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Tech: Prising back off sealed speaker cab ???

GUEST,punkfolkrocker 10 Feb 11 - 01:46 PM
pdq 10 Feb 11 - 01:51 PM
GUEST,pdq 10 Feb 11 - 02:20 PM
GUEST,punkfolkrocker 10 Feb 11 - 02:25 PM
GUEST,ChrisP 10 Feb 11 - 02:30 PM
GUEST,punkfolkrocker 10 Feb 11 - 02:51 PM
pdq 10 Feb 11 - 03:20 PM
GUEST,Tony 10 Feb 11 - 04:08 PM
Richard Bridge 10 Feb 11 - 06:17 PM
Q (Frank Staplin) 10 Feb 11 - 07:24 PM
JohnInKansas 10 Feb 11 - 07:39 PM
GUEST,punkfolkrocker 11 Feb 11 - 11:31 AM
GUEST,punkfokrocker 11 Feb 11 - 11:40 AM
Richard Bridge 11 Feb 11 - 12:44 PM
GUEST,punkfolkrocker 11 Feb 11 - 01:05 PM
Bernard 11 Feb 11 - 01:15 PM
Richard Bridge 11 Feb 11 - 01:50 PM
Bernard 11 Feb 11 - 02:58 PM
The Fooles Troupe 11 Feb 11 - 05:50 PM
Richard Bridge 11 Feb 11 - 07:11 PM
The Fooles Troupe 12 Feb 11 - 12:09 AM
GUEST,Ian Ward 10 Mar 13 - 08:45 AM
Bernard 10 Mar 13 - 02:54 PM
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Subject: Tech: Prising back off sealed speaker cab ???
From: GUEST,punkfolkrocker
Date: 10 Feb 11 - 01:46 PM

hello, do any experienced old hands here have practical tips
how to prise the back off a sealed speaker cab without damaging vinyl covering or plywood ???

It's a new 50 watt VHT 1x12" [AV-SP112-VHT] and I intend putting a 20w Celestion heritage greenback in it.

Trouble is, I've removed all the screws from the back panel and it wont budge.
The jack socket is attached internally so I can't unscrew that
to get my fingers in to pull the back out either..

Right now my only option seems to be digging a knife blade between the back panel and cab sides and jemmying,
which is bound to cause damage.

Unless some of you guys can please help with better advice ???

It's a reasonable quality Chinese made budget priced finger-jointed plywood cab with a decent speaker,
but it's too loud even with a 5watt valve amp
and I want to replace the 50 watt speaker
with a good old fashioned new reproduction inefficent 20 watt greenback..

.. errrrm.. surely they wouldn't have glued the back in.. would they..????


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: pdq
Date: 10 Feb 11 - 01:51 PM

Can you go to a dealer who sells this item and ask him?


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: GUEST,pdq
Date: 10 Feb 11 - 02:20 PM

Hi pdq, I'm impatient to get the job done asap tonight / tomorrow.

Bought it mail order from Thommans Germany, because the only UK dealer Dawsons is way too expensive,
and the guys working there know as little detail about the products as I do [not their fault - unhelpful UK distributor]..


So, good or bad idea..

giving the rear edges of the cab a few minutes blast with a hairdryer or fan heater
to help loosen it up.. ???


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: GUEST,punkfolkrocker
Date: 10 Feb 11 - 02:25 PM

sorrry, of course that was me..   got confused typing..

..while listening to the mrs droning on in the background
about something someone at work or somewhere said or did or something... ????


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: GUEST,ChrisP
Date: 10 Feb 11 - 02:30 PM

This may seem like a stupid question, but don't you have a volume control?


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: GUEST,punkfolkrocker
Date: 10 Feb 11 - 02:51 PM

Hi Chris sadly, it's the never-ending obsessive holy grail quest for quality tone at civilised low volumes..

.. any valve amps master volume and power valves need to be pushed hard at 10
to hit the speaker cone into creamy compression & crunch..
while maintaining control from the guitar vol knob.

Even a 5 watt amp [or my 3w & 1w amps] walloping into an inefficent 20w speaker will still be a bit too loud
for practice in a terraced town house.. or stage volume for smaller venues..
but with help of an in-line / power-soak attenuator at least more practicable & acceptable..

