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M-Resist MR5-120
Categories: Crossover Resistors - 5 Watt Mundorf M-Resist

Non inductive MOX (metal oxide) resistor with excellent sonic performance - ideal for loudspeaker crossover networks of the highest quality. Close tolerance, 2% of rated value.
Length: 24mm
Diameter: 8mm
Leadout: 35mm per side, 0.8mm wire.
Part No: MR5-120
Datasheet:
Full range from 0.1 to 56 Ohms in stock.
fine, the resistors matched their values as requested, matched pairs, will I use Willy's hi fi again? yes, no problem
Thanks for the review Col !
Will & Caroline
1990 Linn Index II LS120 Crossover and wiring upgrade.
Truly Outstanding performance upgrade flying in the face of conventional wisdom.
The resistor value is increased from 2.2 to 2.7 and is an official Linn Service 'performance' upgrade.
HF
C1 3.9uF Jantzen Superior z-cap
C3 1uF Mundorf MCap EVO Aluminium Oil
R1 Mundorf M-Resist 5W 2.7 Ohm 2% MOX
LF
C2 5.1 uF split
3.3 uF Mundorf MCap EVO Aluminium Oil
1.8 uF Jantzen Superior z-cap
Carded lambswool replacing original poly wadding. Increased weight replacing 132g ea. for 215g ea. This was weighed out in stages and determined by sonic performance.
Small amount approx 15cm sq of Bitumen foam panel placed in two pieces in base of cab. (leftovers from another project.)
Jantzen solid core speaker cable AWG 17/ 1.15mm stripped of PVC outer sheath to leave only high performance PE insulation. Doubled and twisted Star-Quad. 2.3mm
x2 400mm lengths ea.
Replace binding post steel nuts and locking nuts on back of PCB with copper nuts x8 and locktight. (steel nuts in signal path???= Nuts)
Remove all Plastic front panels and rubber securing bungs. Seal air holes in front baffle sockets. (Holes!)
Total cost £190.00.
Worth every penny! The cost of replicating this level of performance will be many, MANY times this amount. This understanding determined my budget. Happy to spend £200 upgrading on a gamble for the knowledge and experience. The results are very serious for this money.
I purchased these new in 1990 and paid £220.00. They were never highly regarded but always delivered a satisfying sound I never bored of even though Bass is not a strong point in this sealed design. Proximity to rear wall is everything here.
No previous experience with crossover upgrades. Never built a PCB. Very limited knowledge of electronics A beginner !
Every sonic element is vastly improved. Detail everywhere, Soundstage opened up. Depth, Clarity, Definition, Truly remarkable the level of performance these 'nothing special' loudspeakers are now delivering. They are being driven by Oppo 105 upgraded, John Sampson upgraded Musical Fidelity A1. All solid core power/interconnect/speaker cables.
This project was only completed 'confidently' with the kind, generous help and insights from Willys HIFI who supplied all the excellent Mundorf components.
Cannot thank Will enough for his patience and knowledge. My lack of knowledge and understanding was never a barrier to success only because Will was so helpful, enthusiastic and interested in my enquiries. Will cautioned against my extravagant choice of caps. The results could not be predicted and so a more responsible and cost efficient choice was Will's sagely recommendation. Trustworthy, Knowledgeable and Approachable. How refreshing. My choice was a gamble to push the limits and the budget, the results are beyond my hopes and expectations.
Highly commendable service and support. Outstanding in the Audio/HiFi marketplace.
Thank you Will.
John.
Thanks for the comprehensive review John !
Will & Caroline
Friendly technical support
40+ years in the trade
UK family run business
Excellent customer service
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The crossover was constructed well, I just need to figure out the best way to attach it to my Kef Concertos as they are bigger than the ones supplied by Kef that are mounted on the front of the baffle board.
Very nice deep bass look amazing with my custom made speaker
Great speedy delivery and very easy to fit. The plastic in my drivers had perished and they had suffered one too many parties! No need to make any adjustments (someone above did suggest that). I just screwed them in and the foam compressed into place. Before and after below (before I changed speaker number 2). Thank you!
Thanks you very much for the kit. I found back my kelidh after nearly 27 years. The filter were really dead and one tweeter damaged. Very happy to decide to repair/ upgrade rather than change. I found back tone and stereo stage like in the old days probably even better.
I didn't know soldering material was so important thanks for providing some.
Quite easy to recap filter and change tweeters.
Also wanted to thank you for this little note hand writen in French just for me. Very nice attention to see.
Next step is the next question do I change first the drivers with the monacor as I ve lost dust caps but they still work properly or do I change my old arcam alpha 8. Is there really something to gain moving to an newer arcam sa10 or Radia a5? Are newer amplifier much better than the old days one?
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 ❣️
