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Farty rattle


Merton
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OK, so my "big" rig (Trace AH300-12, Trace 2x10 and Trace 1x15) has been in storage recently while I sort out my house purchase, but I got it out yesterday for band practice. Well, the amp and 2x10 anyway. So I get to the rehearsal room early to set up and have a play but notice at any useable level (i.e. above about 1.5) there's a really nasty farty/rattly sound coming out. It lasts about 4 or 5 seconds or so before dying away (if playing a long note). The speaker grille isn't moving at all, and neither are the handles.

So I'm gonna take it apart at lunch today to have a peer inside and play with the cones to see if there's anything obvious.

What should I be looking/listening out for on the speakers?

If it is a blown driver, any suggestions of good replacements (I'll swap 'em both out to keep em matched)?

Cheers!


[size=1]Oh, and if this gets moved to Repairs then fair play, I couldn't decide which forum to put it in :) [/size]

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one of our monitors is doing that - for us it's the mounting screws around the driver that are loose, settles a bit after a while as the driver beds itself in (until moved again) - i've just been too lazy to tighten the screws

note to self: tonight, tighten screws on monitor (and fix the dodgy cables)

Edited by colda
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I think i know what the problem is, I has the exact same thinh happen when I bought my TE cab in from a garage where it had been for the winter.

You will find that the voice coil on one or both of the drivers has corroded and is sticking, hence the noise being intermittent. The damp cold air gets to the coils if exposed long enough.

I had my drivers replaced and the cab was fine after that.

Take a look at www.bluearan.co.uk for replacement drivers.

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[quote name='neilb' post='74947' date='Oct 16 2007, 09:38 AM']I think i know what the problem is, I has the exact same thinh happen when I bought my TE cab in from a garage where it had been for the winter.

You will find that the voice coil on one or both of the drivers has corroded and is sticking, hence the noise being intermittent. The damp cold air gets to the coils if exposed long enough.

I had my drivers replaced and the cab was fine after that.

Take a look at www.bluearan.co.uk for replacement drivers.[/quote]
Is this something I should be able to see? The drivers are out of the cab now and I can't see anything explicitly wrong, there are no nasty grating noises if you push on the cones gently; should I prod anywhere else?

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theres also the gamma 10 which has a wider frequency, if thats any good though i know not. its also in a 16ohm. wonder wether they are better than what comes in the ashdown mag stuff and wether they would change the tone alot?

merton i would have thought if the coils were having problems then you would hear a scratching noise from the driver when you move the cone, maybe you need to move the cone more than you are to reach the problem point.

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It isn't always a fool-proof test but you can gently push the cone centre back (press gently with fingers placed around the dust cap) and then release to see if there is significant scratching or if a coil is seized. Speakers will sometimes still operate fine if there is some scratchiness but it will be a dead giveaway if one is much worse than the other.

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[quote name='lowhand_mike' post='75039' date='Oct 16 2007, 01:23 PM']theres also the gamma 10 which has a wider frequency, if thats any good though i know not. its also in a 16ohm. wonder wether they are better than what comes in the ashdown mag stuff and wether they would change the tone alot?

merton i would have thought if the coils were having problems then you would hear a scratching noise from the driver when you move the cone, maybe you need to move the cone more than you are to reach the problem point.[/quote]

Yeah, looked at the Gamma too, but to be honest the performance differences are minimal and I'm not one blessed with a subtle ear. Gone for the last two Betas in stock at Blue Aran after a brief chat with two of their bods, will see if it makes a difference or not. If not then I'll have some spare drivers for sale PDQ... :)

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hopefully they will fix the problem, can't think of anything else in the chain of things that would cause it to make anoise like that. theres nothing loose inside the cab so it logically points to the coils, i had a set of car speakers that did that, kinda of dropped off line and made a scratchy noise but you could hear them scratching when you moved the cone.

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[quote name='Merton' post='74936' date='Oct 16 2007, 03:57 AM']So I get to the rehearsal room early to set up and have a play but notice at any useable level (i.e. above about 1.5) there's a really nasty farty/rattly sound coming out. It lasts about 4 or 5 seconds or so before dying away (if playing a long note).[/quote]
Usually that's a piece of schmutz that's got itself wedged between the cone and frame. When you initially hit the note the cone hits the junk, but as the note fades and excursion diminishes it no longer hits and the rattling stops. You can usually find the source quite easily by taking the driver out of the cab and running a low level signal through it.

