Bass Reflex on Yamaha NS1000M

[idb]

Hi - This of course may not be true to all NS1000 owners. However, in my room I was not at all happy with the bass coming out of the NS1000m.

I thought something was wrong with the crossover capacitors and opened the rear plates holding the crossovers and was mighty surprised!!!!!

The bass became much lower and detailed. The whole speaker sound much much better, and I was not the only person thinking so...

Of course the L-Pads came very handy as the complete balance of the speakers changed, but I was able to reach satisfactory results after some L-Pads playing.

This may be crazy, but for me, bass reflex on my Yamaha is no longer out of the question. Opinions on the matter will be appreciated. Again, I don't want to improve or claim the engineers behind this masterpiece did a bad job. This is far from being the case. This is one of the best if not the best I am yet to hear. Yet, in my room, and with my equipment, The Yummies are better with the small back plate removed (open).

I tried them with both tubes and solid state (Jadis and Mark Levinson) and the results are amazing in this configuration.

Thanks
IDB

[rabbitz]

Might be now working like an Aperoidic speaker (resistively leaky closed box) and not as a vented speaker.

[idb]

Thanksi Rabbitz. Maybe I should have given another title to my post above.
As soon as I discovered the positive change in bass quality, once releasing the crossover plates, I thought of the Variovent approach. My plan is to work in this direction as well as capacitor exchange in the crossover.

[weltersys]

Originally Posted by idb

Thanksi Rabbitz. Maybe I should have given another title to my post above.
As soon as I discovered the positive change in bass quality, once releasing the crossover plates, I thought of the Variovent approach. My plan is to work in this direction as well as capacitor exchange in the crossover.

You simply have ported your formerly infinite baffle speakers.
The cabinet material is probably 3/4", there are on line calculators that you can input the port area and depth and you can find the Fb (box tuning).

The NS1000M sealed alignment starts rolling off at about 80 Hz, the ported alignment may be flatter to Fb, but then rolls off steeper.

With a tone generator you can determine the actual Fb, the cone movement will be at minimum at Fb.

You can tune the speaker lower by extending the port, or reducing the size, but small ports tend to "chuff" when the speaker excursion goes up.

Although your speaker may now have louder bass, it will also have more excursion below Fb and around 1/3 octave above Fb, be careful at higher volumes with bass heavy music.

Have fun !

Art

[rabbitz]

What's the size of the hole with the crossover plate removed and the thickness of the box in this location?

IIRC, these are 100% filled with damping material (fibreglass if similar to the NS10M?).

[LafeEric]

What's the size of your listening room, and how far do you position them from the wall?

[idb]

Originally Posted by rabbitz

What's the size of the hole with the crossover plate removed and the thickness of the box in this location?

IIRC, these are 100% filled with damping material (fibreglass if similar to the NS10M?).

The size of the hole created by the removal of the crossover plate is 12cm wide by 17 cm. The thickness of the enclosure in this location is 25mm, although the crossover plate is flush Mount and in fact creates a slightly bigger opening of 15.5cm by 20cm with a 17mm step all around.

The enclosure is filled with yellow wool. I don't think it's fiberglass.
Some further idea how to apply a Variovent or any other port is highly appreciated. Thanks

[idb]

Originally Posted by rabbitz

What's the size of the hole with the crossover plate removed and the thickness of the box in this location?

IIRC, these are 100% filled with damping material (fibreglass if similar to the NS10M?).

The size of the hole created by the removal of the crossover plate is 12cm wide by 17 cm. The thickness of the enclosure in this location is 25mm, although the crossover plate is flush Mount and in fact creates a slightly bigger opening of 15.5cm by 20cm with a 17mm step all around.

The enclosure is filled with yellow wool. I don't think it's fiberglass.
Some further idea how to apply a Variovent or any other port is highly appreciated. Thanks

[idb]

Hi LafeEric. My room is 5dx2.8wx2.6h - pretty much a shoe box shape.
My listening position is close to the wall on one side of the room and the speakers are in the middle. Basically, they are far away from the back wall (about 2.5 meters) and 30cm from the side wall. Although this is a tiny room, a huge sound stage is created behind them and the bass does not dominate the room. The Yamahas do not disappear like my Sonus Faber Extremas, but the do image well nevertheless.

I tried positioning the speakers on one end of the room, near the rear walls, but was not happy.

Thanks!

[rabbitz]

Using a 45-50 litre volume, that opening would give an Fb around 92Hz which would give a 9-15dB peak around 100Hz. That would make it very chesty, plummy but with the damping in the way it would not be working like a real vented design.

Boomy, 50 - 80 HZ
Chesty, plummy, 100 - 150 Hz
Boxy, hollow 150 - 300 Hz

For a Variovent you can make one using damping material (high density) sandwiched between some mesh material (like gutter mesh for leaf control).
Scan-Speak

For a Variovent to work properly it needs a clear path from the woofer to the vent.

For a vent with 120mm x 170mm opening, the port would need to be roughly 485mm long to achieve an Fb=45Hz for 50 litres and 550mm long for 45 litres. Once again it need a clear path from the woofer to vent. You could make one out of cardboard for a trial with it sticking outside the box.