Bridge Rectifiers Big Ass Diodes Custom Amps DIY Style!

freshkryp69 · Post by **freshkryp69** » Fri May 04, 2012 7:20 am

In a car alternator, the bridge rectifier is a serious weak link and usually 99% the cause of a alternator to fail. So im going to make a huge (840 amps) ( 12 or 24 big ass stud mount diodes) one for my ride with a big slab of heatsink I cut down from a junk amp I had.

Is it also true that the bridge rectifier is a serious weak link in a car amp as well? if so, I have a cool idea. I have a extra dual mono ms2125 that i want to convert to screw in stud type power diodes. Im still trying to figure the volt and amp rating ill need. the volts can be higher than what the amp runs at, so in that sense it will be MUCH more robust. Same goes for the amp rating? but since the voltage drop across the diodes increases with the amp rating? is that true? so ill need to factor that in when I make it correct?

Does each phase of the alternator have a pos and neg diode inline? or are they all pos or all neg's???

I know these amps use Bi-polar junction trannys, in parallel right? 3 sets per channel. I want to convert it to use T03 outputs, but doubled up, for 6 pairs. do they make the T03 in BJT???? Or are they mosfet style?

Im doing this for FUN, for the hell of it. I assume Ill be having to wind up some new torrids for this. so ill be figuring out how to do that in the meantime. Im sure the math will be a bitch, since I dont know the formulas. and im sure any regulation the amp does will have to be modded as well?

I know Im redoing the wheel, but its for fun and to learn. So please dont discourage and say its a waste of time! as I want to make my own DIY amps when im capable and with help from a few peeps from the DIY crowd that want to share their knowledge.

If your so inclinded to get involved, feel free to add any info or advice, it would be much appreciated!!

Brad

Post by **ttocs** » Fri May 04, 2012 8:28 am

yes they are often cheap on alts but that is the difference in a cheap alt and a good one. Been waaaaaaay too long since I studied them in school and have not touched them since....

jbob0124 · Post by **jbob0124** » Fri May 04, 2012 8:41 am

Bridge rectifier sounds like some medical term I should be afraid of

Good luck with the project.

Post by **ttocs** » Fri May 04, 2012 11:01 am

its actually a pretty simple circuit with just some diodes arranged in a funny lookin square...

jbob0124 · Post by **jbob0124** » Fri May 04, 2012 2:44 pm

Like this?

nutxo · Post by **nutxo** » Fri May 04, 2012 4:04 pm

My alternator

Thats one external rectifier. It has one internally as well and I could out on a third if I had room.

Thumper88 · Post by **Thumper88** » Fri May 04, 2012 4:42 pm

http://www.alternatorparts.com/quicktif ... ifier.html

freshkryp69 · Post by **freshkryp69** » Fri May 04, 2012 6:19 pm

Thumper88 wrote:http://www.alternatorparts.com/quicktif ... ifier.html

I talked to guy today actually,picked his brain a lil, cool guy! Im getting a front housing for my cs144 to fit my silverado that has the small 244 on it. I seen the remote rectifier, the big one 420 amps..Im going double and DIY.. I need to find the highest amp stator and armature something much bigger that 240 amps, more like 400. adj regulator too, I can make that tho, but for 40 bucks its pre made but the pot is inside the alt so id have to take it apart to adj it.. I want it on the dash for on the fly adjustments. I have 2 200 ampers alts on the bench I could throw on, but dont want to tax the serpentine belt system and the added HP (about 25 full tilt) it takes to drive 2 alts. So ill stick with just 1. and 3 big MK power batts.

Dam big diodes arent cheap! Wish I had a couple old welders I could snag them out of!! but new is always better! I did find some for 12 bucks each, I can live with that.

I checked out some vids on the subject on youtube, lots of good info. but nothing on a huge ass rectifier like I wanna build.

Ill post pics soon as get started..

Brad

dBincognito · Post by **dBincognito** » Sat May 05, 2012 7:10 am

Don't forget to throw a Optimizer on there

What you working with now days ?

Probably something that makes you go

freshkryp69 · Post by **freshkryp69** » Mon May 14, 2012 11:35 pm

Looks like ill be scratching out the t03's..

00goobs · Post by **00goobs** » Mon May 14, 2012 11:55 pm

I've always wondered if using batteries together with the on board caps would keep the rail voltages solid. I would think the rail voltage would be the first to show signs of letting go when the amp is pushed very hard. Stiffen the rail voltage, maybe the rms and thd may show signs of improvement at high output levels.
Other than that, I think the only other way to get better sound at moderate levels is to go class A. At least, that's what I've read as far as reviews on the 2250 vs others....

At 300+ watts RMS per channel on the OG MS2250, do you need more? I think the front channels on my ti500.4 is loud enough, hehehe...

00goobs · Post by **00goobs** » Tue May 15, 2012 12:02 am

A few areas to look at improving, which may be simple, is the bus bar contact at the terminals. I really think a bit more contact would be nice. Like a half moon beneath the bar opposite the set screw. On the 2250 vs the 2125, the input voltage torroid thing is mounted directly to the bus bar instead of on the circuit trace. Not sure how, but a bit more contact would be nice there too. Also, maybe a step by step by the local wizard on upgrading the rail voltage on the MS2250TA would definitely keep me busy.

Lastly, the ultimate tool you or I would like is the THD analyzer or spectrum analyzer using the input and output of the amps we work on to see if they really need to be modded, hehehe....

00goobs · Post by **00goobs** » Tue May 15, 2012 12:12 am

Sorry, one last thing. There was a ti amp modded with a tube preamp section. I have been playing with a headphone tube amp and either I am just tricked by reading all of the great reviews, or the blue light of the tube is hypnotizing me, but it sounds great. I think it is more cerebral than aural, but my brain is happy.

I would like to try using a tube preamp on an MS or M series and try to hear a difference between the two. From reading, the biggest difference would be class A (I assume) and the very high input impedance (which a PG PLD1 has on paper). So, to clarify if tube is any help on the preamp/gain stage on an amp, it would be nice to attempt on an amp we are not planning on letting go. A member here local to me, I believe won with a tube preamp head unit, old school amps and nice speakers. Was that tube preamp the deciding factor?