? on 4-channel amp and ohms

a.stewart4242

I'm looking to get a four-channel amp to run the door speakers and two 8" subs. I'm not new to audio systems, having built fiberglass boxes and hooked up several systems in the past, but I've never used a 4-channel amp in this way. Am I able to run 2 channels at 4 ohm, and 2 channels at 2 ohm? My concern with this is that if I run two channels at 2 ohm and two at 4 ohm, that it will be interpreted as a 3 ohm load. Thanks in advance.

RonRizz

AS long as the amp is stable to 2 ohms in stereo , you're good to go

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P99rs Head Unit--- Amps- 2 Pioneer Prs800d --- Zapco ST1000MX---Zapco ST-4XSQ---- SI BM mk5 Subs---SI TM65v2 Midbass--- SI M3 mids--- SI M25 xbl2 tweeters ----- 2016 MECA street class 3rd place at world finals

a.stewart4242

Thanks for the quick reply. I thought so, just didn't want to assume.

RonRizz

Most amps are nowadays, but you may find a few out there that are not.

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P99rs Head Unit--- Amps- 2 Pioneer Prs800d --- Zapco ST1000MX---Zapco ST-4XSQ---- SI BM mk5 Subs---SI TM65v2 Midbass--- SI M3 mids--- SI M25 xbl2 tweeters ----- 2016 MECA street class 3rd place at world finals

SouthArk370Z

As per RonRizz, most amps will handle an impedance mismatch reasonably well. There will be some added distortion but, if you don't push the amp hard, it shouldn't be a problem except for with the worst-designed units. However, if pushed hard into a low impedance, it will sound bad and can cause damage to the amp and speakers. Try to match impedance as closely as possible, but a small mismatch is not the end of the world.

Keep in mind that driver/speaker impedance is given as a nominal value and will, at resonance, be lower than the spec. A 2 Ohm speaker may have 1 Ohm impedance at resonance.


Edit: Oops. Impedance is at it's max at resonance. It's at the frequencies above and below resonance that impedance drops.

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RonRizz

That southark, he's one smart cookie.

__________________
P99rs Head Unit--- Amps- 2 Pioneer Prs800d --- Zapco ST1000MX---Zapco ST-4XSQ---- SI BM mk5 Subs---SI TM65v2 Midbass--- SI M3 mids--- SI M25 xbl2 tweeters ----- 2016 MECA street class 3rd place at world finals

a.stewart4242

Thanks for the response. While I know many of the basics, always nice to get some confirmation (and learn something new) from those with more experience.

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SouthArk370Z

Thanks for the compliments. I was a big audio nut back in the '70s and '80s. Somewhere around the end of the '80s, between my ears deteriorating (age and too many rock concerts) and audio equipment getting better, I lost interest in chasing "hi-fi". In the early-'80s, digital got rid of most of the problems inherent with analog, which improved overall sound quality many times over, making it unnecessary to spend big bucks to get decent sound. Although the equipment has gotten (a lot) better over the years, it's still the same basic electronics (mainly "souped up" versions of old designs) and the physics/perception of sound hasn't changed any.

Now that you have my CV, here's my words of wisdom on car audio:
1) A car is a really crappy environment for audio reproduction. The smaller the car, the worse the situation. The noisier the car, the worse the situation. 370Zs are small and noisy - you'll never have anything approaching high fidelity in one. So go with what sounds good to your ears and don't worry about what others think.
2) Among the major names in consumer audio electronics, there's not a nickle's worth of difference in the sound you will get in a small car. The differences in specs has gotten to the can't-hear-except-under-the-best-circumstances and a car is nowhere near best of anything when it comes to audio.
3a) Transducers will make the biggest difference in sound quality. Since most of your inputs are digital, they are not going to make a lot of difference. Back in the days of tape, the transport could make a big difference; not so much with a CD or MP3 player.
3b) It's all about the speakers nowadays. Get the best speakers and enclosures that you can find/afford and EQ out the rest.
4) A surprising number of people don't realize that it takes 10X the power to get 2X the sound. A 100W amp is not that much louder than a 50W. You would need 500W, and speakers to handle it, to get twice the volume. If you want to get LOUD, you're going to need a LOT of Watts.

OK. I'll get off my soapbox now. As always, when it comes to audio, YMMV.

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