Upgrading a Rockford Fosgate Punch 601s to an 801s with just a handful of parts

[Simon] had a Rockford Fosgate Punch 601s amplifier in his car, and while it was a great piece of equipment, he wanted a little more power behind his stereo system. It turns out that with just a handful of parts and a bit of soldering work, he was able to increase his amplifier’s output by 200 watts, putting it on par with a Punch 801s.

The main board in each amp is laid out identically, making the conversion a relatively easy process. A handful of MOSFETs need to be added, along with some resistors and capacitors. Most of the work can be done with a decent soldering iron, though you might want a hot air reflow station to handle the smaller resistors – it all depends on your skill set.

We’re really not sure how big the price difference is between the two amps, but we’re pretty certain that the conversion would be worth it. [Simon] sells conversion kits on his web site for under $60, but you may be able to find the parts for a bit less if you hunt around.

Comments

  1. Techie says:

    From 0 to deaf in 2.4 seconds… Do you really need 200 watts (extra) in a car?!

    • tomas316 says:

      Do you really need all that extra horse power in your car? Do you really need all that extra room in your house? do you really need all that extra money for working at you job? Do you really need all that extra cpu power in your computer? Do you really need all that extra hard drive space to save your junk?
      How about you just say “Good job!” and move on???

      • xorpunk says:

        Continued..

        expensive trendy clothes, conformant home in a suburb or a mansion, center of attention etc..

      • Devin says:

        No, you don’t need any of that.

      • bio says:

        you dont NEED anything but water, food, air and a place to take a crap
        everything else in your life is just vanity :P

      • bio says:

        i like this mod … 600 watt is good but 800 watt is great (tho it has 2.1 fewer channels than id like XD )

        nice job sticking it to the man! :P

      • soli says:

        Agree with Techie and others. I see the ghetto culture loving high power amps and superficial things for their cars. So lame.

      • Kat says:

        Should people have the right to put the biggest amp they want into their own car? Absolutely… there’s too much government regulation as it is. But that doesn’t mean that it isn’t a stupid idea.

        Most “dangerous” things that people do are only incidentally dangerous. That is to say, the desired end-product of their effort is usually benign… it’s all the things that could wrong around the activity that represents the collateral hazard.

        A huge audio amplifier in a confined space, on the other hand, is not benign. The damage inflicted is not incidental. The very thing that a large amp provides, high sound-pressure levels, is the thing that is destructive to your ears.

        In fact, hearing damage more-or-less follows the rules of dosimetry. You can deafen somebody with a single high-amplitude event, or you can deafen them by prolonged exposure to far lower levels. Either way, you’re going to pay the piper.

        My dad spent many pre-OSHA years in a factory. His hearing was damaged by prolonged exposure to machinery noise far less than the noise a 200-watt amp can produce within the confines of a car. He struggles every day now, trying to understand the TV or radio, the clerk at a convenience store, or the person at the other end of a telephone. Hearing damage is a a socially-destructive and incredibly isolating condition.

        You can blow-off the people who warn you about this, but you do so at your own peril.

    • N0LKK says:

      @soli Ghetto culture? shees.. Their rides aren’t anymore lame or superficial that the the customs street machines, street rods or any other than stock vehicle in any neighborhood, that may or may not have high power audio systems. As long as we don’t have to listen to them, I’m not sure why we should be concerned.

    • Malikaii says:

      He’ll be fine:

  2. Stephen says:

    Does the amps massive heat sink get any hotter?

    • Ren says:

      It may, but since huge heat sinks are eye-candy, both models may be over “engineered” for that or use the same ones. I.e. the company saves money by using the same heat sink for multiple models.

      This reminds me…
      One of my electronics teachers showed us some formulae (yeah, I know, spell check doesn’t recognize that word) regarding heat dissipation.
      He said it was good information to know, after all, he didn’t want any of his students in a subsequent job interview answering the question,
      “What is a heat sink use for?” with, “That’s a place you dump the heat when you’re done with it.” B^)

  3. monsieur2 says:

    You need 10x the wattage to get a 2x or 10dB increase in loudness : 10log(P2/P1). I’m not sure it would be worth the effort to go from 600 to 800W with this mod (1.25dB) when the human ear has difficulty perceiving levels with less than 3dB of difference.

    • Ren says:

      Thanks for doing the math on this. $60 (the price of his kit) for 1.25dB is not worth it IMO, but that shouldn’t stop him from making income off of people who don’t understand decibels.

      Yeah, 10 watts in my car audio has been sufficient (excessive?) for me and my passengers. Before I buy anything more, I’d better look for ways to reduce road/engine/wind/tire/offspring/etc. noise first.

