[YashN]

I want to build my first Open-Baffle speakers and this is quite exciting as I now listen to my DIY Single-Ended Triode Tube Amp which brings a lot of satisfaction (based on the Tubelab SSE PCB!).

Currently, I am using Totem Mites, which are not as efficient as I would like, hence the new build. I have been reading about Open Baffle designs and so far I have a few questions which must be those of a total newbie (which Open Baffle-wise, I am!):

Are there advantages of having a single baffle with the 3 drivers as opposed to say 1 baffle for full-range + tweeter and another one for the woofer?

I have even seen a commercial open-baffle use three small baffles in a plane for each driver. What are the pros and cons of doing it this way as opposed to one continuous baffle surface or two?

The SET amp will tackle the mid-range as well as the highs for now and a SS amp the woofer/bass/sub, but since the SET amp is low power (sounds fantastic though!) and I would need to look for high-efficiency drivers does it always follow that I would need two woofers?

Thirdly, let's suppose I make the Full-range to Woofer cross-over at 250Hz to simplify, could I consider building a single Sub-woofer box with two drivers? In that case, would that affect stereo imaging at all at these low frequencies?

And finally for now (but do expect some more questions as go along ), how does one size and shape the baffles? Are there systematic calculations starting from driver parameters or characteristics that are used to derive the best size and shape for each baffle?

[G Georgopoulos]

for low end efficiency make the baffle big
mid and high drivers are out of the equation
choose a woofer with qts =>1.0 for greater low end response
system response q will fall to low levels with greater low end response

all the best

cheers...

[FullRangeMan]

Use 1 Alpha15A not two, less is more.
Xover is just 1 air core inductor 4.7mH cut is 280/290Hz 6dB/8ª.
A 15'' woffer wont need EQ or DSP; use one single baffle to help form soundstage, woofer near the floor.

Dont use tweeters favor two-way Woffer+FR.
Stay away form subs they flatulent, one Alpha15A will do the job very musical.
This is a tested successfully project from a AC member:
http://www.audiocircle.com/index.php?topic=108662.0

[gils]

 

Hello ,

Yes , QTS speaker > 1.0 12" / 15" / 18" for bass system and  > 0.6 for medium  < 10"
My system have 2 ERS TS 30-150/300 (QTS 1.04 mesured) + compression with pavillon 19"/ 8"  , system at 98 db   

good works  35 Hz at 20 kHz // crossover  800 Hz more 6dB attenuation of the compression makes the original 105 db

just a 10 Watt amplifier makes you deaf !!

http://www.audiocircle.com/index.php?topic=121548.msg1520916#msg1520916

 

[matevana]

Multiple baffles allow for the alignment of each drivers acoustic center. Based on placement, you can alter the arrival of each drivers output at the listening position. Typically bass drivers, with their slower moving forward wave, are placed a few inches closer to the listening position which will affect both arrival time and relative phase. Multiple baffles give you the ability to adjust this physically, w/o any further degradation to the signal path such as with ASPs/DSPs. Additionally bass drivers will benefit from H, W, or U frame folded enclosures while shorter wavelength producing drivers enjoy narrow baffles with short or non existent sidewalls. Lastly, isolating the bass driver in a separate enclosure with the use of a bridge system (Linkwitz LX 521 style) will result in less of the woofer's vibration traveling up to the critical midrange driver.

[YashN]

for low end efficiency make the baffle big
mid and high drivers are out of the equation
choose a woofer with qts =>1.0 for greater low end response
system response q will fall to low levels with greater low end response

Hi G, thanks for the guildelines as this can be very helpful, so with OB, we can't really get good low end unless we do use large baffles and woofer Qts >= 1.

Not sure what you mean by "mid and high drivers are out of the equation", but to simplify my implementation, as I'd rather build something rather than explore all possible alternative implementations, I'll start with the mid-range SQ and driver as fundamental quality, especially because of the SET Tube Amp

Therefore, I would need a good, high-efficiency wide-range driver and use its best ability for the mid reproduction first and foremost, and then choose the woofer and the tweeter accordingly. If I'm not mistaken, I need to strive and get the woofer and tweeter to be as near in efficiency as possible, correct?

