QSOURCES Infra-Qsources Qohm Istruzioni per l'installazione
INFRA-QSOURCES
User instruction
Qohm omni-directional mid frequency sound source
Date: 181115 – Batch Gamma
By: LMB - P GL, Qsources BVBA
Content:
1. Intended application
2. Placing the source on a stand or tripod
3. Connections and powering
4. Warranty and liability
5. Prevent damage
6. Specifications and conformity declaration
7. Questions and Answers
8. Shipment instruction
Please always use ear protection when working with this product.
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Ketelwinning 38 B-3290 Diest Belgium
Copyright Qsources BVBA
1. Intended application
The 12-driver sound sources are optimized medium fre-
quency measurement applications. The Qohm source easily
satisfies the ISO 140 and ISO 3382, ISO 16283-1 require-
ments.
The intended frequency range for high noise levels is from
the 50 Hz third octave band till the 16 kHz third octave
band. It is possible to use the source at lower frequencies,
with reduced level. Wide band signals like white noise,
pink noise, chirps etc. can be used as well as sine signals.
The source is intended for use indoors, or in any moderate
moisture and moderate temperature environment. If
exposure to splash water or severe humidity is
unavoidable, the source can be wrapped in a thin plasic
bag. But this will resitrict cooling and therefore the level
and/or duration of operation should be reduced.
If used for music reproduction, it is advised to keep the
Qohm sources clear of walls, floor by at least 1 meter for a
natural effect.
2. Placing the source on a tripod or other stand.
In most cases a light weight tripod is provided with the source. The lower stud of the source
fits to the these tripods. But the sources also have a 3/8 thread at two ends. The 3/8 tread is
commonly used on microphone stands.
A support or tripod can only support the source if the underground is stable and horizontal,
the spread of the legs is wide enough to allow the height, if the cables are protected against
tugging. And, any tripod can malfunction or slip. Make sure the set-up is secure.
The sources can also be placed on the circular handle, using it as a short support, but it should
only be done with the cable secured to the underground and only on a completely stable
underground.
3. onnections and powering
The sources as a standard have a neurik 2 pole socket.
To remove, turn the plug a few degrees and pull it out. The plug
should be easy to extract, when rotated at the right angle
The Qohm has a thermal switch that can prevent large damage
due to overheating. It will cut the power from the source during
20 to 30 minutes, depending on the ambient temperature, until
the speaker has cooled down sufficiently.
Caution: if the amplifier is still active the source may restart
unexpectedly after cooling down.
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Copyright Qsources BVBA
4. Prevent damage
We have implemented mechanical and thermal protections. These protection will allow
normal use of the sources for their intended application or for music replay at moderate
levels. But, the protection is not absolute, because that would restrict normal use.
A special environment, special signals or loud music signals, or a fault in the amplifier, or
another special situation, could cause damage. It is expected that the user remains vigilant and
the user remains responsibility to prevent damage.
A. Protect the source from impact loads in use and in shipment:
–
Secure the tripod and cable,
–
The provided soft-bag and felt pouches are not intended for shipment,
–
They will not prevent against a fall,
–
They are only intended for taking the source from office to car, from the car
to the site, etc,
–
For shipment see the added instructions at the end of this document.
B. If the sound from the source changes suddenly;
–
there is more than 3 dB loss of low frequency output,
–
the sound becomes clearly distorted,
–
a sharp or rattling noise occurs,
–
or some speaker parts come loose and visibly move
it probably indicates a beginning damage. In any of these cases further use should be suspen-
ded immediately, and it is advised to contact our support and/or send the source in for dia-
gnosis. Continued use when a beginning damage occurred will likely cause secondary damages
to all speakers and can cause out of warranty damages.
