Hi Guys,
Newbie here!
I have a 15" powered PA speaker box. It's a RCF 425-A (pretty sure it's a MK1 not a MK2). I think they were similar but maybe the MK1's had a different tweeter?)
Anyway, there seems to be a very tricky problem with the amp module as I have had two pretty reputable local audio repair guys try to exactly diagnose and repair it (after lots of time trying apparently) with no luck. To replace the amp module I have been told it would be approx $650 AUS plus labour. I have been advised it is not worth the replacement amp cost and I agree ;-)
My question is, can anyone suggest a reasonably priced separate amp and components I could DIY to get this thing running again and sketch me out a wiring diagram? Looks don't matter, happy to slap some plywood to the back of it. The speaker and horn have checked out to be fine btw.
I have attached and linked anything that I thought may be of interest including a spec sheet of the MK2 (because there's not much at all on the MK1 online)
Any help would be greatly appreciated 🙂
RCF ART 425-A Active 15" 2-Way Speaker ART 425-A B&H
Newbie here!
I have a 15" powered PA speaker box. It's a RCF 425-A (pretty sure it's a MK1 not a MK2). I think they were similar but maybe the MK1's had a different tweeter?)
Anyway, there seems to be a very tricky problem with the amp module as I have had two pretty reputable local audio repair guys try to exactly diagnose and repair it (after lots of time trying apparently) with no luck. To replace the amp module I have been told it would be approx $650 AUS plus labour. I have been advised it is not worth the replacement amp cost and I agree ;-)
My question is, can anyone suggest a reasonably priced separate amp and components I could DIY to get this thing running again and sketch me out a wiring diagram? Looks don't matter, happy to slap some plywood to the back of it. The speaker and horn have checked out to be fine btw.
I have attached and linked anything that I thought may be of interest including a spec sheet of the MK2 (because there's not much at all on the MK1 online)
Any help would be greatly appreciated 🙂
RCF ART 425-A Active 15" 2-Way Speaker ART 425-A B&H
Attachments
By seperate amp do you mean to run them as passive speakers from a 4 channel amplifier with DSP? (removing the existing plate amp and replacing it with a speakon connector and filling the hole)
If so one of these will provide 4 channels of amplification (one for each driver) and the DSP that will perfrom the crossover and EQ you need:
the t.amp Quadro 500 DSP – Thomann UK
If your looking for a simple option having the DSP in the amp is a bit easier and more compact than seperate DSP and amplifiers.
you will also want to get a measurment microphone like the UMIK-1 so you can work out the crossover from the measured driver responses.
If so one of these will provide 4 channels of amplification (one for each driver) and the DSP that will perfrom the crossover and EQ you need:
the t.amp Quadro 500 DSP – Thomann UK
If your looking for a simple option having the DSP in the amp is a bit easier and more compact than seperate DSP and amplifiers.
you will also want to get a measurment microphone like the UMIK-1 so you can work out the crossover from the measured driver responses.
+1 on all that, you should be able to produce factory like performance with some time spent building up the processing.
Kipman725 do you have any experience with any of the T-amp line? This particular amp looks like a great product for this type of project, I had a quick look and there doesn't appear to be any other models like this with built-in DSP which is too bad, I'd like to find something like this with twice as much power.
Kipman725 do you have any experience with any of the T-amp line? This particular amp looks like a great product for this type of project, I had a quick look and there doesn't appear to be any other models like this with built-in DSP which is too bad, I'd like to find something like this with twice as much power.
No idea about price/performance but Wharfedale have just announced a couple of slightly higher power 1U 4ch units: Wharfedale Pro Expands DP Series Of Digital Power Amplifiers - ProSoundWeb
Then there's Powersoft T-series (and higher) if you really want to spend some coin.
Then there's Powersoft T-series (and higher) if you really want to spend some coin.
Those look nice but this company doesn't exactly inspire confidence, surely they have this backwords...
"The DP-4100D is stated to deliver up to 1,500 watts per channel at 8 ohms, while the stated spec for the DP-4150D is 1,000 watts per channel at 8 ohms."
"The DP-4100D is stated to deliver up to 1,500 watts per channel at 8 ohms, while the stated spec for the DP-4150D is 1,000 watts per channel at 8 ohms."
The cheaper option would be to fit a passive crossover crossed say at 2500Hz & a speakon, You can then use any standard stereo 300W amp.
Thanks so much for the input guys, very much appreciated. I'm tending to err on the cheaper side and internally box mounted if possible. I probably don't need a 4 channel unit with dsp. The passive crossover sounds good. Any particular standard stereo and crossover amp suggestions? the opening cavity I have to play with is 420 x 110 x about 150mm depth (see attached) before it butts up against the back of speakers.
