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Old 19th November 2011, 01:45 AM   #471
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Because according to the board is suppose to be 680
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Old 19th November 2011, 02:03 AM   #472
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Exclamation 680ohms

Ok let me explain, at the binning I thought that the resistor was 1.2K close to the trim pot so I changed to 680ohms like the silkscreen said maybe I wasn't pay attention so just work at the first try, so after that the sound was even better I mean response nicely, damn take it easy
we all humans!
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Old 19th November 2011, 03:27 AM   #473
a.wayne is offline a.wayne  United States
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Errr OK... pass the Bacardi ......................
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Old 19th November 2011, 03:54 AM   #474
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I wish brother but I'm good is my eye site no good. funny comment by the way
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Old 19th November 2011, 01:04 PM   #475
BMW850 is offline BMW850  Netherlands
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Quote:
Originally Posted by vargasmongo3435 View Post
Ok let me explain, at the binning I thought that the resistor was 1.2K close to the trim pot so I changed to 680ohms like the silkscreen said maybe I wasn't pay attention so just work at the first try, so after that the sound was even better I mean response nicely, damn take it easy
we all humans!
You have changed the resistor 1.2K to 680R because you have a lower transformer voltage used?

At what transformer voltage you need 680R resistor in there.
I have 2x 42 volts transformer I need the 1.2K resistor?

Regards,
Rudy
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Old 19th November 2011, 01:37 PM   #476
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Exclamation My bad

Because I thought that the resistor that goes there was 1.2K in my set up the power supply I have produce +54V 0 -54V and the resistor was 1.2K, so I wasn't able to adjust the pot to 1mV my results was always 0V with the 1.2K after I changed and adjusted the pot to 1mV the performance of the amp was lovely so it was my bad we all humans, but good question is that matter if you have less voltage from the power supply uhmmm interesting .

here is what mister Carlos put out for me:

About bias adjustment:


- When you cannot decrease the current you should increase the resistor value you have in series with the bias adjustment trimpot

- When you cannot increase the current you should decrease the resistor value you have in series with the bias adjustment trimpot

- Depending the transistor gain and also the supply voltage, you may need to adjust the resistor you have in series with the bias adjustment trimpot.... values suggested worked into the simulator and also worked real life...but replacing transistor model, or replacing transistor by other with different gain, we have to tweak the adjustment once again.... usually the trimpot has range enough to "cover" or compensate these variations...but if you face troubles and cannot adjust....if current is too much high even increasing the trimpot resistance...or if the current is too much low and you cannot increase the current decreasing the bias trimpot resistance adjustment..them proceed to replace the resistor that is in series with the trimpot in order to make it work to your special case.

regards,

Carlos
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Old 19th November 2011, 01:59 PM   #477
BMW850 is offline BMW850  Netherlands
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Oke thanks for your answer,
I thought there might be a formulle to calculate the appropriate resistor?

Yesterday 20 pieces 1 watt resistors retrieved and I have again a wrong order placed, because it does not fit on the print.

See picture ...

Regards,
Rudy

Edit:
This is on the parts list: R24 A to J
2.2 1W 10mm PR01000102208JR500 Vishay Metal Film Resistors - Through Hole 1watt 2.2ohms 5% 10
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File Type: jpg 1W Resistor.small.jpg (179.3 KB, 261 views)
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Last edited by BMW850; 19th November 2011 at 02:04 PM.
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Old 19th November 2011, 02:09 PM   #478
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Default Sadly your last recording was not good Juan

Too much distortion, too much treble and mid...bass disappeared almost totally.

It looks camera does not make nice audio recording... Sony cameras usually are not good for this purpose... Canon cameras are much better.

Also too much loud, huge distortion of 5 percent or more.... really not good that one.... it looks your black speaker is playing without coil in series and without the mufling capacitor (220uf units in series)... it looks it is playing mids and highs and also that lovely white speaker playing together mids and highs creating a terrible unballance of tones.

I suggest you, dear Juan, to delete this one because have not resulted very good and this is not good to present our lovely amplifier...but go ahead trying and do not give up because your videos are lovely... this ones not very good but this is not a reason to give up...make them better as you know how to do...if you do not know, i am here to help.

This black speaker should have the coil to block mids and treble....the capacitor from positive input to negative input (black speaker) should be installed to filter mids and treble not blocked totally by the coil...and then the external speaker should play having at least two times its's impedance in series.... or a resistor of 8 ohms in series to produce a more ballanced sound... you should play low volume,testing in a try and error basis to see the level your camera would register without capture too much noise.

thank you...i will be waiting a better recording dear friend.... this was not faine..but i am sure you can make it better.

Well.. some of mine recordings are awfull too...you are not the only one...it is a problem to make recording with these digital cameras... very hard... bandwidth is not that good, these cameras have noises (hissing noise) also use limiters and compressors...well... they made all they could to make recordings terrible in these cheap cameras... they succeed to make sound terrible.

Cannon does better.... much better.

regards,

Carlos
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Last edited by destroyer X; 19th November 2011 at 02:11 PM.
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Old 19th November 2011, 02:21 PM   #479
BMW850 is offline BMW850  Netherlands
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Also, I ordered these heatsinks see photos
Formaat 35,5 x 19,5 x 9 cm (l x br x h)

Regards,
Rudy
Attached Images
File Type: jpg Heatsink1.jpg (60.0 KB, 252 views)
File Type: jpg Heatsink2.jpg (59.5 KB, 244 views)
File Type: jpg Heatsink3.jpg (49.6 KB, 238 views)
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Old 19th November 2011, 02:22 PM   #480
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Default BMW...there's not a good formula to everything

in special because we do not know the variables.... for instance..what is your particular transistor gain?... what is your supply voltage?..... what is your real resistor values?

Usually the trimpot has range to compensate...but not always.

You see the simulator resistor value have not worked...in my personal amplifier the value was different..then i built another one and the value was again different and then Vargas found another value... it looks each case is a case.

These things are not that easy alike a shoe... you can have a number 10 shoe that may fit several people, but someone may have a slightly different foot and for him will not match.

Simulator results says a thing.... real world says a different a second different thing and calculating we have a third different thing.... because of that we install a trimpot...as you know you can variate resistance from the fixed resistor value to the fixed resistance added by the maximum resistance the trimpot can achieve in it's range.

A 2K trimpot will do the job... if you connect it from base to emitter, removing that series base resistor and the original trimpot...the 2K trimpot will have range to all different sittuations, different transistors, different tollerances in your circuit resistor and different transistor gain/models.

If a fixed calculated value could be used...and if we could find a resistor with 875.234 ohms, then we could use a fixed...but also you should use a transistor with the correct gain...or you should buy 100 transistors, from 10 different suppliers and pray to god to find the one match the gain i would inform you...so....this is not a very good idea to have a fixed resistor..not only because strange values are not available but also because transistors are different too..also you voltage maybe a little bit different...your current a little bit different.

Do not think calculations is the solution.... the real world is the solution.. calculation is a reference only and it is based in parameters.... when you do not know parameters your calculations will present a fake result you will not apply to real world.

In other words..we start from calculations..then we check using simulator (fixed standard optimized parameters to transistors, not real.... hard to find a transistor with that "correct" optimized parameter).... then we assemble and we have to fix the whole thing, to re adjust, to trim, to tune and to make it work.

regards,

Carlos
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