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design help needed

  • Thread starter The unknown Posterchild
  • Start date
J

John Woodgate

Jan 1, 1970
0
I read in alt.binaries.schematics.electronic that The unknown
I don't do electronics math so I have no idea about impedance issues
with the output

Why don't you take up brain surgery instead? How on earth do you hope to
get anything to work if you don't understand ANYTHING about it?
 
J

John Woodgate

Jan 1, 1970
0
I read in alt.binaries.schematics.electronic that T N Nurse
It's a Baxandall circuit. It's fine with linear pots.

It absolutely ISN'T a Baxandall, which IS an active circuit.
 
P

Pooh Bear

Jan 1, 1970
0
The fets are not in ay way connected to the tone controls.
Look at the circuit again. it's not passive. You fucked up. Admit it
or piss off. Or not, it doesn't make much difference. No matter
what, you were wrong and all your grandstanding can't change that.

You're talking out of your arse.

You clearly know bugger all about audio circuits.

That circuit is about the worst trash I've seen in several decades.

Graham
 
P

Pooh Bear

Jan 1, 1970
0
The said:
What makes it active? the N FETs? ..they are in the preamp phase...
I admit to scouring the net and stealing what I found...
Before today, I didn't kniow a fet from an accompli

I am going to separate the bass and treble to separate tone controls...with
center being neutral and less and more being left and right. Does that mean
I need more amps on the + side of the controls?

Bear with me...really..up till today I never tried doing this..does it show?

It does I'm afraid.

There are much, much better examples of what you're looking for out there.

There's so much that's fundamentally wrong about the link you posted that I
barely know where to begin. It takes truly the wrong approach to just about
every single aspect of design.

Graham
 
P

Pooh Bear

Jan 1, 1970
0
John said:
I read in alt.binaries.schematics.electronic that Pooh Bear


So is the input impedance.

Oh, I see; the OP is using crystal microphones.(;-)

And the 'balance' control is wired as a master volume control.

Worse than that - the 'balance' control shorts out all of the signal at 0% or 100%
travel !

Whoever came up with that abortion should be strung up.

Graham
 
P

Pooh Bear

Jan 1, 1970
0
The said:
let's see...circuits came from...

tone: http://amps.zugster.net/articles/tonestacks/
preamp: http://www.till.com/articles/GuitarPreamp/index.html
balance + volume: http://sound.westhost.com/pots.htm

as for resistors and caps ..it's what the circuits said.
I thought they were modern audio log pots...

I am still looking for an active tone control circuit but can't seem to
understand what I should be looking for,,,some kind of opamp circuit for
that?

..and since I am not using pickups but condenser microphones, the amp
circuit may have to change a bit.

I don't do electronics math so I have no idea about impedance issues with
the output

For starters, do you want something battery powered ?

You want to mix 2 inputs and then have a common EQ ? Just 2 band ?

I don't see the point of 'balance'. Why not simply have a volume control for
each input - then you don't even need a master volume ( unless you specifically
really do want one ).

Graham
 
P

Pooh Bear

Jan 1, 1970
0
John said:
I read in alt.binaries.schematics.electronic that The unknown


Why don't you take up brain surgery instead? How on earth do you hope to
get anything to work if you don't understand ANYTHING about it?

All to common today John. look at some of the clueless posts here in s.e.d.

You recall Charlie Boy got himself in hot water for saying kids today all expect
to be rock stars or brain surgeons too ? p.s - without having studied anything of
course

Graham
 
P

Pooh Bear

Jan 1, 1970
0
T said:
It's a Baxandall circuit. It's fine with linear pots.

No it isn't.

You use linear pots around a ( Baxandall ) circuit with feedback That one isn't
one. Try finding the feedback loop !

If anyone has the National Semiconductor Audio Handbook the difference is
explained on pages 2-40 thru 2-48. ( active vs passive tone controls ).

The Audio Handbook has been reprinted btw. Amazon has it. A good reference work
despite its age.

Graham
 
J

John Woodgate

Jan 1, 1970
0
I read in alt.binaries.schematics.electronic that Pooh Bear
Worse than that - the 'balance' control shorts out all of the signal at
0% or 100% travel !

I think you are looking at the first version. My comment refers to the
'improved' version.
 
