Sub cable question

Badger0-0

Distinguished Member
Hi guys

Sorry if it's been asked, but I have searched :smashin:
Basically, I have a Yamaha 557 amp with (I believe) line level output IE one Phono.
But on my Mordaunt Short 309W, I have L and R. Two phonos.

I just read, after much searching, that I should connect to both inputs on the sub, as a 6Db gain is achieved (that's 4X, if I remember from my ham days :eek: )

Can anyone confirm this and recommend a cable seller (I don't believe all this mega price stuff is any better) before I send the missus out for a cable.
If this is true, I'm firing off a letter to MS, as the information in their manual is poor to say the least :mad:
 

bob1

Well-known Member
You won't gain anything from using the 2 inputs other than if your sub as auto on ,sometimes the signal from the amp is too weak to auto power on the sub properly.Even if you did get 6Db gain at the sub end (more like 2-3db) you would have to turn the level on the sub down by that amount if you set the levels up correctly.If auto on isn't an issue just go for a single lead,as for cables check out the markgrant cables on the forum, but i'm sure a old ham could make his own.
 

Badger0-0

Distinguished Member
bob1 said:
You won't gain anything from using the 2 inputs other than if your sub as auto on ,sometimes the signal from the amp is too weak to auto power on the sub properly.Even if you did get 6Db gain at the sub end (more like 2-3db) you would have to turn the level on the sub down by that amount if you set the levels up correctly.If auto on isn't an issue just go for a single lead,as for cables check out the markgrant cables on the forum, but i'm sure a old ham could make his own.
I never thought about the auto switching, thanks for that :smashin:
I was thinking more about a under/overdriving issue, in that I don't want to underdrive the amp and overdrive a section of the sub. My experience (again ham experience) is that it's not ideal, even though it can give the same end result, power-wise. Linearity suffers.
Having said that, I don't know which type of amps they are :confused:
More research is needed, methinks :smashin:
As for the cable, yes I could knock up a pukka 75 ohm job :smashin: but will take your advice about the Mark Grants. That is, I'll have a look.
Cheers Bob
 

Carl Stock

Active Member
Hi. :)

Regarding MS subs (and indeed others in the Audio Partnership ‘family’, like Gale), it is only necessary to use the left input for a single sub (mono) cable. There is no need to use a Y-splitter to feed the output to the right channel as well. Admittedly, some subs do require a left and right feed – one is the Gale Sub 5, which is a very basic sub, that needs a left and right feed. However, MS and newer Gale subs do not require left and right feeds.

So, don’t worry about the inputs. :) A Mark Grant sub cable will fit the bill – highly recommended – and they’re here:

http://www.avforums.com/forums/showthread.php?t=107778

Regards,

Carl :)
 

Badger0-0

Distinguished Member
Cheers for that Carl :smashin:

I just wish the manual explained that.
It doesn't even mention the 309W, just the 308, which is totally different :thumbsdow , very poor, IMO and I didn't get a setup disc either :mad:
I know I can ask Tons of fun ??? for a disc :smashin: , but for a non sub expert like me, the omission of relevant facts in the manual, the lack of a 25p?? CD and a p*ss poor website, support-wise, doesn't do MS any favours :(

Never mind, I'm sure I'll be very happy when I sort it :smashin:
 
B

billym

Guest
Never got a manual with my MS309 either Badger - I've posted a thread to ask for anyone that has one, there was apparently a pdf version available at some point and maybe tons of fun will be able to help us out. Great sub though (I'm using a single sub connect cable into the left input and works just fine.
 

Badger0-0

Distinguished Member
TBH, mine doesn't seem right.
I've got the speakers all set to small, output set to sub only, etc but the output is non- existent unless I'm on 5.1.
I understand the sub is supposed to do .1, but I thought with the crossover set at about 100k, it should cut in quite often, even on standard telly.
Then again, the telly's practically on silent cos of the neighbours :smashin: so it probably isn't getting the minimum power to fire it.

I'll come back when I can turn it up a bit at the weekend :thumbsup: ;)

I doubt very much I have it set up properly.
 
B

billym

Guest
Based on other postings on the forums I've got the cross-over frequency on my amp set at 100MHz and the one on the sub set at 200MHz - I don't notice much coming from the sub at lower volumes or lower telly but that's what I'd expect.
 

