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AK4490 USB Dac with dsd support.

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#222
Would it be possible to run the signal straight from the AK4490 dac(board) to the output sockets and bypass the output shield / opamp? Lampizator was famous for recommending this mod on voltage out dac chips in cd players. My guess is that the signal will be too low and the impedance too high (in the kohms?)
 
#223
pdb said:
Would it be possible to run the signal straight from the AK4490 dac(board) to the output sockets and bypass the output shield / opamp? Lampizator was famous for recommending this mod on voltage out dac chips in cd players. My guess is that the signal will be too low and the impedance too high (in the kohms?)
Click to expand...

It is nonsense to do this. The high frequent noise from the dac will if not filtered be rectified and amplified in the following stage.

Also the output is balanced and centered about 1/2VREF voltage . (Here it is 6.1V VREF).

Max load is 2K to ground....
 
#224
Thanks for your reply. It was more a hypothetical question - a theoritical exercise if you will. I had no plan to actually ask you to do this for me 😉 merely getting your opinion on it. I have thought about asking you for quite some time (it was not related to your post about the balanced / discrete outputshield). I think those who have done it have had a (filter)cap between dac vout and sokets and some decoupling.

Longing so much to get out of bed and be able (with help from my wife) to set up yout dac and enjoy it... Being bedstriken most of the day is no fun... 🙁

Thanks again for taking time from your busy schedule to answer my questions.
 
#225
pdb said:
Thanks for your reply. It was more a hypothetical question - a theoritical exercise if you will. I had no plan to actually ask you to do this for me 😉 merely getting your opinion on it. I have thought about asking you for quite some time (it was not related to your post about the balanced / discrete outputshield). I think those who have done it have had a (filter)cap between dac vout and sokets and some decoupling.

Longing so much to get out of bed and be able (with help from my wife) to set up yout dac and enjoy it... Being bedstriken most of the day is no fun... 🙁

Thanks again for taking time from your busy schedule to answer my questions.
Click to expand...

No problem. I just think that Lampizator constructor maybe should do his homework... Because no filtering and no buffering puts the DAC's perfomance lightyears back.

I hope you gain some strength to get up .... 🙁
 
#226
sonnya said:
No problem. I just think that Lampizator constructor maybe should do his homework... Because no filtering and no buffering puts the DAC's perfomance lightyears back.

I hope you gain some strength to get up .... 🙁
Click to expand...
Thanks a lot - I hope too... Regarding the direct out mod, I think my memory has failed me. After some intense searching it seems that Lampizator suggested / did opamp and output stage bypass through transformers - or through his own tube output design...! I am sorry for the confusion. But several has done like I mentioned with only a cap between the dac and the output sockets - for instance this CS4398 dac All the best, Per
 
#227
sonnya said:
Discrete opamp for new outputshield

We have just ordered the discrete opamp modules for the balanced shield.

The opamp if 35x25mm in size even though the pinout is identical to standard single opamps, the row spacing does not match. Simply .. it draws to much current to replace any opamp. It is drawing 30mA, so i decided not to cramp it down.

Row spacing is 20mm.
Mountinghole spacing is 29mm.

It is an JFET folded cascode design with very low distortion. See it as an AD797 seasoned with jfet's (the salt).



Simulated distortion with 2 x gain is 0.002231% @ 200KHz, 8Vpp, 10kload, feedback resistors 2K,2K.

under same condition 0.000120% @ 10KHz

The opamps them self will cost 50€.

But the shield with 4 x of the opamps will cost 166€

How many active parts? 24 bjt's,4 jfets, 2 leds.
Click to expand...

Sonny - balanced + SE, or balanced only?
 
#230
sonnya said:
I get this one when i try to attach files to the first post.

"The administrator has specified that you can only edit messages for 30 minutes after you have posted. This limit has expired, so you must contact the administrator to make alterations on your message"
Click to expand...

I am sure if you ask an administrator, he can arrange that. Wait until you have all the documents and ask to be posted on the first post - or links to the relevant posts. This will be of great help to all interested. It has been done before.
 
#231
MisterRogers said:
And when do you think it'll be available for purchase?

Started casing up your DAC yesterday. Honestly hadn't planned too, but I'm very much enjoying it.
Click to expand...

Glad you like it 😀

The discrete opamps will arrive 25. june 2015. So we will test them next week.

I will be on holiday between 30. june - 7. july. I will order parts for the new shield for production in week 28.

Regarding front panel. They will also be in production from week 28.

BR

Sonny
 
#235
vulejov said:
There is no photos yet..
There is no any specific information about the output stage..
There is no data related to the device in terms of power consumption, output voltage, there is no driver for Windows..
There is no technical instructions for the release device in operation..
Click to expand...

I have updated my homepage. Try go to : my shop

I hope it is better than before, please give me some feedback.
 
#237
Regarding the XP Power ECL30UT03 (30 watts) psu listed in your shop, I'm a little confused... I thought you recommended / used the 15 watts psu ECL15UT03 for the Mirand Audio USB DAC? Have you changed your mind or is the ECL30UT03 for another purpose than the DAC?
 
#240
sonnya said:
I have updated my homepage. Try go to : my shop I hope it is better than before, please give me some feedback.
Click to expand...
In an earlier comment I wrote that it was really nice. That was before I click on each item and read the detailed descriptions.... Better than before? You bet...! It's EXCELLENT. It even answered my question about the different stages in TSSA and how it works. Not many webshops show THD graphs, too. Congratulations 🙂
 
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