Son of Frank amp-n-stein

The Son of Frank amp-n-stein was Phoenix Gold's second special edition amplifier. It consisted of an MS2125 and an MS275 in the same heatsink. The heatsink was powder coated black with a purple glitter clear coat. We also included an AX406a 3-way crossover with matching color scheme. The set was shipped in a "body bag" packed in a wooden "coffin" crate with straw. The original retail price was $2000 for the amp and $300 for the crossover. These amplifiers have become one of the most sought after amplifiers PG has ever produced second only to the original Frank amp-n-stein. Last production was in 1995.

MS2125 section

Dimensions	28.0"L x 11.4"W x 2.4"H

Output Power per Channel at 1% THD (all channels driven)
Into 4 ohms @ 12.0 VDC	125 watts x 2
Into 4 ohms @ 14.4 VDC	160 watts x 2
Into 2 ohms @ 14.4 VDC	255 watts x 2
Into 1 ohm @ 14.4 VDC 	360 watts x 2*
Bridged into 4 ohms @ 14.4 VDC	510 watts x 1
Bridged into 2 ohms @ 14.4 VDC	720 watts x 1*

Frequency Response	±1dB from 20Hz to 20kHz
Signal to Noise Ratio	>100dB
Lowest THD	0.02%
Damping Factor	500 to 1
Input Sensitivity	200 millivolts to 2 volts
Input Impedance	30k ohms
Input Voltage Range	10.5 volts to 15.0 volts
Typical current draw at idle	3 amps
Continuous current draw @ full power**	35 amps
Peak current draw @ full power***	100 amps
Bass Boost	+12 dB @ 45 Hz
Recommended Fuse Size	80 amps

* Low impedance operation requires cooling fans, large gauge power cable and at least 1 farad of capacitance. MINIMUM SPEAKER LOAD IS 2 OHMS BRIDGED OR 1 OHM STEREO.

** Average continuous current draw when playing typical music material

*** Average peak current needed for musical peaks (<20 ms) when playing typical music material.

Bridging the amp - If you have two RCA inputs cables, use both input jacks and set the STR/BRDG switch to STR. The BRDG setting ignores the right input jack and allows you to use the left input only. Connect the speaker load using the left + and right - output jacks.

Unlike most recent amp designs, The MS series has no "governor" or "limiter" circuits to restrict its power supply when you run at lower impedances. This means if your careful and no what your doing, you can get a lot of performance out of your amp.

Bridging the MS2125 to a 2 ohm load is no problem IF you pay attention to a few basic things.

1. Run 1/0 wire from front to rear. Then use 4 gauge wire from a distribution block to a minimum 1 farad capacitor. Finally, 4 gauge from the capacitor to the amp. Add more caps if you can afford them and fit them into your install. A 4 gauge ground wire to the rear frame assembly will provide a good ground.

There's no need for a dedicated fuse for this amp. The MS2125 has two 40 amp AGU fuses inside to protect itself. However, for competition you may want one anyway to meet the "easy and quick access" judging rules. If the amp were mounted upside down under a quick opening Plexiglas panel or something, that would take care of it.

The reason for all the power wiring overkill is a matter of basic ohm's law. The amp will TRY to double its power and make about 1,000 watts. However, the size of the amp's power supply will only allow it to make about 720 watts. To make that much power, the power supply MUST have adequate amounts of current. How much? At max undistorted output with typical music material, about 65 amps continuous with peaks (< 50 milliseconds) of around 100 amps. Any amount of resistance in the power or ground side of the circuit restricts current flow. If we restrict current flow then the voltage at the amp's B+ and B- terminals will sag when heavy bass notes hit. And when the voltage sags so does output power.

When everything is complete, you can check the voltage drop at the amp's power terminals with the engine idling and no electrical loads turned on. Then play the system at maximum and watch the voltage sag with heavy bass notes. Maximum allowable drop is about 1 volt. Ideally, it should be less than 1/2 volt.

2. You'll need cooling fans. Extra power means extra heat. The heatsink isn't large enough to naturally dissipate the heat generated from low impedance operation. This is another reason people like to put the amp upside down under Plexiglas. With an enclosed amp rack and a couple of 3 inch fans on each end (two pushing and two pulling), you can force the air through the heatsink fins.


