Rockford Fosgate PUNCH PR-250 IIR User manual

PUNCH PR-250 IIR
INSTRUCTION MANUAL

Dear Customer:
Congratulations on your purchase of America’s finest car audio components. At Rockford
Fosgate we are committed to musical reproduction at its best, and we are pleased you chose
our product. Through years of engineering expertise, hand craftsmanship and critical
testing procedures we have produced a wide range of products that reproduce music
with
all the clarity and richness you deserve.
For maximum performance we recommend you have your new Rockford Fosgate product
installed by an Authorized Rockford Fosgate Dealer, as we provide specialized training
through Rockford Technical Training Institute (RTTI). The length and nature of your
warranty are dramatically affected if you install the product yourself. Please read your
warranty and retain your receipt and original carton for possible future use.
For your musical enjoyment, Rockford Fosgate offers everything from two channel
Punch
®
amplifiers, the more powerful four channel Power amplifiers, to three lines of
speakers: Pro Series, The Punch
®
, and Series One
™
. In addition, we offer two-, three- and
four-way speaker systems, and subwoofer and full range enclosures. For sound reproduc-
tion at its best, we offer signal processors: equalizers, pre-amps, and crossovers.
To insure overall installation quality, Rockford provides top quality wire, connectors,
carpet, grille cloth, “Colours” speaker grilles and amplifier shrouds, high output
alterna-
tors, and many more accessories through our Perfect Interface division.
To add the finishing touch to your new Rockford Fosgate image, order your Rockford
P.0.P. which includes everything from t-shirts and jackets, to key chains and neon hats.
To get a free brochure on Rockford Fosgate products and Rockford P.O.P., please call 602-
967-3565 or FAX [phone].
And Remember. . .
PRACTICE SAFE SOUND™
CONTINUOUS EXPOSURE TO SOUND PRESSURE LEVELS OVER 100dB
MAY CAUSE PERMANENT HEARING LOSS. HIGH-POWERED AUTOSOUND
SYSTEMS MAY PRODUCE SOUND PRESSURE LEVELS WELL OVER130dB.
USE COMMON SENSE AND PRACTICE SAFE SOUND.

IN CASE OF DIFFICULTY
PROBLEM
Short Stop
Circuit
Activated
Fuse Blows
Noise Pickup
From Alternator
Or ignition
Distorted Sound
Overheating
CAUSE/CURE
1. Speaker wires shorted or grounded to each other or car
body.
2. Less than 3 ohm speaker load.
3. Power ground incorrect.
4. Recheck installation instructions.
1. Power and ground wires reversed.
2. Unit incorrectly wired: refer to diagram.
3. Recheck installation checklist.
1. Run power lead (direct to “+” battery terminal).
2. Black ground wire should be grounded close to where
power-amp is mounted. Must be good solid ground.
3. Radio modified incorrectly for hi-impedance output. Shield
must not touch case, only ground side of volume control.
4. Dress audio cables away from large power and ground
wires, or automobile cabling.
5. If noise only happens on tape player, it’s possible the noise
is being induced directly into the tape head from automo-
bile wiring. Re-locate.
6. Insert choke in power lead to radio/tape unit. In stubborn
cases, try noise suppression at the source alternator and
ignition coil.
7. When all else fails, insert a high current choke, Fosgate
part #FA-505, in the power lead to battery.
8. Recheck installation checklist.
1. Check for shorted or grounded speaker wires.
2. If input signal is large, the input level control may have to
be adjusted.
3. If there is a wiring problem, the unit may be oscillating and
causing the power supply to go into overload protection.
4. When this happens, the L.E.D. indicatorwill be dim. Check
wiring per diagram.
5. Recheck installation checklist.
1. Lower than 3 ohm load.
2. Re-mount for better air flow.
3. Too small wire to battery.
4. Recheck installation checklist.

