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Old 25th June 2004, 07:26 PM   #1
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Location: New Mexico
Question 2 Ohm Mono Power Output?

I have an Earthquake PA2075. The specs are as follows: 320W x 1 Channel Mono Bridged at 4 Ohm, 160W x 2 Channels at 2 Ohm, 104W x 2 Channels at 4 Ohm. Some other info: Damping factor = 200 (don't know if this matters).

I'm running this mono to an Orion XTR 15" DVC sub (old one). Each coil is 4 Ohms and I'm running them in parallel so it is a 2 Ohm connection. I was wondering what the power output is. As stated above there should b 320W at 4 Ohm mono but I'm running it at 2 Ohm. Yeah, I know, most wouldn't recommend this but A) I only have the one DVC sub and B) this amp can handle it but it isn't listed in the book.

Any help much appreciated!
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Old 25th June 2004, 11:16 PM   #2
clayton is offline clayton  United States
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If its running 320 watts x 1 @ 4ohms, its runnig 640 watts x 1 @ 2ohms. But it won't last,you will fry that amp before long. This is highly not recomended. You are just asking for trouble.
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Old 26th June 2004, 01:09 PM   #3
sreten is online now sreten  United Kingdom
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Due to resistive losses you will probably only be getting about
300W into your severely mismatched effectively 1 ohm load.

Connectiing it properly, i.e. each channel to each coil for proper
4 ohm per channel loading will give you over 200W and far more
reliability at the cost of < 2dB in output level, piffling.

sreten.
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Old 26th June 2004, 02:44 PM   #4
sreten is online now sreten  United Kingdom
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just a further note :

If the amplifier current limits at the equivalent of say 200W
into 2R per channel this gives a current capability of ~ 10A.

Bridged into a 2R load you will only get 200W out before
the current limiting kicks in, which is no better than using
each channel to drive each voice coil, which will not current
limit but voltage clip at around 200W.

Voltage clipping is much better than current limiting.

sreten.
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Old 28th June 2004, 06:06 PM   #5
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Clayton - through electronics theory you are correct that the power out should double but from what I've read about amplifier specs and true power output I doubt I'm really pushing 640W. Also, I doubt this is going to fry. As I stated, most wouldn't recommend the way I hooked it up but from my history with this amp it can because it has done so, in the past, for approximately two years straight. Plus, I took the endplates off the amp and drilled many holes and mounted a processor cooling fan, effectively forcing lots of air through the amp.

I was just wondering if anybody could tell me what the approximate power out is.

Streten - "severely mismatched effectively 1 ohm load" I don't understand how you get a 1ohm load, please explain. Also, I would like to connect it in stereo and just have 2 - 4 ohm channels but the reason I went mono is because I wanted to utilize the mono subwoofer output in my deck. It has built in gain and high/low pass crossover settings so by hooking the amp to the normal preamp outputs kind of eliminates those nifty options. The sub, however, is pretty worn out and needs replacing. In the future I will probably replace it with a SVC 12" of good quality.

Thanks for the inputs!
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Old 29th June 2004, 01:24 AM   #6
clayton is offline clayton  United States
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Quote:
Originally posted by phlegmhurl
I would like to connect it in stereo and just have 2 - 4 ohm channels but the reason I went mono is because I wanted to utilize the mono subwoofer output in my deck. It has built in gain and high/low pass crossover settings so by hooking the amp to the normal preamp outputs kind of eliminates those nifty options. The sub, however, is pretty worn out and needs replacing. In the future I will probably replace it with a SVC 12" of good quality.

Thanks for the inputs! [/B]
WHy not get a y-adapter & connect it to your HU mono sub output & connect amp to it. This way you can run your amp stereo, which would be alot less strain on the amp.
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Old 29th June 2004, 01:45 AM   #7
sreten is online now sreten  United Kingdom
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Quote:
Originally posted by phlegmhurl

Sreten - "severely mismatched effectively 1 ohm load" I don't understand how you get a 1ohm load, please explain.
Thanks for the inputs!
You''ll notice bridged output into 4 ohms is exactly both channels
into 2 ohms, this is because bridged each channel sees a 2ohm
load, and currents are the same for 4 ohm bridged and 2 ohm
per channel.

So bridged into 2 ohms each channel sees a 1ohm load, and
output will be the same as both channels with 1 ohm loads.

IMO output is likely to not be more than 200W to 250W,
assuming the current limiters kick in at around 10A rms.

If there is no limiting max power per channel into 1 ohm is
going to be around 190W, given the ratings into 4 & 2 ohms.

sreten.
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Old 29th June 2004, 02:24 AM   #8
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Quote:
Originally posted by sreten
Due to resistive losses you will probably only be getting about
300W into your severely mismatched effectively 1 ohm load.

Connectiing it properly, i.e. each channel to each coil for proper
4 ohm per channel loading will give you over 200W and far more
reliability at the cost of < 2dB in output level, piffling.

sreten.


Yes and remember phlegmhurl, it takes a 3db change before the human ear can detect a change in volume, so save yourself some headaches and probably some distortion and follow the above advice provided by sreten


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Old 29th June 2004, 01:32 PM   #9
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Thanks for the tips! I'm going to rewire this weekend. The HU is a Sony M-630. It has front, rear and subwoofer mono outputs. The x-over settings might apply to the rear output but the documentation is really crappy. The manual just tells me how to get to the Hi and Lo x-over settings but not where they apply or how to make them sound good.

I believe the subwoofer mono output is setup as a Y already (inside the stereo) and having dual voice coil still makes me put it in 2 Ohm parallel or 8 Ohm series. The dust cover on the sub crumbled (it is 10+ years old) so I'm looking at buying a new sub anyway. In the meantime, I might attempt to fabricate a new dust cover and glue it on with liquid nails or something. It would be a new challenge.

The amp does behave well until it gets hot outside. I live in the desert and when the temperature is around 100F the amp will run for about 7 minutes and then starts overheating and shuts off. In the cool evenings I can run it without problems. I think changing it to stereo will cool it down enough but if the trunk temperature is still a factor then I'm going to mount it under my dash and route a new A/C duct into the end of it. That ought to keep it cool! Anybody ever tried this before?
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Old 30th June 2004, 07:07 PM   #10
jp88 is offline jp88  United States
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Just run it 8 ohm mono that is effectively th same as 4 ohm stereo and will be much easier on your amp and will not require a y cable or anything
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