Mjölnir Subwoofers - Page 3

Your electrician is thinking about much crazier power demands that what you will actually be pulling with the 2 amps. Hence the word "appliances". Guaranteed he has no clue what type of power these amps will draw. Crown probably has a chart showing the current draw and consumption at 1/6th and 1/3rd power. Even 1/6th power is far more continuous draw than you will likely ever see in practice.

Look at how prosound outfits who these amps are designed for distribute their power to these amps.

2 of these on a single 240v 20 or 30amp line will be fine. These are not continuous drawing appliance type devices.

Here is the amp draw of an iTech 8000 @ dual 1-ohm @ -10db full excursion @ 16hz.

Looks like 7-10 amps @ 240v/60hz.

Using a y-splitter will make it sound worse; the iTech's can be daisy-chained with XLR, do that instead.

You can loop 240v, the physics supports it, one 30amp wire in parallel is the same as two direct 15amp wires; a total of 30amps is drawn from the 2-pole service in both instances, but perhaps it's just not to "official electrical-code"

Another thing you should be aware of is that unless you flip the blue breaker at the back of the amp to the OFF position (or equivalent), the amps are still technically ON and will draw 15kW/hrs per day (yes, even when turned OFF from the front panel). I learned that the hard way... you can save yourself from the increased electrical bill.

When turned on and idling, but not actually outputting any music, it will draw 34,000watts of power per 24 hours. They are like mini space heaters in that mode.
and heaven forbid if you actually left it playing loud music for 24 hours, then it would be closer to 100,000 watts per 24 hours.

They are not very "green" amps, consider yourself warned.
Edited by BassThatHz - 11/13/12 at 12:37am

That wiring is correct, but you'll want to have both amps be in Y-input mode.

You want the input signal to be hovering around an average of -10db or so.

Now depending on the output voltage of your Onkyo, you may have to play with the input gain and EQ input gain and the Onkyo's output signal strength to achieve this. I was feeding mine with a Behringer EQ and a Emotive UMC-1; obvisously your equipment will be vastly different.

Just make sure to turn the output volume to roughly -90db (near mute or disconnect the sub wires); and then starting at a very low input volume, work up from there until the input signal is hoving around -10db (or there abouts). Once you have that dialed in (at this point you'll want your main-speakers running), you can increase the output level and enjoy the extra bassy music. (I wouldn't recommend ever going much above -10db on either the input or output signal).

If your feeling "extra-adventurous", you can attempt to disable the High Pass filter (and starting at a low volume)... actually, I wouldn't recommend this unless you really know what you are doing.

The goal is to have all the electronic devices reach their maximum level at the same time; not that you would ever run it at maximum however, but rather just be equally-levelled to that.
Basically you want to avoid having one device idling along while all the others are clipping; or any combination thereof.

Easier said than done, specially when mixing pro-gear with home-gear.

That is normal.

Your Onkyo is set to maximum sub out? Lower voltage is greater sensitivity.

If that doesn't work, increase the bandpass gain. Failing that increase the Input EQ gain.

Here is the LMS at the point where it begins to overheat after 4 minutes. At a few feet away the mic is being subjected to SPL in the 120-130db range (per sub).


With all 4 of yours going it should be loud enough to break some door hinges.


I don't use a receiver and I don't use a LFE/sub-out channel.
My system is completely different than yours so it won't translate at all really, but... I run mine as a 2-ch hardwire and have the knob set to 70db out of 80db, my Behringer floats between -6 and -20db, and the iTech about the same. Which drives the Behringer EQ and iTech to it's fullest capabilities.

1) Boost it, why? The itech has 48db of gain at 2volts, that's more than enough to boost any signal from any decent device.

2) Why, are they giving you problems? Mine is flat to single digits with the high pass disabled. Even with this preset of 28hz (i.e -12db @ 14hz), it still goes down to 20-25hz @ -4db

Question: What input level are you getting with the sub-out set to max, on loud action movies?

We are waiting for your review, so how does it sound? The best ever? Better than before? Meh?
BTW, What were you upgrading from?

Have any pictures, videos or measurements of it working? We all want to see those four LMS's pumping in unison.

Personally I like these binding posts: http://www.soniccraft.com/products/connections/bindingpost/vampire_bp15hex.htm I have never had one strip and you can tighten them down with this: http://www.musicdirect.com/p-227-audioquest-binding-post-wrench-bpw.aspx

For wire Monoprice carries a decent 12 awg and bluejeans cable has the Belden 12 and 10 awg wire which is good as well.

Those vampire binding posts used to be a lot cheaper so maybe you can google them for a better price. I bought a bunch of them when they were about half the price they are listed for now.

May have missed something, but why not speakONs as mentioned earlier? I personally love speakONs and a cable like Canare 4s11 (11ga. when paralleled). Super-clean install, especially with 90deg connectors, no muss, no fuss. And a lot cheaper/easier/cleaner/reliable than boutique binding posts and bananas. There's probably good reason pros use them almost ubiquitously.

Unless you have a HUGE room then I would rather have 4 LMS Ultra than 8 SI 18's or Dayton HO 18's.

I used to have a pair of LMS Ultra's and now have a multiple sub system which includes (4) Dayton HO 18's, (8) 12" sealed and (8) 10" sealed and soon another 4 SI 18's. I can shake my room and house better than my buddy with quad LMS Ultra's but I have to admit that his setup sounds cleaner.

If I was you I would finish up the LMS Ultra build and later on add another 2 or 4 SI or Dayton 18's in another part of the room if you think it's needed. Doesn't look like you have a huge room though so I would be surprised if you are not impressed unless your sitting in a null.

Yeah no kidding man!! Youre room is the definition of TACTILE FEEL!!!!

Hold on a minute here!!! Something isn't right... Where are your Ultras? Where are the iTech's? I thought you were basically done?
This looks like an old pic.

That room is barely large enough to house or contain the output of quad Ultras.
I'm getting somewhere between 110db to 114db with just 1/4th of your rig in a 4000cubic foot room.

I could understand that you may not be "accustomed" to hearing the lack of distortion eminating from the subs, the inverse of which contributes a large degree in the perception of "loudness".

Do you have an SPL meter? Audessy? Have you taken any measurements yet, with say... REW?
What was the output level according to the iTech's? Did the Ultra's appear stressed out or something?

You will not gain many db's more, unless you go with quad RE-18's in a IB, at max excursion. Or a line-array of JBL horns with a gigawatt
You are already basically using the best subs money can buy. So that's all the SPL you're going to get.
Something doesn't add up here. Bad room-acoustics?

Ah I see now... so you were just getting cold feet; and were theorizing that you'd want even more output after you were done.
In that case, just install as many subs as will fit in the room, like Dayton Pro 18's or RE-18's in an IB. But you might want to wait until your are done the first phase, as these four alone should age your house structurally by 10 years or so.