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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => LAB Lounge FUD Forum Archive => Topic started by: Ronnie Reels on July 07, 2010, 02:54:51 pm

Title: Opinions on QSC PL6.0 PFC
Post by: Ronnie Reels on July 07, 2010, 02:54:51 pm
I want to try one of these to run 4 UCS1's. I have blown drivers using CE4000's bridged (2 boxes per amp) so its time to change gears. This may be too much power also. I have a Pro9200 on 4 but it doesn't seem to do much.   I hear the low end is great on the 6.0 and 6.0pfc but am aware of the reliability issues.  Just how bad are the issues?  Would you buy it?  MA5000 maybe? Damn these things are heavy amps.
Title: Re: Opinions on QSC PL6.0 PFC
Post by: Dale Black on July 07, 2010, 03:26:27 pm
wow, I use a pro9200 on 4 sub boxes and it freakin kills.

everyone around here seems to like the PL6.0 and use them with out problem.

Title: Re: Opinions on QSC PL6.0 PFC
Post by: Dave Sturzenbecher on July 07, 2010, 04:26:24 pm
Are you implying that you are blowing woofers because you have too much power?  If you are, then don't waste your money on new amps.  Get a decent DSP so you can protect your drivers via High Pass filters and limiters.

Title: Re: Opinions on QSC PL6.0 PFC
Post by: Ronnie Reels on July 07, 2010, 05:05:15 pm
Of course I am using hi pass and brickwall limiting.  
Title: Re: Opinions on QSC PL6.0 PFC
Post by: Dave Sturzenbecher on July 07, 2010, 05:14:30 pm
Then i suspect that it is not properlly setup, what DSP are you using, and what are the settings looking like?
Title: Re: Opinions on QSC PL6.0 PFC
Post by: Elliot Thompson on July 07, 2010, 05:17:21 pm
Ronnie Reels wrote on Wed, 07 July 2010 22:05

Of course I am using hi pass and brickwall limiting.  


Hi.

What are trying to achieve moving from two Crown CE 4000's bridged to one QSC PL 6.0 PFC in stereo mode?

If you are constantly damaging speakers, more subs would be a better choice. Looking for another amplifier that is slighlty lower in output may cause the same amount of damage as the CE 4000s in bridged mode.

Best Regards,
Title: Re: Opinions on QSC PL6.0 PFC
Post by: Ronnie Reels on July 07, 2010, 06:15:54 pm
I am trying to achieve "better" sound.  Tight, low thunderous bass. I've used CE4000's for years just ready to try something different.  The 9200 is no where near the output of the 4000's.  I have 8 UCS1.....I've blown 3.  DR260....35hz-90....limited hard.   The amps rarely see clip.
Title: Re: Opinions on QSC PL6.0 PFC
Post by: Elliot Thompson on July 07, 2010, 06:56:26 pm
Ronnie Reels wrote on Wed, 07 July 2010 23:15

I am trying to achieve "better" sound.  Tight, low thunderous bass. I've used CE4000's for years just ready to try something different.  The 9200 is no where near the output of the 4000's.  I have 8 UCS1.....I've blown 3.  DR260....35hz-90....limited hard.   The amps rarely see clip.


Okay.

If you use the QSC PL 6.0 PFC @ 4 ohms per channel you will have more headroom. Headroom can relate to tightness since no headroom offers a higher degree of distortion with the end result of a less than accurate response.

However, if you are using the QSC PL 6.0 PFC @ 2 ohms per channel, you are driving the amplifier at full capacity. So, the response may resemble what you are currently getting through your two Crown CE 4000’s @ 4 ohms bridged mono.

Since sound is subjective, it will be very hard to say if you will hear a difference using two CE 4000 amplifiers bridged mono @ 4 ohms against one QSC PL 6.0 PFC  @ 2 ohms per channel.

Generally more power will play a large factor and, to be honest the margin is not wide enough to make a significant difference going for a QSC PL 6.0 PFC.

If you are feeding two CE 4000 200 volts, you can achieve 7200 watts based on your current configuration. One QSC PL 6.0 PFC offers 3500 watts per channel @ 2 ohms. As you can see, the wattage difference are basically the same.

Under those conditions you will need an amplifier in the range of 14000 watts. This will bring forth more output with a better sound due to having +3 dB of headroom from your current set-up.

“Tighter bass” usually stems from less low frequency extension so, rolling off a lot of information around 40 Hertz will help. This may even save you the ordeal of swapping amplifiers. Try crossing from 100 - 40 Hz and see if that helps before spending money on amplifiers that may not be needed.

Best Regards,

Title: Re: Opinions on QSC PL6.0 PFC
Post by: Caleb Dick on July 07, 2010, 07:08:55 pm
Ronnie Reels wrote on Wed, 07 July 2010 15:15

I am trying to achieve "better" sound.  Tight, low thunderous bass. I've used CE4000's for years just ready to try something different.  The 9200 is no where near the output of the 4000's.  I have 8 UCS1.....I've blown 3.  DR260....35hz-90....limited hard.   The amps rarely see clip.


UCS1's are great, but maybe they just don't go deep enough.  

Are they phase (time) aligned with the tops well?

