Hi guys
Today I received 3 Yamaha NS-10M monitors from a client. He also gave me 2 spare woofers for the monitors (scratchy, therefore discarded) and a tweeter in a new sealed box.
So in total I have 5 woofers, 4 of them are scratchy. And 4 tweeters, one has an open voice coil.
The client wants me to assemble at least one of the monitors with the available parts. He also blames the amplifier for destroying the speakers... Is that even possible?
I managed to assemble one working monitor already, found one of the discarded ones that was working ok but had the dust cover pushed in. I used my magic vacuum cleaner and now it looks almost perfect.
What can these woofers turn scratchy?
I read somewhere that the glue that hold the magnet to the basket gets loose over time, causing the magnet to be misaligned with the voice and rub against it
Also that pieces of fiberglass can get into the voice coil and destroy it...
How easy (or difficult) is it to realign magnet and coil?
Today I received 3 Yamaha NS-10M monitors from a client. He also gave me 2 spare woofers for the monitors (scratchy, therefore discarded) and a tweeter in a new sealed box.
So in total I have 5 woofers, 4 of them are scratchy. And 4 tweeters, one has an open voice coil.
The client wants me to assemble at least one of the monitors with the available parts. He also blames the amplifier for destroying the speakers... Is that even possible?
I managed to assemble one working monitor already, found one of the discarded ones that was working ok but had the dust cover pushed in. I used my magic vacuum cleaner and now it looks almost perfect.
What can these woofers turn scratchy?
I read somewhere that the glue that hold the magnet to the basket gets loose over time, causing the magnet to be misaligned with the voice and rub against it
Also that pieces of fiberglass can get into the voice coil and destroy it...
How easy (or difficult) is it to realign magnet and coil?
The usual cause is too much power or a general overload, user error.
Ask what the amplifier is that was driving them.
Yamaha can supply replacement elements for these.
Re-coning is not an option.
Ask what the amplifier is that was driving them.
Yamaha can supply replacement elements for these.
Re-coning is not an option.
Ask what the amplifier is that was driving them. Hafler P3000 power amp (150 WPC at 8 ohm)
Yamaha can supply replacement elements for these. He bought the replacement woofers from Yamaha
Re-coning is not an option. Ouh (sad face)...
Yamaha can supply replacement elements for these. He bought the replacement woofers from Yamaha
Re-coning is not an option. Ouh (sad face)...
Hafler P3000 power amp (150 WPC at 8 ohm) 150 RMS would be more accurate, WPC could mean anything if not specified. At least it says that the amp has more than 1 channel, 2 in this particular amp.
I am not sure if easily available where you are located but their has been some manufacturers of replacement NS10 drivers. Maybe a search for Bold North or Avantone could be fruitful. I imagine it all depends on how deep his pockets are and does he want his NS10's serviceable again.
It is definitely worth verifying that the amp is not outputting a big switch on thump to the speakers and has low DC voltage offset on both channels. 20mV ?? or what the spec has *** a maximum allowable.
A Hafler will be getting old now, unless it has been checked out by a good service technician who has taken care of component drift or things going out of spec.
It is definitely worth verifying that the amp is not outputting a big switch on thump to the speakers and has low DC voltage offset on both channels. 20mV ?? or what the spec has *** a maximum allowable.
A Hafler will be getting old now, unless it has been checked out by a good service technician who has taken care of component drift or things going out of spec.
I serviced a large recording studio that wiped out NS-10s. New woofers from Yamaha. I was authorized warranty.
You can blow them as they aren't high powered speakers. I wouldn't worry about sound quality too much as they are obviously running them too hard. They will probably blow whatever you put in there. You'll want something the same efficiency so the are roughly balanced if you don't use the originals.
Honestly, the owner may be further ahead buying something current. Blow them up and call it cost of doing business. I can tell you they were hitting the back plate and sounding distorted anyway. Don't let his problems become your problems.
