Please help me identify possible sources for this audio crackle (Yamaha NS-1000 speakers)

[TB2]

Hi!

I'm not quite sure if this is the right place to ask, but I got a feeling that someone will immediately know what's going on when watching the example videos.

Bought this pair of Yamaha NS-1000 (rare non-M) speakers in very good-looking condition. Seems that the left mid-range speaker has a bad buzz. Here are two example recordings:

Debussy - Clair de Lune: https://streamable.com/ksugwq
Dom and Roland - Sandcrawler: https://streamable.com/6a53r8

In these videos, I'm switching to the right speaker as a comparison for what it should sound like (no crackle).

I've already ruled out any other sources, i.e. I've used another audio source, another amplifier, and I've swapped left and right speaker channels; the problem's definitely with this left speaker.

Any idea what's causing this? I'm thinking capacitors... Could it be the driver itself or some trapped hair or something? From the outside it appears to be in mint condition. I haven't had a look inside yet as I'm considering to return it, but I know that these speaker units are enclosed, so foreign debris under the membrane seems unlikely. I also haven't swapped just the speaker units for the same reason.

Any suggestions as for the source of this noise is greatly appreciated. Thanks!

 

[voodooless]

Sound like the midrange is broken. Maybe this will help repairing it:

Yamaha NS1000 Mid and Tweeter driver repairs

My Yamahas have had a hard life. Getting married and kids relegated them to the garage for a few years, then into the workshop where the angle grinder gets used quite a lot. As part of my recent workshop upgrade, I thought I would upgrade my sound system and the Yamahas didn't sound like I...

www.diyaudio.com

And beware of the health hazards of handling beryllium!

 

[TB2]

Thanks for the feedback. So, "broken", as in there's a physical problem with the membrane and/or cone, huh. I'll have to negotiate with the seller on what to do.

 

[MAB]

Hard to tell. Possible voice-coil rub, or partially-blown voice coil, or other damage. Not so sure it is the crossover or volume control thingies. You will need to remove the driver to test in more detail. If the VC is partially blown you will typically see that driver has a lower DC resistance than the good driver. You might be able to inspect for damage.
Perhaps review here:

Speaker Failure Analysis

ESP - The Audio Pages. An analysis of speaker driver failure with particular reference to high powered audio systems as seen in the worlds of Sound Reinforcement and Disco

sound-au.com

Also, Dayton has a very nice speaker tester. It has a voice-coil rub feature as well. https://www.daytonaudio.com/product/1650/dats-v3-computer-based-audio-component-test-system
There are often used beryllium mids available from Japan. So all hope isn't lost!

 

[Doodski]

I'm thinking capacitors...

The only way to know is to swap the mid range drivers from speaker to speaker and use a flow chart to diagnose it. Frequency sweep with this.

Online Tone Generator - generate pure tones of any frequency

szynalski.com

 

[TB2]

The only way to know is to swap the mid range drivers from speaker to speaker and use a flow chart to diagnose it. Frequency sweep with this.

Online Tone Generator - generate pure tones of any frequency

szynalski.com

Very useful, thanks. https://streamable.com/hk95ie

I will discuss with the seller before starting to mess with the cabinets.

 

[MAB]

Very useful, thanks. https://streamable.com/hk95ie

I will discuss with the seller before starting to mess with the cabinets.

Yes, that would be best. No matter what, you have one speaker not working properly. As Doodski says, sweeps will help further diagnosis. And any further actions likely mean partial disassembly of the speaker, not hard but best to ask the previous owner before venturing down that path.

 

[MAB]

Very useful, thanks. https://streamable.com/hk95ie

I will discuss with the seller before starting to mess with the cabinets.

As promised, the issue is really noticeable with sweeps! I imagine you had to find just the right tracks to hear this clearly. Thanks for following the most excellent advice from @Doodski , you would be surprised how much pushback we get when we say music is not always the best way to look for things!

 

[Doodski]

It puts the value of the gear in perspective. To frequency sweep and know what is at hand is a good example of a working condition unit. Otherwise not and that merits some discount.

