Presented here is the recent refurbishment/rebuild I carried out on my Yamaha NS-1000M speakers.

I have tried to consider every aspect of the original design and improve on it where appropriate. However, care has been taken to maintain the strengths of the original design.

The work that has been done:

1/ The cabinets have been stripped out, the finish sanded down, the back edges sanded flat and then the entire cabinet laminated in high gloss, black, melamine.

2/ The L-pads have been removed from the front baffles and the holes have been filled.

3/ New badges have been made from glass effect acrylic. Care has been taken to use exactly the same font and design as used originally. These are laser etched on both sides and attach via 3mm standoffs.

4/ The crossovers have been removed and completely rebuilt. The circuit has been laid out to separate the bass, mid and tweeter sections; the input is now bi-wired. All crossover components have been upgraded and value matched (though the same values as originally used have been chosen) and the L-pads have been replaced with fixed value resistors – all components are hard-wired together. Custom cases for the crossovers have been used, with custom cut and engraved input and output panels. The crossovers now sit on individual granite and acrylic isolation bases.

5/ The internal wiring has been replaced.

6/ The rear terminal panel has been replaced with a custom made, and etched, design that is a laminate of acrylic and MDF. The original wood screws have been replaced with T-nuts and M4 machine screws.

7/ The mounting for the mid driver has been internally reinforced.

8/ A large brace has been added to the back of the bass driver. This is a combination of a bridging element and an M16 threaded rod that tightens up against the magnet of the bass driver and the rear corners of the cabinet. Tension can be adjusted through the rear terminal access panel and custom tools were made to facilitate this. The brace also serves to reinforce the rear panel of the cabinet.

9/ New gaskets have been made from 1mm thick, high density, neoprene sheet.

10/ The drive unit surrounds have been masked out and the baskets have been sprayed satin black.

11/ All fixings have been replaced with high-tensile, socket head, steel machine screwes.

12/ Custom designed ‘anti-diffraction’ foam surrounds have been made for the tweeter and mid drivers. These are an exact fit and simply push fit on to the heads of the drive unit fixing bolts.

13/ Custom stands have been constructed from thick wall steel tube (filled with lead shot). These use custom made M16 spikes to couple to the floor and a ball bearing and cup arrangement to couple to the base of the speakers – a 2.3 degree, rearward, tilt is designed in). The stands are shown in another thread on this site; although the speaker mounting method has since been updated from that shown.

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An in-depth description and discussion of the whole rebuild process can be found here:

http://www.audioflat.co.uk/phpBB3/viewtopic.php?f=7&t=159

Lots of pictures, taken during each stage of the work, are included.
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Future plans include the potential addition of a super tweeter (output sockets for this have already been included on the back panel).

I also intend to convert the bass drivers to active operation.

Comments

• calvinbigbucks
• 11 June 2016 at 08:44PM
• what a fabulous job you did on a great set of speakers,that melamine really looks(to me) better than the piano finish...
  I have for years thought about
  doing the same thing only with coloured melamine(RED). BUT ! I
  COULD NEVER FIND RED MELAMINE.
  so its been sitting on the shelf
  waiting for a decision.
  you have done such a NICE JOB ,I now think ,I will do my Leak Sandwich 500 speakers in black, OR
  maybe in white...hmmnnn