March Audio P701 Mono Block Power Amp

[DonH56]

Below are the specs I found on the website, same as previously posted? There are four woofers but I do not think they are all in parallel. I find it hard to believe they would rate "4 ohms nominal" and yet have <1 ohm for the woofers. I suspect the woofers are actually a series-parallel arrangemnet internally to hit around 4 ohms.

Concentro Floorstanding Speaker
Product Specifications
Tweeter: JET 5, modified
Midrange: 70/140 [mm]AS-XR Ring radiator
Midbass: 220 [mm] AS-XR Cone
Bass reflex tubes: 2 off 120×350 [mm] Cone
Woofer: 4 off 250 AS [mm]
Bass Loading: Vented Box
Crossover Frequencies: 120 / 360 / 2700 [Hz]
Frequency range ( IEC 268-5): 18 – 50 000 [Hz]
Sensitivity: 90 [dB/2.83V/m]
Recommended amplifier power: 80 – 600 [W/Channel]
Suitable for amplifier rated between: 4-8 Ω
Rated power (Continuous): 400 [W]
Rated power (Dynamic): 600 [W]
Rated impedance: 4 Ω
Binding posts: 5-way custom; bi-wirable
Magnetic shielding: No
Weight: 140 [kg]
Dimensions (WxHxD): 460 x 1680 x 610 mm with spikes

 

[March Audio]

Below are the specs I found on the website, same as previously posted? There are four woofers but I do not think they are all in parallel. I find it hard to believe they would rate "4 ohms nominal" and yet have <1 ohm for the woofers. I suspect the woofers are actually a series-parallel arrangemnet internally to hit around 4 ohms.

Concentro Floorstanding Speaker
Product Specifications
Tweeter: JET 5, modified
Midrange: 70/140 [mm]AS-XR Ring radiator
Midbass: 220 [mm] AS-XR Cone
Bass reflex tubes: 2 off 120×350 [mm] Cone
Woofer: 4 off 250 AS [mm]
Bass Loading: Vented Box
Crossover Frequencies: 120 / 360 / 2700 [Hz]
Frequency range ( IEC 268-5): 18 – 50 000 [Hz]
Sensitivity: 90 [dB/2.83V/m]
Recommended amplifier power: 80 – 600 [W/Channel]
Suitable for amplifier rated between: 4-8 Ω
Rated power (Continuous): 400 [W]
Rated power (Dynamic): 600 [W]
Rated impedance: 4 Ω
Binding posts: 5-way custom; bi-wirable
Magnetic shielding: No
Weight: 140 [kg]
Dimensions (WxHxD): 460 x 1680 x 610 mm with spikes

Yes this makes sense and as I originally thought.

 

[restorer-john]

He should measure the impedance of the speakers and sub-woofer section if electrically separate.

Who knows what it will be, but until we know, we can't advise him. My nominal 4 ohm rated Jamos with dual internal push-pull woofers are actually 2.6 ohms through part of the low-med bass.

 

[Doodski]

Yes this makes sense and as I originally thought.

Can you please tell me the make and model of the test unit used by amirm for the DACS, amps and other stuff? I can't remember what it is and after extensive searching have found no details about it. I need the make and model details for the Wikipedia listing details.

 

[March Audio]

Can you please tell me the make and model of the test unit used by amirm for the DACS, amps and other stuff? I can't remember what it is and after extensive searching have found no details about it. I need the make and model details for the Wikipedia listing details.

Audio Precision Apx555

 

[restorer-john]

Can you please tell me the make and model of the test unit used by amirm for the DACS, amps and other stuff?

You mean the Audio Precision APx555? (his is not the B series)

 

[March Audio]

He should measure the impedance of the speakers and sub-woofer section if electrically separate.

Who knows what it will be, but until we know, we can't advise him. My nominal 4 ohm rated Jamos with dual internal push-pull woofers are actually 2.6 ohms through part of the low-med bass.

He say he has measured the dc resistance so has a meter. He can measure the resistance at the amp end of the speaker cables (disconnected from the amp of course) and that will confirm what's going on.

 

[Doodski]

Yes, that's it. Thanks it seems so clear now but I just couldn't remember it. Thanks again @March Audio and @restorer-john .

 

[restorer-john]

He say he has measured the dc resistance so has a meter.

Depends on his meter. DMMs are notoriously bad in the low R values and often inexpensive ones will give erroneous readings due to the inductance of the woofer's internal series network.

 

[March Audio]

Depends on his meter. DMMs are notoriously bad in the low R values and often inexpensive ones will give erroneous readings due to the inductance of the woofer's internal series network.

Sure but it will clearly tell us the difference between 3.2 ohms and 0.7 ohms which is all we need to confirm.

@AnLaoJin are the subs you refer to in the speaker or external boxes?

 

[restorer-john]

Sure but it will clearly tell us the difference between 3.2 ohms and 0.7 ohms which is all we need to confirm.

It can't be 0.7 Ohms. Only kids in their basements would wire up multiple woofers to present that kind of impedance- surely not a commercial product...

