This is topic CP650 bypass in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Aileen D'Esposito (Member # 1967) on 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?
 

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Posted by Manny Knowles (Member # 1171) on 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 ]
 

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Posted by Steve Guttag (Member # 268) on 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
 

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Posted by Gordon McLeod (Member # 33) on 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
 

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Posted by Steve Guttag (Member # 268) on 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
 

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Posted by Manny Knowles (Member # 1171) on 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.
 

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Posted by Jon Bartow (Member # 241) on 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
 

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Posted by Antonio Marcheselli (Member # 373) on 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
 

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Posted by Daryl C. W. O'Shea (Member # 1303) on 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.
 

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Posted by Steve Guttag (Member # 268) on 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
 

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Posted by Aileen D'Esposito (Member # 1967) on 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.
 

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Posted by Manny Knowles (Member # 1171) on 11-12-2003, 02:34 AM:
 

quote:

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the I/O switch does not turn red like the manual would lead me to believe it should.

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