Hi Steve! That's super thanks! I put the tweeters from my kef celeste 4 into the goodmans yesterday eve and the 'seemed' to sound a bit better . I wil rotate the woofers this eve after work. Thanks a million for the great reply. I love goodmans , I love these speakers they are my second pair. I am on the lookout for a pair of magisters. Some of my family are from Wembley where goodmans started out I think
I didn't spend too much time on simulating it, but I don't think the capacitor change from NP types to MKP could have done a lot to possibly wreck things. We're looking at 0.5 to 1 ohm ESR change. Not much.
Big old heavy 12" woofers often sag and rub voicecoils with time. That sounds rough. Traditionally you rotate them 90 degrees for a quick fix, but maybe 180 degrees is doable here.
You might reflow some solder contacts in case there is a break somewhere. It's very easy to just put your hand over a tweeter or mid and listen to the other drivers on their own too. Usually tweeters fry first at parties and actually are easy enough to replace with something similar. Perhaps the voicecoils have turned into a bird's nest.
I've worked at the old Goodmans factory in Havant, Hampshire as it goes. I even applied for a job when I first came to Portsmouth, but they were past their hayday and moving production to China. It now distributes stylish and comfy mostly Indian cotton clothes to a familiar high street retailer. 🙂
hi again steve
i was considering replacing the mid units with either new equivalents or there is a pair of originals on bay. there is a '6oh' stamp on back o magnet so i guess they are 6 ohm. i like the lok of the audax aerogel mids 10cm, but they are 8 ohm. im nor sure if they are autable. also unsure if the mids on ebay would be better or worse that whats already in them
I didn't spend too much time on simulating it, but I don't think the capacitor change from NP types to MKP could have done a lot to possibly wreck things. We're looking at 0.5 to 1 ohm ESR change. Not much.
Big old heavy 12" woofers often sag and rub voicecoils with time. That sounds rough. Traditionally you rotate them 90 degrees for a quick fix, but maybe 180 degrees is doable here.
You might reflow some solder contacts in case there is a break somewhere. It's very easy to just put your hand over a tweeter or mid and listen to the other drivers on their own too. Usually tweeters fry first at parties and actually are easy enough to replace with something similar. Perhaps the voicecoils have turned into a bird's nest.
I've worked at the old Goodmans factory in Havant, Hampshire as it goes. I even applied for a job when I first came to Portsmouth, but they were past their hayday and moving production to China. It now distributes stylish and comfy mostly Indian cotton clothes to a familiar high street retailer. 🙂
hi steve
ok spun around woofers at lunchtime, and left amp running with tuner playing. will have a listen this eve when i get home. i also have the b&W celeste 4 tweeters in there. a couple of people have said to me to reduce the treble at the crosssover stage. the midrange is defo overpowering the tweeters thats for sure. the kef tweeters are only in temporarily as a test
We are still in the investigation stage, Patrick, so no firm conclusions yet. 🙂
I had a another look at your capacitor change, particularly on the midrange. An 8 ohm driver usually measures 6 ohms DC. Just how it works. And 1 ohm resistance in front of a filter produces 1dB reduction. 3dB is half power.
Potentially the NP replacement with MKP lifted the mid 2dB. But it might also do something similar to the tweeter. The bass rolloff becomes peakier with the loss of an ohm in the shunt. It's pretty common to throw a few ohms into the bass capacitor shunt to stop a peak as I do below.
That treble filter looks odd to me. 2.2uF is not a usual sort of component unless they are wired in parallel for a 4.4uF second order. This celestion treble filter is about as good as it gets. SO, here's roughly how your speaker works, and you can see that the original NP capacitors have damped down the mid by an audible 2dB and where any (red) resistance should be added. Going to be hard to replace those mids. They need to be quite efficient, above 85dB IMO. The tweeter needs to be a 90db model too IMO.
Of whoops, I forgot to include baffle effects when resurrecting an old project! That bass coil will be a lot bigger, maybe nearer 3.9mH. But it doesn't affect much else in the reasoning... LOL
I had a another look at your capacitor change, particularly on the midrange. An 8 ohm driver usually measures 6 ohms DC. Just how it works. And 1 ohm resistance in front of a filter produces 1dB reduction. 3dB is half power.
Potentially the NP replacement with MKP lifted the mid 2dB. But it might also do something similar to the tweeter. The bass rolloff becomes peakier with the loss of an ohm in the shunt. It's pretty common to throw a few ohms into the bass capacitor shunt to stop a peak as I do below.
That treble filter looks odd to me. 2.2uF is not a usual sort of component unless they are wired in parallel for a 4.4uF second order. This celestion treble filter is about as good as it gets. SO, here's roughly how your speaker works, and you can see that the original NP capacitors have damped down the mid by an audible 2dB and where any (red) resistance should be added. Going to be hard to replace those mids. They need to be quite efficient, above 85dB IMO. The tweeter needs to be a 90db model too IMO.
Of whoops, I forgot to include baffle effects when resurrecting an old project! That bass coil will be a lot bigger, maybe nearer 3.9mH. But it doesn't affect much else in the reasoning... LOL
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