Any car stereo nerds around here?

[NoSlo5.0]

Put up a new page on my website to detail the building of two new amps for my car. They are going to be way overkill, but that sorta fits the theme of the car anyway.

Here's some shots of work in progress, about 70% done I'd say.


They're gonna go in these heatsinks after I get them polished up.


Anyone else into this stuff?

[Showrides]

I don't know much about what you are doing but it looks cool. Do you make your own amps? if so let me know more about it. like how long does it take and if you would be willing to make more of them.

[NoSlo5.0]

The story behind these particular amps is a long one...

I managed to get my hands on a burned up (1 channel was) RF Power 300. This was in 90 and right around the time these amps were running for a grand on sale and $1399 retail. I paid this drug dealin pimp $45 for his broken amp. He had so many speakers running in parallel that the circuit board burned through on one channel.

I was going to just fix it but time wore on and instead I decided to build one from scratch instead. So I removed all the components one by one noting their values and locations and tried to make new PCB artwork using what computer programs were available at the time. More time passed and eventually RF gave me the schematics for the amp, they were reluctant at the onset of my project. By now, software for schematic capture and CAD were much more powerful and I was able to make the CAM outputs for the circuit boards. I had 8 prototypes made, they ended up looking just like the original.

The first two boards that I made worked great, and have been for about 4 years now. Everyone familiar with Rockford Fosgate knows what their stuff is made of and these amps are no different. In fact, they are better because of the improvements in MOSFET technology since the originals were made. These run even cooler.

My plan is way overkill, but I plan on making 4 amps and mounting two each in the heatsinks that I bought. Each "amp" will essentially be an 8 channel monster. One will run in bridged mode giving 4 channels of ridiculous power to drive a pair of DVC subs. The other amp will stay in 8 channel mode to drive a mess of speakers. I'm also thinking about just using one amp in my car, that's basically what I have now and it's loud as hell by itself. Then I'd sell the other on fleabay to help pay for the project.

It takes a few days to solder all the components on the boards. I spend about $40 on new parts for the amps, I have some surplus boards laying around for other components. The heatsinks are $40 a pop, and the boards set me back $200 for a run of 8. So there is some cash invested, but still not the cost of one original amp, not even close.

If I thought there was much of a market, I'd make and sell as many of these as I could. But audio prices have come down so much in recent years that I can't see someone paying for my stuff when they can get a brand new warrantied amp for a tad more. I think I'd have to sell mine for around $200 for an 8 channel setup or $150 for the 4 channel to be allright on the bottom line. It's mostly a geek hobby of mine, along with the woodworking and car building...

[Showrides]

Still very cool. You deff have some talent. Let me know how it all turns out.

[audiobahn81]

you deff have talent iand i would love to know how it all turns out.but i do have a quesstion i have an old punch 250 a2 i had it in my old car one day out of the blue it started my subs on fire i thought it was a short in the wiring but i hooked it up to a buddys car with an old speaker we had laying around and it started the speaker on fire just by hooking it up to the amp do you have any idea what could be the problem. I would apprecait the help

[NoSlo5.0]

you deff have talent iand i would love to know how it all turns out.but i do have a quesstion i have an old punch 250 a2 i had it in my old car one day out of the blue it started my subs on fire i thought it was a short in the wiring but i hooked it up to a buddys car with an old speaker we had laying around and it started the speaker on fire just by hooking it up to the amp do you have any idea what could be the problem. I would apprecait the help

With no input and the sub catching fire, it's pretty clear that the output stage of the amp is stuck on a rail voltage. Basically one of the output stage devices is shorted through and applying a high voltage (relative to your 12vdc car system) to the speaker terminal. Could be a few other things wrong, but I'd say one of the output MOSFETS has failed. That's a cheap fix if you don't bugger it up desoldering/resoldering a new component in there. Other things could do this too, but they are far less likely.

Don't hook any more speakers up to that badboy until it's fixed

[audiobahn81]

havent hooked that amp up in many years where could i get a new mosfet power supply and thank you for your help

[NoSlo5.0]

Well, you won't need a power supply. What you will need are some electronic troubleshooting skills and a voltmeter.

Do you remember which channel had the problem? That would make it very easy. If not, power the amp up and measure the output on each speaker output. No speakers connected of course.

