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Electronic design and prototype development.

These are some selected examples of products, that I have been involved in designing, manufacturing or modifying for different manufacturers of PA equipment. Some products sold under my own brand name - PP - are also included.
The examples includes 2 channel 2-way / 1 channel 3/4-way modular active loudspeaker crossover network - PP type XO01, 1 channel 2, 3 or 4-way modular active loudspeaker crossover network - PP type CS01, cinema surround sound active subwoofer loudspeaker crossover network, low cost 2 channel 2-way active loudspeaker crossover network with sub-woofer output, direct inject box (linedriver or DIbox) - PP type DI02, 2-way passive high-power, low-weight crossover network for stage monitor, gramophone preamplifier with feedback canceling filter for PA and discotheque use - PP type RA03.

Active loudspeaker crossover network
2 channel 2-way / 1 channel 3/4-way crossover network, PP type XO01
Half-width 19" 1-unit modular loudspeaker crossover network. Extremely compact high-performance crossover network for PA and studio applications. The function of the XO01 is determined by the modules installed in it. Some features are transformer balanced inputs, 24 dB/oct. high-pass filter, 24 dB/oct. crossover filters, up to 4 band fixed equalizer on each output, limiter on each output and up to 4 channels 2-way crossover network in a single unit 19" rack space.
PP XO01 datasheet
2, 3 or 4 way PA loudspeaker crossover network, PP type CS01
19" 1-unit crossover network with 2, 3 and 4 way modes.
There are outputs for subwoofer, low-frequency, mid-range and high-frequency. On/off switches for the sub-woofer and high frequency sections selects the filter mode. When the sub-woofer is turned off, the low-frequency band will also reproduce the sub-woofer band. When the high-frequency is turned off, the mid-range band will also reproduce the high-frequency band.
Some key features are:
  • Each output:
    • Level control on front panel.
    • Mute switch.
    • Phase reversal switch.
    • Peak meter.
    • Limiter with side-chain link, adjustable under rear panel cover.
    • Optional output transformer.
  • Subwoofer output:
    • Selectable, separate input.
    • Input high-pass filter with selectable frequency and Q.
    • Subwoofer signal (and limiter side-chain) can be linked to other filters via link-cable.
  • Low frequency output:
    • Selectable delay for time-alignment with mid-range.
    • Adjustable equalizer for baffle reflection compensation.
    • Input high-pass filter with selectable frequency and Q.
    • Separate high-pass filter for subwoofer on/off modes.
  • Mid range output:
    • Selectable Constant-Directivity horn frequency response compensation.
    • Separate horn compensation for high-frequency on/off modes.
I have designed the circuits, the PCB, the mechanics and a PC controlled test procedure and manufactured and tested 50 filters.
Cinema surround-sound sub-woofer crossover network
The filter is based on a commercially available crossover network with plug-in filter modules.
The loudspeaker system has 2 satellite speakers with a single sub-woofer. The satellite speakers are able to handle the entire frequency range, but provides insufficient low-frequency output for the application. To maximize the low-frequency output, both the satellite systems and the sub-woofer reproduces the low frequencies. To obtain proper acoustical summation of the outputs from the sub-woofer and satellite systems, the filter contains a phase alignment for the satellite systems so that they are in phase with the sub-woofer over its operating frequency range.
I have designed the filter circuit and modified and tested 1 filter.
Low cost PA loudspeaker crossover network
19" 1-unit 2 channel 2 way crossover network with sub-woofer output.
The crossover network is built on a universal PCB, that can be loaded as required. Rather than saving on component quality, cost savings have been obtained by omitting all features that are not absolutely necessary for crossover operation.
The following filter functions are available:
  • 4 crossover filters with up to 24 dB/oct. filter slope.
  • 4 fixed 4 band equalizers for frequency response correction.
  • 2 delay and phase compensation filters.
I have designed the circuits, the PCB, the mechanics and a PC controlled test procedure and manufactured and tested 50 filters.
Direct Inject box
Direct Inject box, PP type DI02
Compact, phantom powered DI box, that provides the impedance- and level-matching required for a high-impedance music instrument signal to be connected to a mixing console's microphone input.
DI02's high-impedance input and its symmetrical, low impedance output insure that almost any high-impedance signal can be tapped and fed to a long microphone line without loss of signal quality.
DI02's heavy duty rectangular enclosure guarantees a long life on stage and allows easy packing of any number of units for transportation.
I have designed the circuits, the PCB, the mechanics and a PC controlled test procedure and manufactured and tested 150 linedrivers.
PP DI02 datasheet
Passive loudspeaker crossover network
Passive loudspeaker cross over network for high-power stage monitor
2 way 24 dB/oct. crossover network for a 15"/2" coaxial driver. The filter is designed in PSpice with driver models generated from level, phase and impedance measurements on the drivers. Measurements were made with Audio Precision System One and transferred to PSpice with my APXPS software. The filter is built with inductors wound on gapped toroid cores to save weight (total weight saving compared to air-wound inductors exceeds 10 Kg).
Pick-up preamplifier
RIAA amplifier with Feedback Canceling Filter PP type RA03
The feedback canceling filter reduce the acoustical feedback from the loudspeakers to the gramophone and enables up to 10 dB higher SPL before feedback becomes audible. The special differential filter adds the two channels to a mono signal at low frequencies. The idea of summing low frequencies into a mono signal to avoid feedback is not new, but all earlier implementations uses some sort of crossover network to extract low frequency information, adds the two channels and then add this signal into the stereo high-frequency signals. This topology gives an undesirable phase response and will in some cases make the acoustical feedback problem worse. The Feedback Canceling Filter uses a special differential filter that acts like a wire if it's input is a mono signal, but will add the low frequency content of the channels if they differ.
PP RA03 datasheet
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Product design
PCB lay-out
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Hi-Fi products
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Poul Petersen, C/Faya 14, 35120 Arguineguín, Las Palmas, Spain.
Tel/Fax: (+34) 928 152 807, Skype: poul.petersen.gc.
http://www.poulpetersen.dk, E-mail: pp@poulpetersen.dk
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