[etteoh]

I don't think power issues are affecting the D1. The power delivery is pretty stable at my place...I never had any issues with it with my other audio gears. I tried using some RCA caps on the other RCA input / output sockets at the back, which is supposed to help a bit with interference (or so I was told by a friend who swears by them - he has a Pass Labs - Wilson Audio combo by the way) but no luck. The distortion part when no opamp on the DAC section is present is indeed mind boggling...
 
Quote:

Wish you could disable all outputs you are not using, or implement some kind of switch on the front.  I doubt it has any burden on SQ though~
 
I was thinking power issues as well but the variance shouldn't to such levels as to effect the entire system.  Fact that it distorts with no opamp is puzzling as well.

No luck and still looking for the root cause of the problem...it is only problem-free (so far) with the LM4562. I have a few other variants coming today and hopefully we can get a better insight as to how the D1 does with them. The draining issue on the DAC sounds serious. Damn! I hope there's nothing frigging wrong with mine. The DAC is after all the heart and soul of the D1.
 
And yes, the imbalance always occur at the same volume level / position.
 
Quote:

Any succes on finding the cause yet?
 
If not, have you checked what happens when you remove the tube?
 
The only reason I can think of channel imbalance is a situation where the output of the DAC is drained to such a level that it can't produce the normal output anymore. Since its output is split over the three channels (headphone, normal out, tube out) a change in either one of them could cause a change in the channel you are listening to.
 
And another relevant question: is the imbalance always around the same position of the Volume control?
 

 

[ninjikiran]

I mean power issues when said opamp is connected, once the power from your wall goes into the mav its converted to DC power which is generally regulated. That is unless the power supply is bad, but if it were I have a feeling you would be having more problems.

 

[etteoh]

Well, to be honest, the whole power supply thing did come across my mind at one point...Because of that, I tried several things that include:
 

• Removing the PK 1KVA power regulator - nada
• Upgraded the power cord (Transparent) - nada (funny how the cord itself already cost more than the D1)
  
• Removing all other sources from the power strip - nada
• Plugging the D1 directly to an independent single power socket - nada

 
I even upgraded the Coaxial cable to a DH Labs D75 but still - nada. I tried going from one source to another (CD transport on coax - PS3 on optical - DVD player on analogue-in - iPod on line-in) problem still there.
 
It is only when the "magical" LM4562NA opamp goes into the DAC that the problem goes away.
 
Sonofabeech

 
Quote:

I mean power issues when said opamp is connected, once the power from your wall goes into the mav its converted to DC power which is generally regulated. That is unless the power supply is bad, but if it were I have a feeling you would be having more problems.

 

[ninjikiran]

Ouch you actually bought one of those crazy power cords

 

[etteoh]

Waterfalled really...I used to have a full blown hi-fi setup where I spent half of my paycheck on...those were the days of course. Having my 15-month old son around meant I was not able to indulge in that hobby anymore. So I sold off all the gears and kept only those that I would be able to reuse in a Head-Fi setup. Power cords and interconnects mainly. The DH Labs D75 was a new purchase though since I never had a proper coax cable.
 
I didn't want to invest too much in Head-Fi because I don't know how well I would be able to adapt coming from speakers...but I have to admit, it is very engaging

 
Quote:

Ouch you actually bought one of those crazy power cords

 

[ninjikiran]

I would never invest much more then $5 for a power cable, no matter how high end my system.   I am likely to spend on analog cables though.
 
Quote:

Waterfalled really...I used to have a full blown hi-fi setup where I spent half of my paycheck on...those were the days of course. Having my 15-month old son around meant I was not able to indulge in that hobby anymore. So I sold off all the gears and kept only those that I would be able to reuse in a Head-Fi setup. Power cords and interconnects mainly. The DH Labs D75 was a new purchase though since I never had a proper coax cable.
 
