# B&W CM1



## rhino2 (Sep 27, 2006)

Just got back from shopping for home theater toys.....listened to a whole bunch of different speakers (not that I need any more mind you) but the ones that blew me away for size versus performance were the B&W CM1's mini bookshelf speakers. Unbelievable sound clarity and quality I honestly liked them better than the 802's (although it could have been the different room they were in as well....). 

Anyways are there any DIY current speaker designs that would come close to these? I have been contemplating the Nat P's for a while but if I could make something close to what I heard today I would be a happy fellow. They wanted close to a grand for a pair so if I could do it for about $400 and under that would be a reasonable starting point. 

I am open to any and all suggestions, I just want that type of sound quality. TIA


C.


----------



## BoomieMCT (Dec 11, 2006)

*Re: B&w Cm1*

I also like B&W speakers. Your comment puzzles me a bit though. What exactly are you trying to do? There are many designs out there for high end 2-way bookshelves. Or are you trying to replicate the B&W sound specifically. A few things I've noticed of B&W,

1. Kevlar woofers.
2. Metal tweeters (aluminium for the CM-1).
3. Wide bandwidth drivers.
4. Simple crossovers.
5. They use acoustic labyrinth and transmission line enclosures a lot. To me this is responsible for most of the B&W sound. 

Now let's look at the CM-1 specifically.
1. Aluminum tweeter.
2. 5" Kevlar woofer.
3. F3 of 55 Hz.
4. Crossover of 4000 Hz.
5. Ported enclosure.

I'd start by looking into parts that will fit this bill and do some modelling and/or testing. Try finding woofers that will play high and tweets that will play low and experiment with low order crossovers. Drivers I might look at first include;

Aurum Cantus AC-130MKII 
HiVi F5 5" Bass/Midrange
Eton 5" Hexacone
I also thought Usher made a wide bandwidth 5" kevlar driver but I can't find it.
Dayton RS28
Seas 27TBF

This is largely guesswork on my part but it is a place to start.


----------



## BoomieMCT (Dec 11, 2006)

*Re: B&w Cm1*

Hmm, the Etons would probably be your best bet for a woofer. And, hey, they are on sale at CSS.


----------



## rhino2 (Sep 27, 2006)

*Re: B&w Cm1*

Thanks for the quick response and great links. I know I can't duplicate the CM1's exactly but would love to have small bookshelves with that depth of stellar performance. I definitely see why you listed the individual speakers that you did, they all seem like they are what I was looking for but unfortunately I also need a proven design to go with them.... I don't currently have anything to test or model speakers with. I don't have any problem with enclosures since I am a professional woodworker but don't have the needed knowledge and skills to design my own speaker from the ground up. And so far the only project I have tackled so far is a subwoofer for the home theater which was any easy project. 
Boomie do you know of any online examples of designs using the components you linked to?? Sorry that I am so helpless but the design part of it is completely outside my range of understanding.


----------



## BoomieMCT (Dec 11, 2006)

*Re: B&w Cm1*

No worries. It isn't as hard as it seems as long as you are willing to experiment a bit. If you are interested the cabinet size and tuning should be easy to figure out. Using wide bandwidth drivers makes the crossover easier to design / experiment with. 

As far as pre-designed kits I do not know of any with this combination. There was a CSS kit that used the 5" Eton woofer and a ribbon tweeter. Madisound has some 3-way kits that use the 5" Eton woofer. And a few places I've seen a 2-way bookshelf with a dome tweeter and the 7" Eton woofer.


----------



## BoomieMCT (Dec 11, 2006)

*Re: B&w Cm1*

Or as another option, call a company like Meniscus or Madisound and tell them your situation and what you can and can't do. You could get the drivers from them, have them design and build the crossover and make the cabinet yourself.

Please note I have no firsthand experience with them, but I've heard good things.


----------



## rhino2 (Sep 27, 2006)

*Re: B&w Cm1*

So far all of my searches so far have turned up projects like the following: http://www.rjbaudio.com/Microbe/microbe.html. Which I like the style but I don't know how it would compare performance-wise. I know Madisound offers their services (for a fee) to design a speaker crossover for you but I haven't heard positive or negative feedback about the quality of the end result. From looking through their catalogues it seems like a lot of their designs (and catalogue) seem to be dated and somewhat older. But that could just be my incorrect assumption since I am new to this whole speaker design thing. 

C.


----------



## Anthony (Oct 5, 2006)

*Re: B&w Cm1*

Madisound has been around a long time and gives good advice (anecdotally, I haven't asked their advice). I agree that their catalog could use a revamp. Not enough info on what they sell, especially when compared to Parts Express (pdfs of FR, impedance, theile-small, etc).

