[francisdemarte]

Yes, ordering IC can be a confusing experience! Sometimes product numbers vary for reason that do not matter to us small project consumers. One reason for difference may be packaging, some opamp are packaged in tubes others in long reels. The difference only matters if your buying thousands and will use them in machines that solder them on to boards in your manufacturing plant.

Other times the difference may be various environmental certifications such as RoHS which means they were produced to "green" eco friendly standards.

In the first example you have there looks to be no difference in the chip, different product number maybe to identify 2 difference batches of manufacture.

In the second example there is a difference in voltage requirements. One of the chips maybe a slightly higher spec then the other. Probably makes little to no difference used in the Aune.



Quote:

Originally Posted by milagu /img/forum/go_quote.gif Great, thanks! What are the differences between some of the chips? They have very slightly different model numbers: OPA2107APG4 Texas Instruments Op Amps and OPA2107AP Texas Instruments Op Amps I looked over their spec sheets and they seem IDENTICAL. But on the 744s, there are some differences in specs (Input Offset Voltage) Digi-Key - AD744JNZ-ND (Manufacturer - AD744JNZ) and Digi-Key - AD744KNZ-ND (Manufacturer - AD744KNZ) There's actually more 744s listed on their site too. I'm thinking of replacing the 2604 with dual 744s and possibly the 2134 with a 2107.

 

[francisdemarte]

Just picked up a OPA2107 off ebay for $5.50 shipped from seller AudioSector. Gonna try it in the Aune when it gets here.

So far I am really enjoying the Aune with my HD650's!

 

[TheDuke990]

I hope someone can help me or has an idea what is broken.
I own an aune too but after testing different connections (USB -> switch to SPDIF -> switch to RCA etc) the SPDIF input is no longer working.
USB and analog RCA are still working fine but the SPDIF not. I tested the aune with different sources but SPDIF is not working (led is always on -> independent from the signal on SPDIF input or the switch position (USB -> SPDIF).

 

[francisdemarte]

Contact Coolfungadget, he may be able to help you diagnose the issue.

Has the coax connection every worked for you or did it just stop working one day? Make sure you have the switches set to SPDIF and "A".

You may need to open it up and check the board for broken solder joints on the Coax connector.


Quote:

Originally Posted by TheDuke990 /img/forum/go_quote.gif I hope someone can help me or has an idea what is broken. I own an aune too but after testing different connections (USB -> switch to SPDIF -> switch to RCA etc) the SPDIF input is no longer working. USB and analog RCA are still working fine but the SPDIF not. I tested the aune with different sources but SPDIF is not working (led is always on -> independent from the signal on SPDIF input or the switch position (USB -> SPDIF).

 

[TheDuke990]

Quote:

Originally Posted by francisdemarte /img/forum/go_quote.gif Contact Coolfungadget, he may be able to help you diagnose the issue. Has the coax connection every worked for you or did it just stop working one day? Make sure you have the switches set to SPDIF and "A". You may need to open it up and check the board for broken solder joints on the Coax connector.

I already contacted Jeffrey but he was not able to help me.
And yes the coax connection works for round about 1h but after switching between different input connections it stops.
Also I opened it but I don't found a broken solder or something else.

 

[francisdemarte]

So it work initially but stops working after you switch back and forth between sources? Does this happen everytime?

Sounds like one of your switches maybe faulty or their connection to the circuit board may be bad. If you have a soldering iron, try re-flowing the points where the switch connects to the main board.

 

[TheDuke990]

Quote:

Originally Posted by francisdemarte /img/forum/go_quote.gif So it work initially but stops working after you switch back and forth between sources? Does this happen everytime? Sounds like one of your switches maybe faulty or their connection to the circuit board may be bad. If you have a soldering iron, try re-flowing the points where the switch connects to the main board.

Yes it works initially. But during changing the sources (means change cable connection from onboard SPDIF to X-FI and back) and the switch position the coax input stops working.

Does this happen everytime? No ... it happens one time and unfortunately it is permanent

. Means no sound anymore when I switch to coax.

But I will try to re-flowing. Thanks for the tip.

 

[francisdemarte]

Quote:

Originally Posted by francisdemarte /img/forum/go_quote.gif Just picked up a OPA2107 off ebay for $5.50 shipped from seller AudioSector. Gonna try it in the Aune when it gets here. So far I am really enjoying the Aune with my HD650's!

Update:

My OPA2107 arrived from ebay. Looks like USPS did their best to try to destroy it. Took it out of its padded envelope and the DIP8 pins were bend all over the place and the plastic container it came it was smashed to shards. I shot a quick email to the seller and they said they would be sending out another! Good seller!

I took a chance and carefully bent the pins into position and installed it into the Aune in the buffer (OPA2134) position and moved the AD744 back into the headamp (OPA2604) position.

It's not burned in yet but the new opamp seems to have warmed up the sound a bit. This works well with my AT headphones which are a bit on the bright side. I feel the highs and mids are a little more recessed now making the sound seems a bit slower, not sure if I like that. Hopefully they will open up as the chip burns in.

Will report back in a few days.

 

[TheDuke990]

I changed my OPA as well. Changed both to 49720 (LME 49720 NA). It seems the aune works a little bit better (clearer) but maybe the change is only in my mind

.

 

[Fidelity]

Quote:

Originally Posted by francisdemarte /img/forum/go_quote.gif Update: My OPA2107 arrived from ebay. Looks like USPS did their best to try to destroy it. Took it out of its padded envelope and the DIP8 pins were bend all over the place and the plastic container it came it was smashed to shards. I shot a quick email to the seller and they said they would be sending out another! Good seller! I took a chance and carefully bent the pins into position and installed it into the Aune in the buffer (OPA2134) position and moved the AD744 back into the headamp (OPA2604) position. It's not burned in yet but the new opamp seems to have warmed up the sound a bit. This works well with my AT headphones which are a bit on the bright side. I feel the highs and mids are a little more recessed now making the sound seems a bit slower, not sure if I like that. Hopefully they will open up as the chip burns in. Will report back in a few days.

Anyone tried using two OPA2107 installed on the buffer and head amp section?

Initial thoughts on the dual OPA2107 I just installed, the sound seems bright and the bass is more controlled, will let it run for a few days...

 

[buz]

Is that the same unit or a copy (fake?) AUNE MINI USB DAC Sound Card + Headphone Amp Amplifier - eBay.ch (endet 23.03.10 04:11:33 MEZ) 99USD would be a good deal and significantly cheaper for me than getting an uDac shipped to Switzerland...

 

[francisdemarte]

Thats the new Mini version. Pretty nice if your looking for something smaller and more portable. It's probably not as powerful an amp as the full size Aune and the opamp are not swappable.

 

[buz]

Does not seem to be very portable to me when it still needs a PSU (would really rather not have to use one). How would the sound be compared to an uDac, especially with IEMs? Also, how much do I lose by not being able to swap opamps (i.e. how good/bad are the stock opamps?)?

 

[buz]

The Aune Nano (as it is really called) seems to be a decidedly mediocre piece of kit which even creates some hiss with an external amp according to On it's way, the AUNE Nano USB Dac

Going to stay away

 

[miyinan]

Question:

If I just use the Aune Mk2 as a dac/amp combo (stock) without any external amp or dac, it will be the opa2134 that is being used all the time, right? The opa2604 only comes into play when I use rca connecting it to an external dac, did I understand this right?

If I want to swap in an opa627, which one (opa2134 or opa2604) should be replaced with?

Lastly, as buz asked above, "how much do I lose by not being able to swap opamps (i.e. how good/bad are the stock opamps?)?"

Thanks,

Sorry, I am only a newbie.