You can blow them as they aren't high powered speakers. I wouldn't worry about sound quality too much as they are obviously running them too hard. They will probably blow whatever you put in there. You'll want something the same efficiency so the are roughly balanced if you don't use the originals.
Honestly, the owner may be further ahead buying something current. Blow them up and call it cost of doing business. I can tell you they were hitting the back plate and sounding distorted anyway. Don't let his problems become your problems.
Yes.
One side of a Hafler DH-200 amp (200w@8ohms) driving my Tannoy PBM 6.5 speakers had a little DC voltage on one channel that slowly grew from a small fraction of a volt to 5 volts over the course of 20 years.
5 volts into a “100watt 8ohm” Tannoy PBM 6.5 woofer's DC resistance of around 4 ohms, just 6 watts, was enough to cause the woofer's voice coil to burn, as the DC held the voice coil in a fixed position, allowing little cooling as the speaker sat powered, but idle.
I never noticed any distortion, but one day noticed the left woofer was not working..
Simply driving an amp into hard clipping can increase the average power enough to take out tweeters near instantly, or woofers over more time.
Before the voice coil actually burns up, the adhesives can melt, and the voice coil can start to drag.
Any fiberglass insulation fibers making it's way into the gap usually are blown back out, never have seen coil damage from that.
Magnet shifts occur from hard knocks after the glue has become brittle.
A shifted magnet will pinch the voice coil, it can't move and the woofer will not make any bass- it will sound "tinny", not scratchy.
If you can move the cone by hand, the magnet has not shifted.
The only way to fix it is removing the voice coil, demagnetization, realignment, then re-magnetization.
Removing the cone and voice coil without damage is near impossible if the magnet has pinched the coil.
A Misco replacement would be less expensive.
Art
The customer gave me his Hafler P3000 for inspection.
On ch1 the bias is in specs (200 mA, according to manual). DC offset is 70 mV but there are no indication about max allowed voltage in the manual, other then "the lower the better".
On ch2 I was unable to check the bias, this channel went right into short circuit protection. DC offset is 3-5 mV which is excellent compared to ch1.
When I tried to check bias again on ch1, it also went right into short circuit protection.
I followed the instructions to the letter. Either I´m missing something or the amp has a serious issue. It does sound OK with gain set 0 dB (2 o'clock).
With gain controls at maximum, the way my customer uses to run it, all hell breaks loose when turning on, even with input at a very low level.
On ch1 the bias is in specs (200 mA, according to manual). DC offset is 70 mV but there are no indication about max allowed voltage in the manual, other then "the lower the better".
On ch2 I was unable to check the bias, this channel went right into short circuit protection. DC offset is 3-5 mV which is excellent compared to ch1.
When I tried to check bias again on ch1, it also went right into short circuit protection.
I followed the instructions to the letter. Either I´m missing something or the amp has a serious issue. It does sound OK with gain set 0 dB (2 o'clock).
With gain controls at maximum, the way my customer uses to run it, all hell breaks loose when turning on, even with input at a very low level.
I read about old or brittle glue.
After checking the amp, I think it was run at levels where the voice coil gets so hot that the isolation on it expands and rubs on the magnet but not to such levels that it shortens out or breaks. But that's just my interpretation.
After checking the amp, I think it was run at levels where the voice coil gets so hot that the isolation on it expands and rubs on the magnet but not to such levels that it shortens out or breaks. But that's just my interpretation.
Having owned some of the bigger Yamahas of that era (NS1000M, NS-690), I can tell you the glue thing is very very very likely the cause. The glue becomes brittle, the space under the magnet rusts, the rust lifts the glue, then any jolt can slightly dislodge the magnet, causing the voice coil to rub. This was how I received a set of DOA NS-690s, and scratchy is exactly how I would characterise the sound from the woofer when moving the cone back and forth slightly with my finger tips. The magnets need to be removed, the surfaces cleaned, and then they need to be reglued in a jig.
It may not be worth the time, if they are not special to the client in some way.
It may not be worth the time, if they are not special to the client in some way.