Crossover design is all about trial and error. You get close with a program, pre-made, or advice from strangers. But in the end, that will only get you close. You'll need a little more inductance here, less capacitance there, maybe a resistor to lower the tweeter level, or a notch filter to tame a mild peak. All of these things just require a build, test, tweak, test approach.

So unless you plan to copy someone elses design exactly, be prepared for some back and forth. ****, that's the part of all this that I love!

Good luck.


----------



## Owen Bartley (Oct 18, 2006)

*Re: B&w Cm1*

Chad, good for you for taking on a new design project. Or at least for starting the research, because if you end up like me, you'll look into it more and get scared off and build a proven design, lol. 

Seriously though, it will be really tough to mimic the sound of a particular speaker, but you'll never know until you try, right? It sounds like you're off to a good start, and you'll get good advice from some of the pros here. Have you read the Loudspeaker Design Cookbook? That would be a great first step if you haven't. I got it cheap somewhere (might have been Madisound, I'm sure someone else can remember) for the previous version and it helped me to understand a lot (ok, a little) of the things behind driver and crossover construction.


----------



## BoomieMCT (Dec 11, 2006)

*Re: B&w Cm1*

I'm at work so I can't do any fun simulations BUT here is what my guts tell me would make a good first stab. If you want to attempt this here is a decent start.

(2) Eton 5" Hexacones ($160)
(2) Seas 27TBF ($80)
(2) Nice flared ports ($20)
(2) L-Pads (total of four resistors) ($12 for Mills, $4 for Dayton)
(2) 1st order highpass (total of two capacitors, $7 for Dayton poly or similar)
(2) 1st order lowpass (total of two inductors, $7 for Jentzen air core or similar)
(2) Binding posts (I like the Dayton heavy duty ones, $12)
Polyfill Stuffing ($3 or so)
Enclosure (use woodworking)

Total cost for first test pair: $300ish

CSS (who has the Etons on sale) and Madisound (who carries the Seas tweeters) would be good places to get the parts. You should be able to get everything you need from those two sites. I connect crossovers with alligator clips until I get what I like, then I make a board out of 1/4" MDF.


----------



## 1Michael (Nov 2, 2006)

*Re: B&w Cm1*

Here are some Proven Designs. No need to reinvent the wheel:bigsmile:
http://htguide.com/forum/forumdisplay.php4?f=39


----------



## BoomieMCT (Dec 11, 2006)

*Re: B&w Cm1*



buggers said:


> Here are some Proven Designs. No need to reinvent the wheel:bigsmile:
> http://htguide.com/forum/forumdisplay.php4?f=39


I did a quick series of keyword searches and didn't find any that fit the bill. I could have easily missed one though. Did you see any that fit the descriptions above?


----------



## rhino2 (Sep 27, 2006)

*Re: B&w Cm1*

Thanks buggers .... but like Boomie I also had already looked through most of those designs and didn't see anything that fit my ideals. I had already seen you recommend the proven designs in another thread where you mentioned you were making the NatP's (which I may make sometime down the road). With this design though I am looking for something a little more specific in what I am trying to reproduce. Anyone who has seen and heard the Cm1's will know what I mean by size vs. performance and that is what I want to come as close as I can to (without the $8000 MIT speaker cables they had connected to it though :scared


----------



## rhino2 (Sep 27, 2006)

*Re: B&w Cm1*

Thylantyr I agree that I probably wouldn't be able to duplicate the speakers....however if I could locate a design that would be comparable or be reminiscent of the overall style/design/sound that I was able to witness then I would be reasonably happy. Half of the fun of DIY is exactly that: the process of doing it yourself. Whether you end up spending more money than you originally intended or even end up with a completely unexpected end result the journey is as much a part of the process as the end result. 
You are correct in that if I want exactly what I saw and heard I should just buy the CM1's and I very nearly did. The only problem is I don't need any more speakers around the house and if I purchased a pair I probably would have wanted to get 3 1/2 pairs and replace my current 7.2 setup instead of just the 2 channel in the upstairs. Which of course leads to upgrades in recievers/pre-pro and amplifiers etc. etc. So the path I am trying to take is the somewhat less traumatic for my pocketbook but more fun mentally overall. I was kind of hoping that someone like Boomie who also likes B&W would come along and say oh I know exactly what you mean and the closest thing in they DIY world that I have come across is the (insert speaker title here). Every speaker we listen to has different pros and cons if I can find a design that has more similarities than not I would be sufficiently happy since each speaker we listen to is a series of compromises (although we could just pay for any artist to just come and play directly for an audience of one....) I just want to get as close as possible. Sorry I am rambling now as my run-on sentences give me away.....