    • Eric says:

      2x is 3dB, but you’re right, you would need 10x wattage.

  4. Wiregeek says:

    Brilliant!

    I would implement this in a heartbeat if I had the appropriate 601s. If nothing else, it would let me reduce the amp control while keeping total output the same. I’d much rather run my amp at 80% than 90%!

  5. geekwrench says:

    The idea is luxury in perspective. The more “headroom” you have in your amp, the less of your signal will get distorted, and the better it sounds. The peak output of an amp is never clean. ex: most men are happy with a microwave, a bowl and a fork, but the food from a gourmet kitchen tastes much better.

    • Dopesick says:

      Yeah it seems many of the Techies here are not seeing that wattage gain, vs lower operating level of the amp now for same db output.

      THD is 99.9% of what matters in Audio. Distortion is the shit we don’t want to hear, and the subsequent cause of most speaker failures.

      • NewCommentor1283 says:

        EXACTLY!

        FYI THIS AMP IS 99.9% LIKELY TO BE USED WITH A SUBWOOFER… ALL OF THOSE NOWADAYS
        (unless you want to pay 10000’s $ /1)
        ARE MADE OUT OF PLASTIC!!!
        MODERN SUBS GET CRACKED VERY EASILY!
        THEY CRACK FROM SQUAREWAVES! (severe distortion)
        EVEN LOW POWER SQUAREWAVES!

        why does this matter? cuz a distorted sinewave looks more like a squarewave and will shatter the PLASTIC cone!!! ITS A SUBWOOFER, IT CANT MOVE AT TREBBLE FREQUENCYS, like the edge of the square/distorted wave!,

        WHEN 500 or 1000 watts are involved…
        all i can say is:
        WEAR GOGGLES WHEN TESTING AT FULL VOLUME AND STARING STRAIGHT AT THE SUBWOOFER!!!

        they can and DO put out eyes when they crack!

        PPS: if common sense is defined as common, what happens when most dont have common sense???
        it ceases to be common??? lol

  6. mmon77 says:

    I agree with the statement about headroom. Someone who actually knows how amps work would be doing this mod to increase the available headroom in the amp. The difference in perceived volume would probably be unnoticeable.

  7. gruni says:

    Okay, now where does the extra power come from? I can see how more transistors can enable the amp to provide more current, but you need a higher voltage in order to get more power out of, say 4 Ohm speakers. I think the 800 watt model also has higher supply voltages than the 600 watt model, so adding the extra transistors only makes the amp a bit more reliable, doesnt it?

    • Simon says:

      You are correct for a constant load impedance. However this mod also reduces the current in each transistor, and hence each source/sense resistor allowing higher current delivered to the load before shut-down. In effect, the output impedance of the amp is now lower, and a maximum power transfer requires a lower load impedance.

      One could indeed change the turns ratio by increasing the number of secondary turns on the power supply transformer to match the rails of the Punch 801s (Maybe about +-85 to 90V, an increase of about +-10V) if they want to run higher impedance loads. This might deter lots of folks that are more familiar with just using the modern low 1 or 2 Ohm impedance woofers built for class-D. (This AB amp predates mainstream class-D.) Folks like you, however are another story.

  8. mike bradley says:

    With car audio, sometimes adding more speakers in parallel, willdraw more, hence more mosfets. When I competed, I use to disconect the internal power supply from the power rails and use an ac inverter through some diodes to get good high voltage and current supply, then I would put a bank of caps on the rails, not those stupid 12volt capsat the input, by that time internal rails already dropped voltage. Then finally, triple the output mosfets. Note: bass only competition

  9. echodelta says:

    These are transmitters. As such they should be licensed for safe and proper operation. Both to the operator and area around them. They can be regulated under Federal laws just like the auto it’s in. We must act to get back our quiet. In Chicago if a cop hears you at 75 feet you and ride-boomer each get to go a jail for the night.
    Hack this up; laser on booming car verifies source of noise at a distance, by modulated reflectivity?

  10. N0LKK says:

    Interesting tha these where constructed in a manner that make the upgrade so “easily”. Then again very few will actually go through the effort, so sales may not be impacted so much.

  11. Kevo says:

    See the thing I don’t understand is…. This guy is just adding parts to the amp. I seen the video. Good job btw but…. Did you know the rest of the components need to match, power supply, output fets and rail caps. I would suggest that he replaced all semiconductors for the amp to be 100% reliable. Mismatched fets won’t share the equally it’s important for them to have same date codes. But if it works then no problem.

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