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Using the PRX150-Pro2, PRX150-DAG, DRX or SRX power attenuator with your tube amplifier

1. The ARACOM Attenuators are designed to be used only with tube guitar amplifiers, which means the output section of the amplifier has power tubes and an output transformer. The ARACOM Attenuators are not designed for use with a solid state amplifier or an amplifier that utilizes preamp tubes with a solid state power amplifier section.

2. The ARACOM Attenuators are designed to handle a continuous 150 watts and therefore it is capable of handling the actual power out from most quad amplifiers. A quad amplifier is defined as an amplifier equipped with 4 power tubes. These amplifiers will often have a manufacturer's rating of 100 watts. However the measured fully "cranked" power (volume on max) can be up to 140 watts or even more.

Keep in mind, the ARACOM Attenuators are not designed for use with amplifiers equipped with 6 power tubes often labeled as 150 watt amplifiers, since some of these amplifiers are capable of putting out well over 200 watts.

3. If your amplifier meets the requirements of 1 and 2 above, then the ARACOM Attenuators can handle the power from your cranked up amplifier.

However prior to using the ARACOM Attenuators, you should have already tested your tube amplifier at the maximum volume setting (power out) that you intend on playing your amp, to ensure your amplifier can handle the additional stress at that power setting. This means playing your amplifier straight into a speaker cabinet for an extended period of time at your intended maximum volume setting. For example; let say you have a non-master volume controlled amplifier and you intend on playing it with the Volume Control on 10 with the ARACOM Attenuators, then first ensure the amplifier can handle the stress of being played full out for an extended period of time straight into the speaker cabinet, without the attenuator in the loop.

You should be aware that there is additional stress on your amplifier, when playing the amplifier flat out, with or without an attenuator. When your amplifier is played wide open, maximum current will be flowing through parts of the amplifier's circuitry, power transformer, output transformer, and the output tubes. A byproduct of the maximum current flow, is maximum amount of heat generated by; the tubes, the power and output transformer, and certain parts of the amplifier's circuit. There is maximum stress on the amplifier's components when it is operated at full volume. An amplifier being run wide open can fail with or without the use of a power attenuator, due the additional stress at these operating conditions. Some tube amplifiers will blow a fuse when operated flat out, with or without the use of a power attenuator. If you have never run your amplifier flat out straight into a speaker cabinet for an extended period of time, then you do not actually know if your amplifier can handle this type of stress. Keep in mind, while many guitar amplifiers are very robust, not all can handle the stress of being played wide open.

Some vintages amps have output transformers that were not designed for the amp to be fully turned up and played for an extended period of time. For example, some vintage amplifiers used output transformers that are underrated for the power the amplifier is capable of producing when it is fully cranked up. Many vintage amps used output transformers that were designed to handle only their "audio" (clean) power levels. A lot of vintage amps were designed to produce clean tones and were not specifically designed to be turned up for maximum distortion. For example; a vintage amp might have an output transformer designed to handle 10 watts, since this specification would be more than enough to handle the amp set for a clean tone. However, when fully cranked, the amplifier might be capable of putting out 15 watts or more.

If the vintage amp is run at or near its maximum power capability for an extended period of time, the underrated output transformer could overheat and fail. The same could happen if a boutique amp is using an output transformer built to vintage specifications.

Also, running an amp flat out with or without an attenuator will normally reduce the life of the output tubes, since maximum current is flowing and maximum heat is being generated during this condition. If your amp should happen to have a marginal power tube, the tube might operate fine at lower power levels and then could exhibit problems or fail with the amp cranked up with maximum current flowing through the tube. The same could be true for any marginal component in the power tube section of the amplifier.

For amplifiers equipped with a Master Volume (MV) Control, there is a benefit to backing off the MV Control a bit, instead of having it on "10". When the MV Control turned down a bit (with or without an attenuator), there is less current going through the power tubes and therefore, the power tubes are generating less heat. The power tubes are stressed less and therefore, they might last longer. There is also less stress to the output transformer and power supply section of the amplifier.

The following article has more information on using the ARACOM Attenuator with an amplifier equipped with a Master Volume Control:

ARACOM Attenuator - Master Volume Amplifiers - Article

Note: Using the ARACOM Attenuators or any power attenuation device might void the warranty on your amplifier. Therefore, it is recommended that you check with the manufacture of your tube amplifier to get their statement about using the amplifier with a power attenuation device.

We suggest that you consider the above information before using your amplifier with the ARACOM Attenuators or any power attenuation device.

Use the ARACOM Attenuators attenuator at your own risk.

Related Pages:

PRX150 vs PRX150-DAG Product Page

The PRX150's Advantages

DRX Attenuator Product Page




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