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I just ran into a deal on an old school MMATS 500.1 amp (500W RMS @ 1 ohm); and apparently these things are underrated. I have an alpine SWS-1023D 2 ohm DVC 10" Type-S rated at 300W RMS (150W per coil). I am using a Qlogic single sub box found on this site for my F150 with a stock head unit. My question is two fold.
1.) If I wire the sub at 1ohm (two jumpers); could I just lower the amp's gain or will I readily blow it using the 500W amp. If I do lower the gain, will it affect sound quality?
2.) If I run this amp with a 4ohm load (one jumper), is there a way to calculate the RMS i would be getting.
Looking around, it seems to upgrade the sub to match the amp will be tough because I am really limited by the depth of this box. Thanks
jcran171.) If I wire the sub at 1ohm (two jumpers); could I just lower the amp's gain or will I readily blow it using the 500W amp. If I do lower the gain, will it affect sound quality?
Should be able to lower the gain and be fine. Just use a DMM. Also it shouldn't affect SQ.
jcran172.) If I run this amp with a 4ohm load (one jumper), is there a way to calculate the RMS i would be getting.
I believe so but I'll leave that to TigerHeli. I'm not exactly sure of the process to figure that out. I believe he does know how to do it.
GMC Sonoma, JVC KD-A95BT, 2 Pioneer TS-D601P in doors, 2 Pioneer TS-G4644R in dash, 2 JL W3v2-D2 10 inch subs, Lightning Audio B4.250.2, Soundstream TX1.1300D
Thanks teddy. I will see if tiger replies, but it sounds like my best bet is to just lower the gain.
i would say best bet is to lower the gain. Also usually a higher ohm load gives you better sound quality. But its such a small difference its insignificant
JVC KD-AVX44, 2 Massive Audio Hippo 8's , Hifonics Colossus going back in soon, MB Quart ONX216, Fli audio FL450S-F2, Energy ENC693x2 in rear deck, 6 gauge kit plus a huge 3 gauge kit. Custom built box for my 8's :)
I'm having a hard time finding info on the amp. What is the internal fuse rating - that might give us a rough idea of what it really puts out.
First off - let's answer the SQ question - lowering the gain won't hurt the SQ except that the amp will be providing less power. Similarly - running the same power at 4-ohms or 1-ohm you see slightly better excursion control at 4-ohms, but in this case you would be running less power at 4-ohms so sound quality would decrease - but you sub may well thank you.
Q1 - You can use a DMM to limit the gain so the amp only outputs 300W RMS to the sub, but you might need to limit the HU volume as well.
Q2 - Somewhat. I did find specs on the current MMATS 600.1 - it is 600W RMS at 1-ohm and 350W at 2-ohms and the fuse rating supports that. That is 58% at 2-ohms. Assuming your amp is similar, it should be around 290W at 2-ohms and 170W at 4-ohms, which is about 60% of what the sub wants. If the amp is under-rated, it might put out more than that, but you can't tell how much more really without benching it on an oscilloscope.
What you might want to do it try it both ways and see what works best for you.
Hope This Helps!!!
Anyone else have suggestions?
2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock
speakers, no amp, no subs
Thanks Tiger. I am not surprised you can't find much info, it is a pretty old amp. I don't have the amp with me now, so I am not sure of the fuse. Is there a direct correlation between fuse and potential output?
I think you are probably right in saying I should try both ways and think I will do that to see what sounds better. Based on the recommendations, I will start with 1ohm and low gain and go from there. Thanks to everyone for their help.
Not direct, but a 500W Class D amp should draw 43A at clipping.
If it has only a 40A fuse, it might be slightly more than 80% efficient, or it might be slightly less than 500W.
50A Fuse, roughly 580W (or they put a bigger fuse than needed in or it's REALLY ineffcient - but the first is unlikely b/c they don't want the amp burning up before the fuse blows for liability reasons).
60A - 700W, etc.
I checked the amp and it has 2 x 20a written on the amp and two 25a fuses installed. I found some extra info on it and apparently these amps have efficiencies in the mid 90's. I am hoping to get it installed this weekend if I can get the power wires etc together. I will let you know how it works out. Thanks again
It's probably a good idea to swap the fuses in the amp back from 25A's to 20A's, but it's probably not a huge deal.
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