will NC252MP amplifier module drive my speakers?

[DKT88]

I'm wondering if a Hypex 252MP 250W per channel amp will drive my speakers (Thiel 2.2) to modest listening levels at about 10 feet. I suspect the answer is yes but I have some uncertainty and can't demo it. The speakers are 86db sensitivity and are nominally 4 ohm with a minimum of 3 ohms. Is there anything about the class D amp performance specifications that I'm missing?

 

[RayDunzl]

Is the rated power appropriate?

Yes. Should be more than enough for "modest" levels.

 

[andreasmaaan]

If I make a couple of conservative assumptions about your speakers and room:

• speakers require around 1W to reach 82dB/1m (based on 2.83V/86dB/3Ohm)
• critical distance in your room is around 5 feet (in most domestic rooms it is less)

You will achieve 83dB RMS (my definition of “moderate”, based on the recommended level for mixing/mastering) at the listening position with about 1.5W of input power. Assuming a 20dB crest factor (ie for more dynamic recordings), that would mean 150W for peaks of 103dB. You’d then want some headroom, say double or 4x the power required for 103dB peaks, which would get you to wanting about 300W or 600W (although the speakers may not be capable of handling this much power).

Also note that I’ve made quite conservative assumptions here, basing the numbers on a higher than typical critical distance and the lowest impedance of the speakers.

 

[Ron Texas]

Typically, an NC252 requires 2.35V to drive it to full power. Few unbalanced DAC's have more than 2.1V maximum output.

 

[HammerSandwich]

You will achieve 83dB RMS (my definition of “moderate”, based on the recommended level for mixing/mastering) at the listening position with about 1.5W of input power. Assuming a 20dB crest factor (ie for more dynamic recordings), that would mean 30W for peaks of 103dB.

How does +20dB correspond to 20x power output?

 

[RayDunzl]

You will achieve 83dB RMS (my definition of “moderate”, based on the recommended level for mixing/mastering)

Opinion:

I find my C-weighted long term Leq SPL value for modest listening to be in the low to mid 70s range...

Dire Straits - Making Movies

 

[March Audio]

Typically, an NC252 requires 2.35V to drive it to full power. Few unbalanced DAC's have more than 2.1V maximum output.

That does depend on the load impedance. 4 Ohms it's 2 volts.

 

[March Audio]

I'm wondering if a Hypex 252MP 250W per channel amp will drive my speakers (Thiel 2.2) to modest listening levels at about 10 feet. I suspect the answer is yes but I have some uncertainty and can't demo it. The speakers are 86db sensitivity and are nominally 4 ohm with a minimum of 3 ohms. Is there anything about the class D amp performance specifications that I'm missing?

Hi

As the other members have said the 252 will drive your speakers to fairly high level.

If you have any specific questions please don't hesitate to ask.

 

[andreasmaaan]

How does +20dB correspond to 20x power output?

Brain fart - thanks. Should have been 150W of course. Post edited.

 

[Ron Texas]

That does depend on the load impedance. 4 Ohms it's 2 volts.

I got the 2.35 V spec from Nord, and can't remember if they said 8 ohms, but your statement makes sense.

 

[March Audio]

I got the 2.35 V spec from Nord, and can't remember if they said 8 ohms, but your statement makes sense.

Yep, 2.3 is about right for 8 ohms.

 

[DKT88]

Thanks to all for the help. I was thinking about the problem narrowly as steady state output from an amp and had missed the other factors including input V , dynamic response, headroom and what "modest" means in terms of SPL.

 

[Trdat]

Typically, an NC252 requires 2.35V to drive it to full power. Few unbalanced DAC's have more than 2.1V maximum output.

I'm trying to research more about how a preamp(DAC)will effectively drive a Poweramp and I stumbled here it seems I'm getting closer. In my case I need to power my NC252 and have the minidspDAC8 with only 2Vrms. Is the Vrms the only thing we are looking at in a DAC when it comes to choosing a DAC preamp? And if it's only 2 V how much am I loosing out on and what can I do to get to full power on the NC252?

 

[boXem]

I'm trying to research more about how a preamp(DAC)will effectively drive a Poweramp and I stumbled here it seems I'm getting closer. In my case I need to power my NC252 and have the minidspDAC8 with only 2Vrms. Is the Vrms the only thing we are looking at in a DAC when it comes to choosing a DAC preamp? And if it's only 2 V how much am I loosing out on and what can I do to get to full power on the NC252?

This 2.3V is linked to an old erroneous spec from Hypex. For the NC252MP, 1.82V are enough to get it clipping into 8 ohms. So your minidsp DAC8 is perfectly fine.

 

[Trdat]

This 2.3V is linked to an old erroneous spec from Hypex. For the NC252MP, 1.82V are enough to get it clipping into 8 ohms. So your minidsp DAC8 is perfectly fine.

Thanks. And what specification am i looking for on the power amp for this?

 

[boXem]

Thanks. And what specification am i looking for on the power amp for this?

https://www.hypex.nl/img/upload/doc/ncore_mp/nc252mp/Documentation/NC252MP_02xx.pdf
pages 6 and 7

 

[Trdat]

Hey Boxem,

I have been looking at the specifications page but can't quite figure out which exact column I am looking at? Could you direct me to the exact specification?

In another amplifier I got Maximum gain (0.775V) 42.4V. Is this something different or what im looking for?

 

[Matias]

Hey Boxem,

I have been looking at the specifications page but can't quite figure out which exact column I am looking at? Could you direct me to the exact specification?

In another amplifier I got Maximum gain (0.775V) 42.4V. Is this something different or what im looking for?

This part of the datasheet shows that for full power (250W) at 4 ohms it requires 1.66 V RMS, which is below the standard 2 V RMS for RCA or 4 V RMS for XLRs that sources usually have.

 

[HammerSandwich]

You need the voltage gain from the table and the equations under "input sensitivity." Hypex shows you exactly how to calculate input levels for the rated 250W at 4Ω.

The numerator of the first equation - sqrt(Wrms * Rohms) - converts the amp's output in watts to Vrms. The denominator then uses the gain to scale that to input level, also in Vrms. If you want to get lazy, 26dB is a voltage factor of 20x, so you can simply assume the denominator = 20. That will be close, unless you gain-mod the amp.

TLDR? Because the 4Ω output is less than double the 8Ω, the amp needs more input to clip 150W at 8Ω: 1.82Vrms. Boxem already mentioned this in post 14.

 

[Trdat]

This part of the datasheet shows that for full power (250W) at 4 ohms it requires 1.66 V RMS, which is below the standard 2 V RMS for RCA or 4 V RMS for XLRs that sources usually have.

View attachment 40632

So if 1.66 Vrms is needed to power the amp to its maximum than what is the 2.34 V peak? Is that the peaks it can reach?