Hi Everyone. I'll start here by way of introduction instead of the intro section as my posts (at least for the forseeable future) will be about this project - I'll have nothing to offer anyone elsewhere!
I just treated myself to a speaker project and will need lots of help to get it right. Speakers in question are a set of 25 year old transmission lines build by a company called "Punto Musica" in Rome. (Model "Dyna T"). They stand about 1250mm tall, 300mm square and weigh maybe 30kg each. Drivers are (were) Dynaudio 24W100 9" woofers, D76AF 3" dome mids and D28/2 tweeters. All are in rough condition. Woofers need surrounds and all 4 domes are bent and horrible. Sucking them out with a vaccuum (gently) hasn't made them look any prettier!
A quick connect and prod with a signal suggests 5 of the six drivers still work... one of the woofers is dead or disconnected.
Price paid (£150) is basically for the cabinets which are solid but will need refinishing. Drivers can either be replaced or fixed - I've been quoted about £350 to restore all 6. I won't be jumping at that yet, but it may be the best option.
I've pulled one apart so far. Crossover boards are large and contain lots of expensive looking German inductors and caps with names like Mundorf, Solen, Wima... Cabling is heavy looking stuff... someone's spent some money putting these together. Seller who bought them new in the early 90s says they were about £2.5k back then and the equivalent of £6-7k brand name speakers. I can believe it...
Not quite sure where I'm going with these yet. Your comments and suggestions welcome!
I just treated myself to a speaker project and will need lots of help to get it right. Speakers in question are a set of 25 year old transmission lines build by a company called "Punto Musica" in Rome. (Model "Dyna T"). They stand about 1250mm tall, 300mm square and weigh maybe 30kg each. Drivers are (were) Dynaudio 24W100 9" woofers, D76AF 3" dome mids and D28/2 tweeters. All are in rough condition. Woofers need surrounds and all 4 domes are bent and horrible. Sucking them out with a vaccuum (gently) hasn't made them look any prettier!
A quick connect and prod with a signal suggests 5 of the six drivers still work... one of the woofers is dead or disconnected.
Price paid (£150) is basically for the cabinets which are solid but will need refinishing. Drivers can either be replaced or fixed - I've been quoted about £350 to restore all 6. I won't be jumping at that yet, but it may be the best option.
I've pulled one apart so far. Crossover boards are large and contain lots of expensive looking German inductors and caps with names like Mundorf, Solen, Wima... Cabling is heavy looking stuff... someone's spent some money putting these together. Seller who bought them new in the early 90s says they were about £2.5k back then and the equivalent of £6-7k brand name speakers. I can believe it...
Not quite sure where I'm going with these yet. Your comments and suggestions welcome!
There is potentially a lot of value there to just scrap crossovers and drivers. It's worth the 350 just to see how they sound. You could have something great. The risk is that the designer was not skilled. I'd restore the drivers and find out. Especially since the crossovers seem to be of high quality, it's at least a hopeful sign. I think about what will happen to all my speakers someday after I'm gone. It's nice to imagine someone will give them some tlc and bring them to life rather than scrapping the drivers and just using the cabinets. Good luck! Craig
Take the tweeters apart and try pushing the domes out from behind. The ferrofluid may need to be cleaned out and replaced, not a big job. I don't remember if the D76's are as easily serviceable, it's been a very long time. The big domes may be more difficult to reshape and their sticky coating is annoying, but well worth the trouble IMHO.
The domes will likely have 'reset' themselves to the pushed in shape if they have been sitting like that for ages.
I have had success pulling dome drivers apart and pressing a few layers of aluminium foil behind domes to hold them in the correct dome shape. Then I heat the domes from the front with a hair dryer (until too hot to touch, they may also start to smell like hot plastic, keep the hair dryer moving to prevent hot spots and melting) and then leave them to cool back to room temperature. After 5-10 heating and cooling cycles, the foil can be removed and they should self-support in the domed shape. Be careful not to bend the voice coils during this process. Support the diaphragm assembly by the frame during cooling - do not rest the coil on a table otherwise you will warp the surround which may make the coil rub.
I have had success pulling dome drivers apart and pressing a few layers of aluminium foil behind domes to hold them in the correct dome shape. Then I heat the domes from the front with a hair dryer (until too hot to touch, they may also start to smell like hot plastic, keep the hair dryer moving to prevent hot spots and melting) and then leave them to cool back to room temperature. After 5-10 heating and cooling cycles, the foil can be removed and they should self-support in the domed shape. Be careful not to bend the voice coils during this process. Support the diaphragm assembly by the frame during cooling - do not rest the coil on a table otherwise you will warp the surround which may make the coil rub.
Last edited:
Thanks for the responses, Gents. I've only looked at the drivers briefly. I always overwhelm myself with projects, so I'm trying to limit myself to one thing at once. At the moment I'm stripping them down and defining what's there. I've removed all drivers, crossovers and cables, leaving just box and padding. The padding is acoustic foam stuff stuck to the internal faces and a very small amount of wispy woolly stuff. The veneer is dried out and cracking, chipped in places, and lifting in one or two small areas. I'm not a big fan of the veneered finish, they look horribly old fashioned, so I will tidy/glue/fill the surfaces, sand them down and paint them. What I haven't admitted to so far is that these are too big for my lounge (or my wife) so are destined for my double garage sized workshop. I may get adventurous with the colour... or I might just paint them black, who knows?
