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Author Topic: CP650 bypass Aileen D'Esposito Film Handler Posts: 11 From: Pittsburgh, PA, USA Registered: Oct 2003 posted 11-11-2003 01:03 AM                     for the second time this year the center channel was blown in our system. The first time, for a quick fix we just threw the CP500 we had into bypass and it worked well enough to continue the showings until the problem could "properly" be remedied. Since then a CP650 was installed. This time when it blew, we went to throw it into bypass only to find that it didn't work. Any ideas on what could be going wrong there?  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 11-11-2003 01:08 AM                     Check your bypass trimpot. It might be turned all the way down. I'm interested in the details of your system. Obviously, you don't want any more busted loudspeakers. Are you running SR-D with your CP650 or is this a CP650-SR (analog only)? What make/model loudspeaker is behind your screen? Are the EQ sliders slightly adjusted or are there any radical settings? Where are the channel faders set on your amplifiers? (e.g. noon, 3 'o clock, maximum.) What is your usual fader setting for playback? EDITED ... As, Steve mentions (below) it would be useful to know which amplifiers you are using and whether you are bi-amping. Are you using a crossover in the CP650 or in the rack? Or is the crossover in the loudspeaker itself (as in the JBL 4670D)? Knowing the exact or approximated dimensions of your auditorium and screen might be useful, too. In short...we wanna know EVERYTHING BTW, When you switch into Bypass mode, does the 1/0 switch turn red? This would at least indicate if you've got a good power supply. Also, I recall hearing it said at the Dolby seminar that the CP650 only uses one of its boards during Bypass operation...If you are not getting any Bypass sound at all then this suggests a defective board. I think it is Cat. 772 (?). Or was it the trimpot? Oh...and when you say the centre channel was blown...you mean the HF driver only or...? [ 11-11-2003, 01:11 PM: Message edited by: Manny Knowles ]  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-11-2003 07:29 AM                     And yet more importantly...what brand of amplifiers do you have? If they are Ashley, then THEY are the source of "blown" speakers. Steve  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 11-11-2003 10:16 AM                     Also your speakers may be underpowered for your room size If necassary because it is impracticle to replace the speakers then install a compressor limiter like the afterburner  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-11-2003 12:37 PM                     Generally, Compressor limiters should not be used to overcome equipment inadequacies...they will heighten the problem somewhat by having the signal stay towards one level. Steve  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 11-11-2003 01:00 PM                     Steve -- Don't just "hit-and-run" like that!!! I'm interested in hearing more about Ashley's and your experiences with them damaging loudspeakers. There are a quite a few Ashley amps in one of my locations (all the others use QSC) and so I have a real need to hear what you have to say on the subject. Or, have you gone through this before...if so, just bump the thread and I'll read it. Thanks, Manny.  |  IP: Logged Jon Bartow Master Film Handler Posts: 287 From: Massachusetts Registered: Nov 1999 posted 11-11-2003 02:23 PM                     The older Ashley's did not have a protection circuit. As such when they went into an oscillation mode "POP". I had one theater that I found 18 blown subs and the matching oscillating amps that were powering them! (the local shop where I brought the subs (2245H an 18" cone) just about had a heart attack when I brought in 18 18" cones, however they recovered quite nicely when they realized how much money they were going to make ) The newer Ashley's do have a protect circuit so they are much less likely to melt your speaker, but I have had a LOT of problems with the protect circuit. Namely there is a resistor that is part of the circuit that holds in the protect relay that is undersized (i.e. they used a 1/4 watt and it should have been a 1/2 watt or 1watt) so it overheats and burns the circuit board. At one multiplex over two years I had an 80% failure rate for their new Ashley amps. Now to give Ashley credit they repaired all of them for free. I have also had several of them actually catch fire and spit ash (ASHley) out the back. Do yourself a favor and replace them with QSC. Jonathan  |  IP: Logged Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 11-11-2003 03:26 PM                        Aileen Does the CP650 has the "standby" led (between M1 and M2 led under the fader setting) light on? If so, you have a fail in the bypass power supply. But as Manny says you probably have the Bypass trimpot at minimum. Bypass level in CP650 has to be set by rotating that trimpot until the Bypass level and the normal level are as same as possibile (do your tests without audience!). THEN, you can always adjust the bypass volume rotating the fader knob, also if it is indicating nothing on the front panel. Hope that this can help. Bye A  |  IP: Logged Daryl C. W. O'Shea Film God Posts: 3977 From: Midland Ontario Canada (where Panavision & IMAX lenses come from) Registered: Jun 2002 posted 11-11-2003 09:02 PM                        I find it somewhat amusing that nobody ever spells Ashly right. Anyway, older Ashly amps liked to do nasty things like put out square wave DC or pass 120v AC, neither of which your loudspeakers will appreciate. In the last three years I've only had one DOA Ashly FTX series, and none that have died. That's only out of a few hundred though, your mileage may vary.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-11-2003 11:32 PM                     Manny, Others have stated the Ashly amp pretty well on the fact they probably have caused more driver failures than just about any other cause. As a reconer, I can always tell if there is an Ashly amp being used...they leave their mark. As to the amp itself...I think it sounds horrible depsite the FET design. Steve  |  IP: Logged Aileen D'Esposito Film Handler Posts: 11 From: Pittsburgh, PA, USA Registered: Oct 2003 posted 11-12-2003 02:21 AM                     Manny....you said you wanted to know everything, and the only thing i have to say to that is so would I. The space is not exclusively used for film presentation and therefore not taylored to our needs when it comes to running a film. The people in charge of the space wouldn't even put in a perf screen and drop the speakers behind it when we requested it (apparently not even with a good deal on a the screen.) They also let the installation of a new speaker system go to the lowest bidder this summer. Hey, you get what you pay for...would have been nice though for them to atleast consult us before doing this..but hey, little late for that. It's my opinion that they should just collect their losses and go to somebody competant to redo it. After several meetings (that i had to miss, unfortunately) and appraisals of the system, the problem is most definitely in their corner not mine, I only want to know that i can deal with the headache they've given me. Which brings me to..no, the I/O switch does not turn red like the manual would lead me to believe it should. what can i do about that? I'll talk to some people tomorrow to find out what i can, and what i missed at yesterday's meeting so i can provide you with a more detailed description of the equipment if you so desire.  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 11-12-2003 02:34 AM                     quote: the I/O switch does not turn red like the manual would lead me to believe it should. Possibly a blown or missing fuse for the bypass power supply? This is located inside, behind the plastic cover, just above the 1/0 switch. While you are at it, you might also check the voltage selector for the bypass power. In either case, consult the CP650 Installation Manual for directions if you are authorized to do this kind of work. [ 11-13-2003, 09:52 AM: Message edited by: Manny Knowles ]  |  IP: Logged

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