Yesterday I also made a post in the scoop forum for driver recommendations where we're deciding to go for 2x 8ohm or 2x 4ohm drivers for our hog scoops (so resistance of circuit becomes 2 or 4 ohm respectively). The amp that we will use is the MC2 E45, which according to the spec sheet should be able to power a 2ohm circuit with a max output power of 4200W. Now this seems more appealing than a 4ohm circuit which has a max power output of 2500W. 

Many times I read that 2 ohm is not good for the amp etc. but can anyone explain why this is? If the spec sheet says the amp supports 2 ohm circuits, then what would hold us back from utilising that? I've been reading up on it but I can't really find a definitive explanation. We've been discussing this topic with the people of our soundsystem but we don't really know what to do (we don't have a lot of experience). If anyone could shine a light on this that would be really helpful!

Cheers

or 2ohm playing 10khz at low volume ... 

Both are quite a different load on an amplifier, but both are "2ohm"

(also before the nerds get at me, that's 2ohm nominal, very much aware it changes with frequency etc etc )

There is definately a different understanding in sound when it comes to different music genres.

Personally I would not bother about the last 2dB (its a very small difference).

If you really want that extra, you would be better of with more cabs imho.

What kind of music is it actually?

And yes, the E45 could handle 2 Ohm loads (with the test conditions specified in the manual), however, I would not run it that way for different reasons like durability etc. Heavy 2 Ohm load will require more current which then results in more heat. 

PS: if you're after a transformer amp, I have a Infinite 7v2 for sale. Not a 8v2 but it can do for some occasions.

Driving the amp at 2 ohms will shorten it's life by years. And as hinted above, any gain you think you are getting is destroyed by power compression.

Stick to 8 ohm drivers - and you could then, at some point, add another cab per side without over-stressing the amp - which is far better. 

Void Inf8 v2 will do it on a decent supply (seen peaks of 40a on the front doing what you're asking, "2ohm" load per side), but also probably pop fuses internally, again seen it happen.

This was a 4 x 8ohm drivers per side (so 2ohm nominal), running the frequency you want to play, at loud volumes

smitske96 wrote: What kind of music is it actually? And yes, the E45 could handle 2 Ohm loads (with the test conditions specified in the manual), however, I would not run it that way for different reasons like durability etc. Heavy 2 Ohm load will require more current which then results in more heat.  PS: if you're after a transformer amp, I have a Infinite 7v2 for sale. Not a 8v2 but it can do for some occasions.

Mixed genres basically, mostly dub/dnb/techno I'd say.

Could you explain what a transformer could mean for us in this scenario?

cravings wrote: if your car is sold as being capable of 150mph, you probably shouldn't drive it at that speed all the time.. cos it'll start to wear out.

That makes sense 

Earplug wrote: Driving the amp at 2 ohms will shorten it's life by years. And as hinted above, any gain you think you are getting is destroyed by power compression.  Stick to 8 ohm drivers - and you could then, at some point, add another cab per side without over-stressing the amp - which is far better.

Yeah that sounds like a solid plan for the future. But then for future expansion we could also have gone for 2x 4Ohm drivers per channel instead of 2x 8 ohm drivers. But reading all the other comments I guess we should waive that idea. It just sounded attractive as the output power is higher but I'm starting to understand that this is just bad for the amp.

Sinai Sound wrote: Powersoft K10 / K20 will do this. Ran it like this in anger many many times until upgrading to X8.

I'm afraid that's a bit out of our budget haha. I guess moral of the story is that we should not go for a 2ohm nominal circuit. Did your void amps survive that current? 

Yes we've got all cabs already. Only need to put drivers in our hogs, the rest is all done. Never heard/read about paraflex cabinets yet, got some links to read up about?

I can send you the link if you want.

" It just sounded attractive as the output power is higher"

Yes - it can be difficult to understand that more power might actually not lead to more SPL. Far better to add square inches (or centimeters) of cone!  

