Right then guys and gals, feel free to tell me this is a bad idea!
I have a pair of B&W DM603s, I've played around with them already by removing the passive radiators, pictures attached. My ears can hear the difference, and measurements show improvements so all good.
And it got me thinking as I now have a free mounting place in the cabinet, could I introduce another driver? The answer to that is yes I can, no problem, easy! Except of course it's not that easy because having mounted it I then need to get it to work! And this is where I would need help.
I would need to keep the speaker at the same impedance, 8 ohms. And then there's the issue of what size driver to fit. My single figure IQ tells me that it would be sensible to fit another B&W driver of around 100mm or so, (existing mid/bass driver is 180mm).
The existing B&W XO is, (I believe), 3KHz, so my guess is the tweeter works from this up to 20KHz.
Have been looking at assembled crossovers but am unsure as to what to go for, and if I should go for two or three way.
Anyway, is this idea stupid? Ultimately I'm not going to do anything that is not reversible, and I fully understand that if I do go ahead that the speakers my end up sounding worse rather than better, (hence the reversibility). What I absolutely do not want to do though is risk the AVR; which for clarity has it's XO set to 120Hz, (work in progress with REW and MSO) and is driving two SB3000s through a MIniDSP 2X4HD.
I have a pair of B&W DM603s, I've played around with them already by removing the passive radiators, pictures attached. My ears can hear the difference, and measurements show improvements so all good.
And it got me thinking as I now have a free mounting place in the cabinet, could I introduce another driver? The answer to that is yes I can, no problem, easy! Except of course it's not that easy because having mounted it I then need to get it to work! And this is where I would need help.
I would need to keep the speaker at the same impedance, 8 ohms. And then there's the issue of what size driver to fit. My single figure IQ tells me that it would be sensible to fit another B&W driver of around 100mm or so, (existing mid/bass driver is 180mm).
The existing B&W XO is, (I believe), 3KHz, so my guess is the tweeter works from this up to 20KHz.
Have been looking at assembled crossovers but am unsure as to what to go for, and if I should go for two or three way.
Anyway, is this idea stupid? Ultimately I'm not going to do anything that is not reversible, and I fully understand that if I do go ahead that the speakers my end up sounding worse rather than better, (hence the reversibility). What I absolutely do not want to do though is risk the AVR; which for clarity has it's XO set to 120Hz, (work in progress with REW and MSO) and is driving two SB3000s through a MIniDSP 2X4HD.
Attachments
That you can hear the difference is no wonder. 😉 That you think it is an improvement, I could not argue, but that your measured an improvement, in what manner? You have turned a reflex into a sealed enclosure, which isn't such an out-there thing to do. I have no clue what the original enclosure alignment was, but you probably now have a higher f3 and higher damping. Nothing wrong if you prefer this mind you.
So you want to make this a 3-way? The location of the new mid driver would be too far from the tweeter and cause a lot of combing effect. Not to mention the crossover should be redone from the ground up. Nothing off-the-shelf is likely to come close that what I assume is a competent design for the existing 2-way setup.
My opinion: leave it sealed if you prefer or turn it back to a reflex system, but perhaps look at a whole new project if you badly want a 3-way.
Thanks for the replies.
@AllenB, happy to move the 180mm driver to the bottom mount, but ultimately if the project is reversible then I can swap it back if required.
@IG81. Measurements were taken with a UMIK-1 and REW. I did sweeps with the ports bunged and open, the passives in place and removed with all permutations of both options.
I am trying to learn, but the curve is very steep and to be honest it may not be the right time, but I need to try and keep my mind active and escape for short periods of time from life issues.
I was just looking to tinker for the above reasons, like I say, might be a few quid wasted but it was/is a little project. Was looking for advice on three way or any other way that may work. Info on my speakers here, along with what was the next step up, the 604.
https://proxy.bowerswilkins.com/sites/default/files/2019-03/ENG_FP10254_DM603_manual.pdf
The new mid driver would sit directly below the tweeter and the existing 180mm driver moved to the bottom mounting.
I was looking at pre-built XOs here:-
https://www.soundimports.eu/en/crossover-components/assembled-crossovers/
However building a couple of XO's isn't beyond my capability, except when it comes to the design, I could build something if I knew what to build! I have soldering skills, (learned from my father who was an electronics engineer), but have very little knowledge of electronics per se.
My only fixed and absolute "want" is not to damage the AVR, (which is shown as capable of driving 6 ohm as well as 8 ohm speakers).
Not in need of a three way at all, just seems pointless in having a couple of cabinets with a free mount that could be used! 🙂 I do like to make things. However starting from scratch, although appealing, is not an option for me at present.
@AllenB, happy to move the 180mm driver to the bottom mount, but ultimately if the project is reversible then I can swap it back if required.