I didn't want to invest too much in Head-Fi because I don't know how well I would be able to adapt coming from speakers...but I have to admit, it is very engaging

 

 

 

[etteoh]

Believe me, power cord was the last upgrade I spent on after I was convinced it made an improvement on the Krell KAV-300i I had. Before that, all I used was kettle cord since I was a non-believer in them...and a very firm one at that

However, that Krell just demanded every inch of upgrade money can buy. The power cord made the Krell produce better slam and dynamics which was really audible. I'm not the only Krell owner to say this as I have met many kettle cord owners and all swear by the upgrade.
 
Oddly enough, the power cord made no audible difference on several other amps (albeit lesser) we tried - Primare A21, Exposure 3010, Audiolab 8000S and Atoll IN-100.
 
And to admit it, the power cord made virtually no audible difference on the D1 too

 
So unless you have power sensitive gears that demands it, you probably will never benefit from a good power cord.
 
Quote:

I would never invest much more then $5 for a power cable, no matter how high end my system.   I am likely to spend on analog cables though.
 

 

[middachten]

Channel imbalance could normally not be caused by a power supply issue. Considering the fact that a dual OpAmp is used, fed from one power supply. If there is an issue with the power supply, both channels must be affected.
Distortion with no OpAmp could be explained by the fact that the signal will then go trough the feedback resistor circuit (un-amplified). With the OpAmp gone the (virtual) high input impedance of this circuit is also gone. The DAC chip now sees a much lower impedance, which again could cause a to high drain on its output.
 
Have you tried to swap the original LF353 between the headphone and line position?

 

[middachten]

Or, just be happy with a (good sounding!) 4562 OpAmp in place.
And forget about all these issues and just enjoy good music

 
Sorry for getting overly technical in my previous replies!

 

[ninjikiran]

Not overly technical at all, but the wierd thing is it doesn't happen to mines or many others using the same config.
 
Earlier in the post he tried all those different opamp configs. 
Quote:

Or, just be happy with a (good sounding!) 4562 OpAmp in place.
And forget about all these issues and just enjoy good music

 
Sorry for getting overly technical in my previous replies!

 

[etteoh]

Hell middachten, you were overly technical dude

but I appreciate your reply. It is always great to look at other potential source of the problem. Sometimes we get overly attached to just one area that the mind stops exploring other possible areas.
 
As Ninjikiran said, I tried rolling virtually all the opamps and only the LM4562 the DAC seemed to like. I have another post coming right up...a more extensive review on the opamps that were recently shipped to me.
 
Quote:

Or, just be happy with a (good sounding!) 4562 OpAmp in place.
And forget about all these issues and just enjoy good music

 
Sorry for getting overly technical in my previous replies!

 

[etteoh]

Finally, the opamps arrived yesterday and man I have had some of the best 5 hours of my evening rolling them in and out of the D1. The candidates in last evening’s tests were:
 
LT1364
OPA2107
LME49720HA (metal can)
 
The first thing I did was I put the LT1364 in the DAC section to test the niggling imbalance issue I am experiencing while listening at low levels. Much to my dismay, the problem was also evident with the LT1364. It is only after the 4^th click does the imbalance go away. As to how it sounded, since I am only evaluating audio via my Grado cans, I can’t really say there is any. I try to listen for something different but nothing apparent as far as I could tell. I’d like to say the mids are a little more refined but I would have again been a victim of psychological effects.
 
I didn’t want to try the LT1364 on the headphones section since it notoriously known for heat it generates and I don’t want to risk anything getting fried. I took out the LT1364 and put in the OPA2107 in place. The same imbalance crap is still there. Fearing that I may have screwed up something while rolling different opamps in and out, I took the OPA2107 out and put the LM4562 back in place. Imbalance problem went away. What???!!! Honestly, I don’t understand why myself but as I said, I’m not about to go and lose hair/sleep over it. If the DAC is happy with the LM4562, I’m leaving it in there. After all, that is a pretty good opamp so I have no qualms.
 
Now, there was only one other opamp that was left lying around which I have not tried ~ the LME49720HA metal can. I didn’t want to test it since I don’t know what the DC offset on the headphone stage is when running this guy…but, yes but, as I kept reading more and more about it, I gave in to temptation and in the end…ah, what the heck. I took out the LM4562 from the headphone stage and in went the metal can. Power up gears, CD in, headphones on…and jaw instantly fell so hard onto the floor.
 