C. Do not expose the sources to:
–
water or other fluids
–
shocks in excess of a drop of 10cm height or equivalent
–
temperatures above 50 degrees Celsius
–
temperatures below -20 degrees Celsius
–
cirect sunlight over longer duration.(It will reduce the life span)
If exposure to rain/splash-water/severe humidity/overnight condensation/severe dust or
powder/etc. or garbage bag) is unavoidable, then the source can be used inside a thin plasic
bag. (Like a disposable shopping bag) at own risk. A thin plastic bag should never allow sub-
merging the source in water or excessive dust or powder. The lack of cooling in the bag will
reduce the maximum allowable sound power level substantially.
D. Do not place the sound sources on soiled surfaces.
Especially not on surfaces with metal scraps, -chips or
-powder. Still, If metal objects have accumulated on
the magnet, they should be removed as soon as pos-
sible. This can be done with adhesive tape or
putty/clay as shown in the photo.
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Ketelwinning 38 B-3290 Diest Belgium
Copyright Qsources BVBA
5. Technical specification*
Frequency range: 47-16000 Hz
Omni-directionality: +-1 dB from 50-1600 Hz
+-3 dB from 1600-2500 Hz
Sound power level: 123 dB SPL, 2 minutes**
116 dB SPL, 15 minutes**
Output level stability: better than 0.5 dB,
10 minutes at 116 dB**
better than 0.5 dB,
1.5 minutes at 122 dB**
Mounting thread: UNC 3/8-16
Dimension, weight: 27 cm diameter (+- 0,5 cm), 3.15 Kg (+-0,1 Kg)
Power requirement: 800 Watt RMS to 4 Ohm***
*These specifications may be adapted if necessary to improve the quality of the product.
**When driven with Qam generated low crest-factor pink noise at 22 Celsius ambient temperature or lower.
*** For maximum performance a dedicated power amplifier type Qam is available from Infra-Qsources.
The source output spectrum for white and pink noise in free field condition are shown below.
1/12 octave band spectra, white noise, pink noise octave band and 1/3 octave spectra white,pink noise
The sliding 30 degrees averaged directionality is given in the graphs below for 1/3 octave and
octave bands.
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Ketelwinning 38 B-3290 Diest Belgium
Copyright Qsources BVBA
6. Warranty and Liability
Qsources stands highly on product quality and provides two years full warranty on all supplied
materials, workmanship and early failure in normal use, from date of delivery, with the
following conditions:
Mechanical damages due to non-careful handling, transportation, excessive
environmental conditions, etc. are excluded from warranty.
Electric overload due to excessive voltage, overheating, are excluded from warranty
In case of a need of service under warrantee or other, the client is responsible for
shipment to and from Qsources in Belgium, insuring that the shipment does not incurr
taxes or other charges for the incoming and return shipment.
www.qsources.be
Ketelwinning 38 B-3290 Diest Belgium
Copyright Qsources BVBA
ISO
Declaration of conformity
Product:
Infra Qsources omni-directional mid frequency sound source
Model:
Qohm
Hereby is certified that the above mentioned product complies with the following
standards:
ISO 3382
ISO 140-3
ISO 140-4
ISO 16283-1
Responsible for this declaration is the producer
Qsources BVBA
Ketelwinning 38
3290 Diest Belgium
Declared by
P. . G. van der Linden
Diest, anuary 2016
www.qsources.be
Ketelwinning 38 B-3290 Diest Belgium
Copyright Qsources BVBA
7. Questions and Answers
How long does it take for the source to cool down?
If the source is used at the absolute maximum level > 122 dB, then it will typically run for 2
minutes before protection occurs. But this time could be longer or shorter depending on ambi-
ent temperature and the type of signal. The protection will typically take 12 minutes to recov-
er for a new test.
It is wise to turn the source on only for short periods during range selection and during tests;
Most of the users typically need only a measurement of 1/2 minute at maximum power, in
most cases. Then reposition microphone or source and again 1/2 minute test, reposition, 1/2
minute test, etc. In that way the temperature will not easily become critical.
How to notice the temperature protection?
