Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Ivan Beaver]

I have run 2 TH118 per side of the ITHD12K.  This works fine, but definitely requires a 208v 20A circuit, and is harder on the ITech as well as makes an amp failure more catastrophic since you will lose the output of 4 subs instead of just a pair.  I have recently acquired more amp channels and going forward will run one Danley per ITHD12K channel. 

The IT12K has enough power to damage a single 4Ω TH118 if left with no limiting.  It probably doesn't have enough voltage output to damage a single 8Ω TH118.

Ivan's idea of 8Ω TH118s run 2 per side on an ITHD12K would indeed work and the resulting output would be more than a single TH118, but each TH118 would be under-driven a couple dB, so you're leaving some output on the table.  Ivan is also correct that the ITHD12K has peak output power at 2.7Ω, so you could run 3 8Ω TH118 per side and still get more out of the amp, but again you're leaving some sub output on the table.

One alternative is to look at the ITech 4x3500 which can do 4 channels of 4000 watts at 4Ω.  http://www.crownaudio.com/en-US/products/i-tech-4x3500hd

Note that running the 4x3500 at full output power will again require high voltage and/or high current supply, so you might be better off with 2 IT12K than a 4x3500 if you frequently need to run from regular 120V 20A circuits.

The idea of "getting every last dB" out of a loudspeaker seems like a good idea.

But that also means running the speaker "on the edge".

Sometimes when you are "on the edge" you fall off.

And  sometimes little things happen that are not your fault-but could damage the loudspeakers.

I prefer to keep everything "nice and happy"-even if it is not at maximum potential level.

It is FAR FAR better to have the speakers work until the end of the gig, rather than it being "a couple of dB louder" for a little while, and then a lot quieter for the rest of the show.

If you are running that close to the edge-you need a larger rig.  In my opinion anyway.

Also remember that the ratings are for a specific time period.

The longer you run loudspeakers, the hotter they get.  It just keeps building up.  It takes longer to cool down than to heat up.

I will admit there is a bit of "wiggle room" in how I suggested setting the limiters.

Sure you can get a little bit (is it worthwhile?) more out of them-but maybe that extra dB is just a little to much.

Once the damage starts-there is no going back.

[Aaron Carian]

If you are running that close to the edge-you need a larger rig.  In my opinion anyway.

The longer you run loudspeakers, the hotter they get.  It just keeps building up.  It takes longer to cool down than to heat up.

The rig being too small is exactly what has taken me down this path.

I can attest to running speakers "hot".  The SRX722s are so hot at the end of some of the shows that the handles will burn you.  Needless to say I have replaced my fair share of 12" drivers with melted voice coils running at the edge.  Hopefully I am past that now, well at least with the mains, still working on the sub solution. 

[Steve Litcher]

I run 16x TH118's on (4) IT12000HD's  No problem.
My only "issue" is the TH118 tends to"walk" when standing up.  I need to strap them together.

You will not be disappointed in the TH118's. 

Also check out JTR's Orbit Shifter.  In the same league as TH118 output-wise.  But different sound.
http://jtrspeakers.com/portable/orbit-shifter-pro/

John R.

Huge fan of the Orbit Shifters here.

We run two per QSC PL380 and we have bass for days. Just got home from an outdoor show this afternoon.... Tent measured 80x100 and was *full* of people the entire day. If I had to venture a guess, I'd say there were around 700 people in the tent.

We ran the show with two Orbit Shifters under a pair of the Noesis 3TX and had more than enough bass. We received a ton of compliments on the sound - those Orbit Shifters are ridiculously good.

[eric lenasbunt]

The 4883s run in cardioid mode help with low-frequency pattern control and make the main hangs more full-range, but there's no doubt the subs can run high enough to meet the 86s if desired.

I have been finding lately that with the 60hz LT full range settings I am not feeling that I need the 4883. For a long time their I wanted to get some 83's, but really haven't found it lacking lately

[Terry Fryar]

Hi Aaron!!!

[TJ (Tom) Cornish]

I have been finding lately that with the 60hz LT full range settings I am not feeling that I need the 4883. For a long time their I wanted to get some 83's, but really haven't found it lacking lately

I've never run my 86s that low - that's going to limit the box's output somewhat, especially for small quantities.

[Aaron Carian]

Hi Aaron!!!

Hey Terry, I thought you retired from all this?   

