Cambridge Audio Minx Loudspeaker Discussion Thread - Page 34

They do quote 80 to 20,000 for that driver...without quoting falloff. The price on those drivers is astonishingly inexpensive. Now all we need is a coloration-free cabinetm and all the rest.

Nope, not joking. There's really no way to tell if CA is embellishing those spec's without a driver to test with, but I think it's possible. The FS is 86Hz, so when placed in an enclosure 80Hz is certainly within range. The 81dB sensitivity scares the heck out of me though. Either that's a misprint or this driver will need a receiver with a stout amp section. The sub $7 price makes me wonder just how good it is too. That seems awfully low for any type of quality driver.

For small full range speakers 4" is about the max you can go before beaming starts to become an issue, so my guess is HiWave won't be producing anything bigger then the 3.5" unit Parts Express is selling.

The "formula" regarding BMR design and beaming is referenced in the following excerpt of a review of one of the Naim Ovator models:

"...The central issue with the breed is beaming over ascending frequencies. That starts once reproduced wavelength exceeds driver diameter. With the BMR this equates to roughly 340m/s (speed of sound) divided by 85mm = 4.000Hz. Because here the driver is already in bending-wave mode, beaming is significantly reduced over cone equivalents..."

From:
http://www.6moons.com/audioreviews/naim5/ovator_2.html

A bit beyond my pay grade, but its clear that there is a threshold for BMR diameter size beyond which beaming occurs.

Hi Jim,

Sorry to butt in, I'm new here. Thought you might like to know they do 4.5" drivers, in fact here is a list of drivers Cotswold Sound Systems have (the guys there used to work for and invented BMR while at Hi-Wave, there is some kind of cross licence going on).

http://www.cotswoldsoundsystems.com/index.php

They also worked with CA I believe on the Minx products. Some of the drivers are Neodymium (lighter, thinner, more expensive) than the Ferrite ones as per your 3.5" model link.

Thanks for posting.

I can see that the two 4.5 inch drivers are only a little over 2db down at 80 hz. That's remarkable. BMR drivers interest me more than any other speaker technology, as they seem to fulfill many of the characteristics of an ideal transducer.

Do you know if these drivers will be finding themselves in affordable speaker systems by any manufacturers?

It looks like the company is actually in the Cotswalds...one of the most charming regions I've ever visited.
Edited by taichi4 - 1/4/13 at 9:48am

I do indeed know about the Cotswold drivers; over a year ago I contacted them asking about distributors in the US, to which they replied there was no intention of having any.

On paper they certainly look good, but just because they're being made doesn't necessarily make them good I'm afraid. Just ask anyone who ever bought a Yugo. They could have a bad beaming issue for all I know, or Cotswold may have found a way to minimize the problem (hopefully the latter). Personally I would love to have a set of satellites with a 3" BMR 'tweeter' and then perhaps a 5" version to act as a midrange, but I'm not counting on it. I'm not even holding out any hope that CA is going to up their game and come out with a larger BMR at this point.

Here a new minx owner, I have the following: 4x min 11, 1x min 21 and a x300. All running through a Onkyo tx-nr809.

I used to have a JBL Northridge 5.1 set (E80, E20, EC250, E150p) plus two horrible noname surround backs, but since my wife never really liked the size of the set, so I thought these little minx'es would sheer her up
So I first switched the E80 by min11's just to check out if they would be capable enough, and after a good setup (audyssey XT) it already sounded acceptable. After selling the old JBL lot I bought the additional 11's, 21 and x300. My wife is really happy with the extra space we have in the living room (which is about 4 x 5,5 meter).
After a good setup and playing with the settings I was very happy with the sound.

But since last Thursday I have a problem with the subwoofer level; when the system was turned on to watch some television, the sub was way too loud, when the volume was turned down a few notches it was OK again. But the next time the system was enabled the boominess was back and the volume had to be set all the way down (another 3-4 clicks) to be somewhat OK, but still too boomy. Then I changed the subwoofer volume in the receiver from +5 dB to -10 dB and turned the sub volume up to a good blend. But the next time is was still boomy. After a hard power off of all the system levels were OK again an I restored the previous settings. but after standby/resume the sub was kickin' ass too loud again...

I'm not quite sure were the problem lies, but I suspect the Onkyo/Audyssey, since the sub should just amplify the incoming signal and not do anything else (or does it have some extra DSP functions?)..

My first guess would be the sub amp actually. The vast majority of the signal processing is happening there, not in your receiver, so odds are the X300 is acting up. One thing to try is a new cable - although not terribly likely there is a chance a flaky cable could cause intermittent issues.

