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SEAS H417 (25TAC/GW)
Categories: 0.75 - 2" (19-50mm) Dome Tweeters
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40+ years in the trade
UK family run business
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In addition to my post from 17/11/2025, here is some information on the final status of the project: Saving the Mission 752 loudspeakers.
Once it was certain that it would be possible to revise the loudspeakers (thanks to Willy), the desire to also replace the low-midrange drivers and convert the crossover to a high-quality version quickly arose. I was fortunate enough to be able to purchase two Burmester 949 MKII midrange drivers from Audax to replace the existing low-midrange drivers (52LFHDA – still available and can be sold). They are practically identical in design, but significantly more refined and powerful. Revising the crossover proved somewhat more difficult because the values of the coils were not printed on them. However, they can be determined by measuring the originals. Mundorf resistors, coils and capacitors of the two highest quality grades were installed. These are not exactly cheap, but once the speaker is finished, the difference is clearly audible. The crossover was also modified slightly. A shunt was integrated into the high-frequency branch. Following a tip in a forum, the crossovers were also moved to the outside. They are currently still on the speaker without a housing. The metal housing provides perfect shielding. As the Willys tweeters are very efficient, they were ‘damped’ slightly. The final cost of the conversion was approximately £600. In return, the speakers now perform at a level that far exceeds their original condition. An exciting project that was only made possible by Willys – thanks to Caroline & Will ❣️
Id had these speakers for a couple of years. I got the S/H and already the tweeters weren't working when purchased. Played them for and while but parked them up hoping one day to organise tweeters. Well that day finally came and i am blown away. Easily better than my Jamo 507A's and TDL RTL 3's. I drive them with an adcom 5300 and nad as pre amp. I am in New Zealand. The turn around time was within 2 weeks. Saving up for the crossover upgrade.
This made a massive difference to my 30 year old Linn Keilidh speakers, giving them a new lease of life.
Willy's is an awesome serivce. I needed a 4" midrange replacement that is a drop in exact fit for the IMF TLS50. If you are ordering from the USA, the Monacor MSH-115, 4" is your best option. I live in Pennsylvania and it only took 5 days from the time I ordered to be delivered from the UK. Royal Mail provides tracking. I dropped in cab and was fired up shortly on the same day. Sounds great. Totally worth buying these instead of rebuilding old speakers.
Willys saved my Mission 752 speakers. The tweeters were defective. The original tweeters are no longer available, and it would have been a shame to throw away these really good speakers. I came across Willys by chance in a chat room. Even there, the company and especially the tweeters were highly praised. I contacted Willys and received a very friendly response. Ordering the speakers went smoothly. However, shipping to and from the UK is a real adventure due to ****. It is expensive, cumbersome and no fun for either side. The tweeters arrived two weeks later and were of course installed immediately. The result is truly impressive. Airy, clear highs (previously a weakness of the 752, which tended to ‘hiss’) and a sound image that really thrills me. The ‘old’ Mission 752s seem to me as if they have been swimming in a fountain of youth. Thank you for the good service and the high-quality tweeters. ❣️❣️❣️
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