Itech 8000/Danley Subs?

John Chiara

John Chiara

Senior
Jan 11, 2011
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Troy, NY
Reinstalled my 4 TH 215 subs in another club. Have been running all four with a QSC PL9..208V Clair Version. This amp works great for 4 Lab subs but doesn't seem as at home with the TH215's.....4-5 cones later. It was a judgement call. All parameters are well within spec on the DSP.

So, would 2 Itech 8000's be a better match. Other suggestions? Really need a bulletproof solution.

 
Re: Itech 8000/Danley?

John Chiara wrote on Sun said:
Reinstalled my 4 TH 215 subs in another club. Have been running all four with a QSC PL9..208V Clair Version. This amp works great for 4 Lab subs but doesn't seem as at home with the TH215's.....4-5 cones later. It was a judgement call. All parameters are well within spec on the DSP.

So, would 2 Itech 8000's be a better match. Other suggestions? Really need a bulletproof solution.
Click to expand...



What was the failure mode of the cones?



John
 
Re: Itech 8000/Danley?

John Halliburton wrote on Mon said:
John Chiara wrote on Sun said:
Reinstalled my 4 TH 215 subs in another club. Have been running all four with a QSC PL9..208V Clair Version. This amp works great for 4 Lab subs but doesn't seem as at home with the TH215's.....4-5 cones later. It was a judgement call. All parameters are well within spec on the DSP.

So, would 2 Itech 8000's be a better match. Other suggestions? Really need a bulletproof solution.
Click to expand...



What was the failure mode of the cones?



John
Click to expand...



Burned/frozen coils.



 
Re: Itech 8000/Danley?

David Sturzenbecher wrote on Mon said:
Correct me if i am wrong, but isn't thermal limiting the same as RMS limiting?
Click to expand...

Yes, but the new iTechs make it easy to calculate.



John,

It sounds like you don't have limiters set up. Give me a call and I can walk you through the best way to do that with your current setup. It also sounds like you don't have enough subs in there if you're blowing them up, the 215 is a great box but it doesn't work miracles. I assume you're not always the one driving?
 
Re: Itech 8000/Danley?

David Sturzenbecher wrote on Mon said:
Correct me if i am wrong, but isn't thermal limiting the same as RMS limiting?
Click to expand...



RMS limiting can be thermal limiting if you apply the appropriate attack and release times. The I-Tech HD has a default 10-second attack time for the thermal limiter, and a much shorter time for the RMS limiter. If you allow it to calculate its own RMS attack and release times, it will pick a faster time for a smaller wattage, probably due to the nature of the signals that smaller drivers produce.



On top of all that, there is still a peak limiter!
 
Re: Itech 8000/Danley?

Bennett Prescott wrote on Mon said:
David Sturzenbecher wrote on Mon said:
Correct me if i am wrong, but isn't thermal limiting the same as RMS limiting?
Click to expand...

Yes, but the new iTechs make it easy to calculate.



John,

It sounds like you don't have limiters set up. Give me a call and I can walk you through the best way to do that with your current setup. It also sounds like you don't have enough subs in there if you're blowing them up, the 215 is a great box but it doesn't work miracles. I assume you're not always the one driving?
Click to expand...



Bennett,



I am NEVER the one driving..and we just persuaded the venue to allow the mix position to be made portable for decent placement..as the current ''off to the side'' setup is completely out of the subs/tops reasonable coverage area. I am assuming the +/- 2 ohm load and the PL9 are not the best fit. I know you talk about damping factor with great conservatism...this may be a situation where it is not helping. Again, I need a bulletproof setup so myself and/or the eventual full owner of the system has as few problems as possible. And AC supply is not endless..already have 2 dedicated 20's set up so the Itechs sound like a decent move.



John
 
Re: Itech 8000/Danley?

John Chiara wrote on Mon said:
I am NEVER the one driving..and we just persuaded the venue to allow the mix position to be made portable for decent placement..as the current ''off to the side'' setup is completely out of the subs/tops reasonable coverage area. I am assuming the +/- 2 ohm load and the PL9 are not the best fit. I know you talk about damping factor with great conservatism...this may be a situation where it is not helping. Again, I need a bulletproof setup so myself and/or the eventual full owner of the system has as few problems as possible. And AC supply is not endless..already have 2 dedicated 20's set up so the Itechs sound like a decent move.
Click to expand...

John,



Damping factor is a sound quality issue, not a power delivery issue. Running at two ohms will also deliver slightly less power than running with less load, with any amp I know of.



