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Old 11th April 2008, 11:51 PM   #1
dangus is offline dangus  Canada
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Join Date: May 2004
Location: Vancouver Island
Default Ppi Pc4100?

Help! I just saw a PPI PC4100 at a local second hand store. They're asking $180. It's not in mint condition, but that's a nice amount of power for the Tempest. Should I buy it?

I did buy the Rockford Fosgate "The Punch" 4080DSM for $44. That seemed like a no-brainer for a US-made amp, even if the finish is flaking in a few places due to corrosion. I just smoke tested it, and got music from all 4 channels.

By the way, you can find the owners manual for the PC4100 at Directed.com:
PC450 PC650 PC4100 Owner's Manual

edit... whoops, I forgot the Tempest is 2 x 8 ohm coils.... so I could run two of 'em off the PC4100. Would that be "enough" bass?
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Old 12th April 2008, 02:46 AM   #2
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I own a PC-4100, and its a nice enough amp. PPI from its day Definitly "Old School". But I used mine for the four corners only, I like my music clear and unclipped.

You can use it anyway you see fit, but I feel its a better highs amp them sub usage. Any class D amp can do a way better job on your subs. The PC-4100 is a very good SQ amp, seems a shame to waste it on bass... just my 2 cents on that I am sure others might not agree...
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Old 12th April 2008, 04:17 AM   #3
dangus is offline dangus  Canada
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Thanks for the reply. I just got back with the amp. It's in rough shape... some corrosion and scrapes. No plug for the power, and some PO obviously removed the end cover, busting two screws to so they could file the hole bigger so they could kluge some other connector in there. On the plus side, I don't have to feel bad if I gouge the case up. Maybe it's not a steal at that price/condition, but these amps must be fairly rare considering the original high price, so WTF.

I'd probably only use it strictly as a sub amp for dB Dragracing... it should run two of the 2x18" ported cabinets I use for parties, or two Tempests (in horns?).

Anyway, I don't even know if it works yet.

--- time passes ----

OK; I was able to remove the stubs of the busted screws with pliers, and 6-32 x 3/8 work as replacements. A peek inside doesn't show anything too scary.

The manual says that quiescent current is only about 3A, so it's OK to hook it up to the Astron SL-11A power supply (7A continuous, $2.50 from a yard sale). Check for DC on the speaker terminals: about -0.6 with respect to 12V common, same for all channels. Hit play on the MP3 player, and there's music from all four channels, and it sounds pretty good.

So, that's a relief, since the store only warranties car audio if you have it installed by an "approved" professional installer, which I am not.

Now... do I sand off the corrosion and give it a coat of John Deere "Blitz Black" paint, and make it an offical "rat amp"?
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Old 12th April 2008, 05:32 AM   #4
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Well The idle current spec is just that, a idle current rating. It will surge upwards of 10 to 15 amps to get the amp to turn on. So you might want to add some high value caps to the supply to get it to handle the start up surge, so the amp won't see a low 12 side drop and trip offline thinking it has a fault.

As for painting the amp, well it was powder coated originally, so you might want to consider the effects of all that paint on the sink and how it effects the emissivity of heat.
Paint holds heat, so more paint will hold more heat. Just something to think about since your insisting on running subs with this amp. It has fins inside the sink, and a fan to force air across the internal fins.

You might try polishing the sink back to aluminum. Then if it must be black I would look around for a local plating shop and see if you can get it anodized black. This will aid heat emission much better then paint.

Try this Amp-guts link: http://ampguts.realmofexcursion.com/PPI_PC4100/

When checking the DC offset at the speaker terminals you always put the voltmeter across the terminals like a speaker would be connected. this gives a accurate DC reading that represents the true DC voltage out to the speaker without a signal applied.

On PPI this adjustable. PPI had two adjustments for each channel. one located in the center of the outputs, this is bias DO NOT TAMPER WITH THIS. Unless you know and understand how to set this one.

The other adjustment is the DC offset null adjustment. there are four of these and they are located almost dead center of the 4 amp channels in a group. < see amp guts 1st pic> these adjustment will allow you to taper off the DC output fairly close back to zero if any are off spec , and they usually are very off spec by my experience.

I would limit myself to this adjustment and no others at this time. Other than that you might want to refresh or replace most of the white silicone heat sink compound. Again this is to help with heat.

Other than that due to age I would be checking the main rail caps, for swelling and leakage. and possible replacement to handle the sub service you asking the amp to do.

Hope this helps, along with the amp-guts pics. this was meant to run beside the PC-2350 as a sub amp. I have two of those, but today any class D amp will run rings around this amp due to efficiency and design differences in the two amps ...Good Luck on your Drags
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Old 12th April 2008, 07:21 AM   #5
dangus is offline dangus  Canada
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Join Date: May 2004
Location: Vancouver Island
Thanks for the info. The Astron supply must have an adequate surge capacity, because both the PPI and RF powered-up just fine off it.

The innards look good at first glance, and the fan spins freely. Nice quality circuit boards and components. I see the cluster of 4 trimpots for offset. Output devices could be the originals. I feel a lot better about buying it now...

I'll check the amp out more carefully once I've got the power connector sorted. I see there's replacements on eBay, but I'll ask at local car stereo shops in case they've got 'em lying around.

Is there a scanned service manual or schematic kicking around for this amp? A torque specification for the bottom cover screws?

Glass-beaded, "engine-turned" or "swirly sandpaper satin" bare aluminum with a coat of clear lacquer might look good. But, if I do a permanent install in my panel truck, it'll be hidden behind a fake heater grill out of sight.
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Old 12th April 2008, 07:44 AM   #6
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The original paint should strip right off with the right paint remover without any hard work at all. then just polish well and seal it with something like clear coat top coat, and not two thick. Your just trying to stop the aluminum from oxiding which will turn it dull Grey.

I know of no freely floating schematics for these anywhere, but who knows maybe someday one of PPI's old tech's will open their stash box's up and post these old school babies . Good luck
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