My Rodgers LS4as are leaking air.

[Citizen]

So I stumbled on one of those lucky facebook marketplace bargains.

A seemingly good set of Rodgers Ls4/a's, Arcam Alpha 3, pair of Target Audio stands and some pretty decent cable with banana plugs on one end.

Not a bad lot for 50 English freedom notes(pounds).

I checked them at the place I got them and they seemed to be in good working order other than the usual browning of the glue on the rubber surrounds but the tweeters worked, the woofers woofed and the amp was a little bit hissy but sounded good for what it is(not the best member of the Arcam family but hey for the money it is really ok).

Cleaned them up a bit and started to listen to them, they sounded good in the mid and high but the bass just seemed to be lacking, I had noticed when pressing the cones in that they seemed a bit unresponsive for a sealed speaker and also noticed a kind of hissing sound, had a good look over the boxes and then I discovered that someone had screwed into the bottom of the boxes(unforgivable hifi sin) and the hole pattern matched the Target stands so I thought I will have to open them up to have a look and see if the screws have penetrated the inner skin of the box and also would give me a chance to have a look at the drivers, crossovers etc.

Got the woofer out fairly easily and nothing seemed amiss.

The tweeter in the one speaker I have opened has had it's label rubbed of, it seems to be the right tweeter(seas h414) well some of the letters that are visible match a vid that I saw on youtube so I am assuming it is the correct tweeter, I do however think it maybe a replacement as there were no signs of the missing label inside the box.

I did try to attach some sticky back foam strips to the tweeter as it had no speaker gasket type foam that most speakers usually have but it was just to thick so pulled it of and cleaned it with some isopropol and put it back into the box, I did also note that this is the later model LS4/a with the mdf front baffle, I also checked to see if the screws had penetrated the bottom of the box and was relieved to see they had not.

I have know a few people who have put screws up through the holes on the speaker stand plates, some of them of their own accord and some on the advice of the retailer they get bought from, pretty sure an old Radfords store in Bristol used to advise this practice.

So I then set about putting some washing up liquid on all the seals and joints and was getting no bubbles at all so started to push the cones to see if I could hear where the air was coming from and it seemed to be the dust caps, just so happens I have some 65mm dust caps here for another project and put them up against the cones and pushed them in and surprise surprise the dust caps stay attached to the cones on the outward stroke and fall off after the vacuum ends(I have taken some video of this which I will upload later on this evening).

I took some screenshots of the vid.

So my problem is now what to do, the speakers do not sound right, they don't have the bottom end they should have, I would like to repair them, I have some polypropylene 54mm caps on the way as well as some new ferrofluid but I do not know if I should do this to these speakers, has anyone come across this problem before?

All replies and advice welcome.

Thanks

 

[Citizen]

Here is the link to the video.

 

[DSJR]

Not sure the LS4 ever had much bass (the LS6 did in a well balanced if 'loose' kind of way). Just changing some caps in the crossover won't do it I'm afraid. The tweeter may well be ok and there's a lot of conflicting thoughts on ferrofluid, as that tweeter may well be perfect still (Harbeth boast that theirs - SEAS derived I believe - don't go off at all after thirty years - and did measurements to prove it!!!). DON'T believe all you read...

Thing is and I just don't know here - the surrounds may have hardened and this kills the drivers unless the surrounds are treated carefully and regularly with Dot 4 brake fluid both sides. If the removed driver cone is gently pushed inwards, it should appear to have some rebound to it (you have other speakers which should give a clue). if said cone is very 'tight' when gently pushed, it may well be the surrounds have hardened up - there's a whole production period of Spendors which go like that, from late 80's to late 90's and maybe early noughties before it was identified and corrected in later models..

