Is it possible to check you have sufficient amplifier headroom with a umik-1?

[Razorhelm]

I agree that 200 watts per channel makes sense however my system is a little unorthodox, i have a software crossover running 6 DAC channels so i have 6 amps driving 6 drivers, i am confident i have enough power for the tweeter and woofer but the subwoofer is a 12-inch driver in a sealed enclosed and i have no idea of its sensitivity.

My system is documented here (https://www.audiosciencereview.com/...e-crossovers-via-rephase-and-camilladsp.19910)

The amp is a Harmon/Kardon avr 255 and its specs say 65 watts per channel into 8ohms but my subwoofers speakers are 4ohm so I should get more watts outs. I have also seen measurements of 90 watts per channel in a review.

With this wattage, I feel I'm right on the edge of what I need. I could just buy a new 6 channel amp with a much higher power spec but I don't want to if there is no need, which is why I wanted to find a test method-based approach to have confidence that what I have is sufficient.

 

[Spkrdctr]

Now that I have MUCH more information on your setup, I think you need much more power for the Kenwoods. I would look at something that is up around 400 or more watts per sub. You will then be able to adjust your sub volume and not have to worry about cooking the voice coil from severe clipping. You are in a special case that does not fit into the general run of the mill listener. So, you can go big on your sub power, really as big as you want. 400, 600, 800 watts per channel? I would personally recommend a Crown amp that is rated to around 800 watts at 4 ohms. In that ballpark. The amps are NOT expensive and have a 6 year warranty. Many people use them and they work great. Good Luck!

 

[Razorhelm]

This is what the scope feature of REW shows, this is with the volume on the amp at 0dB and a 42Hz signal at 0.00 dBFS.

Bit unsure now as the lower half looks better than the top.

Maybe I need a bigger amp after all, might be time for a nice crown!

 

[Spkrdctr]

Disregard.

 

[RayDunzl]

This is what the scope feature of REW shows

What does an RTA show - distortion is not always visually obvious in a sine wave, unless severely flattened at the peaks by compression or clipping.

 

[Razorhelm]

Clipping is what i was looking for here, did i find it?

How should I use the RTA to look at this, play a tone and look for the distortion spikes?

 

[RayDunzl]

Clipping is what i was looking for here, did i find it?

The wave is not obviously clipped - no flat or flattened tops.

Doesn't mean it might not be distorted from a true sine.

How should I use the RTA to look at this, play a tone and look for the distortion spikes?

Yes, and the distortion panel for values.

JBL LSR 308 playing a 440Hz sine wave at 82.3dB SPL at the listening position. Below 440Hz, room noises - PC fan, etc.

Tiny 2kHz tone, ?

2nd harmonic at 880Hz, third harmonic at 1320Hz, etc.

If shown on the scope, the eyeball probably wouldn't see a defect in the sine wave. Mathematically, it is there, and audible to the ear.

 

[Spkrdctr]

View attachment 134191

This is what the scope feature of REW shows, this is with the volume on the amp at 0dB and a 42Hz signal at 0.00 dBFS.

Bit unsure now as the lower half looks better than the top.

Maybe I need a bigger amp after all, might be time for a nice crown!

You are good to go. No clipping. I would not worry about distortion. One it is very hard to hear unless you have a lot of it and two, what can you do about it? If the system is not clipping which it isn't, and it sounds very good, you are done. Now if you want to look for very small, almost insignificant stuff that you can't fix anyway, go for it. But at the moment it appears you are all set. All in all, good job!

 

[Razorhelm]

I'm very happy with my system now! It was clipping I was worried about.

FYI @RayDunzl
Here is what I get for a 42hz sine.