Wild Burrow Betsys.

[Anton Mullet]

I have just ordered a set of Betsys for Open Baffle mounting. I was wondering if anyone had had any experience with these drivers and what was considered a good size/shape for the baffles.
Wild Burrow have a plan and then there is the tiny rounded baffle that is made by another fella and available on the Decware website.
Any suggestions about which way to go would be appreciated.
I'm only want to run the speakers by themselves, full range, for the moment. Can experiment later on with crossovers and 2/3 way, etc if needs be.

 
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[HdB]

I figure that the small baffle mentioned on the Decware site needs the floor to produce anything like lower mids and bass

 

The official IEC website baffle size for a 6dB rolloff at 100Hz about 56" wide and 68" high - I got the BetsyK rather than the OB version and am in the process of cutting some folded baffles for a 150Hz Crossover that are 1200mm high and the 3 surface widths of the baffle are 18" (460mm - one side) 9" (230mm - centre panel for driver) and 10" (250mm - other side) - the sides fold back at a 45 degree angle altho not critical - so the sizes when added up is 48" high x 37" wide for 150 Hz - if mounted on top of bass box (2 way system) the face of the bass box contributes to the open baffle length

 

I was a bit surprised at that small size and the 'rave' talk, so intended to cut some 12mm ply at 'guess-timated' size to see what happens - not done yet - I estimated something like 18" x 22" from the 8" driver size, I think.

 

When testing, it was thought these drivers were intended as ceiling mounted FR drivers down to about 60 Hz for hotel systems (Rane, etc) and such use - could be quite wrong too.

 

These drivers are a real surprise when checked/measured, and exhibit quite low distortion above 120Hz, and not all that bad below this point either for a freq response that's also rather good too - I added a circular cowl around the magnet (plastic plumber tube) and stiffened the pressed frame (plumbers FerroPrix 2 part glue) and filled the gap between magnet and frame (Caravan putty - similar to the Planet 10 mods) but didn't need to do anything else to the cone/spider/etc - nice driver at a bargain price 

 

 

[Anton Mullet]

Thanks for the info. I have checked out IEC plans. Good to know the drivers measure well.

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[HdB]

I had a good listen to the video about the small baffles and indeed, it does sound quite good considering the laptop speakers but sadly missing the bass - I'm cutting some ply tomorrow and will knock up a couple similar to the ones on the video - about 22" high, about 18" wide and curved to 12" top/bottom edges with a timber 'foot' - it'll be interesting just where this rolls off with sitting on the floor, and on top of my 15" bass boxes.

[Anton Mullet]

Hi JR. 

One thing I'm not getting is how so many people, including yourself, are pairing the FR drivers with an extra woofer for bass.

Does this do damage to the idea of the single point source and wouldn't a big woofer be slower than the very lite FR cone designs.Or are any losses worth it for a a better bottom end.

Sorry If these are silly questions, as I'm very new to all this stuff. 

I was thinking of building both the larger winged baffle and a little deware style one as well. It's a bit of fun and pretty simple to do. I'm just gonna go for a guesstimate with the little Betsy.

Let me know how you go.

BTW, Doug was a pleasure to do business with. He had the Betsy s in the mail on the day I ordered and as far as  I know this is  a labour of love for him and he is a pretty busy guy. Great work.

 

[tesla13BMW]

@Mullet I have been reading extensively on open baffles and came to Wild Burro Betsy as well.  Haven't purchased yet because there is a discount for getting a second pair :-)

 

When you are searching you will come across a person on several forums called Randy.  He is responsible for Caintuck audio and has a number of designs iterations of how he has used the Visaton B200 and the Betsy in OB.  I liked the look of the WMTMW on his website - New Loudspeaker - Part 3.

 

http://caintuckaudio.com/

 

I received this from Randy just last night when asking about his WMTMW speaker.

 

............as I experimented with baffles of different sizes and shapes, I found that the Betsy drivers could be used in a baffle less than 24" tall and would still throw an image that was as high as the ceiling of the listening room would allow ..... a very cool sonic illusion.

 

I also enjoyed the fact that I was looking over the tops of the baffles from my listening seat with nothing to visually and sonically distract me ..... so the "low profile" baffles became my reference.

Of course, an 8" driver will not produce thunderous bass in a small baffle, so the bottom end has to be supplemented.

