that out with him.


Sounds strange if people are that sensitive to pops when just changing the volume, considering one doesn't need to adjust it all the time.


Edited by Zhirc - 5/10/10 at 6:52am
post #108 of 981
Thread Starter 
Quote:
Originally Posted by Pacha View Post

slim do you get the same volume output on the C2 than on the FUN when turning the knob at the same level?

 

With the HD-650, you have to turn the FUN a little bit up to get the same volume as the C2. But there isn't a big difference. (For instance 8,5 with C2 and 9 o'clock with FUN).

 

Quote:
Originally Posted by Zhirc View Post

 


Anyone?

 

Would be really interested to hear if it's just my crappy unit or if the others have channel imbalance to as high scale too. Kinda annoying with ACSS-cables and high gain, currently using just RCA and low gain when watching TV as the very slight quality difference isn't that big (for my wooden ears at least) than the channel imbalance, as the left channel is somewhat dominating during the whole lower-level stages.

 

Below 8 o'clock, there is a definite channel imbalance. But this is no different from other high gain headphone amps using regular volume pots (Little dot MKIII for example).

 

As I mentioned earlier in this thread, I talked to Kingwa about the issue and said that those who have high efficiency cans can ask him for a "low gain" version of the C-2. I think that he mentioned that changing the resistance value of the volume pot is sufficient to give different maximum gain settings.
 

Quote:
Originally Posted by pategen View Post

I've been thinking about the stepped attenuator and the C-2. Could it be that the unconventional use of the pot would somehow prevent the use of a stepped attenuator with the C-2? And even if it doesn't, are there more things to consider than with the C-2C mod? For instance, the popping noises, which to my understanding are the result of unattenuated signal being let through the attenuator in between the steps. Not a huge problem with the C-2C, but how about with a variable gain amp with such a high max gain as the C-2?

 

I think it is possible to use a stepped attenuotor with the C-2. I believe that the reason Audio-gd discontinued their stepped attenuator is because a lot of people complained about the noise issue. While the popping and noise was moderate with the HD-650, it was much louder with something like the CX-350.

I have been looking around to find a "better" pot and have been looking at the specs sheets of those volume pots. So far I have found that the only solution to get a perfect balance at low volume settings is to go to the stepped attenuator route, and even expensive volume pots (such as Noble, TKD...) also have channel imbalance at the lowest settings.

I think I am going to get a Goldpoint attenuator which are supposed to have excellent tracking and noise characteristics as well as reduced popping noises compared to conventional ladder attenuators.

 

Those who haven't ordered their C2 yet can either ask for a lower gain version or even send their own stepped attenuator. Personally, I don't recommed using Audio-gd's stepped attenuator with high efficiency cans as the popping noise will be annoying.
 

post #109 of 981

Hi slim.a,

 

  I'am planning on swapping the stock OPA with LME49710, would you know much about it.Kingwa apparently said that many have tried it with the C-2 and got nice results as it is very neutral.

 

The reason I want to change the OPA is because the highs get a litlle too sibilant with my K701's above 11'o clock on high gain.

post #110 of 981
Thread Starter 
Quote:
Originally Posted by kunalraiker View Post

Hi slim.a,

 

  I'am planning on swapping the stock OPA with LME49710, would you know much about it.Kingwa apparently said that many have tried it with the C-2 and got nice results as it is very neutral.

 

The reason I want to change the OPA is because the highs get a litlle too sibilant with my K701's above 11'o clock on high gain.


Hi kunalraiker,

 

Sorry, I haven't tried the LME49710 with the C2. So far I have only tried the OPA604, OPA Earth and Moon (and I have ordered a pair of AD797).

So far I have found the OPA604 grainy, the opa Earth detailed and natural sounding, and the Moon smooth sounding with a big soundstage. I ordered the AD797 because I will be comparing some RCA interconnects in the next few weeks, and the 797 are supposed to be "revealing" opamps.

 

BTW, I have tried the LME49720HA on the FUN and I found that opamp to be relatively transparent (tonally similar to the OPA Earth but quicker). If you are looking for a smoother top end, you might have better luck trying the OPA627 or the OPA Moon.

 

Also, you might want to try different interconnects, something like the Kimber PBJ will have a cleaner and smoother top end than many entry level SPC cables (including Audio-gd's Sharkwire cable).

post #111 of 981
Quote:
Originally Posted by slim.a View Post




Hi kunalraiker,

 

Sorry, I haven't tried the LME49710 with the C2. So far I have only tried the OPA604, OPA Earth and Moon (and I have ordered a pair of AD797).

So far I have found the OPA604 grainy, the opa Earth detailed and natural sounding, and the Moon smooth sounding with a big soundstage. I ordered the AD797 because I will be comparing some RCA interconnects in the next few weeks, and the 797 are supposed to be "revealing" opamps.

 

BTW, I have tried the LME49720HA on the FUN and I found that opamp to be relatively transparent (tonally similar to the OPA Earth but quicker). If you are looking for a smoother top end, you might have better luck trying the OPA627 or the OPA Moon.

 

Also, you might want to try different interconnects, something like the Kimber PBJ will have a cleaner and smoother top end than many entry level SPC cables (including Audio-gd's Sharkwire cable).



you are absolutely right I find the OPA604, grainy in the high end,i was afriad to say that because other members wouldn't be happy consideirng such high reputation of Kingwa.

I don't understand why he uses it, if its that bad.