Good troubleshooting, Sub Dude.

Boston Acoustics apparently has incorporated BMRs in their new surround and center speakers.
The surround speaker looks similar to the Min 21 in the combination of a 2.5 inch BMR coupled with a small woofer, that apparently reaches down to 95 hz...lower than the Min21.

They seem a bit pricier than the CAs, but I welcome the spreading of BMR technology.

http://www.bostonacoustics.com/US/Search/Pages/ProductSearchResult.aspx?k=BMR

That's certainly encouraging, that someone else finally recognizes the value of BMR's. Seems to be a good news, bad news situation though...

As you say they're very expensive, especially considering Parts Express is selling that driver -- or something very similar -- for about $7. BA also seems to have mis-matched them; the center is bass reflex and uses 4.5" woofers, while the surround is acoustic suspension and has a 3.5" woofer. That strikes me as speakers that will have a different sound signature, as well as a vastly different crossover.

Yes, the crossover looks quite different.

I agree that the thing looks expensive...based on the particular 4.5" driver on the parts sight.
But I have no idea if all these drivers are the same, and there is the cost of implementation, the surrounds and cabinet used, etc.

I can't imagine Boston Acoustics releasing a BMR speaker with a bad sound, though.

I see it as good news because people are recognizing the benefits of BMRs, which we agree are lessening of crossover use, wide dispersion, and great coherence. It's the dispersion pattern, the coherence, and probably the effective near masslessness of the ripple action "tweeter" (enhancing transient response) that gives the BMR its great transparency. Some compare the openness of BMRs to electrostatic or planar drivers, probably because of the low mass transients,

And I'm still curious about the wireless Minx Air 200. How difficult would it be to make a wireless 5.1 Minx system?
That would be cool.
Edited by taichi4 - 1/7/13 at 8:07pm

Do you mean an array of small BMRs?

Even though we discussed this concept earlier, I'm wondering if you would potentially get cancellation effects with such an arrangement.

Maybe I'm all wrong about this, but it seems to me that the drivers in typical vertical arrays do not have the broad dispersion pattern that BMRs have, so they are unlikely to cause so many complex interference patterns. It would seem to me that an array of BMRs would result in some reinforcement and some cancellation.

If I'm not mistaken the various Naim Ovators use a single, isolated BMR in vertical array with non BMR
drivers for the lower frequencies. You would think that if an array with multiple BMRs was possible they would have tried it to eliminate all crossovers.

Since I don't design and test speakers, this is all conjecture on my part.

I thought I'd preface the rest of my reply with a bit of background information. I don't own the Cambridge Audio Minx speakers, and I wouldn't say I'm a high end audiophile or have any great technical speaker knowledge. I am a (very) long term shareholder of Hi-Wave and as such I seem to have amassed a lot of information of their products through research so might be of interest to you, well I would say so from some of the recent posts.

I haven't heard the 3.5" ferrite versions, and do believe they are very cheap (I just wish they were as cheap from our suppliers on this side of the pond!). I know that Parts Express stocked the 4.5" neo speakers for a brief spell, not sure why they took them down, but they sold for around $60 - the price you pay for lightweight and high earth metal costs.

With regard to larger speakers, and value of BMR, one of the first to market with BMR was these LR Braggs Acoustic Reference speakers, and of interest to you as they are 8" BMR speakers.

http://www.lrbaggs.com/amp/index.htm#overview

They received rave reviews iirc, although I've not seen any 8" BMR speakers since.

You'd be surprised to how many BMR implementations there are out there. You've picked up on the NAIM high end, but also for kudos they are in the new Bentley Continental (http://www.bentleymotors.com/models/new_continental_gt_speed_convertible/technology/).

Down at the lower and smaller end, you can get USB implementations (Soundscience QSB), wireless (QB Mito and AQ Audio) and Revo (a Scottish DAB radio manufacturer) use BMR in most of their range.

If you're interested in the DIY angle, and I note someone mentioned using BMR in a Line Array, there are a few people trying these out - for example:

http://www.diyaudio.com/forums/full-range/191853-near-full-range-bmr-balanced-mode-radiator-3.html - see post #23, Derek is putting together a line array using the 4.5" versions
http://billfitzmaurice.info/forum/viewtopic.php?f=5&t=18759&sid=3abdddb00abc68553ffec75924cb3445 - A guy making a line array using the 3.5" Parts Express product

I've recently found this Kickstarter project that might interest you, and contains some nice technical details. Geoff Boyd is an ex-employee of Hi-Wave.
http://www.kickstarter.com/projects/320792163/the-coleridge-design-acube-bmr-speaker-system

Me...well I'm tinkering with some of them, just out of interest more than anything. I've got a few ideas I'd like to make myself, nothing commercial really.

