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Postovi objavljeno od Mikorist
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@Mikavidi sta sam (samo ) nakupio
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a ima i josh jedna tema ovde :http://www.diyaudio.rs/topic/446-gain-clone-amplifier/page__view__findpost__p__21490
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da ne kaze neko da trujemo samo sa pass pojacalima posle...
Analysis of the pictures of the Gaincard innards
by Mick Feuerbacher, October 2005.
In 2002 in a thread in Audio Asylum some pictures were presented that were said to show the inside of an original Gaincard. Shortly thereafter Yoshi Segoshi of Sakura Systems responded, claiming that the photos were not of a 47 Labs Gaincard and when asked to provide photos of the internals of a real Gaincard, he refused to do so. Recently, some new images occurred in a 6moons review of the Gaincard. These images showed a very similar board with similar looking components and soldering style, similar cables and connectors and a similar stepped attenuator. These pictures were officially provided by the manufacturer. Comparing the old images with the new ones, I am now quite convinced that the images shown on Audio Asylum were showing the inside of the real Gaincard.
I carefully analyzed them in order to deduce the parts and schematic used for the original Gaincard. Most probably this has been done by millions of DIYers out there before, but I could not find the information in the internet. Maybe my findings are interesting for others as well, so I present them here. I am open for discussions, of course. If you don't agree with my conclusions or want to add something, please contact me (m at dogbreath dot de) ....
The first of the images appearing in the Audio Asylum thread. It was said that the pictures were taken by Craig Fraser. I hope he does not mind that I use them here.
This is the top side of the board with the two skinned supply bypassing caps. On the bottom of the picture the 12 position stepped attenuator with the green switch is seen.
The second image, showing the bottom side of the board.
Rectified image with the connectors labelled. The chip is a national LM3875. O: output; +: pos input; -: neg input; V+ and V-: pos and neg supply; n: not connected.
Bottom of the PCB with connectors labelled. In green are shown the locations (and connections) of the parts located on the front of the board.
The non-connected pins are cut off, only pin 11 (left) was left in order to fix the chip and make a connection to V-. There must be a bridge from pin 11 to pin 4 (V-) under the chip. The Resistor on the top side of the board (previous image) goes through a hole at the position of pin 3 and is bent to connect to the negative input.
There is only one ground on the board, the copper area in the front of the image. No separation of power and signal ground is made.
By careful inspection of the images I have deduced the schematic used. It is a non-inverted rather minimalistic approach. The number of parts, excluding the attenuator and R0, is nine as claimed by the manufacturer.
Although the design is non-inverted, a DC blocker cap is used at the input. I am surprised to see that they used an electrolytic here.
Resistor R0 extends the range of volume control by one step (Thanks Stabist!). This is on the cost of the fully attenuated position. You have to use mute switch for total silence.
A Zobel network is used on the output.
The switch is not a power switch. It simply disconnects the output from the speakers.
What is what on the pictures...
The labels shown are identical to those used in the schematic above.
Indeed, if you scale the image and calculate the length of the signal path (if you do not include the Zobel and Rg) you arrive at something close to 32 mm, as 47 labs claims for the Gaincard.
The values of the resistors are: Rg: 22k, Rf: 22k, Ri: 680. The gain is 33. All resistors seem to be carbon film types. Tolerance is 5 %.
There is no way to identify R0 or the capacitor values. At least, we can determine the dimensions of the components. The Cs caps have a diameter of 15 mm, Ci of 5.4 mm, the dimensions of Cz are 2.6 mm x 7.5 mm. Judging by the color, they may have used a WIMA 100 nF polyester cap for Cz. 100 nF is the value specified in the LM3886 datasheet and the WIMA measures 2.5 mm x 7.2 mm, which fits very well. Maybe someone can identify the makes of the other caps according to their size (let me know if you do). The value of the Cs caps is 1000 uF for the 25 + 25 W version and 2200 uF for the 50 + 50 W version.
The PSU (Power Humpty)
This information was collected from other sources in the internet. The Power Humpty contains a high quality non-toroidal 170 VA transformer. Secondaries are 23.5V, 3.6 A. There are only four diodes, used for the positive and negative rails. The diodes are FE5D 9808 (General Semiconductors). There are no capacitors in the Power Humpty. The ground connections of the positive and negative rail are separately led to the amp boards.
FROM:
http://dogbreath.de/...d/GainCard.html
Next is a best-guess schematic showing a possible physical layout. Grounding is critical. The chips should be well heatsinked, but electrically isolated from the heatsink. An isolated version of the LM3875 exists which makes this easy to do. Both channels should be mounted on the same heatsink if possible.
