CHT VS 18.1 Test Results - Page 4

The prerequisite for knowing anything for a consumer would be to know what is their preferred EQ setting..... This can vary by content (many like different curves for movies/music) and loudness. They would need to understand the various contexts and how they affect things to make a good decision.

Assuming first that we have a system capable of producing a flat response, we can save the "current" eq as the baseline.

Now, you could have the customer listen to different content and vary the EQ to their taste. This would need to be done at different levels (i.e. 75, 85, 95 dB, etc...), as our perception of the loudness of different frequencies varies with the intensity. After a long and exhausting gathering of data we would have the customer's ideal EQ settings for various sources/volumes....

The customer could then take their various EQ settings and find the most demanding one of the set and look for a subwoofer which could match that setting up to the level (dB) they prefer. A really cool processing system could apply their various preferences as sources and level change dynamically....

A sub may produce 120+ dB at 50 Hz, but after you EQ it to your preference, you may only reach 110 dB, since you've essentially chopped off the top to bring up the lower frequencies.

A sub with a naturally flat response and a sub with a processed flat response are two different animals.

I will take the one which can produce the curve I want at the levels I want.... I'll do my own EQ as it most likely is not flat not one of the provided "presets". Everyone is different.

Everyone's perception of loudness and frequencies also varies from person to person, so to keep a system in its tip-top EQ, it would need to be regularly calibrated to your own tastes. Lets not even add how aging affects our hearing....

Most active subs have some sort of built in EQ that often cannot be disabled..
My Epiks for example have bass boost at 30Hz that is worse than useless in my room because it simply adds to the room mode and eats up the power that could be used elsewhere.
I think whatever EQ is applied must be driven by the in room measurements, not some ideal FR curve. That's why I favor passive subs and find all the fancy servo controlled designs a waste of money.

My pro amp with fan is dead silent.

Driver is the same for both. Comparing the sealed enclosure to the vented is apples to oranges, nor does it explain multiple sealed users hitting 15, 10 and even 7 Hz in room.

Well a bass reflex design is going to be more sensitive at tuning as can be seen on the pb13 u.



In a sealed system low end sensitivity will decrease the smaller the enclosure size. I don't have win isd on my desktop and don't have the laptop handy just throwing it out there for discussion.

I wasn't discussing in room measurements, boundary gain, pressure vessel gain, and eq can bring the low end up significantly.

Like I said the measurements on the VS are good and it looks to be a fine implementation of the driver.

Plugging the port on what is an enclosure primarily tuned for bass reflex won't yield the same results as a sealed box purpose built for the same driver. Most likely, the sealed box would be smaller, basically enabling heavier EQ while making the design amp limited, as a good sealed subwoofer should be. But I do get what you are saying, bass reflex is more sensitive around tune.

It is refreshing to see you break room gain down in this fashion. Most people associate room gain with boundary gain only.

And they would be correct. Without boundaries, you'd be outdoors.

Also, it would take quite the sub to make use of pressure vessel gain, outdoors.

When do you want to find out what your two sealed 18s hit? I could also bring mine over and we can kind of see how the vented would do in your room since you were thinking of swapping to those at a point. If we use 28 Hz Low Damping on mine, it rolls off an extra 2 dB more than the VS from 40 to 20 Hz but much less than the VS does from 20 to 10 Hz which is expected. To get a better idea of the 10 to 20 Hz area, I can run a sweep with a 3rd order high pass and then another with a 5th order rolloff at 20 Hz and the vented 4th order rolloff would be in between those two. Hopefully this will put some of the questions/thoughts to rest. It shouldn't take very long and I'll even bring over a Double Wide IPA .

http://personal.inet.fi/private/zipman/shootout4/diy%20rythmik%20audio%20damping%20low.png
Edited by kwarny - 8/30/12 at 12:18am

We could do it next weekend, after I have recuperated from recent dental work.

Could anyone recommend a good pro amp to go with a pair of the VS-18.1's? The ep-4000 is out there, but I'd prefer to get something that has DSP capabilities.

I am pleased with inuke-3000DSP. DSP features are exceptional IMHO.
I am running my bridged to power SS-18.2
the only negative is fan noise. For me, however, it is not an issue, the amp is in the closet.

for two VS-18.1 6000DSP may be a better option

The NU6000 would give me plenty of amp headroom. I'd have to keep an eye on the gain though with 3000W x 2 at 4ohms. Any other suggestions?

Also, Is the fan noise distracting? I'd have to keep the amp near the subs at the front of the room.

the noise would be hard to ignore imo.

it should not be difficult to swap the stock fan with something less noisy.

Also, I'm assuming it does, but does the Inuke DSP have a HPF option?

Yes, it does. I do not think it can be set below 20Hz though. I think for VS-18.1 that should be fine.

I'm leaning towards the Nu6000. The 20hz HPF is the same on both the Nu6000 and the Sub1 amp that CHT sells.

My question is how Ricci measured 16hz in-room response with the 20hz HPF set on the Sub1?

http://www.data-bass.com/data?page=system&id=83

"The high pass filter also seemed to be a very good match for the VS18.1 cabinet when set to its minimum 20Hz setting. After listening to the VS18.1 with the Sub1 for awhile I found it to be a good sounding system without any one note qualities and with plenty of power for even large rooms. Real world in room output into the 16Hz range with power is a realistic expectation."

you can download the DSP software and play a little to get some idea of what it can do.

http://www.behringerdownload.de/iNuke/RnD_Soft_DE_Data_AmpRemoteV010_2011-04-14_Rev.0.zip

AFAIK, in-room LF extension below tuning frequency is fairly common.

I ended up placing an order for the dual VS-18.1 plus the NU6000 today!

cheers!

Please report back with results

It isn't a "brick wall" at 20hz, there is output (lower) below the filter.

I think it starts rolling off at 20 Hz as most LPF do. I don't know the slope, but I would guess anywhere from 12 - 24 dB/octave. I don't know the exact specs of the Sub1 off-hand.

Converting the static images over to dynamic data is time consuming, but we will get it done.

Our system is still very rough around the edges. Once we get the data categorized a little better i think that feature will be much better. I also need to add a new feature to get the THD graphs working with the new graphing tool. The goal is to be able to compare any systems data to another.