Two words – HOLY HELL! Make that three words – HOLY FREAKING HELL! What is this opamp made of? It sounds bloody wonderful! If you remember, I wrote about the “blanket” effect on the soundstage when using the LM4562, well that blanket’s gone now. On top of that, the lows are even more astounding than that of the LM4562, which is already good by most standards. With the LME49720HA, I can literally feel the drivers on the Grado move when the lows kick in. Even with that kind of depth, the mids are still strong and projected just nicely on my Grado. Just the way I like my music served. Could this be the be all end all opamp for me? It sure is looking that way because while the LM4562 was great, I wasn’t entirely happy with the “blanket” effect it had on the soundstage. That was the only thing that prevented me from saying, yes, the LM4562 is the one for me. Although the DAC seemed to think so.
 
My music never sounded SO good until now and the synergy the LME49720HA has with my Grado is spectacular. Playing Cassandra Wilson’s Right Here Right Now and Time After Time scared the bejesus out of me! Details galore, the distant reverb is something I never heard in the past and the music in general just flows effortlessly! PRaT monster I tell you! Also, for the first time ever, I noticed that the guy playing the guitar is actually moving around on stage. Sonofabeech! Just how accurate can you get?
 
My wife who is a die-hard fan of Carmen Cuesta’s, admitted she has never heard her songs sounded so good before. She said that her all-time favorite single, Paralelo, which she is totally familiar with the track (make that her very own reference track), sounded extremely engaging! I listened and I fully agreed. Imagine that, even my wife seems to thinks so! I love it so much that I actually decided not rolling any more opamps. That is how good I found the metal can to be.
 
I admit, the only thing I am worried about right now is the DC offset when using it but the sound is soooooo smooth, sooooooo good, soooooo engaging that I’m already contemplating on living with the unknown since I really want to enjoy my music at its best. If only I knew how to test the DC offset for this guy (*hint* somebody please?)…but everytime I put on my Grados, it makes me forget what the fuss is with DC offset. Let’s put it this way…you really want to know just how much I love the metal can? So much that I am willing to buy another Grado if it fries the one I have right now. Yes, that much.
 
The metal can gets my very firm vote ~ two thumbs up, eight fingers and ten toes too if they count for something. I really don’t care if there is a better sounding opamp out there because I have not been able to fault the LME49720HA, regardless of what I played and how hard I tried and I have always been pretty adept at faulting something. I’m listening to Patricia Barber’s Verse album as I type and the hair on my back is starting to stand up.
 
Ok (before you guys gang up and b*tchslap me to smithereens), I really need to stop raving about the metal can. And for the record, no, I don’t work for NSC and neither do I have any affiliation with them so don’t think for one minute I’m doing sales talk for the metal can. I know and understand we all have different ears, tastes and preferences but I felt the need to share my point of view with the rest since this is the first time an opamp has gotten me this excited. I can say with confidence that my opamp rolling days has come to an end…at least for the foreseeable near future.
 
Have a great weekend my fellow TubeMagic-ians.

 

[middachten]

Good to read that you enjoy the LME49720 so much!
 
The only way to actually measure the DC voltage is by using a multi-meter. The ones you can buy at sub $10 price levels are usually not the most accurate ones, but accurate enough for this measurement. Something like this: http://www2.conrad.nl/goto.php?artikel=122999 would be perfectly ok.You can often buy them at Home DIY shops and car equipment shops.
 
Another way you could test this is by inserting the headphone plug into the D1 with an unused input selected. If there is DC on the output you will hear a noise when you 'click' into the first contact. The sound can vary from a clear click (=high DC, potentially dangerous for your headphone) to a vague noisy plop (=low DC, probably harmless). This approach is not very scientific, but it might put your mind at ease (or not

) 

 

[ninjikiran]

I have been thinking of putting a metal can 49720(TO-99) into the dac output, I have a biased 49720 dip package thats biased in my amp.

 

[uelover]

interesting findings!
 
I am just curious. If one is enjoying the sound that high DC offset is supposed to threaten, why would one need to worry about the DC offset anyway?