For the tweeter, I want to go with a Ribbon or AMT Tweeter. As it's going to be my first OB build, I'd want a pair of affordable Tweeters with good specs, but something way out of budget like the RAAL or HEIL AMTs. Affordable Chinese ones can do, provided they have good extension and attacks.

[YashN]

Use 1 Alpha15A not two, less is more.

Thanks for all the recommendations, FullRangeMan, I like this build: simple and clean, looks easy to DIY. It looks like his build has some little curved wings on each side, doesn't it?

I see a lot of people tried the Alpha, but I see some new recommendations about the Beta, supposedly better.

Xover is just 1 air core inductor 4.7mH cut is 280/290Hz 6dB/8ª.
A 15'' woffer wont need EQ or DSP; use one single baffle to help form soundstage, woofer near the floor.

I like the idea of a simple cross-over implementation, but I think in mine, I'll use the simple passive XO between the Full-Range and the Tweeter (both dealt with by the SET Tube amp) and the main, more complex crossover will be an active one done on the computer and crossing between the Woofer and the Full-Ranger/Wide-Ranger.

Dont use tweeters favor two-way Woffer+FR.

Thanks, I'll keep that in mind as an implementation alternative, and in fact, if I already have all three drivers for one channel, it will be easy to test with tweeter and without.

Stay away form subs they flatulent, one Alpha15A will do the job very musical.

Yes, subs when done incorrectly can do that for sure. I think the implementation with just woofers is OK, but here as well, there may need some compensation EQ or mechanical build-wise, see below for some ideas I've found interesting to try.

[YashN]

Yes , QTS speaker > 1.0 12" / 15" / 18" for bass system and  > 0.6 for medium  < 10"
My system have 2 ERS TS 30-150/300 (QTS 1.04 mesured) + compression with pavillon 19"/ 8"  , system at 98 db

Thanks for those specs, gils, very cool efficiency here!

So, the two ERS provide greater efficiency in your build?

good works  35 Hz

That's a pretty good low-end extension!

[YashN]

woofer near the floor.

In OB builds, generally, is the location of the woofer driver near the floor making as if the baffle extends with the floor?

[YashN]

Multiple baffles allow for the alignment of each drivers acoustic center. Based on placement, you can alter the arrival of each drivers output at the listening position.

Multiple baffles give you the ability to adjust this physically, w/o any further degradation to the signal path such as with ASPs/DSPs.

Very good points, matevana, thanks a lot.

Additionally bass drivers will benefit from H, W, or U frame folded enclosures while shorter wavelength producing drivers enjoy narrow baffles with short or non existent sidewalls.

I am wondering about the sizing and shaping of the baffles for the full-ranger and tweeter.

The H, W or U frames help with the speaker parameters for the bass drivers, extension, efficiency?

Lastly, isolating the bass driver in a separate enclosure with the use of a bridge system (Linkwitz LX 521 style) will result in less of the woofer's vibration traveling up to the critical midrange driver.

Yes, that's the kind of thing I would like to avoid and the kind of info I was looking for as it will help orient the design and the build! Many thanks for that. Now, as I understand it, for a single baffle containing everything, some people then use two drivers so that one's force cancels the other's, thereby minimising the detrimental effects, correct?

Here is a design I thought was quite interesting, the K-aperture, Z frame. Thing is, when you start with that frame and the increased SPL, then you also see some resonance, then you start working on braces to tame the resonance, and pretty soon, you're adding colourations and further trying to tame those, just as if you were working on boxes, so perhaps there's a way of doing that simpler.

This design was based on a Nelson Pass slot-loaded open-baffle design as well as a Karlson build, so I am wondering why one couldn't use two face-to-face drivers firing into a K-aperture.

[FullRangeMan]

In OB builds, generally, is the location of the woofer driver near the floor making as if the baffle extends with the floor?

Yes.
This photos are the most elegant Alpha implementation I have see here AC, I would put the Alpha a bit more lower to the floor than this image.

