mtx81000d

[05_ZX636 10+ year member]

i have searched and read hundreds of posts, but they are half and half. Does anybody run mtx 81000d at 1 ohm daily unmodded? i see some say it will be fine and some say dont do it. thanks

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[dB-r 10+ year member]

SSP45N20A output FETs likely cannot be had anymore. If you blow the output transistors in this amp, there are no known working substitutes, you will have to throw it in the trash. Cannot be repaired.

Power supply can be repaired, but pray you don't blow the output FETs.

I would not run at 1 ohm.

What is this "1 ohm Mod" I hear people talking about for this amp? Someone sent me one to repair, and it was supposedly "modded for 1 ohm usage" and nothng had been changed inside. It was completely stock.

I replaced the power supply fets with IRF3205 fets, is that what they call a 1 ohm mod? Twice the FET on the power supply so you can pass more current through the amp? The transformer would go up in smoke if it ever maxed out the IRF3205's. I don't get it. What is this elusive 1 ohm mod?

 

[RydHy3845 10+ year member]

mtx will put a brand new board in it for $95.. so it wouldn't be trash..I've had 2 of these amps and still got one that is blown the output fets are gone as so are the gate resistors..but to answer your question no I wouldn't attempt to run it at 1ohm..all the 1 ohm mod is disabling the amp protection circuit all you do is remove a resistor (can't remember which number it is) to disable it..

 

[dB-r 10+ year member]

Suprized MTX still has the boards around. The output FETs can no longer be found. So they must have complete boards, old stock from back when. The power supply FETs can be upgraded to IRF3205s, which are quite a bit stouter than most Power Supply FETs. I did this on the amp I repaired recently. However I would not recommend running it at 1 ohm.

 

[05_ZX636 10+ year member]

thats cool. thanks. well, when i bought these amps the guy also sold me 2 L7 15's dual 4ohm for $200 for both so these amps are gonna turn out good. thanks

also since amp has 2 positives and 2 negatives, if i just wire both voice coils to the amp , will the amp automatically see a 2 ohm load? thank

 

[dB-r 10+ year member]

Yes, the outputs are paralleled inside the amp. So on the amp's speaker connector, the left side + is the same as the right side +. And same for the -.

Chris

dB-r Electronics

 

[05_ZX636 10+ year member]

thanks, i understand now. i was confused at the mono part but 2 + and 2 -'s.