A microphone preamplifier or preamp is a device for amplifying a weak signal; it can be built-in (pre-amplifier circuit) or external (separate device). Is it needed? If yes, then to whom and why? And if you take it, which one? As always, we will understand the theory, features and give useful tips on choosing this device.
What is a preamplifier?
A preamplifier is a device that allows you to connect multiple audio or audio/video (A/V) sources to a single audio output signal. But what does this really mean to you?
A preamplifier is used to connect multiple source components, such as a CD player, DVD player, and Blu-ray player, to a single output signal that can be controlled through the amplifier. (We'll talk more about the differences between a preamp and an amplifier later.) When you use a preamp for this, it allows you to seamlessly switch between each source component without having to unplug one device to use another.
The lamp offers options
I turn on Deep Purple's "Last Concert In Japan". This untidy recording did not require any additional insulation or drive: on the contrary, the transparency of the passive path came in very handy. It was easy to see how the guitar and organ, playing riffs in sync, either merged into a single whole, creating hard rock power, or separated, leaving space for vocals. I want to emphasize: the lamp buffer makes virtually no difference in color; we are talking about interaction with the musical material. By the way, the vinyl rip of Nick Mason's "Fictitious Sports" album, which suffered from a lack of energy on many systems, acquired a little more clarity here in both modes.
If you decide to replace the tube with another one for a new sound color, there is a high probability that you will not stop there.
I’ll complete the list of soundtracks that sound the same with and without a buffer with the DSD version of Dead Can Dance “Within The Realm of a Dying Sun”. There, besides the above-mentioned change in volume, the magic lamp did not have any other effects. For balance, I’ll mention an album that was completely transformed by going through the lamp: David Byrne & Fatboy Slim “Here Lies Love”. In it, the bass began to pump as it should, and the vocal parts became closer and warmer.
Five inputs are enough for any relatively extensive system
As the experiment progressed and more and more recordings were listened to, statistics began to accumulate. It turned out that with high-resolution material, Saga basically remains neutral, and with compromise - CDs and rips from them - it offers options for improvement. Commendable quality.
What is the difference between a preamp and an amplifier?
As stated above, a preamplifier converts multiple input signals into a single output, which is sent to the amplifier. The amplifier, in turn, then sends this signal, as well as the necessary power to reproduce the sound, to your speakers.
It should be noted that both the preamp and amplifier will require their own power supplies. These are separate and distinct devices that often require the use of another to produce rich, high-quality sound. So, if you are choosing a preamp system, it is important that your amp works with the preamp you choose.
For what?
Optimal signal level without distortion is an important point in the recording process, when the ideal ratio between clean signal and noise is achieved. The purpose of a preamplifier is to amplify a weak signal to linear level, that is, to the level of the recording equipment signal. The fact is that the microphone signal is quite weak, so you need to “finish off” it with additional decibels (around 30-60 dB). Guitars also require amplification of their signal, but not as significant as a microphone (about 20-30 dB).
That is, amplification of the microphone and instruments during the recording process is necessary. If you are using an interface or mixing console, then you can get by with the internal preamp circuitry that is found on all such devices. Of course, the quality of the built-in preamplifiers varies between models and significantly depends on the price that is asked for a particular audio interface. That is, expensive audio cards have significantly better preamplifiers. But for the first steps in sound recording, for home studios, the quality of the built-in preamplifiers is quite sufficient.
Does it make sense then to buy a separate mic preamp? In pursuit of a high-quality signal - yes. Since microphone preamplifiers, as a separate device, most often (but not always) provide higher quality sound than those integrated into an audio interface, mixing console, etc. In addition, an external microphone preamplifier colors the sound, giving it some individuality and character, but this mainly applies to top-end models.
Why You Should or Shouldn't Use a Preamp with a Home Theater System
Now that you understand what a preamp and amplifier are for your home theater system, you may be asking yourself why you should or shouldn't invest in them. Let's take a look.
Why you should:
If you want a completely unique and custom home theater system that you have complete control over, then a preamp/amplifier combo is the best choice for you. Why? When choosing a preamp setup, you will need to select each component to use in your home theater system. From the preamp and amplifier to the speakers and subwoofer, every aspect of a home theater system must be carefully selected.
For those who want to go beyond standard 2.1 and 5.1 home theaters, the preamp offers much more. In fact, depending on the device you buy, you can expect even an 11-channel setup to consistently produce crystal clear audio. Some preamps also allow you to connect a subwoofer, making those deep tones even richer as your amp pushes the sound through the surrounding speakers.
With some of the best preamps, you can also stream your music. Wireless and Bluetooth capabilities, as well as HDMI, are becoming more common in preamplifiers.
Why you shouldn't:
If you're not entirely confident in your ability to create a working custom home theater, the preamp option may be too much. An A/V receiver is an electronic device that combines several functions into one device. Over-channel audio processing, video switching and amplification are some of the standard features of modern AV receivers. Modern technology has also made the A/V receiver more versatile, expanding its input jacks to support multiple source types, including RCA, HDMI, and sometimes even USB devices. While it's not exactly an all-in-one home theater system, it's much easier to purchase an A/V receiver instead of a preamp combo.