When the temperature protection becomes active some lower level signal is still allowed to
go to the source. In that case the noise level is far below the normal maximum level, and
even more restricted when the power of the amp goes up. It allows the user knows that the
speaker still works when the temp protection has become active.
How do I recognize a malfunctioning temperature protection?
If the protection fails to switch, the speakers will overhead and some of the speakers will stop
working with fatal damage. They could also start rattling.
If the temperature protection acts too early, the head of the speakers still feels cold or luke-
warm, not hot. Also in this case service is at Qsources is needed.
What can I do when a longer continuous measurement duration is desired?
Do not try to cool the source with water nor with a ventilator pointed directly at the source.
These will cause damage. However, adding external cooling of the source with multiple fans is
an option. It is required to create a very even spread of the flow around the source fans. This
could extend the time up to 20%.
The effective measurement duration depends on the setting and the type of signal that is be-
ing used:
•very slow sine sweeps (slower than doubling the frequency every 10 seconds, or +- 1
minute for the full frequency range) are not advised because it may cause damage.
•Although uncommon to use, a slow sine sweep downwards in frequency is not advised
to use at all, because it can induce damage.
•as white noise (H) has the shortest active time at full power, we did some more tests
on this setting. It shows that a 2 dB lower sound power level can triple the possible
measurement time. We observed here: (the absolute duration may be different for
your source and/or test conditions)
- amp level 60, output 118 dB Lw, 2.5 minutes
- amp level 54, output sound power 117 Lw, 4.5 minutes
- amp level 51, output sound power 116 dB Lw, 7.5 minutes
•when using our own external signals, it is worthwhile to try best level-time combina-
tion before going on-site for tests
•for isolation or facade testing applications it is allowed to use multiple Qohm sources
at the same time. (Each with independent random signal) Then a lower setting on the
amplifier can be used, and the measurement time will increase significantly.
www.qsources.be
Ketelwinning 38 B-3290 Diest Belgium
Copyright Qsources BVBA
Can we use the source in a dirty environment?
Usage in dirty environment should always be done with extreme care and at own risk. We
here by provide some suggestions:
•Bring some foil or paper to place under the tripod and cables. And bring a plastic foil
or cloth to place over the equipment.
•If there is dust floating in the test space or light moisture, there is no problem. This
should also not require any cleaning after a few hours of tests.
•If you have trouble keeping you own clothes clean and dry because of dust, or water,
then you will need to protect the source with a enclosing thin plastic bag. (This is a
fairly normal procedure) This will take away 1 or 2 dB and limits the measurement time
to 1/3 of normal.
•If you forget the source in a dusty environment: gently blow the dust from the speak-
ers with a nozzle from a compressor. Do not use a vacuum cleaner, because it can easi-
ly damage the source. Never use full power from the nozzle at short distance! You can
also use a dry cloth.
•If you forget the source outside in the rain until it is soaked then let is dry at room
temperature. Do not place it against a heating. Drying will take two or three days. If
the amount of water was limited and reasonably clean, then the source may work well
again. Check this with a microphone near each individual speaker and compare the 3rd
octave band or narrow band curves. Place the source on a soft surface with one speak-
er upwards, and place the microphone at the magnet. Run the source at a relatively
low level. Measure spectrum at a fixed amplifier setting with pink or white noise. Re-
peat this for all speakers and compare the differences to the allowable spread within
the ISO standard. The spread should be well below the standard.
What to do when one or two of the twelve speakers, or the housing, is damaged?
To prevent damage amplification, it is necessary necessary to stop using the source immedi-
ately when a strange sound or loss of power occurs. To prevent follow-up damage. If you sus-
pect that one or more speakers, or the housing, is broken, then only use a very low level until
repaired or good functioning of all 12 speakers is assured. So never use the source a high out-
put level if you suspect damage.
