Bridging Amplifiers

north51

I have a MTX 2400 2 channel amp that is running my two MTX 6124 subs. The MTX website says that this can bridged at 425 RMS into a 4 ohm load. Can I wire my two 4 ohm subs so that I can bridge the amp into 4 ohm? My undertstanding is that I need an amp that runs 2 ohms stable, but I'm not sure.

Help!

PoweredByDodge

*scratching head* -- Road Thunder perhaps?

*looks at mtx.com* -- yup, road thunder.

ya bud you're kinda stuck between a rock and John Goodman.

The T6124 6k subs are single 4 ohm coil.

if you wire them in parallel, thats a 2 ohm load, that'll smoke that Road Thunder amp.

If it were the Blue Thunder with the same rated power, I'd say you had a 40/60 chance of being ok (40 good / 60 smoke), but the Road Thunder's had smaller power supplies, not nearly as beefy / durable of an output stage either.

This is not to knock the RT line -- at its specs they did good work... solid amps that performed almsot as well as the Thunders, at half hte price. But you can't drive that down below 4 ohms in the bridge, it wont take it. I saw kids blowin Road Thunder's daily 3-4 yrs ago... 4 channel's especially. kids would get the big RT 4 channel and try to run two subs off it bridged front and rear...it was like 225 x 2 bridged or something like that, but the thing just wasn't made to be run that hard -- PS couldn't keep up with the output. -- fizzle.

You can bridge one of the subs off that amp --- whch is almostdouble its RMS though -- or you can run them in stereo and get like 120 per sub which aint too bad -- aint great but it'll do until u can figure out how u wanna deal with the mis matched components.

north51

Dodge,

Thanks for the help. I do have them set up in stereo, giving me 120 or so per sub. I looking to get a D class amp(4250), to give me a little more power.

Did you ever get any 6.5s yet?

Jason

PoweredByDodge

Jason,

i ended up getting a set of polk dx 6.5's that were in some dude's garage collecting dust -- he had them in for a week, then took them out, sold the car, and 99.9% of the time poeple are bullshitting u when they say that but these things LOOK mint. -- paid 50 bucks shipped -- more htan i wanted to but they're the polk's so i couldn't refuse.

4250D aint gonna do much more power than u're doin already --- i mean its like 300 and change x 1 bridged... 150 / 160 a sub maybe -- u're doin 120 now -- why waste the $$ for such a small power gain.

Take a look at the JBL BP 600.1 -- its 173 bucks on ebay (cheaper or same price as the 4250D) and it does 600 x 1 at 2 ohms -- 300 per sub for ya -- the 6000's are rated 250 but i'm confident they'll do a little over their rating. they're not bad speakers -- little boomy but i enjoyed the ones my girl has.

north51

Dodge,

Thanks for the advice about the amp. I was hoping to get another MTX, so that they match. Do you have any other suggestions? I found a 500d, but I've heard they have lots of problems with them. The one I can get cheap was returned and then repaired. I don't know if it's worth it if they do have problems with that model.

Jason

PoweredByDodge

they have lots of problems with people running them at 1 ohm with the gain through the roof and blowing them to bits.

500D's a good amp -- i had one for a long time, then i got a 6500d cuz i had disconnected my subs for repair but i forgot to make sure the sub speaker wire was not touching each other -- 2 days later --- the amp fried cuz it was running on a short circuit ( zero ohms ) so i got the 6500D had that up until a year ago.

its a damn good amp, does almost 800 watts with the car running / 2 ohms.

just get a blocking diode for the remote turn on lead (like a dollar at radio shack) just one thats tolerant of up to 15 volts and 1/2 amp of current (or 30 volts and 1/4 amp -- 60v 1/8 amp u get the idea)... somethin with the generation 1 mtx class D that if u have another brand of amp on the remote turn on lead (even mtx thunder series... if its not the class D, it'll do this) the amp wont shut off when u turn off the remote turn on lead... i was given two reasons... dont know if either is right.
1- the 500d's remote input is very close to something that causes a big enough M field to pull current through the remote wire and because its a series circuit to which all your amplifiers rem leads are hooked, it turns them all on (doesnt let them shut off).
the diode will prevent current flow backwards, that way this phenomenon is no longer possible.

2- the amp "dissipates heat" through the rem on line. -- i'm pretty sure this is physically impossible given the symptoms. but maybe the guy was trying ot give me the "easy" version of the above explaination.

either way -- little diode saves the day.

I actually liked the 500D better than the 6500D -- 500D came outa the box at 700 watts at 2 ohm at 12.5 volts -- which means its well over 800 at 14.4 -- while the 6500d came out at like barely above 600 with a higher thd.

north51

Dodge,

I picked up the 500d today. I got it for $100 Can plus tax (I think that's about $60 US). Can I install that diode myself or should I get a pro to do it? The other option is to send it to MTX to fix. The problem they explained was almost exactly what you said. Even after they turned the amp off, the red light stayed on for a few minutes.

Thanks for you help!

Jason

PoweredByDodge

Jason,

its an "unfixable" issue -- its actually not a defect or problem in the true sense of the word... its more of a "bug".

Bug meaning that its just something stupid that if u do one little thing it runs like a tank for the rest of its life and requires no repair.

the guys at mtx aren't going to do anything for u other than to tell u to get a diode.

here's the ones that i was using...
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F010%5F005%5F003%5F016&product%5Fid=276%2D1143

$1.39 for two... they dont come in singles anymore.

just use a butt connector or solder to tie the blue remote wire from your head or wherever to the BLACK side of the little diode.... then just stick the STRIPED (or silver) side into the remote screw terminal on the amp.

the diode is only abou tthe size of a pencil eraser head. and 60 bucks for that amp is an absolute STEAL. hell 100 is a steal.... anything under 150 is a great price even if it was used before.

again though, as far as sending it to mitek... they're not really capable of doing anything to solve the bug... its an inherent design flaw that they never chose to fix because most customers only use one amp, in which case this problem would not occur. they might give u a free diode if you ask nice though...lol.

PoweredByDodge

oh by the way -- even with the diode, the power light will not go off right away -- the amp itself will shut off, but the LED red light that goes on when the amp goes on (off when its off) is kinda slow... takes about 4 seconds to fade to "off".... its like watching a sunset at night -- it was kinda funny it used to be so brigt that it would light up the underneath of my truck seat, and then u shut it off and real slow for a few seconds it just faded away to pitch black under there... looked kinda cool. the blue thunder amps did that same "fade out" **** but at least they had cool blue lookin power lights.