xmc-1 new sub amp and parametric eq

[deepstage]

Ok time to teach silly Paul something. I'm just not finding the info I need.

Here's the situation and a few have given me some advice in another post already. But now I have actually acquired my new amp and thought I'd create a new post to taylor it to my exact situation currently

Previous setup
XMC-1 rca sub out to Dayton SA1000 amp with full bass controls (level, phase, boost etc)

New setup
XMC-1 balanced sub out to Cerwin Vega CV-5000 amp. No controls at all.

Should I try an unbalanced connection to the new amp? Do the two different connections produce a different amount of signal to the amp input and affect overall power output given the same output setting on the amp?

Can I achieve control over my sub through the XMC-1? I'm willing to guess the answer is NO as I don't believe I will have any phase control. Can I at least get the crossover portion fully taken care of through the parametric eq of the XMC-1 and the bass management. If I can get a fairly smooth response via sub placement without phase control, is there enough in the XMC-1 to control the sub properly?

I already have some observations on power handling and a comparison of the 2 amps using my Dayton Ultimax UM15-22 sealed sub, but I'd like to make sure everything is in line with my setup before I really let it lose on a movie with high output.

[deepstage]

So comparing the two amps here's the only difference I hear so far.

Both sounds great at everywhere but the extreme. Music, I never drive it that hard to have an issue with either amp. It's when, during movies, I hit a limit when extreme output is called for. I'm talking sub 40hz and usually more under 30hz.

With both amps gain set to produce the same output (via ear only), the Dayton amp lights turn from blue to pink and it cuts out. My XMC-1 volume is usually around -12 to -18 depending on the given scene and the output.
The CV-5000 causes the speaker to pop violently. When this happens, I can see the lights on the CV amp also get to where it says it's clipping (if that is indeed what it's doing).

Here are the specs of what I'm using.

Dayton Ultimax sub UM15-22 in 3ft3 sealed enclosure. dual 2 ohm wired in series to 4 ohms.
Dayton SA1000 amp specs:
950 watts @4 ohms
input sensativity 775mV
input impedance 12K ohms
RCA input from XMC-1 left sub out set to single mono

Cerwin Vega CV-5000 specs:
5000 watts @4 ohms bridged
Input Sensitivity (8 ohms 1.42V (+5.3dB)
input impedance 20K ohms balanced/ 10K ohms unbalanced
Balanced input from XMC-1 left sub out set to single mono

All other settings in XMC-1 identical

I can provide more info from the respective product pages if needed.
The CV-5000 is run straight through with no available processing to the signal. With the Dayton, I didn't use any bass boost, the parametric eq setting, subsonic filter,,,,,,,,nothing.

Dayton gain was turned about half way up and CV gain was a little over half.
Now I'm sure someone in the know can do some calculations and state that maybe one amp is matched to the output of the XMC-1 better for more efficiency. I would guess that would be the Dayton, primarily due to the fact that having a fraction of the power, I get similar results listening wise.

It just seems like there is more left in the sub, but am I reaching it's power handling limits? Wouldn't it reach that with the CV amp way before the lights show clipping? Or is the popping sound when driving with the CV amp not the amp clipping but the speaker itself driven too hard?

If anyone can shed some light on this I would appreciate it. I can provide more specs if needed and also voltage measurements I made from the sub pre out of the XMC-1 from mute all the way to +11 using multiple sine wave signals through multiple sources, which was pretty interesting.

[Deleted]

If you hear violent popping from the subwoofer, that is the sign that you are exceeding its excursion limits ("bottoming out"). The sound is created by the voice coil hitting the back plate of the magnet. Drivers, even robust subwoofers, won't tolerate this for very long until the coil fails mechanically (comes apart). Amplifier clipping usually sounds like popping, grunge, or fuzz on dynamic peaks but not quite as loud as coil bottoming, which is like a clapping sound.

If the CV5000 is clipping, check to see that you have properly bridged the amplifier according to the manual. Normally it isn't as simple as flipping a switch - usually it also requires a change in the way you connect the load.