[my ideal guitar tone is vintage early 70's]


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: pdq
Date: 10 Feb 11 - 03:20 PM

It's likely that there are some screws you haven't found yet, or perhaps there is a "trick" to removing the back.

Hard to believe any company would just glue a box together so the speaker could never be removed, especially if this is a reasonably expensive umit.


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: GUEST,Tony
Date: 10 Feb 11 - 04:08 PM

Manufacturers do sometimes glue speaker cabinets together, but when they do that they don't usually use screws. But a back that's screwed on would normally have a foam plastic gasket, which can get a little sticky after a while. A sharp blow from inside usually frees it and it comes off with no damage. If you can't get inside, you could screw a handle onto the back panel and try pulling it with that.

The front of the cabinet (the "baffle") is often screwed on, too, again with a foam gasket. If there's a separate frame for the grille cloth (attached to the cabinet with velcro or some such thing), then the baffle can be screwed on from the outside. If the grille cloth is attached to the baffle itself, it has to be screwed on from inside.

In any case, woofers and tweeters should be screwed to the outside face of the baffle. If the grille cloth is attached directly to the baffle, and you can't get the back off by any other means, you might consider cutting the grille cloth, removing the woofer, and then reaching in and pushing the back panel off. Then reach in from the back to unscrew the baffle, and staple on new grille cloth after you change the woofers.


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: Richard Bridge
Date: 10 Feb 11 - 06:17 PM

Yes, I was going to say that you may be able to get in via a removable grille. But I've had a look at some pix and that clearly has the Vox style beading meaning that the grill panel will be held in by screws from the inside of the baffle.

I suspect that the best bet may be to remove ALL the screws securing the back (do treble check) and then play it LOUD and see if the back panel moves.


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: Q (Frank Staplin)
Date: 10 Feb 11 - 07:24 PM

It might have been better to look for the fine quality plywood cases that show up in junk shops and Sally Anns, and fit the new speaker(s).

But guest Tony might have provided an answer for you. A set I still have in the basement has speakers that can be replaced from the front.


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: JohnInKansas
Date: 10 Feb 11 - 07:39 PM

A common method that does minimal damage is just to add a couple of new screws in the middle, placed where you need to pull. Leave them sticking out enough to get a grip, and be sure that they don't go through the panel you want to pull out.

Once you get the panel out you can remove your puller screws and leave only the holes. This usually is less than the appearance damage you'd have from trying to dig into the cracks with a knife.

You could just add a small "handle" or something else that you could pretend later was an "accessory" such as a wire guide, or a hook to wind up the cables on, so that instead of holes it would appear that you'd mangled it on purpose(?).

The danger is that if you have missed a screw, or if something is glued together, the additional force you'll be able to apply may just break something.

One ad that comes up refers to "finger jointed plywood" construction. That would normally imply glue, so it's possible that the back is glued and screwed, possibly before the vinyl is put on, so you'll want to proceed carefully.

The ads I found indicate that the same(?) unit is available as an "open back" unit. Maybe a light sledge hammer would be appropriate for converting to that style(?), although a "precision" saw would probably do a neater job.

John


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: GUEST,punkfolkrocker
Date: 11 Feb 11 - 11:31 AM

thanks for all replies..

my guess was that at the cabs price point, there probably wouldn't be any elaborate sealing gaskets
or any thing else fancy construction wise.
But I did suspect the possibility of at worse glue seeping where it shouldn't if the cab had been assembled
too hastily in the factory.

So after a couple of hours preparatory googling I found one guitarist forum thread with the encouraging entry

"I even took the back panel off (it's very tight, so be careful how you pry it off)"

Anyway I was up carefully trying to ease the back off
with expired credit and video club membership cards
until the wife's alarm went off for her to get up for work..

and still I hadn't made any progress..

So when I woke up this lunch time I thought eff it, I'm taking a kitchen knife to the stubborn bastard..
Ater an hour or so I finally eased the back off,
fortunately with minimal abrasion to the edges of the vinyl surfacing.

Ok it's not a hand built British marine grade ply boutique cab,
but for about £80 It's actually quite tidily finished inside, giving confidence for a long useful working life..

