I am giving my speakers a little TLC after around 30 years of loyal service (in my possession only for a small part of this). Part one was replacing the tweeter ferro fluid. That went well and brought a small but worthwhile improvement. Part two is what seems a very simple Xover; Can you see any parts which may have deteriorated over time (coils except) or anything that you would change for a more up-to-date component? As you can gather, I don't know much about this. - Part 3 will be the exterior. Thank you.
Correct, coils do not deteriorate and neither will the 4.7 uF film capacitor and the 2.7 ohm ceramic resistor.
I would leave well enough alone.
I would leave well enough alone.
There are those who will believe that sonic benefits can be achieved by 'upgrading' the film capacitor and ceramic resistor.
If you want to have some fun and become more invested in your speakers then here are upgrade suggestions:
https://willys-hifi.com/collections...roducts/mundorf-mcap-evo-4-7uf-450v-capacitor
https://willys-hifi.com/collections...tzen-superes-10w-2-7-ohm-1-crossover-resistor
Take note of the larger physical sizes of upgrade components and make sure there is room for them in your crossover.
If you want to have some fun and become more invested in your speakers then here are upgrade suggestions:
https://willys-hifi.com/collections...roducts/mundorf-mcap-evo-4-7uf-450v-capacitor
https://willys-hifi.com/collections...tzen-superes-10w-2-7-ohm-1-crossover-resistor
Take note of the larger physical sizes of upgrade components and make sure there is room for them in your crossover.
Only worthwhile x/o modification would involve complete x/o redesign, if this
one proved to lack in that sense. A solidly built Audax unit of the past times.
one proved to lack in that sense. A solidly built Audax unit of the past times.
The tweeter magnet has a little bit of foam at the centre in a well, photos 4 and 6. This has gone hard and deteriated somewhat. I guess this was intended to absorb some rear reflection. Is there any worthwhile point in replacing this? Does the uneven nature of the remains achieve the same kind of thing? Thanks
Yes, the purpose of the foam is to absorb sound waves from the rear of the diaphragm.
If the foam has deteriorated then I would replace it. I believe the foam is glued to the pole piece, so before attempting to remove the foam I would take the precaution of sticking some tape over the voice coil gap to prevent particles of hardened foam and glue from entering it.
I have seen the suggestion of replacing the foam with a felt pad, which would ensure there is no future deterioration.
If the foam has deteriorated then I would replace it. I believe the foam is glued to the pole piece, so before attempting to remove the foam I would take the precaution of sticking some tape over the voice coil gap to prevent particles of hardened foam and glue from entering it.
I have seen the suggestion of replacing the foam with a felt pad, which would ensure there is no future deterioration.
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If it has not yet deteriorated, it will soon. I've seen it in several tweeters and pole core bore of one woofer. If you don't replace it, the crumbles of it will find its way into the air gap, creating friction.
That's in general a very good advice but for drivers with a back chamber (ie big mid domes but also some dome tweeters) it's restricting the air movement, causing it to rise the fs and affect the fr. In such cases it's better to replace it with a bit wool.
I am trying to think what kind of wool would be suitable. I would assume some glass fibre one would be most practical as it is moisture and fungi resistant?
I'd prefer to work with sheep's wool, BAF wadding or polyester wadding.
I do have some 'acoustic grade' fibreglass which I believe sheds fewer particles than ordinary fibreglass loft insulation.
I do have some 'acoustic grade' fibreglass which I believe sheds fewer particles than ordinary fibreglass loft insulation.
It's a good looking crossover. There's nothing you NEED to do, but if you want to know whether you care much about the sonic differences in caps, if any, replacing the 4.7uF with a Mundorf MKP is a cheap experiment. After that an Audyn TruCopper 0.1uF as a bypass. Unfortunately these are all relatively larger caps so I'm not sure how well they would fit.
Resistors tend to be stable unless over driven. There are a couple of technical benefits of an upgrade to a Mills though, lack of inductance and rock solid thermal stability. Not sure if these benefits would be audible for you. Should you? I don't know, I'd probably leave it alone and do this sort of thing on a new build. 🙂
IMHO, my worst mistakes were doing 1:1 part replacements on a crossover which needed a white paper rethink. It was a very expensive lesson. I also think that in general a lot of hobbyists can learn a lot (one way or another) by taking an inexpensive speaker and replacing 1 or 2 caps. Nothing on earth beats first hand experience.
The second worst mistakes are replacing coils without taking the DCR into account. So, really, unless you want to go down a deep rabbit hole of speaker analysis, leave them alone.
Again, if you want to get into parts swapping and learning about how they do or don't work and whether they are worht the cost, build a new kit speaker, especially a pre-made one. I think this tends to be less frustrating and less expensive path to learning about this field.
Resistors tend to be stable unless over driven. There are a couple of technical benefits of an upgrade to a Mills though, lack of inductance and rock solid thermal stability. Not sure if these benefits would be audible for you. Should you? I don't know, I'd probably leave it alone and do this sort of thing on a new build. 🙂
IMHO, my worst mistakes were doing 1:1 part replacements on a crossover which needed a white paper rethink. It was a very expensive lesson. I also think that in general a lot of hobbyists can learn a lot (one way or another) by taking an inexpensive speaker and replacing 1 or 2 caps. Nothing on earth beats first hand experience.
The second worst mistakes are replacing coils without taking the DCR into account. So, really, unless you want to go down a deep rabbit hole of speaker analysis, leave them alone.
Again, if you want to get into parts swapping and learning about how they do or don't work and whether they are worht the cost, build a new kit speaker, especially a pre-made one. I think this tends to be less frustrating and less expensive path to learning about this field.
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I forgot to include good old cotton wool!
The random orientation of its fibres makes cotton an excellent sound absorbing material.
Thanks Galu and ICG. I am debating whether I have something suitable lying around the house as opposed to buying a whole lot of something of which I use a minute amount. I'll figure it out. If I understand you correct Galu, something like cotton cleaning pads, cut to size, would be suitable? I guess they too will deteriorate at some stage but it's an easy swap when they do.
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Thank you, interesting. I really like how the speakers sound. These replaced some Stirling LS3/6's, a relatively expensive and far more recent speaker and yet, I much prefer these ancient Missions. I can't really imagine what using Mundorf parts would do to the sound but as you say, it would probably be doable even for me with some care. Thank you.
Then leave them alone unless you discover any evidence of singed wiring or parts.
I was talking balls - cotton balls! 😀
As a matter of interest, which model are they?