R1 **
R2 22k
R3 680R
R4 22k
R5 1R
C2 4.7 µF / 50V Black Gate N series
C5 0.22 µF / 63V WIMA MKS
C6 1000 µF / 35V United Chemicon LXV or similar
C7 1000 µF / 35V United Chemicon LXV or similar
U1 LM3875T
** 12 step ladder attenuator, use 22k, 4k7, 2k2, 1k5, 1k, 680R, 470R, 330R, 220R, 150R, 68R, 33R. A 50 kOhm volume potentiometer could be substituted.
Junji Kimura
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Stvar ukusa :cheers:ovde je bio ceo forum posvecen ovome :http://web.archive.o...om/ffakeidsfrm1Ништа то не ваља, бољи су апексови .дискО_Сту
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ovde se moze naci prvi text napisan o GC (2002 godina) :
http://web.archive.org/web/20021208152635/home.ca.inter.net/~cfraser/Gainclonehome.htm
sajt ne postoji ali ima ga u webarhivi
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Ja sam se ovde ucio na Schottky diodama - no ove MUR860 su super brze diode - no ima manijaka koji koristei ULTRA brze...za ucenje dobre su i 1N5400, a i cuo sam da sporije diode bolje za ispravljace....
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polozio si testmeri na koji izvod je inner foil spojen a na koji outer foilzna da ne bude svejedno
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zar nisi procitao sta pise tamoA bre, šta meri ?
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eto testa iz znanja elektronike pri registraciji novih clanovaA bre, šta meri ? Napon na kondu koji nije u kolu? Napon na nabijenom( praznom) kondu koji nema nikakvo oscilatorno kolo spolja ( osim osciloskopa)?
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http://jimmyauw.com/2010/04/24/observing-inner-and-outer-foil-of-some-popular-capacitors/Kakav je ovo perpetuum mobile?
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ovi su bas munjeni i nimalo naivni kako rade GC :
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ekipa GC audiofila za ruckom
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da tom GC-u ne izgleda ovako PSU? ::cheers:sto je najbolje ne zezam se:http://jimmyauw.com/tag/gainclone/Evo jednog vrhunskog GC kita sa vrhunskim delovima. Jeste da nije LM3886 ali nema veze .
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sto se mene tice moze iz informatike . posto pojma nemam audio elektroniku u odnosu na ostatak ekipe :)EDIT:da se uvede test pri kupovini racunara - ko ne polozi ne moze da ga kupi :buehehe:svanulo bi mi sledeci danPredlazem da se uvede test iz znanja elektronike pri registraciji novih clanova, tako da pocetnici ne zamaraju experte svojim pitanjuma
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sta nije vise falsifikatOriginal falsifikata
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Najbolje bi bilo za forum da izbacimo jedno 20-ak sema za pocetnike tipa mala skola elektronikeKako sve ovo pomaze hobistima? Vratimo se na post #1.
sa spiskom najboljih delova - sa sve stampanim plocicaama a mozemo da i organizujemo i prodaju Audiokit-ova
za pocetnike....
imali bi neverovatnu posecenost - a mogao bi i vorum konacno da se izdrzava
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a...sta je to... "mali" fi fi forum ?великом фифи форуму.
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Izvorna narodna muzika juzne Srbije postoji vekovima i nisu je doneli Turci, jer je topre (robstva od 6 vekova) nasledjeno u periodu Vizantije a ona od pre od perioda anticke Grcke - koja je koristila motive i uticaje Persije , Indije ....bla bla bla... ovoj temi nema kraja zaustavicu se da ne zavrsi posle kao ona o paradi... :good2:pitaj Crnog Gruju - ostala simpatija od 6 vekova karanja
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Niko ne zna sta je to (do kraja) Turska muzika - muzika Srba (na zalost), niti iko zna sta je to staroslovenska muzika. Pre bih rekao da je “Teheranski zvuk” ukomponovan u nasu novokomponovanu narodnu muziku...
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Nisam siguran bash ko je od koga krao muziku ... Vizantija - ili oni od nje (no to spada u jednu dublju analizu orjentalne muzike - no necu da smaram )Pusto Tursko.
APEX i Kelvin Labs
in Solid State
Napisano
ako se racunaju bio jonizatori - zujalice i ostalo iz male skole elektonike radio kluba i ja se bavim elektronikom preko 25 godina