In doubt, to verify, place the source on a soft surface with one speaker upwards, and place the
microphone at the magnet. Run the source at a relatively low level. Measure spectrum at a
fixed amplifier setting with pink or white noise. Repeat this for all speakers and compare the
differences to the allowable spread within the ISO standard. The spread should be well below
the standard.
Never continue to use the source if in broken condition. It will aggravate the damage and in-
crease the repair costs significantly, and can cause exclusion from warranty.
When using an external input signal, could I damage the Qohm source or the Qam amplifier?
The Qam amplifier input will withstand any type of normal signal coming from any
measurement device or computer on the headphone outlet. The ouput of the Qam amplifier
will just try to follow the input signal up to ss 0.35V.
However, if mains power is somehow in contact with the input, or if the power output of the
amplifier, or of another amplifier is in contact with the input BNC, then this will damage the
amplfier.
The Qohm sound source will also withstand normal test signal at a reasonable level in combi-
nation with a Qam amplifier. Many signals can be applied at maximum level of a Qam amplifier
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Copyright Qsources BVBA
until the source internal protection activates. But not every type of signal allows a maximum
level setting on the amplifier.
For example, not exhaustive, the following signals could lead to damage when applied with
maximum level, before the source internal protection activates:
–pulsed low frequency random or sine below 500 Hz, over-stroke
–sine signals below 300 Hz, over-stroke
–random noise or sine signals above 20000 Hz, local overheating
Over stroke; cone displacements above 8 mm peak-to-peak are audible as a sharp clicking
sound.
When using another type of amplifier, damage is possible if the peak voltage exceeds 70 V
ssph, even with normal test signals like sine, chirps, random.
The user should be careful not to exceed the short term power and prevent overstroke.
Could we use any power amplifier and signal source to drive a Qohm sound source?
In principle, any audio or public address or measurement amplifier for loads between 2 and 8
Ohm impedance can be used. And in principle any type of signal; random, music, sines, chirps
etc can be used.
Nevertheless, there are some risks or limitations when not using a Qam amplifier;
–An amplifier with rated output power of more than 1000 W at 4 Ohm load can
potentially damage a Qohm sound source. To be more precise, if the peak voltage
level exceeds 80 Volt sspk (single sided peak) thee Qohm can damage. This has not
happened so far at customers, to our knowledge, because this is rare and very high
power level for power amplifiers. Especially for portable material. But it is possible.
–Sine signals from external sources, applied at the maximum level of 80 Volt sspk will
quickly heat up the Qohm and trigger the internal protection.
–Clicks or short impulsive signals at 80 Volt sspk could potentially lead to mechanical
damage of the drivers. But these are not normally used for measurements.
–Amplifiers proposed by other measurement equipment manufacturers for
dodecahedron sound sources tend to have actual output power and voltage levels
which are significantly lower than the Qam amplifier. This means that even with a
smart choice of signals the maximum specification of the Qohm is not reached. But:
1. The sensitivity of the Qohm is as high or higher than other dodecahdron
currently on the market
2. Even with significantly lower rated electric power (like 250 Watt or 500
Watt) the output of the Qohm can still be above 120 dB LW, pink noise 50
5000 Hz.
–Some amplifiers, proposed by other measurement equipment manufactorers for do-
decahedron sources, actually connect two or more channels to the dodecahedron. The
Qohm uses one high power channel. So, in such a case only one channel should be
connected to the input speakon socket of the Qohm, and only the output power on
this one channel will contribute. Leaving the other channels unused ( open) will not
harm a normal amplifier.
www.qsources.be
Ketelwinning 38 B-3290 Diest Belgium
Copyright Qsources BVBA
INFRA-QSOURCES
Shipment protection instruction
Infra-Qsources sound sources & equipment
Date: 140619
By: P GL
Carrier personnel does not have the luxury,
nor attitude, to be careful even if boxes are
clearly marked “fragile”
www.qsources.be
Ketelwinning 38 B-3290 Diest Belgium
Copyright Qsources BVBA
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