If you have frozen voice coils too much power is getting to the subs, period. Providing more power certainly won't help this. Adding a limiter will make the system considerably more ''idiot proof''.
 
Re: Itech 8000/Danley?

Bennett Prescott wrote on Mon said:
John Chiara wrote on Mon said:
I am NEVER the one driving..and we just persuaded the venue to allow the mix position to be made portable for decent placement..as the current ''off to the side'' setup is completely out of the subs/tops reasonable coverage area. I am assuming the +/- 2 ohm load and the PL9 are not the best fit. I know you talk about damping factor with great conservatism...this may be a situation where it is not helping. Again, I need a bulletproof setup so myself and/or the eventual full owner of the system has as few problems as possible. And AC supply is not endless..already have 2 dedicated 20's set up so the Itechs sound like a decent move.
Click to expand...

John,



Damping factor is a sound quality issue, not a power delivery issue. Running at two ohms will also deliver slightly less power than running with less load, with any amp I know of.



If you have frozen voice coils too much power is getting to the subs, period. Providing more power certainly won't help this. Adding a limiter will make the system considerably more ''idiot proof''.
Click to expand...



Have the limiter of the Protea set up to not clip the amp. The TH 215's are rated @ 2500 continuous so not sure if the PL 9 is actually delivering too much at present.

Hopefully Ivan will chime in. These used to be driven by a Lab Gruppen FP+ 13000 and never had a problem. Different room of course.



Thanks Bennett,

John
 
Re: Itech 8000/Danley?

John Chiara wrote on Mon said:
Have the limiter of the Protea set up to not clip the amp. The TH 215's are rated @ 2500 continuous so not sure if the PL 9 is actually delivering too much at present.

Hopefully Ivan will chime in. These used to be driven by a Lab Gruppen FP+ 13000 and never had a problem. Different room of course.
Click to expand...

A clip limiter will do fuck all to protect loudspeakers from overheating unless it is set way, way low. Amplifier clipping is a sonic issue, although most amps sound fine with their internal clip limiters (which are also more accurate, usually). A fast peak limiter can be used to prevent overexcursion, but that doesn't appear to be your issue.



Two amplifiers delivering the same amount of continuous (RMS) power will destroy the same loudspeaker in the same amount of time, assuming they are delivering the same signal that is over the loudspeaker's ability to handle. The room, and perhaps room nodes or alignment, is surely your issue here.



I am sure the TH215s cannot handle 2500w continuous power, that is surely a ''program'' number that accounts for crest factor (peaks) in the signal. You should certainly be using a big amp to allow them to provide maximum sound quality and output, but you need a gentle hand on the throttle, an RMS power limiter, or both.



http://www.bennettprescott.com/downloads/LoudspeakerFundamentals.pdf
 
Re: Itech 8000/Danley?

[quote title=Bennett Prescott wrote on Mon, 24 January 2011 13:30]
John Chiara wrote on Mon said:
I am sure the TH215s cannot handle 2500w continuous power, that is surely a ''program'' number that accounts for crest factor (peaks) in the signal. You should certainly be using a big amp to allow them to provide maximum sound quality and output, but you need a gentle hand on the throttle, an RMS power limiter, or both.



http://www.bennettprescott.com/downloads/LoudspeakerFundamentals.pdf
Click to expand...



Got it. The TH 215 is 2400w continuous, 4800w program.
 
Re: Itech 8000/Danley?

John Chiara wrote on Mon said:
Have the limiter of the Protea set up to not clip the amp. The TH 215's are rated @ 2500 continuous so not sure if the PL 9 is actually delivering too much at present.

Hopefully Ivan will chime in. These used to be driven by a Lab Gruppen FP+ 13000 and never had a problem. Different room of course.



Thanks Bennett,

John
Click to expand...

Actually there are 2 versions of the TH215's. Thr origional version was rated at 2500 continous, but it was not around real long. We changed drivers due to availability issues and most of the TH215's are rated at 1400 continuous. The output level was essentially the same-becuase we picked up several dB in sensitivity going to the lower wattage drivers.



So that may be where some of the problems are. Since you are not in direct control of the system, I would set peak limiters around the 3-4K mark (at 2 ohms for 2 cabinets). Depending on the RMS attack times-I would set them in the range of 1400-2800 watts (2 ohms).



Be sure to use a highpass around 25Hz, 24dB butterworth. It wouldn't hurt to go up to 30Hz-for high level useage.



I am oging to make the stupid comment to be sure that the polarities are all correct and nothing is cancelling out. It happens.
 
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