This project has changed a lot during its time, so much so, that it is no longer about the Yamaha NS-1000m or any of its components, so as I've started a new project for an active 3-way and thought I would wind this project up.
I decided to put the NS-1000M back to its original (Passive) specification, I still had the original x-overs so this was not very difficult to achieve.
I've learnt a lot during my experimenting, the most important thing, is that the NS-1000m has it's own character and this shines through whether you are passive/active/digital. Like all speakers, they are not perfect, they have little in the way of deep bass, but what they do have, is plenty of punch in the mid bass due to a rise in response at this point. With a bit of room reinforcement they are good for 50Hz, maybe just under. Where they shine is in the mid range and top end, with clarity and imaging that is rare to find. My original thought was to put the speakers back to original spec and sell them on, trouble is, I'm enjoying them too much.
My advice to any owner of the NS-1000m who is thinking of tweaking, is something I learnt from Paul Coupe (Reference Fidelity Components) and applies to any classic speaker, keep it simple and swap like for like, or you risk loosing the magic you enjoyed in the first place.
To this end, let me guide you through the changes I made and destroy a few myths along the way.
The simple re-cap I completed at the beginning of this project freshens things up and brings the speakers to a level, which is probably not much better than the day they were made, but more importantly, does not change the speakers character, so lets go through what I did to achieve the crossovers pictured below.
My advice on how to freshen up the NS-1000m
1. Change the spring loaded speaker terminals, nothing fancy needed, just some Gold plated Brass posts, as fitted earlier in the project - Avoid cheap white metal posts, if you buy off the Bay, check them by scratching off the Gold at the solder tip with a file. I fell foul of this and purchased some which turned out not to be Brass and had to be changed.
2. Replace the flimsy wires that connect the posts to the PCB, again nothing fancy, I used some Van Damme 2.5mm square speaker cable.
3. Replace the caps for the Mid Range, these are the large silver cans, all identical 3.5uF. There are six (wired in parallel to achieve 21uF) and used in series with the mid driver in the circuit, there is also a single unit used parallel across the circuit. Contrary to common belief THESE ARE NOT ELECTROLYTIC CAPACITORS. If they were they would be around 30,000uF total and not 21uF. They are metallised paper and are a form of film cap, so should be replaced with similar. I chose to use Ansar Supersound Poplyprop Caps. After some experimenting, I found using 3uF of ClarityCap ESA as part of the 21uF total, gave a slightly fuller, richer mid range and removed a bit of grain, but the difference is small, don't expect a huge difference. Do not use electrolytics to replace these caps, it will seriously degrade the sound quality.
4. Replace the two electrolytic caps in the Bass circuit (94uF total) with similar, I chose to use a pair of Mundorf E-Cap bypolar electrolytics. Do not be tempted to use PP film caps here, they have a much lower ESR value and will change the characteristics of the circuit.
5. Replace the film cap (2.7uF) used in series with the Tweeter, use a high quality film cap here, I used a Mundorf Supreme.
A). The level controls need to be in the circuit, if you bypass or remove these, you will have to alter the design accordingly to compensate. Don't ask me how, as I didn't measure the L-Pads, just leave them in circuit and you will be fine.
B). I spent time measuring and matching the bundles of caps to get the desired values, you can probably see the true value scribbled on the side of some in the picture.
If you want the last drop out of the speakers, you can bypass the 2.7uF series cap for the Tweeter and the 21uF bunch in series with the Mid Range with a 0.01uF Vishay MKP1837. I'm not a big fan of bypassing and not had much success with it in the past, but it does seem to work in this configuration, taking the last bit of grain out of the Mundorf Supreme on the Tweeter and opening the sound stage up in the Mid Range. Wouldn't have bet money that such a tiny cap would have made any difference, but my ears are telling me otherwise.
That's it, nothing more complicated is required, the results are superb and without altering the character of the speakers. I'm going to spend some time enjoying mine again. If only they went 15Hz deeper in the bass! ah well, that would make them just about perfect in my eyes and nothing in this game is quite that.
The caps I used in the example above replicate the sound of the original silver cans exactly, if this is what you want then use the Ansar Supersound as indicated.
The stock NS-1000m have always had the reputation of being a bit Amp fussy and needing something rich sounding, with a highish damping factor, like a Luxman, to sound their best. When using my Nakamichi Power Amp (fairly neutral) with the stock speakers, I had to turn the mid range down by 2dB on the level controls and I have to do the same with the Ansar caps fitted. The metal dome mid range just has too much top end bias otherwise.
I have a lot of respect for the work done on HumbleHomeMadeHiFi in the cap tests and I nearly always agree with the results on the caps I have experience with. The comments they make about the Ansar Supersound is that they concentrate on the upper frequencies and are therefor not particularly neutral. I decided to try a more neutral cap, just for the location in series with the mid range driver (21uF) and see how that faired.
I settled on the fairly modest entry level Mundorf MCap MKP. The largest size (diameter) that will fit into the moulded pockets on the rear of the Yamaha x-over plate is the 4.7uF. So I used 4x 4.7uF and a single 2.2uF to make the 21uF needed. When I measured the individual caps for both x-overs, two were just over the nominal value and the rest were all just under. They were all closer than 1% which is a lot better than the stated 3% and something also picked up in the "Humble" tests. I added a 0.1uF to one bunch and a 0.22uF to the other, this gave me totals of 20.996uF and 21.018uF which is more than close enough, note I didn't use a bypass on these. I left all the other caps as previous, including the bypass used on the Mundorf Supreme.
The caps fitted in nice and neat, a bit of silicone sealant was used to hold them in place and reduce vibrations. I ran them in for a couple of days before giving them a listen.
I can not over state how much of an improvement these caps make over either the stock Silver cans or the Ansar Supersounds. They work so much better with the mid range driver. The level controls can be set to normal, they are much more Amp friendly in this respect. The more neutral balance removes the top end focus and gives a slightly richer mid range with better (more realistic) piano in the lower part of the middle of the key board. This has been one of my pet hates on every pair of NS-1000m that I have heard, these caps cure it. They make for a very easy listen, without being over lush, sound stage has improved further and sibilance has all but disappeared (unless on the recording).
I was originally putting my NS-1000m back to stock spec to sell on, that decision may have now changed, as I am enjoying listening to them like never before.
This final combination is a winner, I can definitely recommend it. If you can use a soldering Iron, this simple capacitor replacement is actually an upgrade and will give your speakers a new, more neutral and natural sound. If you have a really bright sounding Amp using a percentage of ClarityCap ESA for the mid range bunch will help, but if your system is neutral this last combination is the dogs whatsits.