Using suitable 12" or 15" bass drivers in separate baffles driven by plate amplifiers works very well.

Being able to place the bass drivers in a different location that the main drivers is beneficial because the optimal location for one is not always the best location for the other.

 

If the amplifier used with the Betsy drivers has adequate top end extension, I feel no need to use an additional tweeter.

One can always be added, but it will have to be crossed over at a pretty high frequency because the Betsy drivers are only down a few db at 20K.

 

I look forward to seeing where you go with the Betsy and your thoughts.

[HdB]

Always a problem crossing a bass driver to a mid/FR one - a lot depends on how low a freq that the FR will function in it's baffle - I had a look at the linked websites and in this baffle, on the floor, the Betsy will go down to about 80Hz with approx. 93dB/W which is a pretty amazing performance - the freq response has a bit of a bump up from about 1.5k to about 5k but as this appears to be part of the 'sound', I wouldn't try changing this - on there own when tested in a acoustical test centre, they exhibit a smoother response so playing with the baffle would sort this out if it was a problem -  IMO here mind you. 

 

Crossover - at 80Hz, you could simply use a subwoofer with it's inbuilt filter and amp - the major difficulty lies in trying to get a clean bass signal out of any of them, including the more expensive ones - it can be done but not so easy

On the website, there's mentioned coupling the Betsy up with a 15" driver also on an open baffle and a separate plate amp - this is a fairly well tried and tested approach and the 15" drivers aren't particularly expensive

 

If you were to go the way of passive crossover, rolling off the bass driver will require pretty big chokes so raising the freq response up to maybe 120Hz will make this more manageable - this is known as the FAST arrangement if you want to read up on it - speaker bug has some Jantzen core chokes that work quite well for this 120Hz Xover (and others too) and you could simply add a series capacitor in line with the Betsy to roll them off a bit above their open baffle point of 80Hz - ie, a 12dB/oct rolloff for the bass and a 6dB filter for the Betsy coupled up with the natural 80Hz baffle rolloff would be a reasonable starting point.

 

There are a number of electronic Xovers available that'll be more precise about matching driver efficiencies, etc but I wouldn't do any of this until the Betsy's are up and working in your room - lots of dsp stuff on offer too but suggest you don't rush these either as a lot of easily made errors/traps in their use

 

I'm a 'bit of a nutter' about clean bass and managed to get Lorantz bass drivers (Dandenong) and this has it's own particular requirements that aren't so simple but I think there's a SEAS bass driver that'll do a pretty good job for the lower 2 octaves (30-60-120) and readily available - a caution here in that really good bass drivers cost  quite a bit of $s - not easy to get cheap & good quality bass anywhere plus, below the v100Hz point, room and bass trapping starts to become necessary - also, amplifier characteristics make themselves known 'down low' too ...

 

While you're organising some plywood, suggest you grab some of those course hair floor tiles &/or some cork tiles to stick/pin to the back of the baffle - not very sophisticated or anything but quite effective and easily (& cheap!) to try.

 

Welcome to 'better hifi'!

[Anton Mullet]

Wow thanks to you both. A great amount of info. Im looking forward to their arrival and to start experimenting.

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[Sub Sonic]

Hi @Mullet, just wondering how you went with this project, and what did they sound like?

 

Cheers,

 

SS

[HdB]

It's still on hold for the moment, unfortunately - these little Betsy K drivers exhibit quite low distortion when crossed over high enough and naturally, the Lorantz drivers are also very low distortion drivers too.

 

However, there's phase/timing problem with the 2 different amplifiers that can't be compensated by an electronic Xover so my attention has been diverted to using a dsp Xover and I'm in the middle of this now - even with help, it's slow going, unfortunately.

 

Personally, I think if you can get high quality bass drivers that'll be usable up into maybe 200Hz+, the Betsy's can then be used with a passive Xover, altho good components at this low frequency are still not cheap.  The surprising clarity of the Betsy K drivers without any fatigue is definitely worth persevering with if you listening requirements run that way.

 

I tried them on the small baffle and am a bit puzzled at the reports about this size, even on the floor, producing bass  - to me, this small baffle struggles to produce signals at about 80Hz but maybe the OB version will do a better job.  Mind you, IMO, good clean bass response is the foundation of good sound reproduction (the 'get the bass right first' brigade) but this mayn't be the same for you.

