ebay:Weiliang Dual X2 AK4399 DAC with LCD

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lomonosoff

Member
Joined 2014
In short the AMP843 frequency more vypukloi,and OP01 sound softer,smoother,cleaner analogami good chip and it is desirable to compare with 797/49710/8610/4627 .AND at all after alteration AK4399 even native 49710 in a plastic case play normalnomu now apply an OP-AMPa depends on subsequent tract-amplifier,speakers,headphones.
 
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NinoSimona

Member
Joined 2011
kukynas said:
... what should I do than with those 2 pairs of Wima 0.1/100v? these aren't in version 1 just in v.2...
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These Wimas are for decoupling +/- 12V, bypassing the silmics. You can remove them if you like, but I think they are better to stay. Just check out what it does to your sound, it depends also on the op-amp.

If you want unity gain for the analog stage, then values of the Bessel filter are as follows: C1 = 150p, R5,R6 = 4k7, R1,R3 = 12k, R2,R4 = 15k. You can also use R1-R4 = 12k for +1dB gain. Other values stay the same as on the picture.
 
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Dave murrey

Member
Joined 2014
NinoSimona said:
The filter is an active filter, hence the capacitor in the feedback loop. Advantages of my filter:
* -40 dB/decade roll-off instead of -20dB/decade
* constant group delay in the pass-band


Not a stupid question at all Dave. You can think of an ideal op-amp as a single component: an amplifier which amplifies the voltage across its both inputs with infinitely high gain. This way it can be used in a lot of ways, just as, for example, a capacitor can be used in various ways. To use the opamp as a buffer or amplifier, you must set the gain using feedback, with resistors, so that part of the output is fed back to the input. You can also include passive components in the feedback loop, the amount of feedback then depends on frequency of the signal, and so does gain. The opamp then becomes an active filter.
The real max gain an opamp can deliver is called open loop gain.
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Thank you for explaining NinoSimona.
 
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esgigt

Member
Joined 2013
kukynas said:
Nino: problem might be import duty and tax, don't know how about other EU countries but I would pay for items over $25 around 25% of total value (including shipping cost) so for me is cheaper hificollective or directly from NewClassD in Denmark even if it's few dollars more expensive on parts itself, this is of course related to Dexa products, don't know about EU shop selling Belleson
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In the EU, import is duty-free up to 150 Euro's. Above that, you pay 4.2 percent extra. Sales-tax is free below 22 Euro. Keep in mind that shipping and administrative costs are also included for sales tax. Besides that, the shipment co. sometimes makes mistakes in their own advantge, calculating the sales-tax.
 
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kukynas

Member
Joined 2014
4.2% is general tariff if you are unable to provide HS code of your imported product, other than that it's calculated based on TARIC tariffs and in certain cases for certain product duty is free, bigger trouble is sales tax (depended on country) which is usually above 20% and as mentioned includes transport and administrative cost...
 
Sunsun22

Sunsun22

Member
Joined 2004
I just received my pair of OP01 this morning. After 10 hours of operations, I feel it is softer and more airy than Dexa but is not as much in details. I would give it another 100 hours to discover its potential.

I also purchased a pair of discrete jfet opamp PCB from eBay. This would be the driving force for me to find out where have I put my few hundreds of K170 and J74 (both BL and GR). They were being lost in my Bermuda Triangle for around five years now.
 
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kukynas

Member
Joined 2014
yep, all of them are mounted on 2xsingle to dual DIP8 adapter like this
images
means you can use single channel OPA on dual channel output stage ;)
 
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