I will continue to look for good ideas and designs (that is half the fun). **** I may make a couple trial pairs and still buy a pair or two of the CM1's.


----------



## Geoff St. Germain (Dec 18, 2006)

*Re: B&w Cm1*

I'm with thy here. If you really want the sound of the B&W get the B&W. You can get great sounding results going DIY, but to sound either exactly like or very close to the B&W is either going to require a clone or a lot of experimentation.

There might be something at http://troelsgravesen.dk that would be close.


----------



## BoomieMCT (Dec 11, 2006)

*Re: B&w Cm1*



rhino2 said:


> The only problem is I don't need any more speakers around the house and if I purchased a pair I probably would have wanted to get 3 1/2 pairs and replace my current 7.2 setup instead of just the 2 channel in the upstairs. Which of course leads to upgrades in recievers/pre-pro and amplifiers etc. etc. So the path I am trying to take is the somewhat less traumatic for my pocketbook but more fun mentally overall.


It sounds like you are convinced to go DIY. For a multi-channel setup you will probably save some bucks and have some fun. However Geoff and Thy do bring up good points - you can probably make a very good speaker with CM-1 like traits but it won't likely be *exactly* like the CM-1. Of course there is always the possibility you'll make something you like more. That is one of the advantages of being able to patiently tweak a design.

Managing expectations is crucial for DIY speaker building.


----------



## rhino2 (Sep 27, 2006)

*Re: B&w Cm1*

Geoff thanks for the link. There are a lot of good designs and interesting things to explore on that site I will probably spend a fair bit of time "researching" over there.

Everyone seems determined to try and talk me out of DIY.... I realize I will never duplicate the cm1's exactly and money isn't the issue (I could just go buy them as an extra Christmas present to me) but I want the extra fun of trying to build something of similar quality. I will continue to look for designs that may get me close and if I can't find any existing ones then I will probably give it a go on my own. In order to design a good speaker you need design goals and I figured that aiming for a moderately priced speaker like the cm1's and keeping the build small would be a good starting point. It's not like I am trying to copy the 800 series, a maggie, or the rotary woofer. I don't think the overall goal of obtaining comparable performance in a similar sized cabinet is that unreachable.

Geoff, on a completely different note it is good to see another 'pegger on the board. Winnipeg is my hometown and I hope to get back up there to visit in the near future since my folks are not going to be able to make it down here for the Holidays. Maybe I will wait for spring though......... . Not counting my wife, Winnipeg is where my heart is. 

Later, C.


----------



## BoomieMCT (Dec 11, 2006)

*Re: B&w Cm1*



rhino2 said:


> Everyone seems determined to try and talk me out of DIY.....


No way man! I want you to make something cool and then post the info for others to follow. You go brother! :bigsmile:


----------



## palm (Dec 24, 2009)

My first post here, please be kind as english is not my native language :wave:

I found this thread while googling CM1 crossover.
Does anyone know more about the crossover?
It's surely a first order at high freq but B&W is mentioning a single capacitor on the tweeter, but nothing about an inductor on the mid woofer... could they rely on a natural roll-off and have it directly connected to the amp ?


----------



## evilskillit (Oct 7, 2008)

*Re: B&w Cm1*



rhino2 said:


> So far all of my searches so far have turned up projects like the following: http://www.rjbaudio.com/Microbe/microbe.html. Which I like the style but I don't know how it would compare performance-wise. I know Madisound offers their services (for a fee) to design a speaker crossover for you but I haven't heard positive or negative feedback about the quality of the end result. From looking through their catalogues it seems like a lot of their designs (and catalogue) seem to be dated and somewhat older. But that could just be my incorrect assumption since I am new to this whole speaker design thing.
> 
> C.


I built a pair of Microbes and they are quite awesome. They have been compared favorably to this speaker.

http://www.stereophile.com/budgetcomponents/408tri/

I could bring up a ton of great designs under $500 that would probably work out for you. But instead why don't I just give you this list and let you go to town.

http://techtalk.parts-express.com/showthread.php?t=211558&highlight=speaker+website+list

FWIW I used to like B&W alot, and I think their high end stuff is very nice, but also very pricy. When I first got into hifi I wanted a pair of 601 bookshelves... because I might have been able to afford them some day. However in retrospect I don't care much for the 600 line and would take my Microbes, or the Triangles I linked over anything below the 800 lineup. So as for being able to faithfully recreate your B&W CM speakers, I doubt I can help with something like that. I haven't even heard the ones you're specifically mentioning. But you can DIY some very nice speakers for very little money.

So far including subs and modifying commercial speakers I'm up to something like 6 or 7 diy projects, with no end in sight.


----------

