Harley Benton PA-250 Power Attenuator User Manual
- June 12, 2024
- Harley Benton
Table of Contents
PA-250
Power Attenuator
User Manual
General information
This user manual contains important information on the safe operation of the
device. Read and follow all safety notes and all instructions. Save this
manual for future reference. Make sure that it is available to all persons
using this device. If you sell the device to another user, be sure that they
also receive this manual.
Our products and user manuals are subject to a process of continuous
development. We there‐ fore reserve the right to make changes without notice.
Please refer to the latest version of the user manual which is ready for
download under www.thomann.de.
1.1 Further information
On our website (www.thomann.de) you will find lots of
further information and details on the following points:
| Download | This manual is also available as PDF file for you to download. |
|---|---|
| Keyword search | Use the search function in the electronic version to find the |
topics of interest for you quickly.
Online guides| Our online guides provide detailed information on technical
basics and terms.
Personal consultation| For personal consultation please contact our technical
hotline.
Service| If you have any problems with the device the customer service will
gladly assist you.
1.2 Notational conventions
This manual uses the following notational conventions:
Letterings: The letterings for connectors and controls are marked by
square brackets and italics.
Examples: [VOLUME] control, [Mono] button.
1.3 Symbols and signal words
In this section you will find an overview of the meaning of symbols and signal
words that are used in this manual.
| Signal word | Meaning |
|---|---|
| DANGER! | This combination of symbol and signal word indicates an immediate |
dangerous situation that will result in death or serious injury if it is not
avoided.
CAUTION!| This combination of symbol and signal word indicates a pos‐ sible
dangerous situation that can result in minor injury if it is not avoided.
NOTICE!| This combination of symbol and signal word indicates a pos‐ sible
dangerous situation that can result in material and environmental damage if it
is not avoided.
Warning signs| Type of danger
---|---
| Warning – high-voltage.
| Warning – danger zone.
Safety instructions
Intended use
This device is used to attenuate the output level of guitar amps. Use the
device only as described in this user manual. Any other use or use under other
operating conditions is consid‐ ered to be improper and may result in personal
injury or property damage. No liability will be assumed for damages resulting
from improper use.
This device may be used only by persons with sufficient physical, sensorial,
and intellectual abilities and having corresponding knowledge and experience.
Other persons may use this device only if they are supervised or instructed by
a person who is responsible for their safety.
Safety
DANGER!
Danger for children
Ensure that plastic bags, packaging, etc. are disposed of properly and are not
within reach of babies and young children. Choking hazard! Ensure that
children do not detach any small parts (e.g. knobs or the like) from the unit.
They could swallow the pieces and choke! Never let children unattended use
electrical devices.
DANGER!
Electric shock caused by high voltages inside
Within the device there are areas where high voltages may be present. Never
remove any covers. There are no user-serviceable parts inside. Do not use the
device if covers, protectors or optical components are missing or damaged.
CAUTION!
Possible hearing damage
With loudspeakers or headphones connected, the device can produce volume
levels that may cause temporary or permanent hearing impairment. Do not
operate the device permanently at a high volume level. Decrease the volume
level immediately if you experience ringing in your ears or hearing
impairment.
NOTICE!
Operating conditions
This device has been designed for indoor use only. To prevent damage, never
expose the device to any liquid or moisture. Avoid direct sunlight, heavy
dirt, and strong vibrations. Only operate the device within the ambient
conditions specified in the chapter ‘Technical specifications’ of this user
manual. Avoid heavy temperature fluctuations and do not switch the device on
immediately after it was exposed to temperature fluctuations (for example
after transport at low outside temperatures). Dust and dirt inside can damage
the unit. When operated in harmful ambient conditions (dust, smoke, nicotine,
fog, etc.), the unit should be maintained by qualified service personnel at
regular intervals to prevent overheating and other malfunction.
NOTICE!
Damages caused by the connection to an enabled amplifier
Always connect the device to a disabled amplifier, otherwise the amplifier may
be damaged.
NOTICE!
Possible staining
The plasticiser contained in the rubber feet of this product may possibly
react with the coating of your surface and after some time cause permanent
dark stains. In case of doubt, do not put the rubber feet directly on the
surface and use a suitable underlay if neces‐ sary, i.e. felt pads or similar.
Features
Power soak for tube amplifiers, ideal for use in rehearsal rooms, recording studios and on stage.
- Power consumption: max. 250 W
- 8 Ω option, 16 Ω option
- Power supply via amplifier
- Inputs: amplifier, optional power adapter
- Outputs: PA equipment/mixing console (low impedance), line, speaker
- Controls: speaker level, line level, fine level
- Silent fan
Connections and controls
1| [BY PASS] | toggle switch for disabling the power reducer. The LED lights.
The signal is output just as loud as if the speaker was connected directly to
the amplifier.
---|---
2| [POWER (db)] | rotary control for adjusting the volume of the signal at the
speaker output when the device is working as a power attenuator.
Turn this control clockwise to reduce the volume of the output signal in steps
of 2…3 dB. Turn the control to ‘–15’ to enable the rotary control [FINE].
3| [POWER] | status LED. The LED lights up when the device is working as a
power attenuator.
4| [8 Ω / 16 Ω] | rotary control for setting the impedance. The corresponding
LED lights.
The impedance must be set to the same value on the Power Attenuator, on the
connected amplifier and on the speaker.
5| [FINE] | rotary control for adjusting the effective signal volume at the
speaker out. The [FINE] LED lights up when the [FINE] control is activated
(see point 2).
Turn the control clockwise to reduce the output signal volume in steps of 4…5
dB up to ‘–∞’ (no sound). If you turn the
control to ‘–15’ , the effective volume is –15 dB less than the not-attenuated
volume.