Additional functions
When buying a microphone preamplifier, first of all, of course, you need to listen and choose with your ears. But then it's worth plugging your head in and paying attention to some factors and features that may be useful to you.
- Number of inputs
refers to the number of microphones that can be recorded simultaneously. The bigger, the better.
- Low pass filter.
Its task is to cut low frequencies, which helps cut off various low-frequency interference.
- Phantom power
, which is necessary for the operation of condenser microphones. By the way, almost all models have it, but make sure of it, just in case.
- Built-in limiter (compressor)
, which is used to compress dynamic range. The limiter also helps to avoid unnecessary overloads. To be honest, this is not a particularly necessary feature, and sometimes it is not worth paying extra for it.
- Level indicators
– an optional feature for every preamplifier, but certainly useful. It's worth paying extra for it.
- Phase switch
will help cope with phase problems when you record several microphones at the same time.
- Equalizer
adjusts the frequencies of the sound signal before sending it to the sound card. Before purchasing, evaluate: do you really need this option?
Pros and cons of using a preamp over an A/V receiver
If you decide to use a preamp, you will likely have to purchase each home theater component separately. That being said, there are a number of pros and cons that you should consider before making this decision.
Pros of Using a Preamp Over an A/V Receiver
- By choosing a preamp, you have greater control over every aspect of your home theater system.
- The sound quality produced by a preamp/amplifier combination is often much better than that of an A/V receiver.
- Choosing a preamp expands your home theater's capabilities from 5 to 7, 8, or 11 channels depending on which model you buy. This means that in larger rooms it will be very useful to use a preamp/amplifier combination. This also means you have room to expand your home theater system over the years, although before you do, make sure you choose a room with proper lighting because it will save you a lot of time and energy. If it's already late, you can read our article on preventing excessive lighting.
- Manufacturers of preamps and amplifier systems are often clearer and more direct in their marketing of their products, resulting in fewer disappointments. Power supplies for these types of devices are usually well designed and provide constant, stable power to each channel. On the other hand, A/V receiver manufacturers often rate their products at 6 ohms. (The standard for home theaters, however, is 8 ohms.) This can lead to confusion when it comes to the power delivered per channel. In other words, that "160W" receiver you were considering can only provide about 50W per channel. This is because their power supplies often start to fail when you go beyond one or two channels.
Cons of Using a Preamp Over an A/V Receiver
- Since you need to purchase several components to use with a preamp, an A/V receiver is often the cheaper option.
- A/V receiver is more convenient; just connect your device and enjoy. By comparison, a preamplifier is much more complex.
- An audio/video receiver often takes up less space due to its versatility.
- If you're looking to buy used, older standard preamps may not be as good as comparable A/V receivers. The new models, however, do a great job of meeting today's industry standards, including HDMI capabilities.
Related questions
Can I attach speakers directly to the preamp? Most preamps do not have speaker terminals because they do not output power. If you're serious about connecting your speakers directly to your preamp, you'll need to purchase self-powered speakers with RCA input jacks.
I keep hearing about the control amplifier; Is this different from a preamp? No. In the electronics industry, preamplifiers are known by many names. Control amplifiers, audio/video processors, audio/video preamplifiers, and preamplifier processors are all types of preamplifier.
Can a preamp/amp combination be too big for the room? It's more a matter of personal taste. Small rooms can be well supported through the use of an audio/video receiver. However, as the space increases, the preamp/amplifier combination will provide much cleaner sound quality. Does this mean that a preamp is too much for a small space? Not necessary. For those with hearing problems, a preamplifier can be useful even in a smaller area. For those who have excellent hearing, a preamplifier may seem unnecessary.
Impedance matching
As mentioned, the second op amp IC1b is configured for unity gain, so its output (pin 7) must be connected to its inverting input (pin 6). Nevertheless, resistor R1 is shown in the OOS circuit. To reduce distortion, the “apparent” resistance at the inverting and non-inverting inputs must be equal. However, a volume control is connected to one input, the resistance of which varies.
If you install a jumper instead of R1, the distortion level will still be very low, see the characteristics graphs. If you want to minimize distortion as much as possible, measure the resistance of the volume control in the position in which you listen to music most often and install resistors R1 (R2) with this value.
Of course, to do this, you will first need to install jumpers and conduct some test listening on your path and after that... there is a suspicion that you will not want to change jumpers to resistances.
Conclusion
In general, choosing to use a preamp with an amplifier instead of an A/V receiver is a personal preference. Both systems will work well, it just depends on the level of control you want to maintain when it comes to selecting the various components. Check out our article on A/V Receivers and Amplifiers. This article will give you a better understanding of the key differences between these two powerful devices.
Recording source: https://thehometheaterdiy.com
Guitar preamp
Preamplifiers are made using tube, analog and digital circuits. There are also modeling and hybrid versions of preamps that combine the clarity and transparency of sound inherent in transistor devices, and at the same time, having the ability to color the sound with the characteristic warmth and richness of a tube preamplifier. In a modeling preamp circuit, unlike a hybrid one, the role of a real lamp is played by digital processing. Despite the huge selection, for many musicians the standard of high-quality sound is considered to be an all-tube preamp.