@IG81. Measurements were taken with a UMIK-1 and REW. I did sweeps with the ports bunged and open, the passives in place and removed with all permutations of both options.
I am trying to learn, but the curve is very steep and to be honest it may not be the right time, but I need to try and keep my mind active and escape for short periods of time from life issues.
I was just looking to tinker for the above reasons, like I say, might be a few quid wasted but it was/is a little project. Was looking for advice on three way or any other way that may work. Info on my speakers here, along with what was the next step up, the 604.
https://proxy.bowerswilkins.com/sites/default/files/2019-03/ENG_FP10254_DM603_manual.pdf
The new mid driver would sit directly below the tweeter and the existing 180mm driver moved to the bottom mounting.
I was looking at pre-built XOs here:-
https://www.soundimports.eu/en/crossover-components/assembled-crossovers/
However building a couple of XO's isn't beyond my capability, except when it comes to the design, I could build something if I knew what to build! I have soldering skills, (learned from my father who was an electronics engineer), but have very little knowledge of electronics per se.
My only fixed and absolute "want" is not to damage the AVR, (which is shown as capable of driving 6 ohm as well as 8 ohm speakers).
Not in need of a three way at all, just seems pointless in having a couple of cabinets with a free mount that could be used! 🙂 I do like to make things. However starting from scratch, although appealing, is not an option for me at present.
The difficulty with desire to transform a 2 way into a 3 way, while improving on the sound quality, is that you can't possibly achieve it without knowing how to. Hoping that universal x/o networks will somehow do the job, is a bit unrealistic.
I'll happily tell you that this is a bad idea! 🙂
However, if you just want a diversion and a bit of fun, you could experiment with the following:
1. Move the 180mm driver to the bottom opening.
2. Find a closed back midrange driver for the upper opening (closed back so it doesn't need its own internal enclosure).
3. Power the midrange direct from the speaker terminals via a 10 uF or so series film capacitor.
You would have to make a mounting plate for a midrange driver that is smaller than the current mounting hole, as are these examples:
https://www.soundimports.eu/en/grs-5sbm1-8.html
https://www.soundimports.eu/en/grs-5sbm-8.html
No doubt it will sound awful, but you'll have the diversion you asked for without it costing the earth - and it will be reversible!
Now wait for the groans from the experts! 😀
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You are measuring the room, or to be more precise, the interaction between the speaker, its position, and the room. If you like the speaker better with port blocked and passive radiator removed, I won't argue on that, but I'm not sure it measures better.
Apart from what others already said about the difficulty to design from scratch a 3-way crossover without prior experience, and the unrealistic thinking that an off-the-shelf crossover will work, there is another problem. A mid will need a separate enclosure, it can't share the same volume of the woofer, so you will need to heavily and possibly destructively alter the existing cab. Frankly I wouldn't do it.
Ralf
That's why I suggested a closed back midrange, Ralf.
Not that I am in support of this project.
Fair enough fella's. I'll leave well enough alone and keep tinkering with the miniDSP and MSO!
I'll take on board the fact that an off the shelf XO would be a shot in the dark, (sort of knew that anyway), but you've confirmed it.
Regarding the enclosure I could have probably built something in that again could have been reversible. However, being honest, I wasn't aware that the mid would need to be separated from the lower driver, (pretty obvious now it's been said), so I haven't investigated or thought as to how I would have done it.
Thanks for the input though, appreciate it. 👍
I'll take on board the fact that an off the shelf XO would be a shot in the dark, (sort of knew that anyway), but you've confirmed it.
Regarding the enclosure I could have probably built something in that again could have been reversible. However, being honest, I wasn't aware that the mid would need to be separated from the lower driver, (pretty obvious now it's been said), so I haven't investigated or thought as to how I would have done it.
Thanks for the input though, appreciate it. 👍
Just for the sake of experiment, try a 2.5 way?
https://www.diyaudio.com/community/threads/2-5-way-crossover-how-it-works.287986/
https://www.diyaudio.com/community/threads/2-5-way-crossover-how-it-works.287986/
So for clarity, (mine!), You are taking about dropping another 180mm driver in?
https://www.ebay.co.uk/itm/125319030116?hash=item1d2d98a564:g:zBEAAOSwlnZig9uN
I'm pretty sure I can't just wire them in parallel as this will half the impedance? How would I bring the overall impedance back to 8 ohms? Place a resistor in the circuit?
https://www.ebay.co.uk/itm/125319030116?hash=item1d2d98a564:g:zBEAAOSwlnZig9uN
I'm pretty sure I can't just wire them in parallel as this will half the impedance? How would I bring the overall impedance back to 8 ohms? Place a resistor in the circuit?
Another driver, but you would need to alter the crossover to produce a 2.5 way configuration.
This requires expertise in crossover design as discussed in chrisng's link.