The XMC-1 is able to put out much more voltage on its XLR outputs than what the CV-5000 requires for full output. Try setting the CV-5000 to maximum gain and then reduce the level in the XMC-1 until the system is providing "enough" bass to balance with the other channels. This will also prevent clipping the input stage of the CV-5000. Don't worry about whether there "could be more" - the system will provide that extra level when it is actually required by the source.

The Dayton Audio amp is a powerful amp, but the CV-5000 should have at least 6dB more available headroom, and you can make use of that with the Ultimax 15" woofer. The Dayton amp has a "soft clip" limiter that prevents the amp from making audible "hard" clipping noise, which may be what you are noticing when you say you get similar results "listening wise".

[deepstage]

Thanks Rory, good info. So setting the CV gain to full and reducing the sub level in the XMC-1 is the basically feeding the cleanest signal through to avoid clipping? I'll try that right now.

The popping sound is violent. It's like having a firecracker go off right behind you. Surely the sound of the woofer bottoming out it seems.

I'm going to setup the parametric filter and try to filter out anything below 20hz as when I run a frequency sweep, there's nothing til right about 20 and BOOM it comes alive. We'll see if there is some extreme low frequencies contributing to this.

I spent a couple hours last night testing the output voltage of my UMC-200 and XMC-1. I sacrificed an RCA cable and attached on end to my fluke. I took voltage measurements on both preamps using a varying sign waves through youtube videos on my Roku, PS4, Nvidia Shield and from REW output to the XMC-1 via HDMI. I disconnected everything and took measurements from 25 to 100 hz every 10 or 20 steps on the volume all the way up to +11. Some interesting numbers. Not really sure what to make of them as I'm not sure the absolute voltages of a sine wave correlate to real world voltages of audio signals being passed through to the amp.

If anyone is interested in seeing the numbers I can post them. I may make a better test setup and rerun them again and put them in a Xcel file in the future.

[KeithL]

The biggest variable when measuring audio signals with a meter is the meter itself.
Many low-end meters (and even some expensive older meters) are really only designed to measure AC power line voltages, and are wildly inaccurate on any frequency other than 60 Hz.
Others measure a narrow range of frequencies pretty well, but become very inaccurate outside that range.
You should really only trust the measurements when YOUR meter has a frequency response spec to tell you over what range it's accurate.
Also note that, with many meters, the accuracy varies widely between different RANGES.... so be sure to read it carefully.

Note:
Some meters are just a few percent off outside their happy range, but others may be many hundreds of percent off, or even not read at all, so do NOT take this for granted.
Note:
If you're using sine waves, then you don't have to worry about things like "crest factor" - because they only apply to non-sine-wave waveforms.
However, things like white noise and pink noise are more critical, and you're better off measuring them with something other than a meter.

Sept 24, 2017 20:21:32 GMT -5 deepstage said:

Thanks Rory, good info. So setting the CV gain to full and reducing the sub level in the XMC-1 is the basically feeding the cleanest signal through to avoid clipping? I'll try that right now.

The popping sound is violent. It's like having a firecracker go off right behind you. Surely the sound of the woofer bottoming out it seems.

I'm going to setup the parametric filter and try to filter out anything below 20hz as when I run a frequency sweep, there's nothing til right about 20 and BOOM it comes alive. We'll see if there is some extreme low frequencies contributing to this.

I spent a couple hours last night testing the output voltage of my UMC-200 and XMC-1. I sacrificed an RCA cable and attached on end to my fluke. I took voltage measurements on both preamps using a varying sign waves through youtube videos on my Roku, PS4, Nvidia Shield and from REW output to the XMC-1 via HDMI. I disconnected everything and took measurements from 25 to 100 hz every 10 or 20 steps on the volume all the way up to +11. Some interesting numbers. Not really sure what to make of them as I'm not sure the absolute voltages of a sine wave correlate to real world voltages of audio signals being passed through to the amp.

If anyone is interested in seeing the numbers I can post them. I may make a better test setup and rerun them again and put them in a Xcel file in the future.