B&W DM70's - top end lacking

Hi Martin

Have you changed your drivers over to eliminate the crossover?
Have you changed the speakers overs to eliminate the amp outputs?

So far I have made no changes to the crossover(s).
I only changed the drivers because my original bass units are faulty.
The first thing that I plan to do is get the diodes in the HT section changed and take it from there.

Does it sound like metal hitting a dense hardwood block? I have heard of dry joints causing noises like this in bass drivers.

One of the original bass units makes a metallic ping when it reaches full excursion.
This is why I am holding back on changing the surrounds myself.
I feel that it is beyond my expertise.
Just now, the Leak bass units work very well.
I friend of mine, who also has a pair of DM70’s, thought that mine sounded very good this last weekend and that is before replacing my diodes.

The speakers were definitely over damped!

I agree about the damping and now use only half of the original damping plus the door mats glued to the rear panel.
The original damping is now in three zip laundry bags per unit.
This keeps the damping from getting into the rear of the bass units and help stop the fibreglass from settling too much.

Lambswool quilting has been applied to the sides and base

Where did you get your Lambswool quilting, as I have had trouble getting hold of this kind of thing?
I would also like to replace the fibreglass with long fibre wool if possible.

This is my other thread:
http://theartofsound.net/forum/showthread.php?57264-B-amp-W-DM70-my-journey-so-far
and another relevant thread:
http://theartofsound.net/forum/showthread.php?50077-B-amp-W-DM70-rebuilding-an-Icon

Ian

Hi Ian,

I brought my DM70 through AoS as 'not working' for only £100.

I have had great difficulty getting hold of natural lambswool quilting. The material that I have used came from the thermal insulation that Completely Fresh previously used in their delivery boxes. It is perfect for my needs. Unfortunately they have changed the material now.

I removed 2 black bin bags full of glass fibre (I loath the stuff) from the cabs.

One of the problems when I first listened to them was that the damping was pushing up against the cone despite the cotton gauze.

I will upload some photos onto your AoS thread.

Martin

Hi Martin

How many grams of wool are needed per cabinet?
I have found a source at £10 per kilo.

Hi Ian,

Rather than 'stuffing' I have used quilting in 25mm thick blankets therefore I have been able to apply to the inside faces and as gravity drop acoustic curtains directly behind the driver. As a mass/ volume I would estimate that I have now only 20-25% of the original.

These speakers are now sounding very good indeed. Speakers, as we all know, are highly subjective and personal. The DM70 are currently in a room with my Magneplanars and Apogees and are more than holding their own.

Best regards, Martin

Hi Ian,

The other foams have arrived. They are the correct size. I will probably change them over at some point in the near future.

Best regards, Martin