[Aaron Carian]

I have been finding lately that with the 60hz LT full range settings I am not feeling that I need the 4883. For a long time their I wanted to get some 83's, but really haven't found it lacking lately

How many 86s a side are you typically running?  Do you still feel the same with only 3-6?

[Terry Fryar]

Oh I did!  I just like to poke around in here.  Been here a long time!  There's a lot of very smart folks in this particular forum, so pay close attention to what they say.  You'd be surprised who all has been here over the years!!  I have had the priviledge to have Tom Danley, Dave Guiness, Ken, Dave Rat, Tim, Bennett and a bunch of other very experienced folks chime in on posts.  This is probably the greatest live sound forum around!

I guess I'll give my .02 on your sub situation.  As you know we used a buttload of 728's with our vertec rig.  Works good, sounds good.  But you need a lot of boxes to get higher outputs (we used 24 or more, but that's with 24 4888's).  The 4880 would be great, properly powered.  Expensive compared to 728, but you wouldn't need very many!  My other suggestion is one of Tom Danelys subs.  We've used his boxes on installs and they are exceptional.  Lots of $$$, but properly powered, a TH118 or something similar would rattle your teeth.  Take note, however, that horn subs or tapped horns give you very good quality, almost hifi like.  But without cone distortion, they have a "different" kind of punch to them.  We used to use KF940 eaw horn subs and switched to the CSM88's and I could tell a difference right away.  Just didn't know what it was back then!

Also, if you get into lines of centered subs, I have some software I made to calculate array steering parameters for DSP units.  Remember as you place lines of subs, the edges begin to narrow as the line grows and becomes quite significant with larger numbers of boxes.  What you do is delay starting at the center and go exponential outwards.  This allows you to "steer" the sub lobe and you can pull it back out to a sphere.  We did this for several years and the sub coverage was exceptional.  No power alleys and even coverage even to the sides.  But, you have to have many DSP channels (or amps).  If you want the software, just lemme know.  I'll send it along with my whitepaper I used to develop it with (pythagorean theorem).

Good luck and stay safe out there.  If you ever need help, lemme know.  I haven't touched much sound gear in the last few years, but I got a strong back!  Have fun!

Hey Terry, I thought you retired from all this?   

[Jake R. Trutt]

Why not the PG118's? They extend lower than the TH118. It's roughly the same cab with an extended path I believe. I'd still suggest the DBH218 over the TH118, if moving them is not a problem. They are thin enough that you can slide them through normal doorways. The touring version is great too, depending on how many helpers you have, you can each grab a handle. I'm not sure what your interest is in when upgrading though. The JBL SRX728 cabs are roughly 130db continuous +/-3db from 33hz-100 and -10 or more from 27hz or below, so there are many wonderful options to replace those dual cabs in many different areas. I presume you will be keeping it passive and purchasing instead of building so here goes:

If it were simply less cabs, more SPL, for a decent price, the LS1208 will be decently louder (136db continuous from 60-80hz). If you want marginally less loud and more clean, for slightly more you could go JTR Orbit Shifter Pro (130db continuous at 60hz and up, with 135db at 100hz and 125db continuous down to 35hz). A variant of that, with more low extension but less loud, would be the JTR Orbit Shifter LFU (121db +/-3db continuous from 20-100hz). Then you have Danley's which are more expensive but can get louder. The DBH218 will beat out 3 LS1208's in SPL, which is great but it costs more like 4 or 5 LS1208's, and it will be as low as 2 (probably 3) JTR Orbit Shifter Pro's and costing roughly the same. Although, the Danley's cannot reach the JTR Orbit Shifter LFU SPL output from 25hz and below, even with 2 DBH218's. So, in all honesty, it depends on what you are looking for exactly. I cannot speak on the PG118's but that would by my pick if it's at least -10db at 24hz and the rolloff from 24hz isn't too significant after that. It'd match the JTR Orbit Shifter LFU and beat it in SPL at the higher hz ranges. The PG118 is the most expensive of the bunch though and the Danley DBH218 isn't far off after that.

Edit: All of my specs include power compression by the way. They are measured results and not based off math applied to the specifications. These are the real world results you will see and are the true calculated SPL that will be experienced (provided proper placement and direction of bass energy). The JTR's do have better short term bursts (around 142db), however these are maximum sustainable output measurements (real world performance). Each of them, except maybe the Orbit Shifter LFU, will beat your current setup in output and the Orbit Shifter LFU will beat most of them (barring the PG118 if it stacks up) at low hz.

[ProSoundWeb Community]