I purchased a Crown XLS 2502 from a seller on eBay that was selling an "Open Box" item. It worked great with my UM18-22 sub in bridged mode for the first two days. Today I noticed the output is VERY little from it. I even hooked it up to some speakers to make sure it wasn't my sub. And the XLR inputs work fine in a different amp. Any ideas what would cause this and how I can fix it?
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Crown XLS 2502 - Defective?
- Thread starter bbxx
- Start date
If the amp works perfectly using one type of input, but not another type of input (RCA vs XLR) then the problem is likely to be in the input / buffer stage, and not in the core amp circuits. (but yes it would be "the amp")
The earlier XPS2500 which I have, has RCA, 1/4" jacks and XLR's as input options before the DSP (with differing sensitivities) - the 1/4" jacks and RCA's seem to be wired in parallel (so would pass through the same circuit) - the XLR's seem to be wired differently with a different sensitivity.
It might be as simple as a bad wire on the RCA connectors...- worth checking!
- Thread Starter
- #5
Yes, it is the amp. I have XLR inputs to this amp and when I switch the cables to my speaker amp, the speakers work fine. I also tried RCA cables to this amp and nothing changed. The lights on the front that show an input signal are working but the output is very weak.
IIRC there is a 3 year warranty regardless of owner, so you might check that. Was there a particular reason you were bridging?
- Thread Starter
- #7
I just figured it would be easier on the amp that way.
How so? It reduces low impedance handling capabilities....
JSmith
Master Contributor
- Thread Starter
- #10
I must admit that I am new to this hobby. I have the coils running in series. I was also under the impression that this sub would be able to exceed the 750w output of one channel. I bought this amp in case I want to drive another sub. This driver is in a Marty Sub that I built from a flat pack. I bought it from GSG Audio.
- Thread Starter
- #11
Thank you. I just blew a bunch of air through the amp, and turned it back on. It's working normally again. I hope that was all it was.
They do have temperature sensors, and a (nice warm!) blanket of dust can cause issues...
You could disconnect them, open up the case, and vacuum the interior - at the very least you will get to see how dirty the insides are.
I too brought my XLS's used, I opened them up, as I needed to switch their input voltage to 240V (imported from the USA to Australia) - but the interior was pretty much spotless in my case.
I'd not bother bridging myself, just run one channel for each sub, and I would recommend duals in any case. I don't know if this caused the semi-shutdown but bridging is often over-promoted IMO.
- Thread Starter
- #14
My amp came in what looked like new condition. I am keeping it in the garage for now because my wife isn't letting me bring it into the house... I guess some dust I kicked up today must have gotten into it. At least I hope that's all it was.
With 440W@8ohm/775W@4ohm/1200W@2ohm - bridging seems redundant.
I did try bridging them into my 1.6ohm speakers - for the heck of it... it made not a jot of audible difference.
Based on my measurements my peak levels reach around 16W @ 8ohm (64W @ 2ohm) ... but it is nice to have plenty of guaranteed headroom
You may use more, even loads more - but the amount of power these amps have is prodigious, there are very very few circumstances where I can imagine someone actually needing the levels of power they produce as standard, let alone bridged - and bridging brings a number of compromises which I am wary of.
In any case, I tried bridging, and it brought no benefits in my setup. (it would mean that the amp was effectively seeing a 0.8ohm load! - and it handled it with ease - which is impressive)
I did try bridging them into my 1.6ohm speakers - for the heck of it... it made not a jot of audible difference.
Based on my measurements my peak levels reach around 16W @ 8ohm (64W @ 2ohm) ... but it is nice to have plenty of guaranteed headroom
You may use more, even loads more - but the amount of power these amps have is prodigious, there are very very few circumstances where I can imagine someone actually needing the levels of power they produce as standard, let alone bridged - and bridging brings a number of compromises which I am wary of.
In any case, I tried bridging, and it brought no benefits in my setup. (it would mean that the amp was effectively seeing a 0.8ohm load! - and it handled it with ease - which is impressive)
- Thread Starter
- #16
With 440W@8ohm/775W@4ohm/1200W@2ohm - bridging seems redundant.
I did try bridging them into my 1.6ohm speakers - for the heck of it... it made not a jot of audible difference.
Based on my measurements my peak levels reach around 16W @ 8ohm (64W @ 2ohm) ... but it is nice to have plenty of guaranteed headroom
You may use more, even loads more - but the amount of power these amps have is prodigious, there are very very few circumstances where I can imagine someone actually needing the levels of power they produce as standard, let alone bridged - and bridging brings a number of compromises which I am wary of.
In any case, I tried bridging, and it brought no benefits in my setup. (it would mean that the amp was effectively seeing a 0.8ohm load! - and it handled it with ease - which is impressive)
I'll give it a try on one channel only. Am I not running the risk of clipping with 775W if my sub can handle 1000W?
D
Deleted member 48726
Guest
Not likely as the crowns dynamic power probably exceeds what your sub can handle anyway. Maybe I missed it, what are the impedance of your sub? Just to assess the best solution. Some serious subs can take a beating so need power, but if your amp isn't liking very low impedances it may be the reason it had issues.
Edit: The Dayton 18-22 driver has dual 4 ohm VC. I would wire them in series and bridge the amp. I would also take the lid of the amp and give it a thorough cleaning.
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You should calculate it in SPL (sound pressure level) terms...
A speaker efficiency is usually quoted in terms of SPL per Watt at 1m (or SPL per 2.83V at 1m - 2.83V at 8ohm is 1W) - and in db
For each doubling of distance the SPL will reduce by 3db
So if your target is 110db - and your listening point is 4m from the speaker you would need 110db + 3db (@ 2m) +3db (@4m) - for a total of 116db at 1m - that would be the output from the speaker needed for 110db at the MLP (main listening position)
a speaker will put out an additional 3db for each doubling of power...
So if its efficiency is 90db SPL / Wm - then output will be:
90db @ 1W
93db @ 2W
96db @ 4W
99db @ 8 W
102db @ 16W
105db @ 32W
108db @ 64W
111db @ 128W
114db @ 256W
117db @ 512W
If you have 2 speakers with the same specs - the sum of the two will add 3db (doubling of power!)
So if you know the efficiency of the speaker - and you know the desired loudness (sound pressure level) - you can calculate your power requirements.
The speaker specifications in terms of power handling are a specification of how much power can be pushed through the speaker before it starts to melt down, or tear itself apart.... - you can pretty much ignore it in other words!!
- Thread Starter
- #19
Thanks, I think some of the posters were assuming I was pushing that much power through speakers. So maybe it is a good idea to keep the bridge after all. You say dual 4 ohm? I thought it was dual 2 ohm. I do have them wired in series.
D
Deleted member 48726
Guest
Sorry that was a typo. I was referring to 4 ohm in series. This should not pose a problem for your Crown. It's rated for 4 ohm bridged. But give it a cleaning!
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