FrankieJ
Jul 31 2005, 03:20 PM
Hi Everyone
After my gig last night I have realised one of my speakers (RCF ART 300) didnt sound that good, I seem to have lost alot of bass. So this morning I opened up my speakers and to my horrow I found 4 of the white strips had broke away from there solder.
Now my speaker works but could this be the reason for loss of sound? Does anyone know what these are called and how much would they take to replace.
Am I looking at a huge bill for these or will it be an easyish job..
spinner
Jul 31 2005, 04:34 PM
I'm no expert but your picture looks like the passive crossover which splits the frequencies in the cabinet. Loss of bass is likely to have been caused by failure of the part of the crossover handling those frequencies. If it's simply a resolder job perhaps you can do it yourself. Otherwise it may mean replacing the complete crossover assembly.
jackwabbit
Jul 31 2005, 04:43 PM
I’ve not seen this particular circuit board before & know nothing about RCF ART 300 speakers, but the large white things are ceramic resisters & with these not being connected would certainly give you problems.
jeffwall
Jul 31 2005, 05:24 PM
Cross over resistors, they filter off the diffrent frequencies and send lows to your base and hi to the tweeter/horn/mid (whatever) ..........(Active crossover)
If you can, resolder them onto the circuit board, or find out the cross over values of your speaker and get a replacement crossover. Any decent crossover will do as long as its rated at the same as this one and obviosly it will fit inside the cabinet?
If the solder connections have come undone in so many resistors, it suggests over heating, you must be driving them too hard and perhaps the speakers have no thermal protection inside?
Hope this helps
stevie
Jul 31 2005, 06:05 PM
where do you live?
im in manchester I can fix the crossover no problem. But agree you must have been givin it some.
will help if i can Steve
brianmole
Jul 31 2005, 09:00 PM
Good news, those are only a few quid each. They are all rated a 20 Watts, from left to right, the values look like 8.2 Ohms x 2, 4.7 ohms x 2, 10 ohms x 2.
Could be worth putting in higher wattage ones, I would also check your other speaker.
FrankieJ
Jul 31 2005, 09:05 PM
Thanks guys, I have my speakers in my boot ready to take to a repair shop tommorow. Fingers crossed it shouldnt be to pricey.
Kingy
Aug 1 2005, 09:23 AM
I have seen this before several times. Its a simple case of the solder has melted. The resistors will be fine. This is caused by over heating of the resistors, which can be directly traced back to one of two things, overdriving or amps going DC.
We used to charge £15 to fix this problem, don't know how much now.
FrankieJ
Aug 1 2005, 09:26 AM
Thanks everyone. How can I stop this from happening again? I never have my amp up to full power so what else could it be?
Kingy where are you based £15 sounds good to me?
DJ Marky Marc
Aug 1 2005, 10:28 AM
| QUOTE |
I never have my amp up to full power so what else could it be?
|
just becuase you dont have the input gains on your amp up full does not mean you are not clipping your amp....
the dials on the front of your amps are just gain controls. like the ones you get on mixers for trimming the level of your cd / phono inputs...
you may turn the gain down a little but if your mixer is able to push a higher voltage then you are back to square one...
This is why i keep the gains on my amps turned up and limmit the levels i push from my mixer.....
Damage to crossovers is normaly due to DC voltage which is clipping from the amp...
to fix this problem you need an amp with more headroom and a compressor limmter
FrankieJ
Aug 1 2005, 11:21 AM
So maybe the problem I could be pushing my volume up too high on the mixer?
I bought my RCF Art 300 speakers along with a Yamaha P4500 Amp. Below is the Spec for my Amp:
720W per channel (4 ohm)
Stereo, parallel or bridged mode operation
Power-on Muting
Balanced inputs
2U
Is this amp ok for these speakers?
I really need to start learning about Speakers and Amplifiiers
Gary
Aug 1 2005, 01:12 PM
| QUOTE (FrankieJ @ Aug 1 2005, 12:21 PM) |
720W per channel (4 ohm)
Stereo, parallel or bridged mode operation
Power-on Muting
Balanced inputs
2U
Is this amp ok for these speakers?
I really need to start learning about Speakers and Amplifiiers |
I had a quick looky on Google and (apparently) The speakers are rated as - 300w LowFrequency / 60w HighFrequency, which sounds little bottom heavy (but not too much). So...360watts total for the cab.
These figures are apparently rated at 8ohms.
Your amp being 720watts at 4 ohm means that it'll do about 360watts at 8ohms (ish) IF its driven absolutely flat out...
To send 360watts out of an amp capable of 360watts is like driving a car with a top speed of 100 at 100 - the poor things going to be thrashed - this is when amps tend to "go DC", sending nasty DC straight into your speakers.
I wouldnt be keen to run a 360watt speaker at 300watts, so perhaps you should look at using a 500watt amp (at 8ohm), at half power(the amp will think its on holiday), to send around 250watts into those speakers - when fixed.
If you need to send more than 250watts out to the audience, in particular venues, then you'll need another amp and speakers (or powered/amp'd, speakers).
FrankieJ
Aug 1 2005, 01:53 PM
Thanks Gary, for the info.
As we speak my speakers are in hospital
the guys have told me to take my amp in so they can see if its compatible for my speakers. Thanks again for looking.
superstardeejay
Aug 1 2005, 10:34 PM
These resistors getting too hot and melting their way out of the board is often a sign of impending driver failure. The voice coil goes low impedance and the resistors take the brunt.
Just a thought if it happens again when you're not pushing the speakers hard. RCF will have designed-in plenty of extra room for the resistors to work under normal conditions.
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