HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

Interesting comment vinylant. I can see that some experimentation is required. I'm going to get the calculator out and see if I can make numeric sense of what is happening.

First I'm going to connect the bass drivers directly to the amp and see what happens - if the bass still sounds 'thin' then I guess that's how they sound. I'll post back when I have results.

OK - a fun day and some results!

Connecting the bass directly didn't make things any clearer. So I tried to reset and get some kind of reference point. To cut a long story short it appears that all the crossovers in my range of old speakers might need new capacitors. I tried two different crossovers from two different 70s bang and olufsen speakers and the original from the Goodmans and they all sounded suspect. I found a much more modern pair of Cambridge audio sirrocco bugetish bookshelf speakers (from our current decade) in the kitchen and tried the crossover in that in the Goodmans and everything improved. I also swapped the original paper tweeter for an Audax unit from the B&Os and now they sound really great. The midrange is not connected at all and the tweeters are sat on top!

So I guess I buy new capacitors to match the original? I'm gonna attach a photo of my current frankensystem in a short while

Sounds more like a fault like an open circuit in the crossovers than capacitors drifting out of spec.
What happens when you put a multimeter across the leads going to the woofers from the crossovers and you play a 50 hz test tone at generous volumes? Do you get pretty much the same AC voltage as at the input to the crossover or output from the amp?

Logical step by step troubleshooting. Trying or testing 1 thing at a time.
I've generally found drivers as far more likely to fail than crossovers. But I guess there's always the odd exception.

The speakers in that photo are so close together that it could be as simple as the woofers being out of phase that's buggering up your bass...

So the new crossover sounds a lot better. The bass is also better. I'm going to check this 'good' crossover with all my other drivers against their original crossovers (which I think might be suspect) to see if the crossover is 'good', that will hopefully give me a benchmark.

Placement of the speakers isn't great - it's just close to my workbench! But I'm going to set up a test spot which is more appropriate.

From what I have seen of the K2 crossover (if the same) it has a second order filter on each driver - bass driver has a series inductor and a capacitor in parallel. So if you end up recapping it then it will be easy and not too expensive. Caps are 5uf and 10uf I think. This presumes that the K and K2 xover is the same.

Hi, I attach a pic of the crossover - I think you're right (though I'm only just reawakening the grey matter around electronics). The bass is connected to the top left cap, under which is an inductor which it shares with the tweeter. The mid only has an inductor unless I'm mistaken. Visually the capacitors look fine but they are 60 years old! I can see that the blue one is not original as it's a different make in the other crossover. Also at some point both tweeter Lpads have been changed also. All looks fairly simple though!

Anyway, currently the plan is to use the good crossover (below) to try to identify bad caps (if any). This crossover has the advantage of being biwireable so I can listen to bass or treble separately if required: