Thanks a lot Teemuk,
I always learn a lot with your replies.
I was thinking that this was a lot more
difficult, but, killed doubts. Thanks.

Blindsjc

Hi friends,
Can someone help me to implement this variable impedance
trick on a LM3886 amp? Maybe this can make it sounds better
with a guitar.

The amps is a
http://sound.westhost.com/project19.htm
built and working...

can I add the info of
http://sound.westhost.com/project56.htm
with this amp just adding the feedback resistor?

Thanks for any info
Blindsjc

Hi zyggurat,
I use a tonemender as a preamp in my handmade amp.
Like this: Vulvan Distortion -> Tonemender -> TDA2050

Did you had some testing with the first opamp as a non inverting
amp? I'm really curious about how much this can make my amp
sound better. Somebody haves any info about this?

Thanks a lot people

Thanks a lot Joe,
this is clear and really helps me.

Sorry,
I think I didnt get it...
U2/U1... so 25/220 = 0.11 ... then the fuse is 0.11 amps?

For a 30watt rms amplifier with a transformer like 2,5 amperes and
12-0-12volts secondary, what is the correct fuse value and type on 110volts?
and...theres difference when on 220volts?

Thanks
Ronaldo

Hi friends,
In the text about star ground (aiken), the author talks about
a two stage ground point to separate the preamp section from
the other high gain stages. In my project I have a preamp, power
amp and two effects. One of the problems I think are these high
gain effects and power amp bringing noise to the preamp.

Can you give me a view about the two stage star ground? The text
is no clear to me and I cant understand where the two points are
really located, and how to test it.

I will read it again, and will search for
something that I probably misunderstood.
After I will post again the results. Thanks
for the help.

Thx

Hi friends,
I'm in trouble with a project ground,
I have a PSU, preamp, poweramp and an effect at the same pcb.
I need to know the best way to ground all these subcircuits to
avoid noise and hum. May I use a star ground, getting all the ground
points in all subcircuits and group then at the chassis ground? The
same with the input and output jacks ground? I'm really lost in
this task, please help. Thanks a lot.

Take a look at the project components:


Link: http://blindsjc.v10.com.br/placas.htm

Ronaldo

Oh yes,
I found some like this on runoffgroove faq,
http://www.runoffgroove.com/phones.png
and I think it will solve the problem.

Thanks again friend, people like you makes
newbies projects possibles. Thank you.

Hi teemuk,
Thanks again, I'll try it today.

Ronaldo

Hi friends,
Someone knows about earphones output schematics or any other information.
I just finished a amplifier with a Tonemender and a TDA2050 but to get sound
directly from the preamp doesn't show good quality.

Every schematic that I know do not show a earphone connection. How the
big ones like Fender and marshall do this outputs?

again, sorry about the bad English.

Thanks
Ronaldo

I agree with all,
Let me tell the whole thing.

1) With +-22, I got a explosive TDA... changed...

2) The second TDA was clipping, a lot, at very low volume...
even with my portable cd player...was using +-22 too... changed...

3) Changed the supply for +-15. Changed for a new TDA... and bingo...
No more problems, great sound, big volume at a 4ohms 10 in. speaker.

In the PSU I used 2x2200uF caps for smoothing after a bridger rectifier.

thx

Friends,
The problem is resolved,
I changed the power voltage to +-15 and all the clipping and burning
chips are gone. Everything is working perfectly. I'm sure that the
datasheet says +-22, but...

Thanks for all replies. Anybody has the same problem before?

Ronaldo

Hi, thx for reply.
There was no oscillation, just a clipping sound
at low volume. Maybe a clipping from preamp
caused by a too strong signal from epiphone
les paul special?

Maybe I'm waiting too much sound from a
single TDA2050.

Thx