 

I'am not looking for a smoother top end i'am looking for a very neutral opamp, witheout the high end harshness which now I feel must be caused by the OPA itself.

 

I use my iBasso D4 as my DAC and a 3.5mm to RCA  monster cable,would it be the cable,I don't feel it would cvause much of a difference, as I don't want to spend much on it considering I will be getting the DAC19 soon and going ACSS.

post #112 of 981
Quote:
Originally Posted by slim.a View Post

 I ordered the AD797 because I will be comparing some RCA interconnects in the next few weeks, and the 797 are supposed to be "revealing" opamps.

 

 

Also, you might want to try different interconnects, something like the Kimber PBJ will have a cleaner and smoother top end than many entry level SPC cables (including Audio-gd's Sharkwire cable).


Can you post your impressions on AD797 when you receive it?

 

By the way, did you find any ACSS replacement cable for the sharkwire ACSS?
 


Edited by Pacha - 5/10/10 at 7:50am
post #113 of 981

Just received lightning mail from Kingwa, nothing exactly new to my issue though. Have to just bear with it and wait until I'll find a proper "upgrade" pot at some point.
 

Quote:
Originally Posted by Kingwa

The ALPS pots can't avoid channel imbalance at low volume, usually want turn to high than 8 o'clock then less imbalance.
But some gears sound dark so it can hide the imbalance, if the gears sound clear, it is easy show the imbalance.
If you want avoid the imbalance, you must change a steps volume pot, otherwise even though you buy a USD100 continuum adjust volume pot, it still has imbalance.
So in our web, we mark the volume imbalance over there.
Ago we applied steps volume pot but some owners explain the "click" noise while change the steps.
So we stop use the steps volume pots.
I ever try a volume pot from USA, it can avoid imbalance and click noise.
But its price is quite costly.

 

post #114 of 981
Quote:
Originally Posted by Zhirc View Post

Just received lightning mail from Kingwa, nothing exactly new to my issue though. Have to just bear with it and wait until I'll find a proper "upgrade" pot at some point.
 



mate could you please explain your current setup and at what gain and volume levels you listen.

post #115 of 981

PC as a source (without fancy transports like m2tech hiface) -> Canare coax -> DAC-19 DSP -> Sharkwire ACSS -> C2 -> K702 (with DHC's OCC cable), so the gain is automatically at high level.

 

Depending of the music I'm listening (abrasive industrial noise vs. calm ambient or piano sonatas) and not taking account channel imbalance issue, the position of the pot would usually be around 7:30 - 8:45, pretty much never going further than 9:30.

 

post #116 of 981

Does your PC have a coax out,that must be very handy.

 

I don't find channel imbalance in my C-2, must just be that pot,I remember Ray Samuels quoting somewhere that he has a  whole pile full of faulty pots, as he's makes sure the pots that are on his amps meet his stringent minimum requirements.

 

I do listen at 9:30 ,you could probably use the RCA's and low gain.

post #117 of 981
Quote:
Originally Posted by slim.a View Post

 

As I mentioned earlier in this thread, I talked to Kingwa about the issue and said that those who have high efficiency cans can ask him for a "low gain" version of the C-2. I think that he mentioned that changing the resistance value of the volume pot is sufficient to give different maximum gain settings.
 

 


So, a cheaper DIY mod to reduce the channel imbalance problem with ACSS connection would be to use a traditional pot with a bigger resistance value. The question is: what's the resistance value of the standard pot?

post #118 of 981

Quote:

Originally Posted by slim.a View Post

I think it is possible to use a stepped attenuotor with the C-2. I believe that the reason Audio-gd discontinued their stepped attenuator is because a lot of people complained about the noise issue. While the popping and noise was moderate with the HD-650, it was much louder with something like the CX-350.

I have been looking around to find a "better" pot and have been looking at the specs sheets of those volume pots. So far I have found that the only solution to get a perfect balance at low volume settings is to go to the stepped attenuator route, and even expensive volume pots (such as Noble, TKD...) also have channel imbalance at the lowest settings.

I think I am going to get a Goldpoint attenuator which are supposed to have excellent tracking and noise characteristics as well as reduced popping noises compared to conventional ladder attenuators.

 

Those who haven't ordered their C2 yet can either ask for a lower gain version or even send their own stepped attenuator. Personally, I don't recommed using Audio-gd's stepped attenuator with high efficiency cans as the popping noise will be annoying.
 


My C2 is ordered but it hasn't shipped.  I'll be using the C2 as a normal preamp much more often than as a HP amp in an ambient music system, so the low gain version may be ideal for me.  That doesn't mean I won't want to crank it sometime down the road, though.  I'm inclined to get the C2 as is and if there is an imbalance issue, replace the pot.

 

If you go with a stepped attenuator, I would be very curious to know how it works out for you.  I second the Goldpoint nomination.  That would be one of my first considerations for a replacement.  Not so much worried about cost given relative performance in the C2/DAC19 combination.

post #119 of 981

If you are afraid of channel imbalance with high sensitivity headphones, just ask audio-gd for a very low gain setting :). I think audio-gd should state on their amp descriptions that you'll probably want to do this if you have headphones with <25 ohm >100dB/mW, and probably mandatory for super high sensitivty phones like the 118dB jh-13.

post #120 of 981

The stepped pot (if it was the same that used to be in the Roc) is not bad as some had posted here. I never noticed anything using it and there was zero imbalance. Ask Kingwa to make it with that pot.

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