B&w Dm640????

[kimschips]

Hello hello

I´ve got a pair off B&W DM640 loudspeaker-> great for me

I am now asking, have any off you guys ever upgraded such a pair and how??

I am thinking off getting started with the crossover components

I can say that for those who don´t know the speaker. It contains a 1" dome tweeter and 1 6.5" middleway units with kevlar and 2 8" bass units.

Best regards
Kim

 

[amirmk]

It can be upgraded with premium parts, but if it's ain't broken, don't fix it.

 

[DcibeL]

If there are cheap electrolytic caps in the crossover you can replace them with polypropelyne caps of the same value. If there are iron core inductors you can replace them with air core of the same value. Resistors can also be replaced with higher quality parts.

From what I have read B&W have rather cheap crossovers so upgrading them is probably a good idea.

 

[kimschips]

Hey

Thank you both very much!

Any other?

All the best.

Kim

 

[qsilverza]

Hi There,

I recently purchased a set of DM640's second hand.

They are in original condition. The Bass ports are the small ones and they are way to bassey for my room size, so i have turned the bass frequencies off to my fronts and let my adjustable sub do the work. I need the accoustitune ports and i only have the small length one = maximum bass.

Anyway,

I plan to seal off the units and perform X-over upgrades including the below in the article...

For fixing a box discoloration when closing the ports...

http://www.avahifi.com/images/avahifi/root/audio_basics/ab_pdf/ab1990-12.pdf



Here are my speakers and there innards, What are the recommendations for replacement ?

http://s370.photobucket.com/albums/oo146/qsilverza/Bowers%20Wilkonson%20DM640/

 

[Inductor]

Parameters are different between "iron core inductors" and "air core", to be replaced just like that, and output curve will change. Actually if you want to add 0,5 ohm to an inductor you can choose an air core with more (or less/meaning good/better quality than standard air cores) 0.5 ohm vs the iron core. But for that you need to know how much measures the original inductor (L/mH and R/Ohm). Probably, if you "seal off the units" (do you mean changing from BR to closed box?) you will need the iron core low resistance again, maybe not, we shall see.

 

[qsilverza]

Indeed, the 640's were sold with three different types of ports. small, long and sealed plug = BR to sealed.

Is there anything that would vastly benefit from replacement or are the x-over's pretty decent anyway ? I dont really want to change the charterstics of the speakers as I am not of such accomplished nature into the audio-phile world to be able to do such a thing.

Regards

Parameters are different between "iron core inductors" and "air core", to be replaced just like that, and output curve will change. Actually if you want to add 0,5 ohm to an inductor you can choose an air core with more (or less/meaning good/better quality than standard air cores) 0.5 ohm vs the iron core. But for that you need to know how much measures the original inductor (L/mH and R/Ohm). Probably, if you "seal off the units" (do you mean changing from BR to closed box?) you will need the iron core low resistance again, maybe not, we shall see.

 

[Inductor]

With the small information we/I have now, I would say, don't repair what is not broken. Let's say you change parameters like the type of the box or your house, size of room, others like place in the living room, materials of decoration, then you will need to recheck, and probably come here again. If everything is ok and you need small changes, then we need to know, like you said to much bass (?). Probably you will be testing different value components before setting your choices definitely.

The Bass ports are the small ones and they are way to bassey for my room size, so i have turned the bass frequencies off to my fronts and let my adjustable sub do the work.

 

[qsilverza]

Indeed, I just need to order the resistors for the box discolouration and will also fabricate some ports.

Any idea how long the long port might be, I emailed B&W still waiting on there response. But I may make a mould or something shouldnt be to hard to do.

With the small information we/I have now, I would say, don't repair what is not broken. Let's say you change parameters like the type of the box or your house, size of room, others like place in the living room, materials of decoration, then you will need to recheck, and probably come here again. If everything is ok and you need small changes, then we need to know, like you said to much bass (?). Probably you will be testing different value components before setting your choices definitely.

 

[sfc1000]

HI all,
I have had a pair of B&W DM630 which I modded by burning a series of holes with a soldering iron in the edge of the spider behing each of the two bass (and mid) units in each loudspeaker. It made the bass go more quick and less muddy.

Later on I got a pair of DM640i (the improved version of DM640), and since they have a much better sound than the DM630 I did not do this mod.
Instead I took the original damping material out, and exchanged it for real fresh cut sheeps wool. I needs to be cleaned a LOT, though. It made them sound more natural, also in regard to voices.
Later on I took it out and installed sheets of asphalt/rubber damping (from auto parts shops) more or less all over inside, and stuffed in the original damping material. Sounded even better.
I gave the cabinets 8 layers of high gloss paint for kitchen kabinets and waxed them 25 times for improved WAF, and the missus' happy
I also changed the spikes for a little fatter model of a spike and pressed these into four pieces of cork (for sanding paint), which gave an improvement in more precise bass due to less vibes.

Now, I have this question:
What is the actual difference between the DM640 and the DM640i ?
Does it include mods like the link describes to two added resistors to the i-model?
Or is it elsewhere that they are improved, and maybe someone could also say a "go" for the added resistors to the DM640i-model?
Other mods?

Much much appreciated, thanks!

Just my two-cents, cheers,
Jacques.

 

[sfc1000]

Update on the B&W DM640i:

I still play stereo music on these, and I still love them.
I've found some answers to my own questions sin then.
The midrange units are improved and a slight mod to the crossover to suit. B&W's own info.
Since last, I have experimented with placing them a Little bit different, which is slightly more out from the walls. Less boos and more precision.
Next, I glued som ethick Wood Sticks inside between the two left/right side of the cabinets. Again better control, more silence, a bit less mud.
Next, I took the grey rubber rings off, and it gave a slightly less good sound, so keep them. I'll paint mine with leather colour from furniture Clinic (UK).
I changed the cables, from single wire Tara Labs Helix6, to two set of theses, and a better sound came with more air in the high frequenzies.
Next, i went to Tara Labs Air1 and they are a step better.
I've now changed my amp from A Musical Fidelity, to a BOW pre and power, and then back to Musical Fidelity class A Integrated amp. Then to a Copland CSA14 hybrid, and then modded that. Sound is improving in my system, and the nice part about it, is that I can hear it, and sometimes go back a step to see, if it was a change or a real improvement. The DM640i seems to play more and more free and natural. Good potential, I'd say.
I'll experiment with cross overs later this Summer.
Cheers,
Redfox.