November 22, 2022

The Different between OTL and OCL Power Amplifiers

A power amplifier is a type of electronic amplifier which has the ability to turn low power sound signals from an electronic device into high power sound signals. Devices like electric guitars and radio receivers produce very low electronic sound signals. If you want to make these sounds loud enough for an entire audience to hear, then you’d have the power amplifiers send these high-power sound signals into one or more loudspeakers.

There are different types of power amplifiers available. The two most popular power amplifiers are OTL power amplifiers and OCL power amplifiers. The OTL amplifiers are output transformerless amplifiers and the OCL power amplifiers are output capacitor-less amplifiers. Let’s explore the difference between the two.

OTL Power Amplifier

The OTL power amplifier is a vacuum tube amplifier (or an output transformer-less amplifier). This means the flow of electric current is controlled by a vacuum that sits in the middle of two electrodes. There is no output transformer in an OTL power amplifier like there is in a traditional vacuum tube amplifier. The latter depends on an output transformer for coupling the output stage of the amplifier to the loudspeaker.

This is not the case with an OTL power amplifier, though. The OTL will either use capacitive coupling or direct coupling to couple the loudspeaker with the output stage of the amplifier. This is helpful for stopping high amounts of DC voltage that comes from the output section. That way, the direct electric current flow won’t cause damage to the loudspeaker or any of its electronic components.

Generally, vacuum tubes have high output impedance and loudspeakers have low impedance. The great thing about OTL power amplifiers is they level out and match the vacuum tube impedance to the loudspeaker impedance. This reduces any problems with the playback of the sound as it comes out of the loudspeaker.

OCL Power Amplifier

The OCL power amplifier is an “output capacitor-less amplifier” because it has direct-coupled capacitorless output capabilities. This could fall under any number of different amplifier classes. Basically, OCL power amplifiers are like push-pull output amplifiers. This means their electronic circuit contains two active devices which absorb electric current from an attached load and supply electric current to an attached load.

There are some pros and cons to using an OCL amplifier (which has no capacitor) versus an amplifier that is coupled with a capacitor. For instance, an OCL amplifier is a lot cheaper to purchase than an expensive output capacitor. An OLC amplifier is also less bulky as well. Best of all, the output power of an OCL amplifier is much greater when you have extremely low frequencies.

On the other hand, OCL amplifiers do waste a lot more power because they pass the DC signal directly through the entire load. But for all the power that is used, the results speak for themselves. You’ll hear much louder and clearer sounds coming out of the speakers. Since you’ll probably use the OCL amplifiers for special events and large gatherings, it’ll be worth using the extra power for this purpose.

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Conclusion

Both amplifiers will give you amazing results. Musical signals won’t have any coloration added to them and you’ll hardly hear any distortion in the sound playback. The largest musical dynamics will be achieved, along with natural harmonics.

If you’re looking to purchase an OTL amplifier or OCL amplifier, then get ready to pay anywhere between $3,000 and $15,000 for a high-quality model. These would obviously not be amplifiers you would want for private use. If you’re going to spend this kind of money, then you’ll want it for commercial purposes.

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