Need help with this preamp circuit

[b0nk3rs]

I need help with this circuit:

http://www.generalguitargadgets.com/...cticemaneq.gif

I'm a bit new with electronics... I want to know how I could put a buffer before the 1uF capacitor on the top left of the circuit where I'm planning to place the "Line In" provision. Also,I would like to ask where the Power supply should be connected and where would the output be? Thanks a lot!

[edl]

Hi,

Check it:
http://sziget.mine.nu/~danko/kapcsrajzok/3cheq.html

[lineup]

Originally posted by b0nk3rs
I need help with this circuit:

http://www.generalguitargadgets.com/...cticemaneq.gif

I'm a bit new with electronics... I want to know how I could put a buffer before the 1uF capacitor on the top left of the circuit where I'm planning to place the "Line In" provision. Also,I would like to ask where the Power supply should be connected and where would the output be? Thanks a lot!

Originally posted by edl
Hi,

Check it:
http://sziget.mine.nu/~danko/kapcsrajzok/3cheq.html

TL071, TL072, TL074
can work good in these filter and Tone Control circuits.

For possibly a bit better sound performance
( if you need highest quality.. instead of lowest cost )
Then try Replace with
OPA134, OPA2134, OPA4134

Like TL074, OPA4134 is 4 opamps in same IC.
OPAx134 and TL07x are both JFET transistor input Operational Amplifiers.
So they are good replace.

If you are happy with normal good audio quality, then you should stay with TL074.
The are considerably lower in price!
And if you upgrade to OPAx134,
I can NOT Promise you will notice in difference in Sound Quality.
.... this is how small improvement will be
.... it is up to you, if you think it is worth the money

Most would stick with TL071, TL072 or TL074 and get good results.


lineup

-------------------------------------------------------
information for compare:
TL071 TL072 TL074 - datasheet PDF
OPA134 OPA2134 OPA4134 - datasheet PDF
.

[b0nk3rs]

could I increase the values of the caps by 5%? I'm having trouble finding capacitor values ranging from nano farads below... should i also change the values of the resistors and pots?

[unclejed613]

try .05uf (actually .047uf), .022uf, and .0047uf since these are the same cap values, just expressed in uf rather than nf. some manufacturers still "skip" the nf range in their catalogs (not that it's not there, it's just expressed in uf)

[sixtek]

Originally posted by unclejed613
try .05uf (actually .047uf), .022uf, and .0047uf since these are the same cap values, just expressed in uf rather than nf. some manufacturers still "skip" the nf range in their catalogs (not that it's not there, it's just expressed in uf)

Yes.
As here: http://users.otenet.gr/~athsam/3_band_eq.htm

[thanh]

Hi !
I'm trying to improve my pre-amp. Schematics at this thread are inverting-converter. Is is better than non-inverting-converter ?
Thanks!

[lineup]

Originally posted by thanh
Hi !
I'm trying to improve my pre-amp. Schematics at this thread are inverting-converter. Is is better than non-inverting-converter ?
Thanks!

I terms of quality there is almost never any difference.
Between inverting and non-inverting use of op-amps.

The only reason inverting input is used, when mixing, adding several signals
is that this is more simple circuit to do.
This is for example when mixing several microphones recordings, into one.
The drawback is, that you may need or want to invert back again
in some later stage.



If you are just building a normal line preamp,
with one signal input at the time
( even when you can select one of 5 different sources, with for example rotary switch )
I would suggest a non-inverting set up.

This way you will keep your signal in phase = normal, non-inverted.


lineup

[thanh]

Thank Lineup very much!

[lineup]

Originally posted by thanh
Thank Lineup very much!

Thanks, thanh

I guess you now about Rod Elliott ESP projects.
He has got several good preamplifiers using Op-Amps.
Project88 is well known at this forum.
Also he has got other preamps, with or without Tone Controls.
Most of us do not use tone controls (if we want hifi we may not want to 'change the sound').

Here is list of all different preamps projects.
I think lower numbers are older projects.
http://sound.westhost.com/projects-2.htm

==============================================
==============================================
Here is the SiteMap of ESP.
It is one of the best places for us DIY-ers
http://sound.westhost.com/site-map.htm

==============================================
==============================================

Also articles, guides & tutorials, like:

Opamps 1 Designing With Opamps I - What they are, what they do, and how they do it
Opamps 2 Designing With Opamps II - Audio applications, filters, crossovers, etc.
Opamps 3 Designing With Opamps III - More Filters, Specifications, Comparators, etc.

Enjoy

lineup