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MC2 E45 amp ability to power 2 ohm circuit
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Randy Bohannon View Drop Down
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Originally posted by BigSoundNorthWest BigSoundNorthWest wrote:

Just quickly.

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.. 




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.
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Originally posted by csg csg wrote:

Have you ever heard of headroom and dynamic range?


I still think people don’t do the maths enough here when considering their setup.

Quick example: assume you have a speaker which is rated for 250 Watts at 8 ohm, nominal. Simple Ohm's Law gives us a demand of ~45 Vrms from the amplifier.

Doesn't sound so difficult, right?

Well, we want to play music & for the sake of keeping the sums easy, we'll use the classic value of a 12 dB Crest Factor at all frequencies.

If we want to avoid serious clipping of the amplifier, or compressing the music, then we need an amplifier which is capable of doing 180 Vpk, unclipped.

That's a touch over 4,000 Watts.

That's one reason why you'll see professional rigs these days using the same, relatively high-output amplifiers for most of the system - even the HF drivers.



This is also why it's amusing when people proudly say "we *only* ran the rig at 50%". That's a dynamic range of <3 dB. Not something that I - or most folk - would find pleasant to listen to for a long time.
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Lets put this into perspective,

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.
“The fact is this is about identifying what we do best and finding more ways of doing less of it better”
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Originally posted by al_x al_x wrote:

I recently borrowed a friends E45 to power two B&C 18ds115 on sub. It managed 6 hours in a hot room, 4ohm bridge on a 13a plug quite happily (playing drum and bass and jungle so a lot of long sustained bass notes)

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. 



Edited by al_x - 04 December 2022 at 9:41am
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How a lightweight amp handles low impedance use is down to how hard you need to push it. If you have plenty of headroom, as it sounds like you have, then you will likely have a fairly low duty cycle and will be completely fine. 
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.
“The fact is this is about identifying what we do best and finding more ways of doing less of it better”
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Originally posted by al_x al_x wrote:


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. 



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.
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toastyghost View Drop Down
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Originally posted by al_x al_x wrote:

Originally posted by al_x al_x wrote:

I recently borrowed a friends E45 to power two B&C 18ds115 on sub. It managed 6 hours in a hot room, 4ohm bridge on a 13a plug quite happily (playing drum and bass and jungle so a lot of long sustained bass notes)


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. 




The MC2 E45 is rated for 1250W per channel at 8 ohm, not 4200W. That's also measured with "continuous music" having a crest factor of 14 dB.

Unfortunately they don't list the peak voltage output.
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Originally posted by levyte357- levyte357- wrote:

Originally posted by al_x al_x wrote:


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. 



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. 
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Originally posted by toastyghost toastyghost wrote:

Originally posted by al_x al_x wrote:

Originally posted by al_x al_x wrote:

I recently borrowed a friends E45 to power two B&C 18ds115 on sub. It managed 6 hours in a hot room, 4ohm bridge on a 13a plug quite happily (playing drum and bass and jungle so a lot of long sustained bass notes)


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. 




The MC2 E45 is rated for 1250W per channel at 8 ohm, not 4200W. That's also measured with "continuous music" having a crest factor of 14 dB.

Unfortunately they don't list the peak voltage output.

We used the e45 in 4ohm bridge mode. So 8400w supposedly across the two 8 ohm drivers. 
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Elliot Thompson View Drop Down
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Originally posted by al_x al_x wrote:

Originally posted by toastyghost toastyghost wrote:

Originally posted by al_x al_x wrote:

Originally posted by al_x al_x wrote:

I recently borrowed a friends E45 to power two B&C 18ds115 on sub. It managed 6 hours in a hot room, 4ohm bridge on a 13a plug quite happily (playing drum and bass and jungle so a lot of long sustained bass notes)


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. 




The MC2 E45 is rated for 1250W per channel at 8 ohm, not 4200W. That's also measured with "continuous music" having a crest factor of 14 dB.

Unfortunately they don't list the peak voltage output.

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, 
Elliot Thompson
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Points: 10866 		Post Options Post Options   Thanks (0) Thanks(0)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post Posted: 07 December 2022 at 11:16am
Originally posted by al_x al_x wrote:

Originally posted by toastyghost toastyghost wrote:

Originally posted by al_x al_x wrote:

Originally posted by al_x al_x wrote:

I recently borrowed a friends E45 to power two B&C 18ds115 on sub. It managed 6 hours in a hot room, 4ohm bridge on a 13a plug quite happily (playing drum and bass and jungle so a lot of long sustained bass notes)


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. 




The MC2 E45 is rated for 1250W per channel at 8 ohm, not 4200W. That's also measured with "continuous music" having a crest factor of 14 dB.

Unfortunately they don't list the peak voltage output.


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


Please don’t think I’m being patronising, but when using it in bridge mode are you connecting the speakers via a dedicated cable that ties the correct terminals of the amplifier’s two channels together?

From the MC2 E45 manual:
Quote Connecting To Your Amplifier: Bridged (Mono) Operation
Use the centre Speakon connector marked Bridge/Stereo, and depress the button between the XLR connectors to the “Channel Link [A]” position.
Connect the speaker as follows: Pin 1-: Cold (A) Pin 2+: Hot (B)
When operating in bridged more, the minimum impedances are doubled.
The minimum load in bridged mode is 4 Ohms.


I've seen a few people in the past get this wrong, as the correct termination varies from amplifier to amplifier. If not, you might not actually be giving the boxes the voltage you think you are.
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levyte357- View Drop Down
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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.



Edited by levyte357- - 07 December 2022 at 11:47am
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