Balanced Input Stage

Bukitoo · 10th March 2004, 10:59 PM

HI !!!!

I have a question for U guys.
Maybe you tried these solutions and want to share your experience.

I was looking for solutions for building my own guitar preamp, but I get to many "strutures".
One of them is the instrumentation amplfier. Another is using a differential pair as input.

Others solutions use a couple of transistors in many configurations.

I was wondering wich of those introduces less noise and distortion. Im very newbie

Thanks in advance !

Nelson Pass · 11th March 2004, 12:20 AM

If you want the ultimate in rejection, RF proofing, isolation
and so on, check out a Jensen transformer. You can find them
on Google, and they're in Hollywood and are very nice people.

till · 11th March 2004, 12:57 AM

Quote:

building my own guitar preamp

the input stage of you guitar amp, or a little preamp inside the guitar?

Bukitoo · 11th March 2004, 01:13 AM

I just try to design an external preamp.
But many posibilities!!

dalbjerg · 11th March 2004, 01:14 AM

First of all, it’s ok to bee confused.
I can understand that you have been looking at some “Instrument” amplifier circuits.
Those are not for music instruments. The name come from laboratory equipment and is often used in the input stage of measuring instruments.
For electrical guitar you use a singe-ended (“normal”) input and not a differential.

You should post your question in the Musical Instruments forum.
Here are a few good links to start building your own amp-
http://blueguitar.org
http://www.diyguitaramp.com
http://sound.westhost.com/projects-5.htm

If you can’t join them beat them.

GRollins · 11th March 2004, 03:03 AM

Oddly enough, you don't want a low distortion circuit for a guitar amp. The trick is to have enough of the right kind of distortion. It's not the same set of requirements as home audio.
Note that all the solid state pieces try to sound like tubes. All the classic amps, Vox, Fender, Marshall, etc. are tubed. The one exception to this is that sometimes a "clean" sound works well for bass. Never for guitar.
It's been a while since I've pawed through his archives, but Ned at www.triodeelectronics.com used to have a wide assortment of schematics, including guitar amps. Most if not all of them will be tubed, but they can give you ideas for topologies.
If you're wanting to go solid state you're going to be using a lot of opamps.
If you search the web, you can find schematics of various amps, although you'll have to go to a dozen different places to get a good overview.

Grey

10th March 2004, 10:59 PM	#1
Bukitoo diyAudio Member Join Date: Feb 2004 Location: Buenos Aires	Balanced Input Stage HI !!!! I have a question for U guys. Maybe you tried these solutions and want to share your experience. I was looking for solutions for building my own guitar preamp, but I get to many "strutures". One of them is the instrumentation amplfier. Another is using a differential pair as input. Others solutions use a couple of transistors in many configurations. I was wondering wich of those introduces less noise and distortion. Im very newbie Thanks in advance !

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11th March 2004, 12:20 AM	#2
Nelson Pass The one and only Join Date: Mar 2001	If you want the ultimate in rejection, RF proofing, isolation and so on, check out a Jensen transformer. You can find them on Google, and they're in Hollywood and are very nice people.

11th March 2004, 01:13 AM	#4
Bukitoo diyAudio Member Join Date: Feb 2004 Location: Buenos Aires	I just try to design an external preamp. But many posibilities!!

11th March 2004, 01:14 AM	#5
dalbjerg diyAudio Member Join Date: Jul 2003 Location: Denmark	First of all, it’s ok to bee confused. I can understand that you have been looking at some “Instrument” amplifier circuits. Those are not for music instruments. The name come from laboratory equipment and is often used in the input stage of measuring instruments. For electrical guitar you use a singe-ended (“normal”) input and not a differential. You should post your question in the Musical Instruments forum. Here are a few good links to start building your own amp- http://blueguitar.org http://www.diyguitaramp.com http://sound.westhost.com/projects-5.htm If you can’t join them beat them.

11th March 2004, 03:03 AM	#6
GRollins diyAudio Member Join Date: Feb 2001 Location: Columbia, SC	Oddly enough, you don't want a low distortion circuit for a guitar amp. The trick is to have enough of the right kind of distortion. It's not the same set of requirements as home audio. Note that all the solid state pieces try to sound like tubes. All the classic amps, Vox, Fender, Marshall, etc. are tubed. The one exception to this is that sometimes a "clean" sound works well for bass. Never for guitar. It's been a while since I've pawed through his archives, but Ned at www.triodeelectronics.com used to have a wide assortment of schematics, including guitar amps. Most if not all of them will be tubed, but they can give you ideas for topologies. If you're wanting to go solid state you're going to be using a lot of opamps. If you search the web, you can find schematics of various amps, although you'll have to go to a dozen different places to get a good overview. Grey

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