 

[restorer-john]

The NS1000 mids are difficult to kill, but the magnetic structure is easy to shift. Over the decades, the adhesive corrodes the pole pieces, swells the gap between the magnet, the metal, and the entire alignment can shift. Or corrosion can touch the voice coils.

They are easy enough to dismantle, but be very careful if you choose to 'clean' them. The domes are, of course toxic.

 

[Doodski]

So... It's a, "Do ya wanna play with the beryllium boyz or not situation?" Those old Be Yamahas sound pretty good and might be worthy of a discount too. I wonder what @dualazmak thinks of these mid range drivers and any issues associated with them.

 

[TB2]

Personally, I love the sound of these speakers. I already have a pair of NS-1000M in a different room. They had a broken tweeter which I was able to repair. I love them to bits. Best speakers I ever had (and I went through a couple of pairs). But maybe I just haven't heard anything better yet. In any case, right now I'm hoping for a discount from the seller so I can get to repairing this driver. This pair of NS-1000 wasn't cheap on account of how almost-mint the cabinets and overall exterior looks of all the components are. I'll apply my most gentle touch...

Thanks for all the advice. I'll be back with an update in a few days...

 

[gene_stl]

Beryllium is dangerous if you are grinding or machining it or doing chemical things.
Handling the domes is not too dangerous. They are brittle and shatter and if that happens you want to pick up ALL the shards so they are not left around to inhale. Use some kind of sticky tape for that.
The beryllium does not particularly rub off if you touch it (but better not to touch it)and it does not corrode in room temp air. Berylliosis IS horrible.
You haven't heard anything better because there IS nothing better.
I would offer the seller the opportunity to buy you a new midrange. The cabinets in nice condition are not common.

I have a pair of 1000M that the wooofers completely dropped their magnets due to epoxy failure. I am going to replace them with smaller woofers (eight or ten inch) and add a bigger "sub" . (ie. fourway)

Berylliosis; Symptoms, Treatments

Learn about berylliosis (chronic beryllium disease) from the Cleveland Clinic. Read about prevention methods, diagnostic tests, and treatments like corticosteroids,

my.clevelandclinic.org

 

[MAB]

Personally, I love the sound of these speakers. I already have a pair of NS-1000M in a different room. They had a broken tweeter which I was able to repair. I love them to bits. Best speakers I ever had (and I went through a couple of pairs). But maybe I just haven't heard anything better yet. In any case, right now I'm hoping for a discount from the seller so I can get to repairing this driver. This pair of NS-1000 wasn't cheap on account of how almost-mint the cabinets and overall exterior looks of all the components are. I'll apply my most gentle touch...

Thanks for all the advice. I'll be back with an update in a few days...

They are quite the speaker. Keep us posted! And good luck. I am sure you can get these to good.

 

[restorer-john]

Personally, I love the sound of these speakers. I already have a pair of NS-1000M in a different room. They had a broken tweeter which I was able to repair. I love them to bits. Best speakers I ever had (and I went through a couple of pairs). But maybe I just haven't heard anything better yet. In any case, right now I'm hoping for a discount from the seller so I can get to repairing this driver. This pair of NS-1000 wasn't cheap on account of how almost-mint the cabinets and overall exterior looks of all the components are. I'll apply my most gentle touch...

Thanks for all the advice. I'll be back with an update in a few days...

The speakers are now around 48 years old. When you buy something that old, I don't think the seller is required to be guaranteeing anything. Just get on with fixing them and enjoy I say.

 

[dualazmak]

Hello OP @TB2,

Very nice to find a new colleague having NS-1000 (not NS-1000M)!! Your visit and participation to my project thread will be highly welcome.

Let me very quickly/briefly inform you here since I will be quite busy today (time here in Japan is now 09:00 AM); I will further respond to you hopefully this evening.

Please do not touch on the highly durable Be-mid and Be-high; to touch on or to have repair service on the Be-midrange and/or Be-tweeter should be your very final option!

First, you need to check inside wiring from binding post to LC network, LC network to attenuators, and attenuators to SP drivers' wiring terminals.

Second, you should check the attenuators; I fully disassembled-cleaned-reassembled them (intensive technical skill needed!); further details will be described afterwards hopefully this evening.