Knyght_byte

Well-known Member
u wont get much bass from TV anyhow.....i have my REL sub set up with both low and high level connections, and it doesnt get hardly any workout except for the odd TV film or program with music on it....even then its limited.......TV bass seems to mostly be at the higher end anyhow.........mebbe tho for subs with auto-on type thing you need to set your sub channel level higher on the amp.....*shrugs*
 

Carl Stock

Active Member
Hi, Badger0-0 and all. :)

Regarding the setup disc, just ask Tons of fun. Unfortunately, he does bite. ;) (Only joking!) He’s helped me out with a few problems I’ve had, so just ask him – he’s very helpful. :) That goes to anyone who needs any missing bits – ask your dealer or MS, because they are part of the package.

Regarding the levels of bass on 5.1 (Dolby Digital or DTS) or non-5.1 (Dolby Surround/Pro-Logic/standard stereo) material, there will be more bass, as it were – or it will be more audible – with 5.1 material. There may be a reduced amount of bass with non-5.1 material – when watching, say, a film on BBC One – because the AV amplifier has to ‘steer’ the sound. This is because the soundtrack on material that is not encoded in 5.1 is matrixed, meaning that the extra sound channels – the centre and rear – are effectively ‘piggybacked’ electronically onto the standard left and right channels, which is done in such a way as not to interfere with the left and right channels. A standard stereo amplifier will ignore these of course because they do not have any surround decoding circuitry, but your AV amplifier can detect these and send the relevant channels to the correct speakers.

However, non-5.1 material only has four channels of surround – there is no proper provision for very low frequency sounds! What’s more, the rear channels are mono, not stereo as with 5.1, and frequency response of the rear speakers is limited to above around 100Hz. What happens in these cases is that the AV amplifier will, depending on how it is set up, send all frequencies below a certain level to your subwoofer. This may be 80Hz or 100Hz, etc. However, with 5.1 material, each channel can be controlled individually, with no steering, digitally. This also means that the rear channels become stereo ones – and with full frequency response – and the subwoofer finally gets its own channel, too. In this case, the subwoofer – and the other channels, too! – can effectively be controlled more accurately. Instead of the AV amplifier steering the sound through each channel, the programme’s director can effectively control each channel. This means that all low frequencies can be sent straight to the subwoofer in exactly the way the director intended.

Dolby Pro-Logic II helps things a bit, creating an almost 5.1-type sound from a standard non-5.1 soundtrack, but it’s still not as good as genuine (discrete) 5.1.

Regarding crossover frequencies on subwoofers, the best thing to do is to set the ‘low-frequency cut-off’ on the subwoofer so that it can be ready to receive any low frequencies sent by the AV amplifier, therefore ensuring the subwoofer is fully ‘open’ to whatever comes its way. This means, therefore, that if your AV amplifier sends everything below 100Hz to the subwoofer, ensure the crossover on the subwoofer is set to well above that – preferably the maximum (or minimum, depending on your point of view!) the subwoofer will go to. On my Gale 3080W subwoofer, which is very similar to an older MS model, that is 150Hz.

Overall, then, when using a sub with an AV amp, just move the low-frequency cut-off on the sub to the highest number in Hz. You’ll then be covered whatever your AV amp sends out – be it 80Hz, 100Hz or 120Hz, etc! :) (However, when using a stereo amplifier and the sub’s high-level inputs – the speaker-type inputs – then you would need to be more precise in setting the low-frequency cut-off to match that of your speakers. AV amps are much easier!)

I hope this makes sense! :) I’ve tried to explain it in a simple, non-AV, way. I do have problems with communications a lot of the time (I have M.E.), so please do excuse me! It’s taken me two days to write this! hehe :)

If you still don’t quite grasp it all, just ask again. :) No-one will mind – I got into a right mess with subs years ago… and I thought I knew a lot about subs! :)

Take care. :)

Regards,

Carl :)
 

Badger0-0

Distinguished Member
Thanks Carl :thumbsup:

Right, as I said, I've come back after a play.

I ran AVIA (very briefly) and the funny thing is I had to turn all the speakers right down on the amp, except the Sub, which I had to turn nearly full up (the sub itself is set about 2/3rds) :confused:
This is the reason I couldn't hear any Bass before.
It sounds nicer now, but it seems strange I had to do that.
I have no SPL, so used my ears :thumbsdow
But I found that trying to equalise the sub to the speakers made the sub click, big style.
This was not loud (I'm guessing 75 Db)
I'm now more confused.
More playing needed, methinks :confused:
 

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