Another Goodmans Magnum project

[Dr Bunsen Honeydew]

When I worked at AR in the early 70's at panic times (VAT rises) we all went to help on the production lines. The efforts that were made to ensure airtight cabinets is something that has stuck with me since as I still use Infinite Baffle / Acoustic Suspension. The test I described was one of the techniques, very often you can hear the leak as you push the driver in as a hiss, it helps you locate it. The blow hiss and the suck hiss even sound different.

[Geoff.R.G]

That's good news for AR owners then but I am sure there are others that aren't so well made. Also, any that have been dismantled by inquisitive owners who don't realise the importance of a sealed cabinet.

[Dr Bunsen Honeydew]

I am still mind boggled that false information like that could become accepted and repeated by people. There are of course other designs of speaker cabinets that shouldn't or don't have to be airtight. Ported, horns, transmission lines (so called), open baffle, etc.

[Geoff.R.G]

Might I suggest that many an "Enthusiast" has little or no technical knowledge but is possessed of a desire to tinker and speakers are much more open to such activities than are amplifiers, CD players of DACs. Next on the easily "tweeked" list is the turntable.

I have no idea what proportion of speakers are IB designs but I would expect a fair proportion of those, particularly the cheaper ones, to leak to some extent if only because gaskets have cracked with age. It is probably also the case that many a crossover capacitor no longer meets the design specification. I wonder how many people are listening to systems that have deteriorated and are completely unaware of it?

[Dr Bunsen Honeydew]

That is another hi-fi old wive tales, that capacitors need replacing. They can do of course as anything can go wrong, or bad choice in the first place. BUT the hi-fi folk law makes it that amps and speakers need servicing if it hasn't gone wrong then there is nothing wrong with it. It is not a car that needs a service, you don't change the oil in a paper in oil capacitor It is just another way to try and take your money.

[Geoff.R.G]

I have worked with enough "vintage" electronics to know that only failed components need to be replaced. I have seen documentation requiring that capacitors be replaced because of failures in service but Hi-Fi is hardly life critical, a failed capacitor is inconvenient, possibly expensive but nothing more. There are plenty of 20+ year old autopilot computers and control panels flying around without any problem so why would an amplifier be any different?

You may have observed the increasing number of advertisements for used Hi-Fi that now state "capacitors replaced" as a selling point. Possibly valid if there is a known problem but to do so just because the item is "old" raises questions, for me at least, as to the quality of components used and workmanship in doing so.

[Dr Bunsen Honeydew]

It has come from people believing the industry bullshit from companies like Naim. It is purely done as a money spinner for the brainwashed to give them more money, and for some stupid reason it has caught on with the pretend expert and gurus on the forums.

[jayman67]

another couple of interesting posts,as someone who has read countless times and takes it as gospel that electrolytic caps need changing as they drift out of tolerance with age,thus shifting the crossover points etc,im talking of early 70's speakers here.
so as i have an open mind and am willing to learn from you guys,is this bollocks?

[Dr Bunsen Honeydew]

Mostly! if something doesn't sound broke then it ain't broke.

I have never had to change a capacitor for age related reasons and I have been using them for over 40 years.

[jayman67]

Mostly! if something doesn't sound broke then it ain't broke..

yep i understand that bit but assuming the fact that the old caps go out of spec with age, are you not by replacing them for new ones bringing the speaker back to how they left the factory so to speak?