[gils]

Thanks for those specs, gils, very cool efficiency here!

So, the two ERS provide greater efficiency in your build?

That's a pretty good low-end extension!

hello ,

http://www.toutlehautparleur.com/haut-parleur-speaker/europsonic-ts30-300-8.html

[YashN]

Yes.
This photos are the most elegant Alpha implementation I have see here AC, I would put the Alpha a bit more lower to the floor than this image.

If the floor is to be a virtual extension of the baffle, how does putting isolation beneath the speaker affect the overall results? Let's say it leaves a 2" gap from the speaker bottom to the floor, does that make for a big decrease in SQ?

[YashN]

http://www.toutlehautparleur.com/haut-parleur-speaker/europsonic-ts30-300-8.html

Hi gils, I checked them out yesterday.

I was wondering if using two on the same baffle provided the heightened efficiency in your build.

I now also wonder how much more they would provide face-to-face and slot-loaded!

[gils]

 

Hello YashN ,

TS-30/300 provide much bass without having to go through low-end subterfuges which harmed the quality of the system to reproduce the bass register, filtering is minimum. Filtering is often reserved for poor speaker used wrongly in this particular system that is open baffle that significantly reduce the quality and rendering speaker.

If you leave on good speaker from the start, you will not be disappointed.

review the minutes of the bass? the camcorder is limited in acute (10 Khz) but played well enough bass.

http://www.sendbox.fr/1110834591f75e5b/bass_guitar_open_baffle.mp4

https://youtu.be/YFwrjBhg0nk

ps:

on JBL 4311B , no filter with bass 2213H

[FullRangeMan]

If the floor is to be a virtual extension of the baffle, how does putting isolation beneath the speaker affect the overall results? Let's say it leaves a 2" gap from the speaker bottom to the floor, does that make for a big decrease in SQ?

With full contact at the baffle/floor there is a bass increase, if you put spikes the bass will be smaller.
But in OB any bit of bass is important.

[YashN]

TS-30/300 provide much bass without having to go through low-end subterfuges which harmed the quality of the system to reproduce the bass register, filtering is minimum.

If you leave on good speaker from the start, you will not be disappointed.

review the minutes of the bass? the camcorder is limited in acute (10 Khz) but played well enough bass.

Salut gils,

Sounds good in the bass department for sure, especially the rapidity of restitution.

I was using AULab for my crossover until Soundflower started bugging on Mavericks.

[YashN]

With full contact at the baffle/floor there is a bass increase, if you put spikes the bass will be smaller.
But in OB any bit of bass is important.

I am definitely not using spikes: they couple to the floor while I want to do seismic isolation a la Townshend.

Thinking about the theory of operation of the open-baffle, we 'open the box' so to speak because then the room is the 'box' if at all there's one. Then, based on the dipole shape of the audio waves, we are recommended to have a high baffle so that the back reflection on the ceiling doesn't affect the response  - the sides have less of that.

So we are using the floor as an extension because the rear cannot reflect underneath the baffle then. But, if the floor touches the baffle, we get the driver inducing vibrations in the floor (that we'd like to avoid, right?), and additionally the seismic detrimental effects into the baffle and driver.

However, if I use a ball-and-cup arrangement to isolate the base, then that could leave a gap below the baffle, so I designed (in my head for now), a slightly raised base so that the baffle does extend very near the floor without touching it. This is because if the baffle does touch the floor, then I'll be re-injecting the seismic effects into the drivers and baffle which I want to avoid.

I do wonder though what to do with that gap even if it's tiny, or in fact because it is tiny, as in whether to add something like rubber or not in it.

[mcgsxr]

From the cheap n cheerful files I would recommend the use of a pool noodle to "fill the gap".

I would think that vibration transfer through that material would be pretty minimal. 

So too would a 1/4 inch gap I would think too.

[rajacat]

Here's some unique OB 3 ways that scored a detailed 6 Moons review. Could be a source of design ideas.


http://www.6moons.com/audioreviews2/kyron/1.html