T

T N Nurse

Jan 1, 1970
0
Pooh Bear said:
No it isn't.

You use linear pots around a ( Baxandall ) circuit with feedback That one
isn't
one. Try finding the feedback loop !

Oops! You're right, I should have looked closer.
 
T

T N Nurse

Jan 1, 1970
0
John Woodgate said:
I read in alt.binaries.schematics.electronic that T N Nurse


It absolutely ISN'T a Baxandall, which IS an active circuit.

Err no. Peter Baxandall's contribution is this cut and boost circuit in
it's a passive form. He later (1952) added an active version which
looks similar but goes around a feedback loop. So both are Baxandall
circuits.

http://www.duncanamps.com/technical/baxandall.html
http://ampage.org/htac/garvin.tone.html
P. Baxandall - "Negative Feedback Tone Control" Wireless World, vol 58
Oct 1952 p.402
 
T

T N Nurse

Jan 1, 1970
0
YD said:
Sorry, it's a James circuit and uses log pots. The Baxandall circuit is
active and uses lin pots.

"James circuit (also known as the Baxandall passive tone circuit).."
To OP: take a look at http://www.epanorama.net and
http://www.headwize.com for some ideas.

http://cidtel.inictel.gob.pe/cidtel/contenido/Publicaciones/rvargas/JBPTC
N.htm

...for a very full explanation - although not for the faint of heart at
maths. Don't worry, it's in English.

But, you're right, the pots are log - I should have looked closer and
realised it was passive.
..
 
J

John Woodgate

Jan 1, 1970
0
I read in alt.binaries.schematics.electronic that T N Nurse
"James circuit (also known as the Baxandall passive tone circuit).."

Maybe 'known as', but it isn't. The Baxandall circuit is NOT the same as
the James, but arranged in a feedback loop. The Baxandall treble circuit
has ONE capacitor in series with the slider of the pot., which in the
original circuit has a centre-tap on the track, with a switch to
optionally ground it.
 
J

John Woodgate

Jan 1, 1970
0
I read in alt.binaries.schematics.electronic that T N Nurse
Err no. Peter Baxandall's contribution is this cut and boost circuit in
it's a passive form. He later (1952) added an active version which
looks similar but goes around a feedback loop. So both are Baxandall
circuits.

Complete nonsense, and I have the Wireless world articles to prove it.
 
T

The Phantom

Jan 1, 1970
0
I read in alt.binaries.schematics.electronic that T N Nurse


Complete nonsense, and I have the Wireless world articles to prove it.

I have the Oct 1952 paper, but I notice in the references in RDH that there was a
"correction" article in Nov 1952. Can you tell me what the "correction" was?

I also notice in RDH a reference to an article by E. J. James in Wireless World, Feb.
1949, titled "Simple Tone Control Circuit". I wonder if that is the "James" tone control
referred to in this thread. Do you also have a copy of that article, and is it just a
passive version of Baxandall's 1952 circuit (with or without a tap on the treble control)?
 
T

The unknown Posterchild

Jan 1, 1970
0
Pooh Bear said:
Yes - correct on all counts !

And don't forget the mid freq control ( variable frequency ). So you get 3
EQ
sections and a filter.

Here's one I made earlier......

http://www.studiomaster.com/c1.html
I don't have a schematic for a mid freq control ( variable frequency ). Is
that what is referred to as a mid sweep?
 
B

Boyd Williamson

Jan 1, 1970
0
Uhhh... This sort of thing is way outside the people in alt.guitar.

Please don't crosspost.

Zoid
 
P

Pooh Bear

Jan 1, 1970
0
The said:
I don't have a schematic for a mid freq control ( variable frequency ). Is
that what is referred to as a mid sweep?

It is.

And you certainly can't do that passively. At least not intelligently.

Graham
 
R

Rich Grise

Jan 1, 1970
0
I read in alt.binaries.schematics.electronic that Pooh Bear


I think you are looking at the first version. My comment refers to the
'improved' version.

Is there a link to the "improved" version? I'm looking at
http://get-noticed.com/darkwood/preamp schematic dual preamp.jpg
and can't figure out what he's trying to do on the left side.
And yes, the tone controls look like they were lifted in toto from
some toob circuit, which would account for the high impedances.

Thanks,
Rich
 
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