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Old 11th September 2008, 08:35 PM   #1
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Default My 2nd Gainclone.

Hi guys, im trying to design a new gainclone to build, now i want to start using more components, and filters (like zobel).

I draw this.

Click the image to open in full size.

I want to know if can give me some tips.

I just finished draw it, some values are wrong.

Thanks for your support.
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Old 11th September 2008, 10:27 PM   #2
CJ900RR is offline CJ900RR  Sweden
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Why do you put 4700uF at the amps output??! Thats my biggest concern. Everything else looks pretty standard. You say that "some values are wrong" and yes they are but I will not go any further about that since you say so your self.

Back to the output-cap, again, why? One big rule is to avoid output-caps as much as you can...
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Old 11th September 2008, 10:50 PM   #3
AndrewT is online now AndrewT  Scotland
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why the V+ and V- decoupling different?
Where is the Zin resistor?
Ro=1k0????
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regards Andrew T.
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Old 12th September 2008, 01:54 AM   #4
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Talking agree100%

I would ask the same question CJ900RR!.I would put the big capacitance next to the bridge rectifier.
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Old 12th September 2008, 02:35 AM   #5
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Quote:
Originally posted by CJ900RR
Why do you put 4700uF at the amps output??! Thats my biggest concern. Everything else looks pretty standard. You say that "some values are wrong" and yes they are but I will not go any further about that since you say so your self.

Back to the output-cap, again, why? One big rule is to avoid output-caps as much as you can...
I put 4700uf Cap because its the value that are used in the Datasheet of the LM3886. Btw how can i calculate wich value will be the best?


Quote:
Originally posted by AndrewT
why the V+ and V- decoupling different?
Where is the Zin resistor?
Ro=1k0????
The V+ and V+ are decoupling diferent because i forget to Fix the V-, both will be like V+

btw, what you means with the Zin Resistor? in the input im using Ri Resistor, i will use an Pre to control Volumen.
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Old 12th September 2008, 07:03 AM   #6
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Talking the best tip!

Well vecino! my best tip for you is "Keep it as simple as you can".if the design is not right!adding more parts does not mean you will get better sound. keep it simple ...keep it right!
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Old 12th September 2008, 07:41 AM   #7
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Quote:
Originally posted by samsagaz
I put 4700uf Cap because its the value that are used in the Datasheet of the LM3886.
You only need that capacitor, if you have a single power supply to prevent DC from reaching the speakers. With your split power supply there is no need to use that capacitor. It will only worsen the sound quality.
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Old 12th September 2008, 11:37 AM   #8
CJ900RR is offline CJ900RR  Sweden
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Quote:
Originally posted by pacificblue


You only need that capacitor, if you have a single power supply to prevent DC from reaching the speakers. With your split power supply there is no need to use that capacitor. It will only worsen the sound quality.
I seccond that!

The best most naturally sounding configuration regarding to my opinion is the first schematic in the datasheet for the LM3886, page 1.

For Rm use 10K, for Cs use 470uF - 2200uF depending on listening-impression plus 0,1uF at supply-pins on the LM3886 to ground.

A zobel network is a resistor plus a cap in series from output to ground, 2R7 and 0,1uF is often used there. More easy to use then the inductor that can be hard to find.

In my opinion you dont need a zobel if cables is short and only one LM3886/channel is used, but I know that other say that you must use it. Make space for it and try both with and without it.

To keep it simple is the best way to go to not affect the sound. Later on you can design a more advanced layout with DC-servo, loudspeaker-protection and so on.

Many people use the LM3886 in a wery simple way and are happy with it. Look at the kits from Audiosector, Chipamp.com etc, popular and simple.

Keep it up
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Old 12th September 2008, 04:05 PM   #9
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Default Re: the best tip!

Quote:
Originally posted by lanchile
Well vecino! my best tip for you is "Keep it as simple as you can".if the design is not right!adding more parts does not mean you will get better sound. keep it simple ...keep it right!
a few months ago i build an GC using the first schematic of the LM3886 Datasheet, now im trying to get it a little more complex. Im just trying to add other components to compare the sound. im really happy with the sound of my first GC. Btw, i read that adding the Zobel is an nice addon.

Quote:
Originally posted by pacificblue


You only need that capacitor, if you have a single power supply to prevent DC from reaching the speakers. With your split power supply there is no need to use that capacitor. It will only worsen the sound quality.
Ok, will remove that Cap.


Quote:
Originally posted by CJ900RR


I seccond that!

The best most naturally sounding configuration regarding to my opinion is the first schematic in the datasheet for the LM3886, page 1.

For Rm use 10K, for Cs use 470uF - 2200uF depending on listening-impression plus 0,1uF at supply-pins on the LM3886 to ground.

A zobel network is a resistor plus a cap in series from output to ground, 2R7 and 0,1uF is often used there. More easy to use then the inductor that can be hard to find.

In my opinion you dont need a zobel if cables is short and only one LM3886/channel is used, but I know that other say that you must use it. Make space for it and try both with and without it.

To keep it simple is the best way to go to not affect the sound. Later on you can design a more advanced layout with DC-servo, loudspeaker-protection and so on.

Many people use the LM3886 in a wery simple way and are happy with it. Look at the kits from Audiosector, Chipamp.com etc, popular and simple.

Keep it up
I build my first gainclone without Zobel Network, this time will try to add it.
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Old 12th September 2008, 05:33 PM   #10
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Now Redraw it with some tips that you give me.


Click the image to open in full size.



can someone tellme chich is the purpose of Ri2?

THanks in advance.
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