Attachments
Same mentality here 🙂
To match original specs you need 300W+100X and a simple fixed 1300Hz crossover.
You can mix and match cheap generic products for that.
This is a self contradicting phrase.
Please pick ONE:
1) you will use a MONO amplifier and PASSIVE crossover.
In that case get an approximately 300W power amp, with integrated power supply *or* search for a suitable power supply matching your amp needs.
You will also need a PRO quality (no home hi fi) rated passive crossover, which can stand >300W *continuously, for hours* which is not a menial task, and to boot you MUST add protection for your horn or it will die on the first feedback squeal or after half hour high power duty.
RCF original plate amp certainly provided some kind of limiter, a passive crossover will not.
Absolute minimum add an 1.5A or 2A (tops) fast blow fuse in series with driver voicecoil, an 1.5A Polyswitch or a 24V 45/50W car/truck lightbulb as current limiter, again in series with HF driver.
2) for cleaner sound, get a 300W Bass amplifier and 60/100W high one,plus an electronic crossover board, plus needed supplies.
Generic EBay/Alibaba/Amazon/local supplier amps work fine.
Please post a couple front/back pictures of original RCF plate amp.
Maybe you can strip the chassis so you plug cabinet back with it, and mount new amp boards on it.
If impossible, you´ll need to have a same size 2mm or 2.5mm plate cut, same mounting holes, to plug the back hole and act as a heat sink.
Even Class D heats up, only somewhat less than Class AB ,so it still need cooling/ventilation.
Post pictures of backplate to see if it can be given a new life.
FWIW I live in Argentina, very similar situation to Australia (including strong Irish immigration and manufacturing Ford Falcons for a long time he he) far away and with annoying Customs and greedy Tax and here lots of people have your same problem: complex heavily processed plate amps are hard to repair, if at all possible, and economically impossible to replace so you see everywhere "good brand" powered cabinets with back plugged with a plywood sheet, speakons and internal crossovers added, and driven by any available rack amp, from an old Peavey CS800 (indestructible!) to cheap "DJ type" amps, think Numark, Pyramid or "mystery brand".
You know what´s funny?: they work and sound good!!! 😱
But you must protect drivers well.
I haven't used the t.amps but some of the other models tested well here: Rob's Amp tests - Page 3 - Bass Gear - Data-Bass Forums
Using a generic passive crossover will work but it is unlikely to sound good as there is no consideration of the drivers relative sensitivities, actual acoustic response and impedance. DSP crossovers are pretty standard in all but the very low end of PA gear.
Using a generic passive crossover will work but it is unlikely to sound good as there is no consideration of the drivers relative sensitivities, actual acoustic response and impedance. DSP crossovers are pretty standard in all but the very low end of PA gear.
Ok, thanks, a bit to take in there.
I had the box with me today and was asking a local production hire company if they may have had any suitable components laying around (from some of the forum suggestions) or further advice. The main repair guy wasn't there at the time but the staff talked me into yet another potential repair attempt (this time without even a diagnosing cost surprisingly).
We'll see eh? Anyway, further to our chat... Amp panel pics attached.
Cheers
I had the box with me today and was asking a local production hire company if they may have had any suitable components laying around (from some of the forum suggestions) or further advice. The main repair guy wasn't there at the time but the staff talked me into yet another potential repair attempt (this time without even a diagnosing cost surprisingly).
We'll see eh? Anyway, further to our chat... Amp panel pics attached.
Cheers
Attachments
... Except the built-in plate amp will have driver-specific EQ and limiting. The latter, particularly, would be difficult to replicate.
Chris
It's not brilliant copy writing (or editing) for sure, but I wouldn't write off a company based on one typo.
Especially as that could have been on the part of the staff at PSW who wrote the article, rather than Wharfedale themselves.
Is this a different place than the last time at least? If they can find the problem that is the best solution because there is quite a bit going on inside these amp modules and you're simply NOT going to replicate it with an off-the-shelf passive crossover and power amp. Yes you could get them to make noise but that is what it will sound like compared to how they sound with the factory amp module. You will get much better results with the DSP amp suggested previously and it won't take long to do that, you could spend weeks learning how to and then tweaking the passive crossover to get 1/2 the results it would take 15 minutes to exceed with the 4-ch DSP amp.
Yes, it is a new and different repairer and he runs alot of RCF speakers in his multiple rigs. So it's probably worth a shot. All valid points re utilising a separate DSP amp. Cheers
Of course, but NOBODY outside RCF has those parameters available, so I suggested a practical - doable solution.
Anything else is dreaming. 😀
In any case, it will be LOADS better than using a singe amp and a passive crossover. 😎