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Audio-gd discrete op-amps reviewed: OPA-Earth, OPA-Moon, OPA-Sun v.2 - Page 2

post #16 of 392
1/6/09 at 6:01pm
Quote:
Originally Posted by majkel View Post
OK, I will let them stay in the socket but it's only one per round possible, so this will take same time. Will I get much improvement replacing the regulators for +-15V range, or would it be just slight? I don't want to do it aimlessly as I will lose possibility of using some chips.
Depends on the circuit. Email Kingwa and ask him a few questions, he may be able to give some other options I don't yet know about that will fit the bill without boosting the V.

Peete.
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post #17 of 392
1/6/09 at 6:03pm
Thread Starter 
OK, so the first one dedicated for prolonged burn-in will be the OPA-Earth as this one is the worst at the moment.
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post #18 of 392
1/6/09 at 7:14pm
It's funny that's what everyone says about the Earth HDAM at first, including myself...the SUN is the fav (out of the gate) but the Earth once formed supplants the (unnatural IMO anyway) SUN V1& V2 rather quickly.....check the Zero thread for many such observations (between pages 500-650 I think). I have to add that I much prefer a neutral OPA in a DAC and Moon module in an analog circuit although I also like the Earth in that position for some music.

I have a review of the original module from last March in that thread. It took me ages to complete it (2 sections to it 3 weeks apart, due to the long burn in ) and was mentioned in this thread already (not specifically).....

I think you'll be surprised by the changes to come..by far the biggest drawback to these is burn in time....although in my mind that really isn't a drawback at all just SOP for these modules.

Peete.
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post #19 of 392
1/7/09 at 5:21am
Quote:
Originally Posted by TzeYang View Post
^Nice! Is that sum OPA + BUFFER Three channel amplifier? Needs more details on the self etching.
I don't know about the amp that you referred. Mine is designed and self-etched by my friend, I only bought all the parts and soldered it all. It's a 3-channel active ground topology, buffer architecture, precision virtual ground reference, Class-A bias at voltage gain stage, Jung multiloop headamp. All opamps is dual channel version:



My friend made another version of this headamp (ver.2) with input caps, single opamps at buffer stage, bass-boost control and dual layer PCB. It's professionally etched but I still prefer his v.1 design. Here's the photos:



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post #20 of 392
1/7/09 at 10:04am
Fantastic write-up, even if it isn't complete yet. Please do give the HDAMs 350 hours and have another listen. I had a weird moment somewhere around that mark with one of Audio-gd's amps, where one week I was listening as usual, then the next week, with no changes, suddenly all the music sounded better.
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post #21 of 392
1/7/09 at 11:00am
Quote:
Originally Posted by Ron.id View Post
I don't know about the amp that you referred. Mine is designed and self-etched by my friend, I only bought all the parts and soldered it all. It's a 3-channel active ground topology, buffer architecture, precision virtual ground reference, Class-A bias at voltage gain stage, Jung multiloop headamp. All opamps is dual channel version:
That's freaking cool. It's like a Smaller PPA V1.

Do you think I can have snapshots of the bottom of the self etched single layer board?

I was going to etch something similar with discrete buffers. I just want to know how clean it looked and add some confidence into self etching solutions.
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post #22 of 392
1/7/09 at 7:03pm
Thread Starter 
OK, so let me report the review is finished at this time. Shocking news will be delivered ASAP when appear.
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post #23 of 392
1/7/09 at 7:40pm
So where does one get the AD797BRZ ?

Is it directly swappable with something like the LM4562?

edit: ok so it seems they are a single op-amp, so for my DAC which needs two dual opamps, I would need to get 4 AD797BRZ and 2 dual adaptors?
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post #24 of 392
1/7/09 at 8:38pm
Thread Starter 
Correct, they are single and you should install them onto the adaptor as they're SOIC only. You can get them from Farnell or DigiKey I suppose. If the LM4562 worked in the circuit, the AD797BRZ x2 would do as well.
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post #25 of 392
1/7/09 at 8:43pm
You need to put an asterisk beside that conclusion stating the results are based upon modules that are no where near burned in.