[Sub Sonic]

Thanks @HdB.

 

i definitely like getting the bass right (I have servo subs) so there is definitely a way to relieve the mains of the lower frequencies.

I’d be interested in your progress, just when and as it happens

 

Cheers,

 

SS

[HdB]

Yeah, no problems

 

One thing, if you haven't already 'got started', is the need to control the bass reverb times - basic acoustics - not at all difficult but the 'terms' are a bit unusual - and you don't need to spend huge $s either.  We've got a rather interesting section here on SNA that's full of useful information and another is the 'Gearsluts' site.

[Anton Mullet]

Hi there.

The drivers are still in their boxes. Life has got in the way of this one.

 

[davewantsmoore]

10 hours ago, HdB said:

I tried them on the small baffle and am a bit puzzled at the reports about this size, even on the floor, producing bass  - to me, this small baffle struggles to produce signals at about 80Hz but maybe the OB version will do a better job.

Do they have a filter you need to apply to the driver (eg. a passive network, electronic crossover, or DSP EQ) to correct it's response to be flat?    You would expect no bass on a small baffle or open baffle, before the driver is corrected.

[Anton Mullet]

Hi there.

The drivers are still in their boxes. Life has got in the way of this one.

Thanks for the pointer to the other forums. 

Anthony.

 

[Sub Sonic]

Has anyone had the chance to compare both the Betsy and BetsyK with each other?

 

I'm interested in getting a pair and am wondering which way to go. Unsure if I'll try sealed enclosure (BetsyK) or open baffle (Betsy). I'm currently using a 10" set of full range speakers and the basic sealed arrangement I have them in has good depth of soundstage, extending behind the speakers, and also great imaging, both characteristics I'd like to keep. Bottom end will be augmented with subwoofers.

 

Thanks,

 

SS

[Anton Mullet]

I have got the Betsys up and running on the Caintuch small baffles. I'm also using them on a new McChanson 6as7 amp.

Always bad to intoducce two new components at once but I felt the little 6w, amp didn't like my Adelaide Speakers Summners. It was  struggling to get any decent level without clipping.

The Betsys don't struggle so much, no crossovers and no impedance dips I'm guessing.

The sound stage has gone ballistic. Walls have dissapeared. Transparency. Big tick. Hearing New things in every recording, loves spatial information.

Betsys are faster. Drums especially noticeable.

The BAD.

Lack of Bass, extreme but supporting with a sub.

Some vocals are nassaly.

Seems to be a hole in the midrange.

I think I'll try them in the larger folded baffles as I've been reading about both the issues of Bass and midrange doing better in this design.

I'm also reading that helper woofers could be a good  idea with their own plate amps.

I have had a radical shift from TL speakers with heaps of Bass and I'm a lover of everything coming from a  rock background to this radical different set up, so I guess I'm adjusting to this less bloated and controlled sound.

It certainly shines with Jazz and orchestral music.

 

 

 

 

Edited April 13, 2019 by Mullet

[Anton Mullet]

They do fine on polite rock n roll but as soon as it gets crazy so do  they but Doug from Wild Burro said as much. My idea was to  make a little system for the back room for more polite music so,  so for this they are doing pretty well with the SET amp. Just got to make the new baffle for a fuller midrange.

[b.d]

I've been using the Betsy's for a few months now in 60cm wide OBs with Eminence Beta 15A bellow 100hz or so. I'm quite happy with them, even compared to some much more exotic OBs I've run in the past.

 

But I likely wouldn't use them without the bass driver, nor probably without EQ. I've also added a cheap rear upward-firing super-tweeter with good results.

 

 

[Anton Mullet]

Regarding the Eminence betas, Im thinking of going this way as well. There is no bass from the Betsys and a lot of the upper bass/lower Midrange is just missing. I'm using a sub at the moment but up around that region upper bass/lower mid it still it sounds tinny.

I'm still to put then in a larger baffle and higher off the ground to see if that helps the upper bass/ mid.

As my new amp is only 6-8 watts, I'll have to run the Eminence alpha/betas from a plate amp.

Have you or anyone had experience with this. I was thinking of just bringing the Eminence drivers  up using the plate amps  xover. My little 6w 6as7 amp doesn't want to waste any energy going through a xover.

