Sub set-up woe

Cloudburst

Active Member
Noob alert! ;)

Evening chaps, I have recently bought my first sub (a Mordaunt Short 409) but I've not had the best of times setting it up. I've connected it to my av receiver (Yammy RX-V2600) with a sub cable (connect sub port on amp to left line input on the sub) and plugged in the sub. Everything lights up but there is no sound from the sub when I play a 5.1 dvd or music from my ipod.

I checked the troubleshooting section in my reciever's manual and it recommended I check the bass out settings are set to both the fronts and the sub (which they are) and now i'm out of ideas.

When I unplugged the sub cable (with everything still on) there was a bit of distortion noise so something is happening, just not sure what I can do to make it work.

Have i missed something obvious? All help appreciated :thumbsup:
 

Member 639844

Former Advertiser
Make sure you alter the settings on your AVR to take account of the sub. You need to make sure the speakers are set to small. On some AVR's this means setting the actual frequencies you want your speakers to produce. Typically you would set your sub to work upto 80hz, and your speakers to the same as long as they can work down to 80hz ok. Check those settings, as if not set correctly your basically asking your speakers to produce the bass, even though the sub is connected.
 

Cloudburst

Active Member
Thanks Moonfly,

I've just checked and all the speakers are set to small and the bass cross over is at 80hz.

Is there anything else I should check?
 

Member 639844

Former Advertiser
OK, play the test tone from your amp and make sure it is playing from the sub when its supposed to. If it doesnt then the problem is almost certainly at the sub end of things. In this case, then the first thing you should check is the cable. The sub will make noise when you plug cables in and out, thats normal, but what that noise does suggest is that the sub is still working fine.

Let us know how you get on with that step.
 

IronGiant

Moderator
Does your amp have a good old record out to tape or video? Plug the sub into that and you should hear something. If you don't the sub may be faulty, if you do we need to investigate the amp more closely.

My old Yammy amp doesn't bother to output a test tone to the sub at all (mad though that sounds) , so that isn't always a reliable test.

Dave
 
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Cloudburst

Active Member
Thanks guys.

I can't check the test tone yet (the CD is in the post).

I'll check if there's a record out now.
 

Member 639844

Former Advertiser
We were talking about the speaker test tones the amp puts out when you check the speakers etc, not from a tone CD. My old Yam amp tests the sub, but perhaps not them all by the sounds of things.

Let us know how you get on anyways.
 

Cloudburst

Active Member
Thanks guys.

I found the test tone on the AV Receiver :smashin:

The power light has now gone off on the sub and refuses to come back on.

This is not looking good :(
 

Cloudburst

Active Member
Ok, so the power's off because the internal fuse has blown. I took the burnt out fuse to an electrical shop that identified it as a 1.6 amp, 250v fuse and replaced it. I put the new fuse in and it blew straight away. I have very old wiring in my flat and thought it might be down to power surges so I plugged the sub in to a multi plug with surge protection, tried one more 1.6 amp fuse and this one blew as well :mad:

Can anyone with this sub help me? I've just checked the plug and it says 'LS-60 10A 250V' on it. Does this mean the electrical shop has sold me the wrong fuse? Do I need a 10 amp one?

Very confusing :confused:
 

swiftpete

Distinguished Member
Ok, so the power's off because the internal fuse has blown. I took the burnt out fuse to an electrical shop that identified it as a 1.6 amp, 250v fuse and replaced it. I put the new fuse in and it blew straight away. I have very old wiring in my flat and thought it might be down to power surges so I plugged the sub in to a multi plug with surge protection, tried one more 1.6 amp fuse and this one blew as well :mad:

Can anyone with this sub help me? I've just checked the plug and it says 'LS-60 10A 250V' on it. Does this mean the electrical shop has sold me the wrong fuse? Do I need a 10 amp one?

Very confusing :confused:
I'm not an electrician but a 1.6 amp fuse for a sub which surely must use a lot of power seems a tiny one so I'd be tempted to whack a 10 amp one in there and see if it works. Of course this could lead to more problems but I'd give it a blast. If it blows up don't blame me though!
 
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Blankfrank

Active Member
Power (in watts) is equal to voltage (in volts) times current (in amps) so with a 230V mains feed and a 1.6A fuse it would be able to supply 368W. Most fuses are fitted to offer protection to the cables or components. If the fuse is specified correctly it could blow because another component is causing too much current to be drawn, and the fuse is there to protect other components.

If you put in a much larger fuse, there is a risk that the components the fuse is there to protect are damaged, or it could even pose a fire risk as some components are allowed to draw so much current (compared to the load they are designed for) they overheat.

If the Amp is rated at 200W then it's likely that it's the correct fuse (the 200W rating will be output power but the amp will consume more than that as nothing is 100% efficient and much of the power is lost as heat)

I'm sure it will be obvious I'm not an electrician either but I would recommend playing it safe!
 

Cloudburst

Active Member
Thanks guys, I will be playing it safe (don't want to be responsible for any electrical drama). I've decided I'll contact the seller I bought it from for a bit more advice, maybe he's had a similar problem in the past.

In the meantime, if any MS409 owners have got any helpful advice please fire away :smashin:
 

Member 639844

Former Advertiser
Thanks guys, I will be playing it safe (don't want to be responsible for any electrical drama). I've decided I'll contact the seller I bought it from for a bit more advice, maybe he's had a similar problem in the past.

In the meantime, if any MS409 owners have got any helpful advice please fire away :smashin:
If is a failed, or failing component causing a power surge through the fuse, then no other will be able to help unless they've had the exact issue, but even then its no guarantee its the same component thats failed. You need an electrician to test the individual components, to find the faulty one. This may mean it needs to go back to the manufacturer for repair unfortunately.

These repairs are usually fairly in expensive though, as the offending components are usually very cheap, not always but usually.
 

lincsflier

Standard Member
Hi Martin,

Never had a problem with the sub i'm afraid not even a blown fuse so not sure what is going on. I have a Yamaha receiver and when the sub was installed had to set things like crossover and tell it there was a sub in line.

Not sure what else to suggest. If you have a THX test disc or Pixar disc with the test on this might help you.

Have sent another disc out to you as well with the MS test tones.

Cheers
 

Cloudburst

Active Member
Thanks lincsflier,

Sounds like I need to contact Mordaunt Short for a bit of specialist advice. I'll ping them an email now.
 

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