DESCRIPTION
The Punch PR-250 IIR equalizer/power amplifier was designed
to provide true state-of-the-art sound in cars, vans, boats or
anywhere a 12 volt storage battery is available.
Extensive field research using spectrum analyzer and pink noise
techniques has proven that all speakers suitable for this appli-
cation roll off characteristics at one or both ends of the audio
spectrum.
Conventional tone controls can only partially correct for these
deficiencies.
Typically when the bass control setting is increased to bring up
the low bass, the mid bass is also increased. This produces a
large “mid-bass bulge,” resulting in a “boomy boxy” sound.
Treble controls rarely correct the high frequency roll off correctly
because different types of speakers start to roll off at different
frequencies and the tone control has only one curve.
The Punch has combination equalizer settings that will
complement virtually any good speaker. The overall frequency
response of your system as heard by the ear will be much
improved. Music material recorded at the same relative loudness
in lows, midrange and high will not be heard in their proper
perspective.
SHORT STOP
Your PR-250 IIR is virtually immune to blowouts from shorts or
overloads because of Fosgate’s exclusive Short Stop begins
operating with computer logic to monitor the power supply output
voltage. If it fails to attain the proper level within one-quarter
second, Short Stop shuts the entire system off. It then activates
a timing circuit that restarts and stops The Punch at one-second
intervals. When the short or overload has been eliminated, your
PR-250
IIR resumes normal operation.
Short Stop performs in the same way to monitor and protect
output transistor current flowing from The Punch.
1

INSTALLATION
Experience has proven that only technically inclined users who
have the proper tools and mechanical ability should attempt to
install the unit themselves.
If you do not feel confident or if you have an unusual installation
situation, have the unit professionally installed.
IMPORTANT: To prevent alternator and ignition noise pickup,
the power and ground connections MUST be wired exactly as
indicated in the Power and Ground Sections on pages 3 and 4.
Do not run the ground connection direct to the battery.
MOUNTING
The PR-250 IIR comes in two parts. The preamp equalizer is
miniaturized so it can be mounted underdash or in dash and not
lookout of place. The power amplifier is intended to be mounted
where it is out of sight. When considering locations for mounting
the power amplifier, keep in mind that it dissipates a considerable
amount of heat and must be mounted horizontally.
Never mount in a confined area or with the heatsinks directly
against any other surface, since this will cause damage to the
unit from excessive temperatures.
NOTE: Units that fail when improperly mounted will not be
repaired under warranty.
After the desired mounting locations have been found, mount
with the #8 sheet metal screws provided.
SPEAKER MOUNTING
~The speakers you select and the way you install them will
~
determine to a great extent how the system will sound. The
~ Punch has a considerable amount of low frequency boost
~ available and even fairly small diameter speakers will sound
~ good. However, the larger the diameter, the greater the power
that can be produced in the low bass range. Where possible use
6” x 9” or 8” round speakers or larger. It’s very important to use
speakers with a wattage rating large enough to prevent speaker
damage (50 watts RMS is recommended).
2

Full range speakers or separate woofers and tweeters may be
used. For optimum bass response the low frequency driver
must be mounted so the sound wave radiated from the rear of
the speaker cone cannot get back to the front of the speaker and
cancel the front wave. The best location in a sedan is the rear
deckwhere the trunk becomes a large, infinite baff le enclosure.
Other locations such as doors or rear-seat side panels will
provide satisfactory performance.
When using separate rear mounted woofers and front mounted
tweeters, you might want to consider wiring in a “crossfired”
configuration. This means the right woofer and the left tweeter
are connected to one channel and the left woofer and right
tweeter are connected to the other. This will add a spacious
quadraphonic effect to the sound and make stereo balance less
critical.
WIRING
All wiring connections to the battery, speakers, radio and/or
tape player must be made exactly as indicated in the wiring
diagrams located on page 6. Failure to wire the unit in this
manner will cause serious problems with noise pickup and
distortion, or even equipment failure.
Keep all audio cables away from speaker, power, and ground
wires as well as automobile wiring cables. Noise can be picked
up even though the cables are shielded.
NOTE: Do not remove the white 9-pin connector or fuse holder
from the power amplifier. Doing this will void the warranty.
POWER CONNECTION
Run the white wire with the in-line fuse through the firewall direct
to the positive battery terminal. This insures a power connection
with low voltage loss and a minimum of ignition and alternator
noise pickup. If the white wire must be spliced, use
#12 gauge
or larger wire. Do not use larger than 12 Amp medium blow type
3 AG fuse provided or the circuit will not be adequately
protected.

