Wild Burro open baffles

[bjlefebvre]

Anyone have experience making OBs with Wild Burro drivers? Now that I'm nearly done building a flea watt amp for my secondary office system, I'm looking for some new speakers, preferably bookshelf-sized. I saw some examples of folks using Wild Burro drivers with open baffles - I think 18" x 18" was one size I saw that looked like something that would fit my space. Noodling around with baffle design now, but was wondering if anyone had advice - this would be my first OB project.

 

[mkane]

They need room to breathe.

 

[maxhifi]

Have a look at this chart, the effective baffle length is the path from one side of the speaker cone to the other, which is conveniently aproximately the same as the diameter of the baffle.

Below the cutoff frequency, bass rolls off at 6dB/octave, so. If you start with 160Hz, you're - 6dB at 80Hz, - 12dB at 40Hz.

Unfortunately there's no cheating physics, open baffles must necessarily be large if they are to make any useful amount of bass. The exception to this being equalized speakers, but those need huge power. This chart is based on the wavelength of sound in air, which applies to all speakers. Speakers with a high Q can offset some of the bass loss, but the main factor is size of the baffle.

 

[maxhifi]

Note to above: for a first foray into open baffles, I strongly suggest the JE Labs open baffle. I built a set out of raw particle board for testing speakers, and with old Goodmans drivers they sounded absolutely fantastic.

 

[bjlefebvre]

Thanks for that. Another question on kind of a side pathj - any designs out there for OB using 4" drivers?

 

[maxhifi]

Thanks for that. Another question on kind of a side pathj - any designs out there for OB using 4" drivers?

The size of the baffle is totally unrelated to the size of the drivers, it's all about the wavelength of sound (remember first year physics?)

The best compact enclosure for a low powered amp I've heard, is a rear loaded horn, the narrow floor standing type. Those aren't super efficient, but are not a demanding load, and tend to mate well with flea power amps. They also have a narrow profile and fit in a room easier than open baffles or the like.

 

[bjlefebvre]

Thanks for that rear-loading horns tip. I'll look into that.

remember first year physics?)

Nope. I'm an English major.

 

[maxhifi]

Nope. I'm an English major.

Have a look here for a bit of info about open baffles and how they work. This article is quite non technical but explains the topic well

http://www.hi-fiworld.co.uk/loudspe...udspeakers-open-baffles-and-bass-part-15.html

 

[audiosignal]

Have a look at this chart, the effective baffle length is the path from one side of the speaker cone to the other, which is conveniently aproximately the same as the diameter of the baffle.

Below the cutoff frequency, bass rolls off at 6dB/octave, so. If you start with 160Hz, you're - 6dB at 80Hz, - 12dB at 40Hz.

Unfortunately there's no cheating physics, open baffles must necessarily be large if they are to make any useful amount of bass. The exception to this being equalized speakers, but those need huge power. This chart is based on the wavelength of sound in air, which applies to all speakers. Speakers with a high Q can offset some of the bass loss, but the main factor is size of the baffle.

View attachment 1303960

Does anybody knows if this chart applies to closed baffled / boxed speakers as well for low frequency response, i.e., even better bass with the wider baffle?

 

[maxhifi]

Does anybody knows if this chart applies to closed baffled / boxed speakers as well for low frequency response, i.e., even better bass with the wider baffle?

No, it does not. The chart is relevant only to open baffle, because with open baffle speakers, the rear wave cancels the front wave under the frequency shown in the chart. With closed speakers, the rear wave cannot get back to the front. Because it is blocked by the cabinet. The cabinet however will have its own resonant frequency, which is one of the reasons open baffle speakers are considered less coloured sounding.

 

[bjlefebvre]

Ok, had an email exchange with Doug at Wild Burro. He said these would work in a 1-cubic-foot sealed enclosure. That sounds do-able.

 

[opnly bafld]

Ok, had an email exchange with Doug at Wild Burro. He said these would work in a 1-cubic-foot sealed enclosure. That sounds do-able.

Betsy-K

 

[bjlefebvre]

Betsy-K

Yup.

 

[Poultrygeist]

I built the Betsy's around eight years ago as my first venture into open baffles. Powered them with a APPJ/Miniwatt tube amp of 2.5 watts. They are high Qts drivers so they produce some bass and maybe enough for some folks. I liked a little more which led to adding 15" woofers on a much smaller flat baffle.

 

[Poultrygeist]

To get more bass I made some new baffles for the Betsy and added Eminence Alpha 15A woofers. Baffle size becomes less important when augmenting the bass with a high Qts woofer. I bi-amped these using a SS amp on the woofers and a tube amp driving the Betsy which continued to run full range.

 

[Poultrygeist]

Another option using much smaller baffles for the Betsy. Easy DIY.

http://v2.stereotimes.com/post/caintuck-audio-betsy-openbaffle-loudspeakers

 

[bjlefebvre]

I saw those and seriously considered doing a DIY version. The fronts would technically fit size-wise. But after some mulling, I think they would be so crowded in the corner that it might almost be besides the point of going baffle-less Also, the WAF of them crowded into the corner would be low, and it's a shared work space for us. If I had seen these earlier in the year I might have tried them instead of the Zu DWs I have in my main listening space.

After some noodling, I'm going to shoot for the Betsy Ks in a sealed ~1cf Baltic Birchwood box. Right now thinking if I want to add a helper tweeter or not, but I'm drawing out the box dimensions in the ol' notepad and will be ordering the BKs shortly.

 

[bjlefebvre]

Also, was glad that review mentioned the Decware triode amp. My plan is to pair the Betsy Ks with a Decware ZKIT build I'm almost done with. The amp is basically a homebrew version of the same amp. Again, the set up is meant for a work space so it's not like it'll have to be a be-all, end-all set up. Right now I've got a SAnsui receiver and NHT Superones in there, just trying to see how a DIY set up would compare (though the Sansui / NHT combo is certainly nice to listen to).

 

[Poultrygeist]

I saw those and seriously considered doing a DIY version. The fronts would technically fit size-wise. But after some mulling, I think they would be so crowded in the corner that it might almost be besides the point of going baffle-less Also, the WAF of them crowded into the corner would be low, and it's a shared work space for us. If I had seen these earlier in the year I might have tried them instead of the Zu DWs I have in my main listening space.

After some noodling, I'm going to shoot for the Betsy Ks in a sealed ~1cf Baltic Birchwood box. Right now thinking if I want to add a helper tweeter or not, but I'm drawing out the box dimensions in the ol' notepad and will be ordering the BKs shortly.

The Betsy K specs call for a seriously large enclosure. The seller uses his in a BIB.

 

[bjlefebvre]

From the site:
"BetsyK was designed for resonant enclosures. Given her high compliance, the best options are big. My pair lives in a pair of 6'6", 13.25x20" BIB cabinets. They should also work well in Metronome's or BVR's. The easiest option is a one or two cu. ft. sealed box."

EDIT: Actually, Doug at WB says the regular Betsys work better in the box. Ok, so that's straightened out. Now just need to figure out if I want a tweeter, and which one....