Use DC volts, 30 or 300 volt range will work (autorange if you have it). You're looking for +24 or -24vdc (you said 50 watt per channel amp right?) The voltage would be higher for a higher power amp and lower for a lower power amp.

If you find one or more outputs with these symptoms, then you'll need to bust out your sleuthin' skills. With the amp powered down/disconnected from any source, take it apart. You'll be able to trace the speaker output connection back to the point of origin on the circuit board. There will be at least two "transistors" there. They should be TO-220 package, look like a 1cm square, 4mm thick, and have three "legs". These transistors (MOSFETS) will be mounted directly to the heatsink, you may have to remove some parts that hold the MOSFETs to the heatsink (usually just a piece of barstock for Rockford stuff) There will be a number on the MOSFET. That's what you will need to order from someplace like Digikey, or Mouser, or some other supplier. It may like BUZ11, or IRF540, IRFZ34, something like that. If there are two different numbers on the output stages, order both.

The old ones will have to be carefully unsoldered, and the new ones installed. If you're serious about fixing it, take a pic or two along the way, and I'll mark them up to show you what you need to do, specifically as I can.

Maybe I'll make a little tutorial on how amps work with pictures and start a thread. something simple that everyone will be able to understand...then everyone will be a stereo nerd!

[storm7127]

how many TRUE watts do you think your amps are pushing? I may be interested in buying a couple from ya... Now I have a 1000 class D Memphis pushing 2 MTX 9500's. They slam but I think I could feed more juice to em. What do you think? I have a 500x4 running my Memphis mids and highs and I am pleased with them. They sound great but the subs...I think I can get louder.

[storm7127]

come see my set up...http://www.gotstang.com/profile.php?storm7127&page=2

[NoSlo5.0]

I don't think what I'm building is what you'd be looking for. A high power class d amp is perfect for those subs. Do you know how long the excursion is on those things? I swear they look like they could move as much air as a pair of plain jane 18's. I never saw an article testing a Power 300. It's an exact copy of the old school RF piece. To put everything in perspective though, it takes double the power to increase output 3db, and 3db only sounds 15% louder. Soooo, if I recall correctly, these amps were only rated 50x4 or 150x2. The best thing I could do with them is drive a pair of DVC 12's. That's only 300wrms per sub. I'm driving two RF 12's right now with just 150wrms each, and it's more than enough power to bottom out the voice coils and they're installed in a slightly undersized sealed box.

[storm7127]

so then you like the 9500's? I love them I just think they could use some more power
you sound like you know alot about this stuff. How much power can I givem without toasting them. I am sure than can handle more than this memphis 1000d right?

[NoSlo5.0]

If you're not reaching a mechanical limit of the speaker (no slapping sounds) then the rms rating of the speaker is the only other limiting factor. Heat dissipation is all it boils down to. I'll have to catch up on the newer gear.

[storm7127]

okay, let me know. Thanks!

[Jesse]

thats cool, i wish somtimes i had learned some electical engenering or whatnot so i could do stuff like that, but anyway i have two 250w walmart amps that got fried if you want em you can have em to further your hobby.

[NoSlo5.0]

Amp update...

I've got two built and mounted on the heatsink. I haven't polished it up yet, just hit it with 0000 steel wool to remove all oxidation. I'm making the endplates and bottom now.

What you're looking at are two old school Rockford Fosgate Power 300's mounted on one sink. Strictly by the numbers, that's 8 channels producing 50wrms each, or in bridged mode, 4 channels at 150wrms each, or 4 at 50, and 2 at 150, you get the idea. Of course, those numbers are waaaaay underrated, and don't even consider comparing them to the class D amps that are on the market today. These are the original bruisers.

My next go at it is going to be to modify the audio sections to support high current/low impedance loads. That'll be a while from now, I'll have to go back to the computer drawing board stage and get new PCB's made for that. Being a nerd pays off occasionally.

[NoSlo5.0]

thats cool, i wish somtimes i had learned some electical engenering or whatnot so i could do stuff like that, but anyway i have two 250w walmart amps that got fried if you want em you can have em to further your hobby.

You don't need to be an electrical engineer to get in on this stuff. The Navy nuke program was the only formal electronics training I ever received. I just had a burning desire to know how these things worked. That was enough motivation to figure it all out.

If you still have those amps, I might be willing to paypal you some cash for them, depends on the brand and size of the heatsinks.