GROUND CONNECTIONS
Connect the black wire from The Punch to ground at the
dashboard, firewall, or car body where the power amplifier is
mounted.
NOTE: It is extremely important to connect the ground in the
above manner or ground loops will result in noise pickup.
SPEAKER CONNECTIONS
For wiring to 4 ohm woofers, use 18 gauge wire if less than 6
feet, Use 16 gauge wire if longer than 6 feet. Use 18 gauge wire
to tweeters.
Observe polarity so each channel is in phase. Do not ground
speaker wires to car body because ground loop will result in
noise pickup and unstable operation.
WARNING! Do not put less than 3 ohm speaker load on each
channel.
SIGNAL SOURCE CONNECTIONS
For flexibility of installation The Punch has the ability to accept
either high or low impedance inputs. In order to obtain top
performance, high impedance inputs should be used.
HIGH IMPEDANCE INPUT
Using high impedance inputs from the tape/radio unit to The
Punch results in optimum performance in terms of low distor-
tion, wide frequency response, and signal to noise ratio. Units
that do not have high impedance line level outputs may be
modified. See “Modification Instructions For High Impedance
Output Jacks” (p. 5).
NOTE: A very small percentage of auto radios may oscillate
with no load across their speaker terminals. This usually
sounds like a low frequency “tone” even when the radio volume
control is down. In these cases, install a load resistor across the
speaker output terminals, A
10 ohm 5 watt resistor should be
satisfactory.
4

LOW IMPEDANCE
Radio and tape players may be wired direct from their respec-
tive speaker output terminals. The advantage of this low im-
pedance method is that no modification is required to the radio
or tape unit. Performance will usually be quite satisfactory,
although not optimum. When using low impedance inputs, the
gain adjustment screws on the top of the preamp must be
turned fully counter-clockwise (see page 7).
MODIFICATION INSTRUCTIONS FOR HIGH
IMPEDANCE OUTPUT JACKS
A professional audio technician should perform this modifica-
tion. The procedure is as follows:
The tape or radio unit must be removed from the car and the lid
or case opened. Locate the volume control. It may be of the
rotary or slider type and will have three lugs for each channel.
Locate the ground lugs and connect to the input cable shield.
Next, locate the centerwiper lugs and disconnect the wires that
connect to the amplifier section. Then attach input cable to the
respective lugs.
NOTE: In some cases, the balance control is wired after the
volume control. It will be necessary to trace the circuit to see
which type of circuit you are working with. On models with the
balance control after the volume control, connect The Punch’s
input cables after the balance control in order to retain adjust-
able balance.
When the correct location is found, connect the red and black
wires to the left and right channels.
In some rare cases, the signal may be too low at this point to
drive The Punch to full level. If so, it will be necessary to tap into
the signal after it passes through the next amplifier stage.
Although rare in automotive radios and tape players, occasionally
one will use a “loudness” type of volume control which can be
identified by the four lugs for each channel on the volume
control. The loudness circuit should be disabled by either
disconnecting the wiring that runs to the loudness tap or by
shorting it to ground.
5

OPERATING THE SYSTEM
Thanks to the automatic power switching circuit, you just turn
your radio or tape player on and off in the normal way and The
Punch will turn on and off automatically. In high impedance
wiring, the signal to noise ratio is better when you turn the
volume knob full clockwise at the radio/tape player, and control
the volume at the preamp unit. In the low impedance wiring, on
the other hand, the signal to noise ratio is betterwhen the radio/
tape player volume knob is tuned to just short of distortion,
again controlling the system’s volume at the preamp unit,
GAIN CONTROL ADJUSTMENTS
If the signal coming into the preamp unit is too large, it could
cause clipping anddistortion in the preamp. Therefore, we have
included input level control adjustments in case they are
needed. To set these trimmer pots, it is necessary to use a small
screwdriver. The adjustments are located
on top of the preamp.
When viewing from the front, the hole on the left is for the left
channel, and the one on the right is for the right channel. These
adjustments are shipped fully clockwise (full volume) from the
factory, preset for high impedance input. If a low impedance
input is to be used the trimmer pots should be turned fully
counter-clockwise.
EQUALIZER CONTROLS
When the “hi” and “low” frequency controls are in the counter-
clockwise position the response is flat with no boost. Each
clockwise position provides increasing boost. To adjust the
equalizer, start with any tone controls that may be located on
the radio or tape unit in the flat position (quite often this is full
clockwise). While playing some good program material, start
advancing the controls until the desired sound is produced.
Experience has indicated that it is usually easier to tell when you
have over-corrected than when you have under-corrected, so
try higher positions until you have over-corrected. Then back
down to a lower setting.
7