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We will ship the package through one of these express couriers: DHL or EMS,
upon receipt of the package , if anyone asks you pay extra shipping
cost , please refuse to pay money and do not
accept the package, and contact us at the earliest .But if custom ask
you pay tax, we can't do anything .If you guess your custom will ask you pay
heavy tax, we advice you ship by EMS, then maybe you can avoid pay heavy tax,
but not 100% can avoid.
If you ever have some unhappy experience either DHL or EMS,
let me know when you make the order, we can shipment by other
express.
After you make the payment,please send us an email to confirm.
Because a lot customers' paypal accounts are different from the
communicate email, so we can't sure who have paid. If we make
something wrong , the customers maybe paid for the other people. |
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A lot of customers use our OPA, the review can be found here (from
pages 530 onwards):
http://www.head-fi.org/forums/f5/review-zero-24-bit-192khz-dac-headphone-amp-pre-amp-269458/index635.html
http://www.head-fi.org/forums/f5/opa-moon-hdam-revelations-pt-1-first-impressions-plus-updates-372219/
Application : Generally the IC opamp application is designed for industrial
usage. When the IC opamp is used for audio, the performance is less
than satisfactory. This discrete opamp uses accurate matching of
components and audiophile grade resistors, combined with dedicated
audio design circuitry which gives a smooth and natural output
sound. This discrete opamp can be used to replace existing opamp in
amplifier or CD/DAC as an upgrade.
Quality assure:
Every OPA is thoroughly tested twice on professional equipments ,
Our priority is Quality first, followed by Efficiency.
OPA – Earth :
Our
first generation discrete opamp has been sold throughout the world
by other marketing means. This discrete opamp utilizes integrated
cascode circuit with the schematic based on single channel circuit
which is an improvement based on new improved parameters and
technology. The sound characteristics is neutral and natural . THD
Less than 0.0005%(1KHz), Operating voltage：±9 TO ±25V，Open loop
gain：35DB，Operating current： Approx. 28MA（Single OPA），Approx.
56MA（Dual OPA）.(Products have been upgraded to Cap Model, using EVOX
MMK capacitors. )
We were the first to make and sell HDAM (OPA):
We were the first to make and sell OPA-EARTH
or sometimes called " HDAM " in China and overseas market . Through
the links below , one can know that we have designed and made the
original HDAM beginning in 29-6-2005 , although these links are in
Chinese , but it has pictures and posting date . Beginning on 2006 ,
we were OEM for huge quantities of HDAM for an agent . We are the
only one in the world, to have the PCB diagrams and files of
original HDAM .
http://bbs.audio-gd.com/dispbbs.asp?boardID=2&ID=2270&page=101
http://bbs.audio-gd.com/dispbbs.asp?boardID=2&ID=593&page=137
OPA - Moon :
This discrete opamp uses dual differential gain stage and single
ended output stage circuit design , we try and audition for a long
period of time . The OPA-Moon sound characteristics is a bit of
tube-like (vacuum valve) , soft and slightly thick, and full of
emotions . THD Less than 0.0008%(1KHz), Operating voltage ：±9 TO
±25V，Open loop gain：33DB，Operating current：Approx. 28MA（Single
OPA），Approx. 58MA（Dual OPA）.(Products have been upgraded to Cap
Model, using EVOX MMK capacitors. )
OPA-SUN (Version 2)
:
This discrete opamp uses full balanced circuit design which is
widely appreciated by our Hong Kong and American followers among our
other products. THD Less than 0.0003%(1KHz), Operating voltage ：±12
TO ±20V，Open loop gain：36DB，Operating current：Approx. 25MA（Single
OPA），Approx. 50MA（Dual OPA）.(Products have been upgraded to Cap
Model, use EVOX MMK capacitors. )
What's new of SUN
(Version 2)
: We
started selling the new version from 15th September , 2008. Taking
into consideration customer feedbacks and suggestions, we adjusted
the circuits and parts , we improved upon the earlier version and
came up with OPA-SUN (Version 2), OPA-SUN (Version 2) does not
sound as bright as the original SUN, but it
maintains the energy, huge dynamics and good impulse response
(fast).
The
discrete opamp not only can replace typical single or double output
opamp, but it also has a separate earth(ground) wire which can be
connected to the earth of the player. Even if the earth wire is not
connected or used, the output sound will have slight difference. The
user can choose to decide on his own, but we recommend to connect
the earth wire to ground. Please do not connect OPAs earth wire to
AC power socket ground.
We guarantee to keep OPA in
working condition without charging any labor cost, but customers
will need pay for shipping charges both ways. The leads are not
guaranteed for repair.
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Dual OPA:It can replace
AD712, AD827, C4570, JRC4580, JRC5532, JRC5532D, JRC5534, LF353,
LF358,LM833N, NE5532, NEC4520, NEC4570, NJM2068D, NJM2114, NJM2214D,
NJM4558, NJM4558D, NJM4560, NJM5532, NJM4558P, OP275, OPA2132,
OPA2134, OPA2604, RC4558D, RC4558, TL052, TL072,LT1057,BA5218,EL2244,LM4562
...
Single OPA:It can replace LF356,
LF357, NE5534, LT1122, OPA627,OPA637,OPA604, AD797,AD811, AD844,OPA603,OPA134...
 Price:
OPA-EARTH Dual OPA
USD22.5/1 unit (24*24*40)
OPA-EARTH Single OPA
USD12/1 unit
OPA-MOON Dual OPA
USD25/1 unit (24*24*40)
OPA-MOON Single OPA
USD13.5/1 unit
OPA-SUN Dual OPA USD30/1 unit
(24*24*40)
OPA-SUN Single OPA
USD16/1 unit
(Without Postage)
Shipping Charge:
http://www.audio-gd.com/enweb/shipping
cost.htm
For
Extension lead of the OPA, please add
USD3/unit,
standard length 100MM, but you can also place an order for
50-100MM, for which we will need 3 extra days to complete your
order.
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About Cap Mod of our OPAs:
Some people have found
improvements in SQ by adding capacitors on OPA. We evaluated the
issue through a lot of listening and testing by professional
equipment , see Figure 1.
We concluded that by adding two capacitors , one connect V+
to earth , another connect V- to earth . The earth wire needs to be
connected to GND of the gear. Through this Cap-Mod you can upgrade
the sound and technical performance.
If you don't connect the earth wire of OPA to GND , Figure 1
Cap-Mod become Figure 2 Cap-Mod . This Cap-Mod only needs one
capacitor connect to V+ to V- , though this Mod you can upgrade the
sound but it does not upgrade the performance technically.
The technical performance can evaluated on professional
equipment which lets us know where the improvement has taken place.
What capacitors can we use ?
If one only needs to change sound character , the use of 0.01
UF would be OK . But we recommend the use 0.1 UF to 1 UF , in this
way we can easily hear the improvements in SQ .
Not any capacitors can be used for Cap-Mod . Different
capacitors will produce different sounds , so the capacitors need to
be chosen keeping in mind personal preference . For example:
WIMA can make it fast , dynamic and clear
SQ . but if you want the sound to be warm and thick (textured) ,
don't use WIMA , in this case, oil- cap will be a better choice .
We use EVOX MMK capacitors in the Cap-Mod of our OPAs . These
capacitors were also called RIFA previously , but now it is called
EVOX , the sound is soft and clear .
Our OPAs have been upgraded to the best Cap-Mod , so people
don't need add capacitors on our OPAs .
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