There are aprently a number of popular basic theorectical designs for pre-amps. When a manufacturer sets out to design a pre-amp, I su ppose they firsts pick a basic type. Why? What is it about these basic dessigns that would make any of the a better choice for a desired result. For instance, why select a tube or solid state design. Why a transformer of transformerless design.
Describe the most used pre-amp designs and how do they differ.
- Thread starter Jeroleen
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well i could tell you that the most use pre amp design is probably the Neve 1073...these things have a transformer on the input and the output...the transformers alone from sowter cost 60 each thats a total of 120 not to mention shipping etc... so the transformers on a nevesque gear is as much as a DMP3 or a VTB-1 in its entirety...that about all i can say about that subject..
longsoughtfor
Searching for the sound
This is a grossly over simplified answer: But basically there are two main approaches to pre amp design: Discrete and IC.
A discrete pre amp is made up of discrete components typically transistors, resistors, inductors and capacitors.
The circuit topology generally involves a couple of gain stages and may or may not include EQ. These amps typically use
transformers on the input and output. Discrete pre amps are almost always what is in "Vintage" gear... Neve et al.
This group would also include tube circuits where the tubes function in a similar fashion as the transistors. Discrete
amps tend to sound "warmer" because of inherent distortion in the gain stages.
Integrated Circuit based pre amps are what is found in a vast majority of new gear on the market today. These pre's
are built around IC Op-amps that require far fewer parts making them cheaper to build then a discrete amp. Because IC OP-amps have a
very high input impedance, they typically do not require input transformers again saving money. These amps are "cleaner"
sounding typically. As with anything else, there are a number of different Op-amp's used by different vendors. Depending
on the cost target of the device, they may choose really nice ones or really crappy ones and because the
pinnout of these devices are often identical, in many cases replacing the IC's in a pre amp with a device that has
better performace can improve the sound of the amp.
I have also seen a third catagory that is a hybrid of the two. An input transformer feeding a discrete stage followed by an IC.
Cheers
Kevin.
A discrete pre amp is made up of discrete components typically transistors, resistors, inductors and capacitors.
The circuit topology generally involves a couple of gain stages and may or may not include EQ. These amps typically use
transformers on the input and output. Discrete pre amps are almost always what is in "Vintage" gear... Neve et al.
This group would also include tube circuits where the tubes function in a similar fashion as the transistors. Discrete
amps tend to sound "warmer" because of inherent distortion in the gain stages.
Integrated Circuit based pre amps are what is found in a vast majority of new gear on the market today. These pre's
are built around IC Op-amps that require far fewer parts making them cheaper to build then a discrete amp. Because IC OP-amps have a
very high input impedance, they typically do not require input transformers again saving money. These amps are "cleaner"
sounding typically. As with anything else, there are a number of different Op-amp's used by different vendors. Depending
on the cost target of the device, they may choose really nice ones or really crappy ones and because the
pinnout of these devices are often identical, in many cases replacing the IC's in a pre amp with a device that has
better performace can improve the sound of the amp.
I have also seen a third catagory that is a hybrid of the two. An input transformer feeding a discrete stage followed by an IC.
Cheers
Kevin.
Jeroleen said:
From an engineering standpoint, you have to go back in time.
The original pre-amps designed in the 40s, 50s and early sixties were using the only available methods. Tubes were it. Transformers were it. Period. No choice in the matter. All that vintage stuff was designed for functionality above all else. Many studios built their own equipment and they were essentially one-offs to more than a few. Today, the design approach is to design using new methods and modern electronics for sale at many pricepoints. The vintage designers never intended the pro studio equipment to be sold to the home studio crowd. Transformers are expensive and give a colored sound that you like or hate. Transistors give a clean uncolored sound that you either like or hate. Then there are the vintage copiers who re-create the vintage sound using tubes and starved plate designs. Hell, people were scrambling around long ago for John Hardy to replace those crappy Neve pre-amps with his own design. This vintage kick is a snob appeal thing like having a Mercedes Benz for a doctor. Most super-high-end pro pres today will kick a Neve pre senseless. But, like rolex and Mercedes, Neve has become the "thing to have" As we die off, the new group of recording buffs will remember their childhood and get teary-eyed over Alesis ADATS and all the other wonderful stuff that will be vintage "must-haves"