Crossovers are in two parts. Bass on one, mid and tweeter on another. While they are made from quality components, they are hot glued onto thin prototyping boards which, in the case of one woofer filter has failed. One of the big inductors was in the bottom of the cabinet, which explains why one of the woofer wasn't working! The mid/high boards were sprayed with glue, wrapped in foam and stuffed in the cabinets, making them difficult to strip and work out the circuit. I've managed to draw circuits for tweet and woofer... band pass filter on the mids is complicated. Once I've got them defined I'll rebuild them on boards and probably leave them external.
It looks like all drivers are working, then. I'll leave them for now and do the cabinets and crossovers, but I'll definitely have a go at them myself. I was wondering if heat might work on the dome. Nice to know someone who's done it. I'll no doubt be quizzing you later! As for the tweeters they appear to be sealed... not sure how I'd get the plastic backs off?
Crossovers are in two parts. Bass on one, mid and tweeter on another. While they are made from quality components, they are hot glued onto thin prototyping boards which, in the case of one woofer filter has failed. One of the big inductors was in the bottom of the cabinet, which explains why one of the woofer wasn't working! The mid/high boards were sprayed with glue, wrapped in foam and stuffed in the cabinets, making them difficult to strip and work out the circuit. I've managed to draw circuits for tweet and woofer... band pass filter on the mids is complicated. Once I've got them defined I'll rebuild them on boards and probably leave them external.
It looks like all drivers are working, then. I'll leave them for now and do the cabinets and crossovers, but I'll definitely have a go at them myself. I was wondering if heat might work on the dome. Nice to know someone who's done it. I'll no doubt be quizzing you later! As for the tweeters they appear to be sealed... not sure how I'd get the plastic backs off?
Tweeters are to be accessed by removing the 3 screws in the front. The voice coil assembly can then be pulled out and the gap in the motor inspected for ferrofluid, etc. I am an old fan of vintage Dynaudio stuff. I myself own a similar combo and I can tell you this is a lifetime keeper once the crossover is done right.
Time for an update...
The cabinets have been given a few coats of Tuff Cab black and are looking very different. The veneer was cracking and lifting in places, so it was not really salvageable. Anyway, they now look suitably industrial for their intended place of residence. Pics once I'm happy.
I've decided next step is to get them playing. The new surrounds for the woofers should arrive today and I have a syringe full of ferrofluid for the tweeters. This weekend will be another deep end experience as I attempt to clean up the drivers and rebuild the crossovers for the woofers.
Any tips, help will be gratefully received!
The cabinets have been given a few coats of Tuff Cab black and are looking very different. The veneer was cracking and lifting in places, so it was not really salvageable. Anyway, they now look suitably industrial for their intended place of residence. Pics once I'm happy.
I've decided next step is to get them playing. The new surrounds for the woofers should arrive today and I have a syringe full of ferrofluid for the tweeters. This weekend will be another deep end experience as I attempt to clean up the drivers and rebuild the crossovers for the woofers.
Any tips, help will be gratefully received!
Started the weekend with a walk to the post office to collect my woofer surrounds. Got home, cleaned the old foam amd glue off and glued the new foams into place. While the glue's drying, pull the tweeters apart, clean them out and refill with ferrofluid. I wasn't prepared for the magnet to pull the fluid out of the syringe! Reshape the domes as much as possible and reassemble. Next, midranges. While I was given useful advice about reshaping them, thanks, I couldn't for the life of me work out how to get them apart without damaging them, so decided to leave well alone for now. Reshaped them as far as possible with a vaccuum cleaner and cleaned them as best I could. One crossover was damaged with the largest inductor broken off and unravelled in the bottom of the cabinet. I rewound it as tightly as possible, mounted the original boards onto a piece of MDF and drilled and tied everything down with cable ties instead of glue... boards were replaced inside in their original positions and the drivers refitted and resoldered (woofers after letting glue dry overnight). Final job was reconnect all the cables back to the binding posts.
Moment of truth... cables in, amp on, and... all works first time. Sounds incredible. Of course, they should, they were very expensive once upon a time and I haven't changed or modified anything from their original design, but it's a good feeling that I got it all right and bought them back to life after their 14 year slumber. They image far better than the old Linn Keilidhs I had in there before... sounds like there's a real bass drum in the fridge! They seem really fast and hard hitting when necessary, and have nice tight, deep bass.
If I was planning to move these into the house, I would be looking to do a lot more to them - recap the crossovers, maybe find replacement mids and tweeters - but for life in my workshop where they'll get fed with Spotify via Chromecast and a big NAD amp, get dusty and knocked occasionally, they're already far, far better than I need. I may, however, have problems getting any work done... I keep stopping and listening to the music!
I now need to clean and rearrange my workshop and get them put in a less prominent position. They'll have to go a lot closer to the walls... more bass? I'll deal with it!
Moment of truth... cables in, amp on, and... all works first time. Sounds incredible. Of course, they should, they were very expensive once upon a time and I haven't changed or modified anything from their original design, but it's a good feeling that I got it all right and bought them back to life after their 14 year slumber. They image far better than the old Linn Keilidhs I had in there before... sounds like there's a real bass drum in the fridge! They seem really fast and hard hitting when necessary, and have nice tight, deep bass.
If I was planning to move these into the house, I would be looking to do a lot more to them - recap the crossovers, maybe find replacement mids and tweeters - but for life in my workshop where they'll get fed with Spotify via Chromecast and a big NAD amp, get dusty and knocked occasionally, they're already far, far better than I need. I may, however, have problems getting any work done... I keep stopping and listening to the music!
I now need to clean and rearrange my workshop and get them put in a less prominent position. They'll have to go a lot closer to the walls... more bass? I'll deal with it!
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.