Edited by Bill Fitzmaurice
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Guest Bald Eagle

I now naff all about speakers really but could it not be a small tear or hole in the cone? I'm thinking if it's damp then driven a problem like this might develop so the farty sound is the paper whatever flapping on the long note whilst the air is pushing through then closing?

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[quote name='Bill Fitzmaurice' post='75260' date='Oct 16 2007, 08:44 PM']Usually that's a piece of schmutz that's got itself wedged between the cone and frame. When you initially hit the note the cone hits the junk, but as the note fades and excursion diminishes it no longer hits and the rattling stops. You can usually find the source quite easily by taking the driver out of the cab and running a low level signal through it.[/quote]
Didn't spot anything but I'll try this tonight!

Cheers :)

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Totally failed to try your suggestion Bill because I was too eager just to try the Eminence drivers instead!! That said, they seem to have cured the rattle rather nicely and I think sound a little "warmer" and less brittle than the Celestions. One thing I was slightly concerned with is a very prominent resonance at F# and (to a lesser extent) B, but I think that was mainly the garage I was in coz when I moved the cab indoors I didn't get the same woofiness. Not sure as I didn't turn it up as loud in the house coz the fish looked scared... Will give it a go in rehearsal next week and see :)

I plugged the new config into WinISD with the current port sizes and it looks OK, -3dB is around 58Hz (but we've discussed cab sizes at length several times....) but vent velocity is nice and low (in the green, hooray!) and generally the frequency response looks nice and smooth.

Since I've not used WinISD before I then plugged in the parameters of my homemade cab. Oh deary dear dear. No wonder it sounds sh*te. Think I might take the driver out, destroy the cab and build a new one which will suit it better.

Anyhoo, thanks everyone for your help!

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[quote name='Old Horse Murphy' post='74937' date='Oct 16 2007, 08:59 AM']Just out of interest (and certainly not trying to teach you to suck eggs) I get the same sort of sound from my amp when the batteries on my bass (Stingray) are dead or dying. I only mentioned it because it took me hours to work that one out and I was convinced it was the amp.[/quote]

Many's the time I've made that mistake! Sometimes it's a cable problem as well...

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[quote name='Old Horse Murphy' post='74937' date='Oct 16 2007, 08:59 AM']Just out of interest (and certainly not trying to teach you to suck eggs) I get the same sort of sound from my amp when the batteries on my bass (Stingray) are dead or dying. I only mentioned it because it took me hours to work that one out and I was convinced it was the amp.[/quote]

That happened to me when I got my new GK rig. Thought it was broken before I even got a chance to use it, then changed the my Ibanez's 9v battery and it soundes great again :)

Glad you got everything sorted :huh:

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[quote name='shaundixon666' post='76340' date='Oct 19 2007, 09:18 AM']Glad you got everything sorted :huh:[/quote]
Cheers. Here's hoping my crap soldering skills hold up now!! Can't wait to try it properly in a rehearsal room to make sure the F# woof was caused by my environment at the time, or else I'll be having to do some maths to change the port sizes :)

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sounds good, i would imagine just from you saying 'garage' that alot of what you were hearing was down to the un damped sound, played in a better environment it should sound fine. we had a practice a while ago in a scout hut that was bare brick walls, man did my ears hurt after that, sound bouncing around like a monkey on crack and the bass sounded awful. back in a normal setting and it sounded fine.
let us know how you get on.

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[quote name='Merton' date='Oct 16 2007, 08:57 AM' post='74936']
OK, so my "big" rig (Trace AH300-12, Trace 2x10 and Trace 1x15) has been in storage recently while I sort out my house purchase, but I got it out yesterday for band practice. Well, the amp and 2x10 anyway. So I get to the rehearsal room early to set up and have a play but notice at any useable level (i.e. above about 1.5) there's a really nasty farty/rattly sound coming out. It lasts about 4 or 5 seconds or so before dying away (if playing a long note). The speaker grille isn't moving at all, and neither are the handles.

So I'm gonna take it apart at lunch today to have a peer inside and play with the cones to see if there's anything obvious.

What should I be looking/listening out for on the speakers?

If it is a blown driver, any suggestions of good replacements (I'll swap 'em both out to keep em matched)?

Cheers!
[size=1]Oh, and if this gets moved to Repairs then fair play, I couldn't decide which forum to put it in :huh: [/size]

MB1. :)
Could be Presoulnations Garlic Rice? :huh:

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