Park® Rock Head 50 Manual Welcome to Park and thank you for becoming part of the Park family. Park Amplification makes some of the finest vintage-style, British inspired tube guitar amplifiers. The Park Rock Head 50 is a newly designed amp based on the sound and feel of the British amps made from 1965 to the mid 1970s. However, it’s a channel switching amp unlike anything made back in the 1960s and 1970s. The circuit in the Rock Head 50 is derived from both the Park 50 and the Colby Mod Machine. Its clean channel is based on the Park 50 and the second channel can go from pure clean to bluesy OD to classic rock and even a bit more. Front Panel Input (top jack) Footswitch input (bottom jack) Volume: Clean channel volume control. Use this to set you clean volume. In conjunction with the PPIMV you can overdrive this channel. Set the Volume low and the PPIMV high for clean sounds. Set the Volume high and the PPIMV low to overdrive the clean channel Gain: OD channel Gain control. The OD channel has been carefully and cleverly designed (if I say so myself, LOL) to be able to achieve great clean AND overdrive sounds. Low settings of this control (and high settings of the Master) will give you a very good clean sounds. Set this control higher for different levels of overdrive Master: OD channel master volume control. Set low to start with especially with high Gain settings. Set higher if you want to use the OD channel as a second clean channel or for a low gain overdrive sound Treble, Mid, Bass, Brightness (presence). All tone controls. Self explanatory…. PPIMV: Overall Master Volume
PPIMV Notes The PPIMV is a very useful tonal tool in our arsenal since it works on both channels. You can use it as an overall Master Volume control. If you like the settings you have chosen for both channels, but you need to raise or lower the overall level, the PPIMV can do that. An example would be if you are rehearsing at one level but need to raise both channels evenly when you gig outdoors. Another way to use the PPIMV is to use it as a Master Volume for the Clean channel for low gain overdrive and the Gain channel as a higher gain overdrive. Other things on the front panel include the On/Off switch, Standby switch and Mains fuse (2 Amp, slo blo). Back Panel HT fuse (0.5 Amp, slo blo)
IEC AC Mains connector Impedance selector (4, 8, 16 ohms) Speaker jacks: Set the impedance to the same impedance rating of your speaker cabinet. The single combo comes with one 16 ohm speaker. The two 12” combo comes with two 16 ohms speakers in parallel which equals 8 ohms. Post Phase Inverter Master Volume (PPIMV) - NOTE - this control is not marked! PPIMV is a master volume control that is after the Phase Inverter which is the first tube in the power amp. Because of this, you can achieve more gain before the PPIMV than a traditional master volume. Amps like the PLH18, Park 45, 50 and 75 are not high gain amps and a PPIMV works better than a typical master volume control. Effects Loop: This is a passive, series loop. What that means is that it works but not in all situations. It depends on the level you are playing at. At home at low levels it will work fine wtih pedals that you normally put in front of your amp. at higher levels, the sound level coming out of the loop send may be too high for you pedals unless they are able to handles high signal levels. The loop will work with rack products or pedals that can typically handle +4. Alternatively you can plug an external active effects loop device in to the Send and Return of the amp and use any kind of effect at any time. These units are available and come in both tube and solid state versions. Both can work well.
Operation There are two channels which can be chosen by front panel push-pull switch or footswitch. The “Clean” has its own Volume control. The “Gain” channel has a Gain and a Master Volume control. Both channels share Treble, Mid, Bass, Brightness (presence) and PPIMV (Post Phase Inverter Master Volume). There are a number of useful ways to plug into a “four-hole” amp. 1) Plug into either top jack and use its associated Volume control. Adjust the tone controls to taste. 2) Plug into the top input of the left (bright) channel and plug a short jumper cable from the lower input of the left channel into the top input of the right channel. You are now plugged into both channels and can blend them for more tonal possibilities. This setup is commonly used on the more aggressive 1970s amps where the left input has very little bass (until you crank it all the way up) and the right Volume control is used to fatten the sound. The left channel on this amp is full with plenty of bass so this is not necessary: but you can if you like! 3) Plug into the top input of the right channel, turn it up to the desired level (louder is usually better!) and then turn up the Volume control of the left channel to add some highs and upper mids. This works because there is some interactivity between the channels. The setting of the left Volume control will vary depending on the speakers,
room conditions and anything else that can affect tone. It is rumored that some famous guitarists used this setup to achieve their sound in the mid to late 1960s.
Specifications Power: 45-50 watts clean, 70 watts when pushed Tubes: two EL34 power tubes, three 12AX7s Front panel: Input, Footswitch input, Volume (ch1), Gain (ch2), Master (ch2), Treble, Mid, Bass, Brightness, PPIMV, On/Off, Standby, Mains Fuse (3A slo-blo) Back panel: HT fuse (500mA), IEC mains (AC) socket, optional Voltage selector, Impedance selector (4, 8, 16), two speaker outputs, Passive/Series Effects Loop Dimensions: (H) 8.5”, 9” with feet”, (W)24”, (D) 8.5” Weight: 32 lbs Service: These amps are equipped with two fuses. One is on the front panel labeled “2 Amps”. There is also a back panel fuse labeled either 500mA or 1A. While either can be used, 500mA is recommended. If your amp is blowing fuses, something is likely wrong and it is highly recommended that you bring the amp to a qualified technician who is familiar with tubes and guitar amps. That said, a bad rectifier or power tube can take out the back panel fuse. Tubes have a life span and can wear out over time. Power tubes (6V6, 6L6 or EL34, etc) typically will wear out faster than preamp tubes (12AX7). If the power tubes are worn out your amp will sound lifeless and may lack power. In the PLH18 you do not have to bring the amp to a tech for biasing., It is a self biased amp and can use either 6V6, 6L6 or EL34 power tubes.
Park Amplification (a division of Colby Amplification) PO BOX 199 City Island, NY 10464 (347) 886-8656 info@parkamplification.com www.parkamplification.com www.colbyamps.com