Wikipedia has a pretty good explanation

Interesting,thanks.

Makes sense.

Yes my 3000-2 is the only one of the four I listed there with capacitor coupling to the speaker due to the fact that it is the only one with a single rail power supply.

Paul

The damping factor and restored products.

The damping factor change significant over time. The reason is components degrading.

I am measuring the damping factor on all restored products and I find result like this:

Beolab 5000 (1967)

Damping factor before restoration: 4 (4 ohm)

Damping factor after a full restoration: 25 (4 ohm)

Beomaster 4400

Damping factor before restoration: 8 (4 ohm)

Damping factor after a full restoration: 75 (4 ohm)

The figures are typical results.

But please remember the cables between the amplifier and the speaker have a heavy influence of the system damping factor. Specially the original cable dimensions for B&O speakers are critical.

Edit(23-4-2010)

The original cables of e.g. Beovox 5000 was actually 0.5mm2 - my point is to show how much you can improve just by using e.g. the cable dimension B&O used later on for loudspeakers. I am not in favor of using expensive cables (I agree with Peters points of course)

/Frede

I have attached a pdf file with the link between damping factor, amplifier and cable dimension.

/Frede

Wow.Nice work Frede

Amazing how poor the damping factor is on an unrestored amplifier! I was always sceptical about the importance of so called audiophile grade speaker wire but it sounds like it is indeed pretty important to have speaker cables of very low resistance.When you are talking about a fraction of an ohm of speaker wire resistance throwing off the damping factor.In the capacitive coupled amp like my 3000-2(and the beolab 5000)these already have a modest damping factor,it seems that a few components in the output circuit must be pretty critical.It wouldn't take much oxidation to get an ohm of resistance out of the speaker switches,or speaker connectors,which would hurt the damping significantly.

Thanks

Paul

Not sure that is quite what Frede is saying - B&O provide perfectly good wire with their speakers and there is no point messing round with ridiculously expensive wire instead. B&O have performed many listening tests on wire and the supplied items are a very good example of what suits the speaker. Obviously with passive speakers, avoid long runs and use decent connectors. Look at the Wikipaedia entry and you will see some audiophiles swear by low damping factor!! 😁

Peter,I didn't know that the B&O engineers had done so much research on this,of course I am not surprised as they seem to have left no stone unturned in any area.I wasn't implying that the B&O cables were sub par,I was simply stating that a quality cable is,indeed very important,and that a low grade cable(or long runs as you mentioned) do compromise the damping factor.As you say,the engineers have already done their homework on this.None of my vintage gear came with B&O cables so I just use a short run of a modestly priced 12 or 14 guage speaker cable.I assume these to be of suitable quality?

Paul

I am sure they will be just fine!

With speaker cables I can see the benefit of having a decent quaity OFC cable with sufficient gauge to ensure minimal resistance, and of making sure you have a very good connection, but that does not mean overly expensive. A few pounds a meter should be the absolute maximum expenditure that could possibly have any benefit. Over that and the marketing hype takes over and all the super-expensive speaker cables on the market are simply audio-quackery.

Simon