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Post by danielquinn on Feb 10, 2015 15:49:24 GMT
Anything too stiff runs the risk of resonating/buzzing inside the cabinet. Use sleeving and ensure that none of it rests directly against the driver when reassembling. If you can use the same cable as you'll be using externally then all the better.Why ? given that the signal must pass through passive components and be electrically manipulated , I cannot think of any SQ benefit to using the same cable . Indeed , will not a big thick speaker cable to the tweeter attenuate the signal . In my speakers I use NVA LS speaker cable and the number of strands going to the + - terminals on the tweeter is 4 and to the woofer it is 10 . Though of course these are hard wired from amp direct to speaker terminals in 3 out of 4 connections . [ tweeter plus as a cap and resisotr on ] |
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Post by Chris on Feb 16, 2015 6:38:17 GMT
Hooked up some internal wires into these yesterday - how do I tell I've done it right before I refoam them? If I hook them up to an amp(won't be a valve amp!!) will I see/hear anything?
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Post by danielquinn on Feb 16, 2015 7:53:01 GMT
Yes. The voice coil will still move in response to am electoral signal and they will still move the cones and produce sound. do it for seconds and on minimal volume. Just enough to see the cone move.
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Post by Chris on Feb 16, 2015 8:14:24 GMT
:)Cheers DQ. Hoping to move on with this today.
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Post by ChrisB on Feb 16, 2015 8:24:51 GMT
Touch the poles of an AAA battery momentarily to wires attached to the terminals. This will send a low voltage pulse through the circuit and the driver will respond by moving.
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Post by Chris on Feb 16, 2015 16:34:18 GMT
Well rewired and refoamed. Don't know what I've done wrong though but they sound horrible. Poor bass,rustle through them just awful.
Hmmmm,
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Post by ChrisB on Feb 16, 2015 18:22:01 GMT
Did you make sure the voice coils were centred Chris?
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Post by istari_knight on Feb 16, 2015 19:46:59 GMT
Hmm yes, "rustle" sounds like voice coil rub.
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Post by Chris on Feb 16, 2015 19:52:02 GMT
The voice coil eh....hmmm....don't know what that bit is as the whole lower drive unit is one piece which is sort of recessed in the housing. What I think the problem is is that the foam is on the outer edge rather than in the recess. Tough one as I've no idea what these were like in the first place. Could well be my wiring,my soldering,my foaming or maybe they were knacked in the first place. It'll be something I've done.
Pics to follow when the cat gets up off my legs.
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Post by Chris on Feb 16, 2015 20:27:40 GMT
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Post by ChrisB on Feb 16, 2015 20:35:51 GMT
OK - a lesson from someone who barely knows himself....
Voice coil - it's a coil of wire which is tightly and closely wound around a cylinder which forms the rear end of the speaker cone. It sits centred in a cavity in the centre of the magnet. The magnet and the coil with electricity flowing through it forms a motor. The movement of the motor is backwards and forwards - that's what makes the cone move in and out.
There is a gap between the coil and the magnet and the gap must be even and properly centred. If not, it may rub on the magnet.
When you glue the surrounds, you need to ensure that the gap is equal all the way round when the glue sets, because that's where it will stay.
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Post by ChrisB on Feb 16, 2015 20:48:32 GMT
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Post by Mr Whippy on Feb 16, 2015 21:27:51 GMT
Where did you get the surrounds from? They look to be too big. If you Google images you'll see a pair on stands in a garden which is an eBay listing. Go back to the original listing and you'll find a decent front image of what they originally looked like. Would have shown it if I could have.
You haven't left any Jaffa Cake crumbs in the gap, have you?
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Post by istari_knight on Feb 16, 2015 21:44:51 GMT
Chris, need to know if you followed any specific instructions/guide for re-foaming or just glued them on ? Apart from the fact they do look a little too big it sounds as though you didn't centre the voice coils when glueing which has resulted in the rubbing.
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Post by Chris on Feb 16, 2015 22:03:02 GMT
Nope,surprise surprise no instructions followed. I also think they happen to be a bit big and did wonder a bit about the fit. They're right bloody between spot on neatly and just off.
Many thanks for the replies as well.
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Post by istari_knight on Feb 16, 2015 22:06:33 GMT
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Post by ChrisB on Feb 16, 2015 22:32:44 GMT
It was from you James that I learnt this tip and it's worked several times for me since without a single problem. Chris: glue the inner rims first, get them as concentric cone as you can - you can often see the line where the edge of the old one was. When you're happy, hold them in place with a load of clothes pegs and give them enough time to set. Next, glue the outer ring and before it sets you can centre with the AAA battery trick. Connect + on the battery to the + solder tab on the speaker driver & similarly for the negative. Only make the briefest contact with one of the connections & immediately disconnect. Repeat this several times and you'll find that as long as the glue hasn't set, the coil will be centred. Try it by pushing evenly on the driver - it shouldn't grate or bind in any way. When you're sure it's central, then get set to with the clothes pegs.  |
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Post by MartinT on Feb 17, 2015 7:00:14 GMT
The battery tip is great for centering the voicecoil before gluing down the surround. Sorry Chris, a bit late I know.
If you gently push down on the cone, do you hear or feel scraping?
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Post by danielquinn on Feb 17, 2015 9:56:02 GMT
martin tip is spot on , push the driver up and down manually , if it is not centered you will hear the voice coil scrapping against the magnet , you can not miss it , you will also encounter resistance, it will not free flow up and down . good news , you just need to unglue it and start again  |
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Post by MartinT on Feb 17, 2015 9:59:12 GMT
good news , you just need to unglue it and start again Cruel!  |
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