 

[March Audio]

It can't be 0.7 Ohms. Only kids in their basements would wire up multiple woofers to present that kind of impedance- surely not a commercial product...

That's why I dismissed it originally, however it could have been 4 external passive sub boxes added to the main speaker by the owner.

I am fairly confident that these are not external added subs and this is just a language barrier. Just the configuration of the speakers which rate as nominal 4 ohms (will probably dip below that at some frequencies).

In which case the previous advice stands; that the NC1200 (our P701) is actually a perfect match in terms of power and can drive these speakers to their maximum capabilities at very low distortion levels. The NC2K offers no advantage in that power range.

 

[thibaw]

I have B&W 805 d3 and will be buying a new power amp shortly. My system is in a relatively small dedicated music room - 5x4 sq metres.
I was very impressed recently when I borrowed a DIY Ncore 400 dual mono amp. It has made me reconsider Class D and a pair of your monos are definitely on my shortlist. Can you give me some advice about relative merits of the P451 vs P701?

 

[March Audio]

I have B&W 805 d3 and will be buying a new power amp shortly. My system is in a relatively small dedicated music room - 5x4 sq metres.
I was very impressed recently when I borrowed a DIY Ncore 400 dual mono amp. It has converted me to Class D and a pair of your monos are definitely on my shortlist. Can you give me some advice about relative merits of the P451 vs P701?

Hi @thibaw

So the P701 is based on the NC1200 module form Hypex. The P451 is based on the 1ET400A module form Purifi. Im not sure if you are aware but the same guy, Bruno Putzeys, designed both modules. He was responsible for the ncore modules at Hypex. He subsequently left Hypex and started Purifi where he designed the 1ET400A. The 1ET is an evolution of the ncore modules and has better technical performance and IMO slightly better sound. It has a slightly more extended "sweeter" high frequency range.

However it does depend on your speakers, room and listening style which amp, P451 or P701 might suit you best. For insensitive and challenging speaker loads, larger rooms and a penchant for high SPL then the P701 is the choice. Otherwise I would recommend the P451.

If the Ncore NC400 provided ample power for you when you tried it out then its simple, go for the P451. If you still felt you wanted a bit more dynamics then its the P701.

Hope that helps

cheers

Alan

 

[thibaw]

Hi @thibaw

So the P701 is based on the NC1200 module form Hypex. The P451 is based on the 1ET400A module form Purifi. Im not sure if you are aware but the same guy, Bruno Putzeys, designed both modules. He was responsible for the ncore modules at Hypex. He subsequently left Hypex and started Purifi where he designed the 1ET400A. The 1ET is an evolution of the ncore modules and has better technical performance and IMO slightly better sound. It has a slightly more extended "sweeter" high frequency range.

However it does depend on your speakers, room and listening style which amp, P451 or P701 might suit you best. For insensitive and challenging speaker loads, larger rooms and a penchant for high SPL then the P701 is the choice. Otherwise I would recommend the P451.

If the Ncore NC400 provided ample power for you when you tried it out then its simple, go for the P451. If you still felt you wanted a bit more dynamics then its the P701.

Hope that helps

cheers

Alan

Alan, thanks a lot for the quick reply. One of my concerns with my B&Ws is that they can get a bit hot in the treble, especially with horns. I liked the NC400 precisely because it took off the hard edge and improved the treble compared to my current SS amp. The B&Ws are rated at 8ohms but dip to under 4. I'm sure the P451 would have no problem with that but will you be doing a NC1200 equivalent Purifi in the near future?

 

[March Audio]

Alan, thanks a lot for the quick reply. One of my concerns with my B&Ws is that they can get a bit hot in the treble, especially with horns. I liked the NC400 precisely because it took off the hard edge and improved the treble compared to my current SS amp. The B&Ws are rated at 8ohms but dip to under 4. I'm sure the P451 would have no problem with that but will you be doing a NC1200 equivalent Purifi in the near future?

The P451 is very slightly more capable than the NC400 in terms of power and current delivery. If you found the NC400 adequate with your B&W, then you will the P451. It can deliver 25 amps and is happy with 2 ohm loads and below.

A higher power Purifi has been mooted for a long time but no sign of it yet. I have not been made aware of any near term introduction. We will of course be utilising it when it is released.

 

[westyjeff]

@g29 A unit is on its way tomorrow.

@March Audio, Did @amirm ever get a P701 for review?

 

[ex audiophile]

Well iv ordered a pair, combining it with my TAD cdp and a anthem str pre .

I want to see if this room correction , dual sub integration DSP preamp combined with class D amps can really deliver as they represent incredible value if they can.

I will hook it all up with basic mogami XLR cables .

It will replace my fancy belles statement monoblocks and top range preamp not to mention insane'o'price wires.

If it sounds bad I'm disowning you all

If it sounds great ... Well I won't stop banging on about it lol

So what do think of the new system? Apologize if you're already updated.

 

[AnLaoJin]

Yes this makes sense and as I originally thought.