Hope that helps, sorry if there is too much there but as I said, it sounds like you guys are interested in the driver despite being off topic on the original Minx.
Edited by Vaugi - 1/9/13 at 2:43am

Thanks for posting, Vaugi. I read about the use of BMRs in Bentleys just recently, and also saw that elsewhere the real world price of the 3.5 seemed to be about $60.

I wish more speaker manufacturers used them, as the BMR solves so many acoustical problems. I also hope that CA will continue to evolve with respect to BMRs.

Where do you hail from?

Vaugi;

Thanks for posting that. I know CA is the main player in the BMR world, but it's nice to know others are involved as well.


According to Martin Roberts of HiWave they "released a small number of ‘pre-production’ 85C20 BMR drivers", so perhaps those are the 4.5" units you're referring to?


A guitar amp?? That one I didn't know about.


Bentley, the Rhythm King speaker and those smaller versions I was aware of already. I maintain a thread that contains tiny full range speakers, and most of those are listed there.

I didn't know about the Kickstarter project though, or that Fitzmaurice was building something with BMR's. He usually focuses on larger projects, so it's surprising he started something like that. I'll have to read both of those articles.


I'd be curious to see what you're working on as well. The more interest generated in BMR's the better!

I can't find a Cambridge S series thread so I hope you don't mind me asking here.

What's up with the colours for the S30? I'm seeing 4. Black outter with silver front and silver driver, wood outter with silver front and silver driver, wood outter with silver front and black driver, and black outter with black front with black driver.

I'm looking for the blackblackblack version. All websites only list 2 colours to choose from, so I'm guessing 2 are discontinued?

Here you go, regarding the S30 thread:

http://www.avsforum.com/t/1327952/almost-got-floored-by-cambridge-s30/300

Great speakers...but I'm a BMR man.

Guys - the Cambridge Audio Minx Air site has been updated, lots of lovely info and pictures of the BMR speakers in situ. Interesting that the 100 has two BMRs for full range and the larger 200 has smaller BMRs for highs and a woofer.

http://www.cambridgeaudio.com/products/minx-air-100

I'm originally from the North West of England, just north of Manchester, but now reside over the hills in the North East near Durham...bit more rugged than the lovely cotswolds :-)

The original small BMR cinema cubes were the Mission m-cubes, although not sure if they are still sold? Your thread contains some good information, I remember looking at it a few months back I think. The 4.5" could have been a pre-production sample, but not sure why Parts Express would sell them, maybe that's why they were taken down though.

I have to admit, I'm not 100% clear on the distinction between what Hi-wave sell and what CSS sell, whether they somehow have a cross-licence that means they must each sell mutually exclusive product ranges, or whether CSS spend more time and effort make the speakers better to sell to higher end audio companies, while Hi-wave pursue more mass market appeal. I might make my way down to the AGM in February and ask the question.

The link was just to a guy using (or not?) Bill Fitzmaurice's plans but substituting the BMRs, not Bill himself. I think his conclusion near the end was that if he did it again he'd still add tweeters. I'm actually quite interested in Bill's SLA's and the use of BMRs, so I might have to purchase his plans.

As I say, I'm a tinkerer but not really expert in speaker tech so rely on a bit of plug and play of off the shelf components. I've actually got 4 of the 4.5" BMRs, I think I might try to build something like those aCube's off Kickstarter.

This is an interesting product too, thought I might see if could do something similar - http://www.frankenspiel.com/panettone.html

I'm also interested in making a small wireless Squeezebox type radio, for which I thought I might get a couple 3.5" BMRs - I've got the squeezebox radio bit working, via a Raspberry Pi and can be controlled through a smartphone, but just need to work on the speakers/case really. Thinking maybe something in very high gloss red for something striking!

I'm in the US, and when I try that link all it says is "Unfortunately the page you are trying to visit is not available in this territory".


Understood. It didn't sound like something Bill would be into.


Dual BMR's in a plastic box -- with a handle no less -- that's designed to look like the container from a loaf of Christmas bread?!? Some things you just can't make up...

Hello,

Ive currently got 5 Min 11 Speakers and a X200 sub and i like them but im changing the colours of my walls and wanted to get some white speakers to match, Ill keep my X200 sub but was looking at getting the Min21.

I was just wondering would i notice much of an upgrade as they almost look identical on paper from what i was reading, What is the actual differences between 21 and 11 ?

Thanks