[1nasty96]

very nice

[Nicoleb3x3]

www.wakefield.com Curious, where did you get the heatsinks from??
I SELL HEATSINKS!!

You should get them black anodized!

[NoSlo5.0]

www.wakefield.com Curious, where did you get the heatsinks from??
I SELL HEATSINKS!!

You should get them black anodized!

Figure the odds. Your company was stored in my favorites. Unfortunately, it'd be cheaper for me to buy brand new amps from a crap company like Pyramid or something just to use their heatsinks rather than do a small run from someone like Wakefield. Sometimes you guys have some cutoffs and samples left lying around though, don't you?

I stumbled onto these just cruising around Ebay. They were only $40 each. The seller is Robot Underground, I think they bought the surplus from a manufacturer that went under. I've amassed enough components now that I'm thinking about doing a few small revisions to my circuit board and having a bunch more produced. I'd like to sell enough to break even on my initial investments. Oddly enough, adequate supplies of identical heatsinks is the sticking point.

[Nicoleb3x3]

rather than do a small run from someone like Wakefield. Sometimes you guys have some cutoffs and samples left lying around though, don't you?

You just need to get a good customer service rep, like me, and find an extrusion that's instock. otherwise, we need to push the metal and it's 500 lbs min on the press.

But; again, find something on the shelf and you'll be all set. Plus, I know how to get things through that normally wound't be offered to general public, as a big company we cannot handle small requests, so I'd just take care of ya.

let me know what you need...for a Mustang Enthusianst, I'll help you anyway that I can. I used to have a bose amp cover at my desk...it's was my favorite heatsink.

depending on what you want I could likely get you a sample or two, if you want to start making more..then I could get a lower than the normal min buy charge going. (we now accept credit cards!)

hey, check out my aluminum ashtray cover on the bottom of page 2...I had that made at work.
it's got to be worth hundreds of dollars for the amount of machining we did to it.

[NoSlo5.0]

I'm a little green with envy! Great job on your car so far.

On the heatsink subject. I can be pretty flexible, function is the most important thing. A finned extrusion that's approx 2-1/2" wide could be used. I guess I'll look over your webpages and ID items that I see potential in. If you have some stuff at work that you supply to an amp manufacturer, maybe I could sneak in a few feet on the end of one of their orders? Thanks for even offering a hand, I appreciate it!

Maybe I could build you an amp in return for your efforts...

[Nicoleb3x3]

that's a generous offer! first we'll see how I'm able to help.

the width you gave me is actually the height, the width you got there seems to be 6 inches??? what is the range on the width?

and, did you want to go with black anodize?

[NoSlo5.0]

The widest point on the circuit board is 6 inches. The overall length needed is about 12 inches. So a conventional sink/extrusion would have to support that.

I could also use someting like the H-1395. Anything that's basically similar would likely work fine. I just have to have enough material to drill and tap screw holes for mounting the MOSFETS and top/bottom/end plates. I could run one down each side in a vertical arrangement and finish the enclosure off in sheetmetal (Imagine just a plain rectangle box shape). It wouldn't look as dead sexy as my Orion heatsinks, but it would be functional. Anodized finish would work fine, it's more traditional and it simplifies construction. Looking forward to seeing what you've got...Thanks!

[Nicoleb3x3]

Well, I assume the first one you're building is good with the sinks you got..

that said, I could fit you into a smaller sink that would be way sexy.
This is a beautiful heatsink, beleive me!
It has fins all around the ouside like most amps do. -And it'll perform better thermally. (btw; how you cooling this stuff down besides the cover??)
It's 5.64 X 1.56 TALL -12 length is no prob.
maybe if you're already doing a redesign...maybe you could get the size down?


You don't plan to sell these commercially...do you? let's just say this is a custom shape that's not a Wakefield design. I could not find a Wakefield design that I was content on offering to you...I want you to have the best!

If you ever want to mass produce these in the future, we may need to design a custom shape for you (in which case is a bit expensive)
but; as long as you just want to make a few of these for friends & stuff, I don't see any problem sellin you this shape.

as far as samples..I could get you a few freebies of this; but the cut lenth is just under 11 inches..and that would be unfinished (no ano)...unless...I get some rejected parts...anway let me know if this interests you

if not, I can keep looking!