It's now reassembled and I'm going to have a nice mug of tea
before I plug in and start breaking in the new speaker..

fingers crossed 20w heritage greenback will = everything from first 2 Steeleye Span LPs
to The Clash vintage guitar tones tones..


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: GUEST,punkfokrocker
Date: 11 Feb 11 - 11:40 AM

oh yes, and I've also now got a spare very decent US designed Chinese made 50w speaker
to upgrade an old solid state combo that I mostly gig with [using digital amp modelling pre amps]
and don't care about leaving overnight in vans or the back rooms of pubs....


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: Richard Bridge
Date: 11 Feb 11 - 12:44 PM

Thread drift setting in - actually I REALLY like the sound of the Eminence Private Jack drive units, but alas I think you can't get the 16 ohm versions any more so my rebuilt 2*12 Laney cab (used to be an amp, now it has a blanking plate over where the amp section was) has two Celestion G12H 100s in, and underneath my old H/H 2*12 combo with the original H/H drive units in the result is really nice (if I turn it up enough) or I can use the speakers without the H/H but an old valve head (Selmer) with 4 EL34 output valves and again, flat out the set of speakers sounds magnificent. But -er - LOUD.


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: GUEST,punkfolkrocker
Date: 11 Feb 11 - 01:05 PM

..when I was about 19 I managed to blow both speakers in my H&H Ic100 Combo..

can't get away with playing that loud anywhere any more...

I think 2 new celestion 12" speakers cost me about £40 in in early 1979..
at least a good couple of weeks Sup Benefit...

Never liked that the sound of that amp.. gave it away to a local musicians community co-op back in the late 80's..


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: Bernard
Date: 11 Feb 11 - 01:15 PM

You don't take the back off!! Either unscrew or prise off the front grille (if there is one) and simply unscrew the bass driver - that is your way in. Okay, with some you need to be a gyneacologist especially with Bose 802s... but conventional woofer/tweeter cabs are easy enough.

In some instances the grille (round) may be held on by the bass driver retaining screws, some are held on by Velcro, and some (particularly in high-end such as some Bose and JBL) are a simple interference fit.

They are made this way for ease of manufacture - a separate back takes more time to construct, and can also give rise to unwanted rattles. It's also much easier to cover the cabinet in Rexine or Carpet.


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: Richard Bridge
Date: 11 Feb 11 - 01:50 PM

That will not work with an AC30 (well, I know it's not closed back) nor the H/H combos, nor the Laney 2*12 combos nor most Marshalls. In them the front cloth is stretched on a wood frame held by screws through the baffle board from the back.


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: Bernard
Date: 11 Feb 11 - 02:58 PM

Different animal altogether, though - with them it's obvious that the back is supposed to come off!!

Modern (30 years, or so) passive speaker boxes (ply, MDF or ABS) tend to be front entry, combination amps tend to be rear entry (oo-er!).


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: The Fooles Troupe
Date: 11 Feb 11 - 05:50 PM

Here I sit pondering my old Laney Linebacker KB80...


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: Richard Bridge
Date: 11 Feb 11 - 07:11 PM

I don't know that one but SOME of the Laneys you start by removing the set screws in the side that secure teh amp section, draw teh amp section out forward, then grovel blindly around inside trying to remove the securing screws for the front panel.


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: The Fooles Troupe
Date: 12 Feb 11 - 12:09 AM

Well, it's lucky I don't want to open it them thanks Richard... just sitting here pondering my old amp ... :-)


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: GUEST,Ian Ward
Date: 10 Mar 13 - 08:45 AM

I've got a house rabbit that ruined my speaker cables, forcing me to replace them. My intention was to join the new cables to the leads insider's the speaker cabinets. However I can't get the rear panels to budge. I've had to connect them externally for the time being, but still want to move the connections inside the cabinets. They are Sony speakers hooked up to a Sony SSA-190, which still works incredibly well. The cabs are made of MDF.


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Subject: RE: Tech: Prising back off sealed speaker cab ???
From: Bernard
Date: 10 Mar 13 - 02:54 PM

Most likely you need to remove the front grilles and unscrew the drivers. That's how it is with most speakers.


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