When you look at the full spec sheet you can see that this amp should be able to deal with 2 ohm load as the power output per channel has only reduced to 4100W even with a crest factor of only 2.8.

https://www.mc2-audio.co.uk/wp-content/uploads/e45_datasheet.pdf" rel="nofollow - https://www.mc2-audio.co.uk/wp-content/uploads/e45_datasheet.pdf

https://www.mc2-audio.co.uk/wp-content/uploads/mc2_amp_power_measurement.pdf" rel="nofollow - https://www.mc2-audio.co.uk/wp-content/uploads/mc2_amp_power_measurement.pdf

The choice of whether to run at 2ohms then comes down to how important maximizing the service life of the amp is for you compared to getting the most possible output power out of the amp.  The amplifier is rated for it but your still doubling the current in the output transistors and running parts hotter.  You could always run 6*8ohm drivers off each amp for 2.67 ohm per channel as a compromise.

To bother with 4ohm drivers to me is more about the driver than the amp, if its a super high performance 21" driver with a 6" coil you might want to consider 4ohm just to get the most out of the driver but if its just an average 18" 4" coil driver then the driver will already be thermally compressing and there will not be much gain by the potential doubled power on the voice coil (apart from a cooked driver).

One of the rare moments, Speakerplans Amp Forum, brings a smile to your face.

EDIT : Would be very skeptical about MC2 E45, having the nuts, to pull 35A off the mains, even though it has higher rated output, at 2 ohms, than Inf 8 MK2..

Hmmm...

csg wrote: Correct, the infinite 8 MK2 is a far superior arc welder.

Are you saying the MC2 E45 is a fantastic beast, that can produce power, without sucking current from the wall !?

I've "PERSONALLY" seen Powersoft K20, suck 34.9A from the wall, while powering 4x 8 ohm subs, so that amp is exempt from this type of argument, forever !!!

Why anyone is interested in balls out performance into 2R both channels sub is beyond me. Power is cheap these days, go with something with plenty of voltage and keep to 8R. 

Returning to this page, as E45s are regularly popping up at reasonable price.

But the question still remains, can the MC2 E45, out perform the Void Infinite 8MK2, on sub notes !?

And for all the 2 ohm haters out there, let us not forget.

A typical Horn loaded 18" Sub enclosure, with nominal 8 ohm driver, in reality, will measure approx 10-12 ohms.

Same with 4 ohm driver, will measure as approx 5-6x ohms.

So 4x cabs loaded with "8 ohm" drivers per side of an amp, will not be 2 ohms,

Neither will will 2x cabs loaded with " 4 ohm drivers", per side of an amp.

Now that is out of the way, an Infinite 8MK2, can power 2x "4 ohm" 18NLW9601 drivers per channel effortlessly, from 38hz to 100hz.

Question is, can the MC2 E45 do the same, given the higher power rating !?

We have some OLD Peavey CS model amps, the 1000 and the 1300, and the PV2000.

All will play 2R, bass, all night, at close to max.. with no problem.

Ok, not at 4odd kilowatt, and I'm sure others have reservations about the brand, or the age, 

but, I'd say, you've a much better chance, mainly, of 2R stability, with toroids.. 

If your chosen music has no such dynamics then carry on. For everyone else, having modern amps with their very much greater, if brief, output voltage capabilities is a major boon to sound quality.

Take it from someone who was operating sound systems when your peavey amps were state of the art, Sound systems have come on a long way in that time!

And, no, 30 odd year old amplifiers of any type will not be as reliable into a 2 ohm load as a similar, new amplifier of similar quality. 

im not advocating just whacking all the pots to 5 o clock and redlining. of course not. and im not entirely sure where you got no headroom or dynamics when i just said "close to max"... of course, allow for enough range. but i thought that went without saying mate. so i didnt.
also, i mentioned that i find toroids more reliable.. didnt mention age.  

and id not suggest anyone else buy 30 yr old amps.