Since you seem to be in the UK, ask Falcon Acoustics if they have any knowledge. Rogers are back in the UK making antiquated BBC designs (the deliberately response-altered LS5/9) for lots of profit in the retro market - sorry, money - and may have some details on the main drivers in yours if they inherited the documentation as well as the name. Wembley Loudspeakers and others do good surround replacements if you need them and should be able to repair the detached outer dust cover if you can't. The holes underneath should be fixable with a decent filler (I use 12mm x 3mm approx. clear adhesive feet stuck on the stand top plates which keep the grip but don't act as soft decouplers - did well in the shop and no lasting damage to veneers).

Hope the above helps

 

[Citizen]

Not sure the LS4 ever had much bass (the LS6 did in a well balanced if 'loose' kind of way). Just changing some caps in the crossover won't do it I'm afraid. The tweeter may well be ok and there's a lot of conflicting thoughts on ferrofluid, as that tweeter may well be perfect still (Harbeth boast that theirs - SEAS derived I believe - don't go off at all after thirty years - and did measurements to prove it!!!). DON'T believe all you read...

Thing is and I just don't know here - the surrounds may have hardened and this kills the drivers unless the surrounds are treated carefully and regularly with Dot 4 brake fluid both sides. If the removed driver cone is gently pushed inwards, it should appear to have some rebound to it (you have other speakers which should give a clue). if said cone is very 'tight' when gently pushed, it may well be the surrounds have hardened up - there's a whole production period of Spendors which go like that, from late 80's to late 90's and maybe early noughties before it was identified and corrected in later models..

Since you seem to be in the UK, ask Falcon Acoustics if they have any knowledge. Rogers are back in the UK making antiquated BBC designs (the deliberately response-altered LS5/9) for lots of profit in the retro market - sorry, money - and may have some details on the main drivers in yours if they inherited the documentation as well as the name. Wembley Loudspeakers and others do good surround replacements if you need them and should be able to repair the detached outer dust cover if you can't. The holes underneath should be fixable with a decent filler (I use 12mm x 3mm approx. clear adhesive feet stuck on the stand top plates which keep the grip but don't act as soft decouplers - did well in the shop and no lasting damage to veneers).

Hope the above helps

Oh mate what an awesome reply, did not know that about the ferrofluid so thanks for that, funny enough I nearly got a pair of the Spendors you are on about(SP2) but they certainly did have bad surrounds and the boxes were really bad, I will get onto Rodgers and see if they are willing to help and also looking at the Falcon site right now, I have some of the furniture non slip sticky backed rubber that I will put over the holes once I have filled them with some e6000, might be able to save them after all, thanks again.

 

[Citizen]

This seems to be a good resource as well.

BBC and Rogers Loudspeakers › Service and Spares

 

[Citizen]

Hmmm, so I am a little bit more confused than before, one of the speakers has an transparent dust cap and the other is not, both have the same feel and same sound, maybe this is how they are design.

The cone seems to be clone of a Chartwell speaker(an expensive one).

BBC AUDIO CHARTWELL SPEAKER - MADE IN ENGLAND - SWISSTONE | eBay

Find many great new & used options and get the best deals for BBC AUDIO CHARTWELL SPEAKER - MADE IN ENGLAND - SWISSTONE at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

 

[DSJR]

Doped Bextrene and polypropylene cones are not the same although maybe the profiles are similar.

 

[Citizen]

So I finally got around to fixing the problem, I put some 54mm polypropylene dust caps on the drivers and one was ok, the cone was now really hard to push in because of the air pressure, the other however was still leaking so I put some soapy water around the rubber surround and just like a bike tire with a puncture there were some little air bubbles, once I started to pull that part of the surround up it kind of snowballed and I ended up with the whole thing off, I removed the horrible brown and tacky glue with some acetone and re glued the surround, put it back in the box and it was still leaking so did the same soapy trick around the raised edges of the speaker basket and got the same bubble so put some gasket sealing tape around the driver and put the driver back in, they now work really well, the bass response is very good considering the quoted figure of 55hz, this also improved the mids a little, really happy with the results, well except for the untidy looking job I did of gluing the surround so I guess I will have to run with the covers, the surrounds was leaking air so had to come off but to be fair it still looks better than the old brown glue.