In case if you would still have the problem,

Third, you would please check the wiring and capacitors on the LC network boards.

 

[dualazmak]

Hello OP @TB2,

As for the overhaul of attenuators of NS-1000 and NS-1000M, this link would be informative for you;
http://audio-summit.co.jp/2019/04/04/ns-1000mのメンテナンス後編（アッテネーター洗浄）/
I hope and believe your web browser would properly translate the Japanese site into English.

Since this procedure needs very careful and skillful disassemble - cleaning - reassemble steps, you may better to ask some professional SP repair shop to do the attenuator overhaul. (I, myself, did it successfully, though.)

 

[dualazmak]

Hello OP @TB2,

After you could successfully fix your Be-midrange problem (I really hope the driver itself would be perfectly fine), I highly recommend you to change all the capacitors and coils, fully overhaul the attenuators, and put them in an outer network box;
https://www.audiosciencereview.com/...ssover-and-multichannel-dac.12489/post-369475
and
https://www.audiosciencereview.com/...ssover-and-multichannel-dac.12489/post-371694
The improvement of sound quality was really amazing. If needed, I will inform you the details of the capacitors and air-core coils I used in my such renovation.

 

[dualazmak]

In my multichannel multi-driver multi-amplifier fully active stereo project (actually 5-way 10-channel) with SPs NS-1000 + L&R heavy-large subwoofer Yamaha YST-SW1000 + L&R super tweeters Fostex T925A, the LC network and attenuators are now completely eliminated/bypassed; you would please find my latest system setup here and here on my project thread.

Rather detailed background and preceding history towards my multichannel multi-driver multi-amplifier stereo project can be found on my thread posts #030, #128, #178, as well as #015(remote thread).

Please find here (on my thread) and here (remote independent thread post) the Hyperlink Index for my project thread and for some of my related posts in remote threads.

 

[TB2]

UPDATE: The seller immediately offered me a 300$ discount after I showed him the videos and told him that used JA-0801 speakers go for around 300$ upward. My guess is he knew of the problem. In any case, I'm OK with this.

Now to repairing it...

I finally had the time to very carefully disassemble the unit. The rubber gasket gave me quite a bit of trouble. I have no experience with the JA-0801 so I'm not sure, but I think these had been refurbished before. One of the wire contacts had a sticker "yellow" on it, so at the very least, the speaker had been removed before, and it seemed to me that the gasket was held in place very tightly with more glue than normal. I tried using a hair dryer to soften the gasket and glue but that did basically nothing. In fact, the metal mesh itself was glued on to the speaker quite tightly. I finally managed to remove the gasket and mesh with minimal damage by using a credit card, insulating tape to protect the metal, a flat screwdriver and a bit of force.



After removing the dome assembly and inspecting everything visually, I can't really find any problem. The dome looks very well attached to the coil.



I could only find a few very minor things:

#1 a tiny piece of copper-colored (but magnetic or at least statically charged) material that sat on the edge of the dome. I guess it's possible that this tiny metal piece vibrated against the dome at certain frequencies but I can't imagine how it could cause that much noise. I removed it very carefully using a small blade that the metal piece jumped to quite readily due to the magnetic field so I could hold it against the knife using a finger and remove it without touching the beryllium dome.


#2 a bit of a goopy feature on the dome, also visible on the first picture above. To me, it just looks like a little bit of the same glue that attaches the dome to the coil. Maybe during refurbishment some of it got onto the dome where it shouldn't be, but I don't see how this could cause a problem.

#3 there are two or three tiny specs of metal dust in the small gap of the magnet where the coil normally sits. I suppose it's possible that these were rubbing or jumping against the coil. No picture, but it's really just some specks of dust in the magnet. Again I don't see how that could cause so much noise.

Any opinions? Do you see something on the pictures that I don't see? Can it be that these dust particles caused the noise I posted?

Debussy - Clair de Lune: https://streamable.com/ksugwq
Frequency generator: https://streamable.com/hk95ie

Otherwise, I think I'll just try to clean up the unit as much as possible and reconnect it for another frequency sweep.