It's misleading as it now stands.

I hope you plan to give these the required time because I can guarentee you they will change quite a bit from where they are now.

Peete.
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post #26 of 392
1/8/09 at 6:53am
Thread Starter 
Quote:
Originally Posted by Pricklely Peete View Post
You need to put an asterisk beside that conclusion stating the results are based upon modules that are no where near burned in.
I will report changes if appear. They had to be a better option for chip op-amps and they are. I'm sorry for taking to comparison not so popular types from better series but the only way to discuss my observations is to use exactly the same chips, especially AD797BRZ, and confirm I'm right or wrong. The LT1028ACN8 is another outstanding op-amp and I don't expect anything to change. Kingwa mentioned on his website 48 hours of burn-in and this condition has been fulfilled. I will try +-15V supply rails probably next week and tell you how it works. Until now, I didn't observe any changes due to burn-in.
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post #27 of 392
1/8/09 at 7:39am
The interesting thing was the reports that the SOIC versus PDIP versions of some of the different opamps sound different, something I was wondering about.
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post #28 of 392
1/8/09 at 11:05am
Thread Starter 
Quote:
Originally Posted by Currawong View Post
The interesting thing was the reports that the SOIC versus PDIP versions of some of the different opamps sound different, something I was wondering about.

The higher grade B series of the AD797 in the DIP package does not exist. The LT1028 CN and ACN series are both DIP, the ACN series has got tighter specs and does sound different. I guess it's another factory with "cleaner" production technology for the higher grade parts.
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post #29 of 392
1/25/09 at 11:55am
Majkel, would you like to try any of my discrete amps, AD797-clone or AD829-clone? AD829 is invisible in RMAA tests, limited by the E-mu 0404 sound card. AD797 measures excellent at 15V but not with 9.6V battery supply. It actually sounds better than it measures, and the harmonics are what's considered perfect with a nice falling pattern from 2nd to 7th. I use a weird ground, TLE2426 for the small signal returns and Sanyo WX caps and a discrete rail splitter for the headphones returns. This gives a much better channel separation and lower distortion at low Z loads compared to passive ground.

My FET/CFP input JLH-clone is so messy, I'm ashamed of showing it to anyone. The le Classe A clone is also messy, and in this one I use the too bright sounding Toshiba transistors. I also have an 18V (not battery operated) version of the AD829-clone with larger voltage drop to the cascode transistors and current mirror.
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post #30 of 392
1/25/09 at 5:57pm
Thread Starter 
Sun v.2 at +-15V is the only complete discrete op-amp, with a touch of wooly-woody-something added. The OPA Earth is like a cleaner AD8397 but tonality is not 100% complete. The OPA-Moon is sweet but tonally even less complete.

Regarding the my "top three" - yes, the OPA211 is great. After listening with the RS1's I borrowed from my friend I have to admit LT1028ACN8 is the best in imaging and smoothness. Best for both GS1000 and RS1.

AD797ANZ is as worse as the BRZ series, as the LT1028CN8 is worse than ACN8 series. Both suffer slight dryness, while the ACN8 is British rich and smooth. I have to say that after further modifications of my DAC - BG added to power supply and analog multiplexer bypass, now it looks like this. The most analog sounding are LME49710NA but they exaggerrate in this to the level imaging is blurry, and soundstage slightly congested. The LT1028AN8 is perfect but with its own, very delicate timbre, less present than in other op-amps like OPA2228 or LM4562.

Regarding measurements - I can't do that and I don't care for their results actually. I am of course curious of listening to some new toys/ NelsonVandal, you're welcome. Regarding IC's - I have to try out the LME49722, it's like decompensated LME49720. Sounds delicious.

My current recommendation list:

1. 2x LT1028ACN8
2. 2x OPA211ID (issues like in the review)
3. 2x AD797BRZ (finally I found slight imaging issues and timbral imbalance)
4. LME49720MA / 2x LME49710NA (I guess I like the former a bit more)
5. OPA-Sun v.2 (thick, flawless, likeable sound)

No more unconditial recommedations at the moment.
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