MS275 section

Output Power per Channel at 1% THD (all channels driven)
Into 4 ohms @ 12.0 VDC	75 watts x 2
Into 4 ohms @ 14.4 VDC	95 watts x 2
Into 2 ohms @ 14.4 VDC	125 watts x 2
Into 1 ohms @ 14.4 VDC	175 watts x 1*
Bridged into 4 ohms @ 14.4 VDC	260 watts x 1
Bridged into 2 ohms @ 14.4 VDC	360 watts x 1*


Frequency Response	±1dB from 20Hz to 20kHz
Signal to Noise Ratio	>100dB
Lowest THD	0.02%
Damping Factor	500 to 1
Input Sensitivity	200 millivolts to 2 volts
Input Impedance	30k ohms
Input Voltage Range	10.5 volts to 15.0 volts
Typical current draw at idle	3 amps
Continuous current draw @ full power**	35 amps
Peak current draw @ full power***	50 amps
Bass Boost	+12 dB @ 45 Hz
Recommended Fuse Size	40 amps

* Low impedance operation requires cooling fans, large gauge power cable and at least 1/2 farad of capacitance. MINIMUM SPEAKER LOAD IS 2 OHMS BRIDGED OR 1 OHM STEREO.

** Average continuous current draw when playing typical music material

*** Average peak current needed for musical peaks (<20 ms) when playing typical music material.

Bridging the amp - If you have two RCA inputs cables, use both input jacks and set the STR/BRDG switch to STR. The BRDG setting ignores the right input jack and allows you to use the left input only. Connect the speaker load using the left + and right - output jacks.

Unlike most recent amp designs, The MS series has no "governor" or "limiter" circuits to restrict its power supply when you run at lower impedances. This means if your careful and no what your doing, you can get a lot of performance out of your amp. Bridging the MS275 to a 2 ohm load is no problem IF you pay attention to a few basic things.

1. Use 4 gauge wire from a distribution block to a minimum 1/2 farad capacitor. Finally, 4 gauge from the capacitor to the amp. Add more caps if you can afford them and fit them into your install. A 4 gauge ground wire to the rear frame assembly will provide a good ground.

A dedicated fuse is required for this amp. The MS275 needs a 40 amp fuse to protect itself.

The reason for all the power wiring overkill is a matter of basic ohm's law. The amp will TRY to double its power and make about 500 watts. However, the size of the amp's power supply will only allow it to make about 360 watts. To make that much power, the power supply MUST have adequate amounts of current. How much? At max undistorted output with typical music material, about 35 amps continuous with peaks (< 50 milliseconds) of around 70 amps. Any amount of resistance in the power or ground side of the circuit restricts current flow. If we restrict current flow then the voltage at the amp's B+ and B- terminals will sag when heavy bass notes hit. And when the voltage sags so does output power.

When everything is complete, you can check the voltage drop at the amp's power terminals with the engine idling and no electrical loads turned on. Then play the system at maximum and watch the voltage sag with heavy bass notes. Maximum allowable sag is about 1 volt. Ideally, it should be less than 1/2 volt.

2. You'll need cooling fans. Extra power means extra heat. The heatsink isn't large enough to naturally dissipate the heat generated from low impedance operation. This is another reason people like to put the amp upside down under Plexiglas. With an enclosed amp rack and a couple of 3 inch fans on each end (two pushing and two pulling), you can force the air through the heatsink fins.

All MS275s have a two-position switch in the middle of the circuit board with a red dot on one side and a yellow dot on the other. At the factory, the switch is set to the yellow position. The red position will limit the power supply voltage and allow for more output current. This can improve thermal performance when the amplifier is driving low impedance loads (2 ohms bridged). This offers an alternative to installing cooling fans.

Early MS275s (as well as other early MS series amplifiers) had another two-position switch on the circuit board with a blue dot next to it. This is the Master/Slave switch. The standard position is towards the blue dot, which is the slave position. There are two 1/8" mono phono jacks for connecting amplifiers together located on the amplifier's end panel.

The Master/Slave switch configures the amp as either the master or slave in a multiple amp installation. One amplifier is designated as the master amp with all others as slaves. This allows the master amplifier to control power supply switching for all amps. By switching all power supplies in sync, AM radio performance is improved by eliminating heterodyne noise. However, if connected and configured incorrectly, power supply damage to all amplifier power supplies is highly probable. For this reason, we eliminated this feature on later model MS amplifiers. The switch can be in either position and has no effect on performance if this feature is not used.