Neither would a QSC PL9, even with all its power and sub warmth, but hoping it will survive each gig.

On FB, many have said E45 is very disappointing on sub, definitely wont meet rated power below 60hz, so that is that.

It's a matter of design goals and final product cost. 

There is no fundamental technical reason why a class AB amplifier with a linear power supply is better suited to low impedance loads than a Class D amplifier with a switchmode power supply, quite the opposite in fact.

Things are just not as overbuilt these days as those Peaveys or if they are, cost as much adjusted for inflation as those things did back in the day.

Option one, Peavey cs800, a fine example of a linear amp capable of producing 400w into a 4r load continuously (40V), and probably around 550w on the occasional peak

Option two, Powersoft X4, representative of a fairly good, fairly up to date modern amp, capable of around 420w into a 4r load continuously ( dropping lower once thermal capacity gets used up) but peaks of 174V which by my math is around 7500w.

It is easy to see that to achieve a reasonable dynamic range of 10db, you can expect the Peavey to use around 55W of its constant power delivery capacity, where you can use all the capacity of the Powersoft.

So, in reality the maximum output of any system whilst maintaining good dynamics is around 10%

And, a modern, peak rated amplifier will offer around 8 to 10dB greater output capability for a similar dynamic range compared with old iron amps.

As the thread has resurfaced, I’ll give some more thoughts. 

I was fairly impressed with the e45 at the time but have since bought a CVR 3302 and powered the same drivers at 8 ohm on each channel, 13a plug.  Completely different beast, despite lower rated power (4200w to each driver on e45 vs 3300w with the CVR). 

I’m not sure how much of a hit an amp will take on sub notes being powered at 2ohm stereo/ 4ohm bridged compared to 8ohm stereo. 

Im guessing that most of these slim, high power chinese amps are based on powersoft k series topology, so should be completely happy providing that thermal limits are not reached.

Fundamentally though, if it works it works, and that is absolutely the best way of determining if any amp is suitable for your needs. There are simply too many variables involved make successful decisions any other way.

Interesting bit of feedback there, can I ask the music material you normally play?
Can you detail the drivers and power rating of them?

Sounds like a contender, for 1U, 1x driver per channel, sub amp.

The drivers are B&C 18ds115 (1700w). Playing drum and bass, jungle, techno. 

We used the e45 in 4ohm bridge mode. So 8400w supposedly across the two 8 ohm drivers. 

The MC2 e45 is put under more strain at 4 ohms bridged mono than the CVR 3302 at 8 ohms stereo mode. So the end result is having more headroom due to a lighter load in favor of the CVR. 

Best Regards, 

Chatting to few people here and on FB, MC2 E45 is not the amp for people, playing bass heavy material, anyway, never mind at 2x ohms.

Many confirmed, even the warm sounding E90, dissappoints those, who bought it to play bass heavy material,  @ 4/2 ohm stereo, with HPF < 50hz.

Feedback on MC2 E100, it fails miserably, with sub heavy material, if used with sub on all channels.

Call it coincedence or circumstantial, just so happens the quoted current draw on these amps, is way below what you would expect, for amplifiers that can truly reproduce 40hz bass lines, with authority, even if only at 4 ohms stereo.

Will say it again, this is not the case with Powersoft K20, if supplied enough wall juice, it will draw what it needs, to get the job done.

Seen it do that, on Proper 32A power, powering just 2x PD1850 8 ohm per side !!

Maybe for HPF above 55hz, it would have faired better..

It’s worth asking as I can see it being overlooked but no, we followed the correct procedure. 

That applies to all amplifiers. The load plays a factor.

4 ohms Bridged Mono: 2 ohms per channel Stereo Mode

Enjoy your CVR 3302

Best Regards, 

Seems in the UK, Admark AD42, is more respected, than the CVR.

Friend has few Admarks, says he will never touch CVRs.

Best Regards,

Maybe we should continue this in another thread, as this one is about that great "mid tops" amp, the MC2 E45..

Best Regards,