MASTERPLANT ATTENUATOR MKIV User manual

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masterplant
™
passive electronics, active sound
ATTENUATOR MKIV
Is there really need for another attenuator? Yes, if you believe that it is important to
keep the impedance constant. Any mismatch will affect the amps frequency
bandwidth and output power. It will also put unnecessary strain on your amp, and can
lead to damage of tubes and output transformer. This unit will keep the impedance
constant at both the input and output. This latest version have an impedance selector
added and separate full range and speaker simulated line outputs.
Constant impedance at input and output
150W power handling
Five steps of attenuation + variable
Full range and speaker simulated line out
Supports 4Ω-8Ω-16Ωamplifiers
Dual speaker out
•1= 0db (bypass)
•2= -3db
•3= -6db
•4= -9db
•5= -13db
•6= -17db (Load and variable position)

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DIRECT Recording
1) Connect amp speaker out to ATTENUATOR input
2) Set amp to match
3) Set Attenuator to position 6
4) Connect Line Out to computer audio card
5) Choose Full Range Line Out if using impulses.
Dry/Wet with attenuation
1) Connect left amp speaker out to ATTENUATOR input
2) Set amp to match
3) Connect ATTENUATOR speaker out to left speaker cab
4) Connect Full range Line Out to input of delay effect
5) Connect delay output of effect to right amp input
6) Connect right amp speaker out to right speaker cab

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Attenuator
1) Connect amp speaker out to ATTENUATOR input
2) Make sure your amp is matching your ATTENUATOR
3) Connect ATTENUATOR speaker out to speaker cab
4) Adjust attenuation level
FAQ
Can I use this unit with any amp or speaker?
It supports 4Ω-8Ω-16Ωamplifiers but the speaker out is fixed at 8Ω. 4Ωand 16Ω
cabs is usually safe for modern amps.
Can I crank my Marshall Superlead into it?
Yes, but I suggest that you remove a pair of output tubes if you intend to run it at full tilt for an
extended period.
Why not add a fan as other manufactures?
There are several reasons but an added fan will affect impedance and also add noise.
It would also make the unit larger, which had to be taken into consideration.
Is this unit safe to use?
Yes, if you make sure that your amp and speaker is matched to the ATTENUATOR. Modern
amps are much more tolerant to impedance mismatch so a 2-1 mismatch should be safe. If
you own a vintage 60’s amp and intend to crank it, I suggest that you do not mismatch.
Are there any other drawbacks to impedance mismatch?
Yes, even if your amp can handle it the tone and feel of your amp might change.

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Is there a Load position?
Yes, set it to Variable and then it is safe to remove the speaker.
In this mode, the speaker output can function as a second Line Out.
TECH SPEC
•Input Power: 150W
•Input:¼” phone 4Ω-8Ω-16Ω
•Attenuate: 6 position rotary switch + variable potentiometer
•Line Out Simulated:<100Ω¼” phone
•Line Out Full range:<600Ω ¼” phone
•Speaker Out: 8Ω¼” phone 2x
•Dimensions: L: 8,4” W: 6,5” H: 2” – L:213mm W: 165mm H: 50mm
•Weight: <2kg - 4.4lbs
Do not block the ventilation holes.
Avoid mismatching impedance as that will put unnecessary strain on your amp and
can lead to damage of transformers and tubes.
2 year limited warranty
The warranty applies to defective material and workmanship and for the original purchaser when
bought from MASTERPLANT or authorised dealer. Opening the unit will void the limited warranty and
any required service or update must be performed by MASTERPLANT. A copy of the original receipt
must be included with the unit. Warranty will not cover damage caused by misuse or accidents. It will
not cover any damage inflicted to other equipment resulting from impedance mismatching or any
other faulty use.