6| [LOAD] | toggle switch for operating mode selection
In the upper position, the device works as a load box (load resistance for the
amplifier, without signal at the speaker output) and the [LOAD] LED lights up.
In the lower position, the device works as a power attenuator (power reducer)
and the [POWER] LED lights up.
7| [BALANCED OUT] | low-impedance XLR output for connecting PA equipment or a
mixing console
8| [GND LIFT] | switch for disconnecting the grounding to avoid unwanted hum
noises caused by ground loops
9| [LINE OUT] | Line output for connecting PA equipment or a mixing console
The LED [OUT] lights when PA equipment or a mixing console is connected.
10| [LINE LEVEL] | rotary control for adjusting the signal volume at the line
out
11| [POWER] | input socket for an optional power adapter
If you want to run the LEDs and the fan permanently stable, you can use an
optional power adapter as power supply.
12| [AUX POWER] | status LED. LED lights when the device is operated via an
optional power adapter.
13| [INPUT FROM AMP] | input socket for connecting an amplifier
The impedance must be set to the same value on the Power Attenuator and on the
connected amplifier.
Connect the device always to the disconnected amplifier, otherwise the
amplifier may be damaged.
The device is powered by the amplifier. The more powerful the amplifier, the
faster the fan runs and the brighter the LED lights up.
14| [8 Ω / BY PASS / 16 Ω] | status LED. The LED lights when the function is
activated.
15| [OUTPUT FROM SPEAKER] | output socket for connecting a passive speaker box
4.1 Connection options
Technical specifications
| Max. input power handling | 250 W |
|---|---|
| Input connections | Amp |
| Power supply | Input socket for an optional power adapter |
| Input impedance | 80,160 |
| Output connections | PA equipment/mixing console |
| Line | 1 x 1/4″ jack socket |
| Speaker | 1 x 1/4″ jack socket |
| Voltage supply | via amplifier |
optional: external power adapter, 100 ∼ 240 V … 50/60 Hz operating voltage: 9
… 24 V ****, 300 mA, centre negative
Dimensions (W x H x D)| 235 mm x 88 mm x 179 mm
Weight| 2.7 kg
Ambient conditions| Temperature range| 0 °C…40 °C
Relative humidity| 20 %…80 % (non-condensing)
Further information
| Noise reduction | no |
|---|---|
| DI output | yes |
| Speaker simulation | no |
| Dummy Load | yes |
Plug and connection assignment
Introduction
This chapter will help you select the right cables and plugs to connect
your valuable equip‐ ment in such a way that a perfect sound experience is
ensured.
Please note these advices, because especially in ‘Sound & Light’ caution is
indicated: Even if a plug fits into the socket, an incorrect connection may
result in a destroyed power amp, a short circuit or ‘just’ in poor
transmission quality!
Balanced and unbalanced trans‐ mission
Unbalanced transmission is mainly used in semi-professional environment and
in hifi use. Instrument cables with two conductors (one core plus shielding)
are typical representatives of the unbalanced transmission. One conductor is
ground and shielding while the signal is trans‐ mitted through the core.
Unbalanced transmission is susceptible to electromagnetic interference,
especially at low levels, such as microphone signals and when using long
cables.
In a professional environment, therefore, the balanced transmission is
preferred, because this enables an undisturbed transmission of signals over
long distances. In addition to the conduc‐ tors ‘Ground’ and ‘Signal’, in a
balanced transmission a second core is added. This also transfers the signal,
but phase-shifted by 180°.
Since the interference affects both cores equally, by subtracting the phase-
shifted signals, the interfering signal is completely neutralized. The result
is a pure signal without any noise inter‐ ference.
1/4″ TS phone plug (mono, unbalanced)
| 1 | Signal |
|---|---|
| 2 | Ground, shielding |
1/4″ TRS phone plug (mono, bal‐ anced)
| 1 | Signal (in phase, +) |
|---|---|
| 2 | Signal (out of phase, –) |
| 3 | Ground |
XLR plug (balanced)
| 1 | Ground, shielding |
|---|---|
| 2 | Signal (in phase, +) |
| 3 | Signal (out of phase, –) |
| 4 | Shielding on plug housing (option) |
Cleaning
Device parts
Clean the externally accessible device parts regularly. The frequency of cleaning depends on the operating environment: wet, smoky or particularly dirty surroundings can cause more accumulation of dirt on the device parts.
- Clean with a soft dry cloth.
- Stubborn stains may be removed with a slightly damp cloth.
- Never use cleaners containing alcohol or thinner.
Fan grids
The fan grids of the device must be cleaned of any contamination, such as
dust, etc. on a reg‐ ular basis. Before cleaning, switch off the device and
disconnect mains-operated devices from the mains. Only use pH-neutral,
solvent-free and non-abrasive cleaning agents. Clean the unit with a slightly
damp lint-free cloth.
Protecting the environment
Disposal of the packaging mate‐ rial
For the transport and protective packaging, environmentally friendly
materials have been chosen that can be supplied to normal recycling.
Ensure that plastic bags, packaging, etc. are properly disposed of.
Do not just dispose of these materials with your normal household waste, but
make sure that they are collected for recycling. Please follow the notes and
markings on the packaging.
Disposal of your old device
This product is subject to the European Waste Electrical and Electronic
Equipment Directive (WEEE) in its currently valid version. Do not dispose with
your normal household waste.
Dispose of this device through an approved waste disposal firm or through your
local waste facility. When discarding the device, comply with the rules and
regulations that apply in your country. If in doubt, consult your local waste
disposal facility.
Thomann GmbH
Hans-Thomann-Straße 1
96138 Burgebrach
Germany
Telephone: +49 (0) 9546 9223-0
Internet: www.thomann.de
21.10.2022, ID: 510412 (V4)
References
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