I have noticed that the Betsys midrange very sensitive to placement and just moving them a little can really change the sound. Very noticeable on voices.

Edited April 17, 2019 by Mullet

[b.d]

Yeah I’d use a plate amp on the bass divers.

 

If you like festive levels with a 6W amp  I’d consider a passive line-level HP xo before the amp?

[HdB]

I'm just about ready to order a pair of the Alnico Betsy's if anyone wants to join - maybe combine postage?  The cost of these will be about A$650 with the gst, I think.  'Normal' Betsy's (and Betsy K's too) are a bit less than A$300, I think.

 

There are a few different reasonable quality electronic Xovers that'll be okay for a 2 way, particularly if looking around the 120 - 150Hz FAST setup - plenty of good bass drivers in both B2 and B4 boxes.  

[Anton Mullet]

The idea of a passive xo brute the amp is something I hadn't thought about. That would really let it sing, relieved of all those before 150 Hz or so  duties. Nice idea. Could it be a light speed attenuator  as well with channel selection.

[HdB]

I tried various types of the passive XOvers but the size of the chokes at this freq produces so many problems that I gave the idea away, even the monster #16 bifilar ( 2 wires in parallel) ones.

 

So, onto the electronic Xovers (with and without ICs), that have much more flexibility but the compromises are just different and produce their own limitations, mainly in the high pass, higher freq area - in the bass, it's not as critical and you don't notice deficiencies as much. Getting the 2 drivers to 'marry-up' is much harder now as the clarity improves (IMO anyway!)

 

If you're using different amps and different type of speakers (like I'm attempting), sometimes the compromises are balanced out but this also limits the arrangement too, so looking for a better alternative and this brings the idea of the dsp into focus and we are now seeing quite a few more designed for the home use rather than just pro-audio.   There are 2 local products too, the Lucy Audio is now available and the Analog Precision is going thru final design, plus quite a few others in hifi stores - a changing world of audio, despite the resurgence of the vinyl TT systems.

 

 I like the sound of the Ayre Acoustic dac and want to see this matched by the dsp units, and because I'm an amateur at these things, the simpler approach appeals more, but a lot of this depends on how you use them in practice - some of them are not at all easy to use unless you're a 'computer person' and it seems to be 'the norm' to misuse them in the attempt to get this supposedly ideal flat freq response and this frustrates the efforts of a 'better sound' and many of us just give the whole idea away and go back to simple analog filters with all their 'warts and all'

 

Anyway, back on topic - IMO, using a separate bass driver (either OB or 'normal' cabinet) offers an excellent simple way of a 'great sound' in the room with less room acoustical difficulties.  The Betsy's are quite robust and produce a rather uncoloured sound above the bass response in an OB.

Curiously, with a reasonably sized baffle and sharp filters, I think it's quite possible to run these drivers down to about the 80Hz area and complete the bass range with high quality subs, but I haven't actually heard this so this is just an opinion based on A/Circle comments.

 

I now use Uriah Daley's "the Clone Note" version of the Lightspeed Vol Control - to me, this is a more transparent sound and has the ability to alter the impedances, but any of the LightSpeed Vol Controls are worth a good listen, IMO.

 

George wasn't at all happy about using an input selector or relays, but if you can get a good switch it's a quite reasonable compromise that I use and no problems so far - I have been chasing a high quality reasonably priced 4 pole 3 position switch for quite awhile now to isolate the ground connections too but they're not common, or cheap.

 

All the best ...

 

 

[Anton Mullet]

Hi.

I have just seen Nelson Pass's crossover which is very reasonably priced if you build it. This may interest you.

https://diyaudiostore.com/products/analog-crossover-network

 

I'm thinking of using my small 6as7 8w amp to run the Betsys and then run another set of speaker cables to a suitable amp to run some Alphas. However as the little tube amp is integrated, I was thinking I could convert the signal to line level with a converter from JayCar, that people have reported works well, and run it into a dayton audio stereo amp that comes with  a variable sub crossover built in.

Would this set up be a bad idea or is it no  different than running speaker cables into a plate amp on the high level inputs.

I'm guessing that that's all a plate amp is doing, i.e. Dropping the hi level signal down so it can use its own amp to  reamplify it.