Caleb
Title: Re: Opinions on QSC PL6.0 PFC
Post by: Silas Pradetto on July 07, 2010, 09:19:32 pm
Ronnie Reels wrote on Wed, 07 July 2010 18:15

I am trying to achieve "better" sound.  Tight, low thunderous bass. I've used CE4000's for years just ready to try something different.  The 9200 is no where near the output of the 4000's.  I have 8 UCS1.....I've blown 3.  DR260....35hz-90....limited hard.   The amps rarely see clip.


If you're blowing subs that are processed and limited properly, then it's time for more rig. It's that simple. You could DOUBLE your amp power (the subs can't take that obviously), and negating power compression and other factors you would see a 3dB increase in output. That 3dB would barely be noticeable for most people.

Doubling the number of subs would yield you a 6dB increase, which is enough to be considered "double the volume" by most people. (Double the volume is usually 10dB at 1kHz and 5dB at 20Hz I believe).

So realistically, more subs with LESS or the same power would be the idea choice. Or different subs.

Also worthy of note is that subs will never sound better as they near the point of detonation--distortion and power compression increase rapidly at that point. You'd have far better sound with a system not pushed to it's limits.

edit:

More information would be nice too, such as how do you deploy the subs (how do you stack them, center cluster or separated, etc), what are your tops (a large part of kick drum sound is above 100Hz, which would not be in the sub range anymore). Also, as Caleb asked, are they phase aligned with the tops. Coherence will greatly improve the sound of the system. Even a millisecond or two is enough to be noticed.
Title: Re: Opinions on QSC PL6.0 PFC
Post by: Phil Lewandowski on July 07, 2010, 10:36:46 pm
Hey Ronnie,

Just throwing something out there, I know you mentioned "limited hard".  And that rings a bell from Bill F, and I see the DR260's you are using, and I know that Bill recommends pretty aggressive limiter settings, especially when mentioning horn subs.



One thing that you might be running into is you might be limiting the UCS1's so hard and when you start running into the limiter and keep pushing it the average "heating" power going to the subs is raised and you end up frying voice coils that way.


So I guess, what voltage are you limiting the UCS1's at?

Also what kind of material is this used for? Playback, live music etc?  Also, what size crowds?




From what I see I would get use an amp capable for around 1000 watts to each UCS1, with *No* hard limiting.  Just keep the amp out of hard clipping and you should be fine.  Yorkville is pretty conservative with their ratings.

Honestly, a Pro9200 would be getting right about 1000 watts per driver with 4 subs on it.  So maybe pick up a second Pro9200 for the other 4 once they are all fixed.  The Pro9200 is known to perform well on sub duty as well.

Honestly going from a Pro9200 to a PL6.0 would be only a gain of ~1.5dB, not noticeable really at all.


So I would really just use the 2 Pro9200's for 8 UCS1, and take out any hard limiting on them and keep the amps out of hard clipping with proper ~35hz 24dB/octave HPF set, and you should be fine with most kinds of music.


Take Care,
Phil
Title: Re: Opinions on QSC PL6.0 PFC
Post by: Evan Kirkendall on July 08, 2010, 01:10:27 am
I drove my UCS1's with about 6 different amp configurations. The best "sounding" amp was by far the MA5000. I tried the PL6.0, 9200 and various bridged amps. The MA5000 constantly gave me the best performance, even when run down to 2 ohms. I also had 2 separate limiters setup for them. I had an RMS limiter that kicked in sooner with a softer knee, and then a hard limiter right below clip.

Oh, and I also had some very specific EQ settings on them that tightened the bottom up, and gave them some more "punch."


Evan
Title: Re: Opinions on QSC PL6.0 PFC
Post by: MARK PAVLETICH on July 08, 2010, 02:34:45 am
I have made exactly the same transition that you are contemplating ( well nearly ). I went from 2 x bridged CE4000's to 2 x dual channel Powerlight 6 ii 's ( non PFC). The bulid quality of the PL 6ii 's is better than the CE4000's and the CE4000's have both failed in service at some point. The Powerlight 6's have been very reliable. Sound (once  sensitivity compensated for ) PL6ii's sound tighter in the bottom end and I think they sound "cleaner" so to speak. They are driving 2 X JBL HLA4897A's each. The greater rated power output from 230 volts ( the mains voltage here), seems to translate to cleaner,tighter,deeper sub bass frequency output.
Title: Re: Opinions on QSC PL6.0 PFC
Post by: MARK PAVLETICH on July 08, 2010, 02:35:27 am
I have made exactly the same transition that you are contemplating ( well nearly ). I went from 2 x bridged CE4000's to 2 x dual channel Powerlight 6 ii 's ( non PFC). The bulid quality of the PL 6ii 's is better than the CE4000's and the CE4000's have both failed in service at some point. The Powerlight 6's have been very reliable. Sound (once  sensitivity compensated for ) PL6ii's sound tighter in the bottom end and I think they sound "cleaner" so to speak. They are driving 2 X JBL HLA4897A's each. The greater rated power output from 230 volts ( the mains voltage here), seems to translate to cleaner,tighter,deeper sub bass frequency output.
Title: Re: Opinions on QSC PL6.0 PFC
Post by: Shanne Flemming on July 10, 2010, 10:00:56 am
I switched from a Crown MA5002 to an IT8000 on 6-8 UCS1's. The IT8000 is a great amp to use on the UCS1's. The voltage limiting and xovers in the IT8000 is a great benefit. Both amps provided a great sound and feel. The IT8000 is easier on power, provided for extra headroom and is lighter.  Using for a hard rock band.