Building some speakers - Anyone done it?

[C2Red]

Crackie said:

A 21st century Huey and Dewey bought to life.

Edited by C2Red on Thursday 4th February 16:56

[Crackie]

C2Red said:

Crackie said:

A 21st century Huey and Dewey bought to life.

I think everyone has a soft spot for Silent Running.

[Crackie]

Pair matching between the two units is very good. The polar response (combination of on and off axis) behaviour results in a very even overall power response. The slightly longer 65mm port results is slightly deeper bass but at a quieter level.... a port 775-80mm long of would be a good option if the speaker is going to be used close to a rear wall. The peak in the measurement seen at 5khz on axis and off 15 & 30 degrees off axis is largely counteracted, subjectively, by the larger response dip seen at 45 degrees off axis. A link to SEAS' spec sheet for the raw driver is here http://www.seas.no/index.php?option=com_content&am...restige-midranges&Itemid=463 . I've added a pic of SEAS response curve to compare to the measurement on the 'JETS'. The raw driver has raised output in the region between 1 and 2Khz. The peak in the polar response at 5Khz and the broad dip centred on 6.5Khz are both there too. I'm pleased with the measured responses, they match the factory results pretty closely. One are where there is a fairly large difference is that the factory measurement tails off quickly above 10Khz on the off axis measurements but I found that there was still good energy off axis. This was a welcome surprise and helps to explain the subjective performance.

I'm getting familiar with the sound and I think they have improved during the past few days........the speakers do that trick that all good speakers do; they sound good when used conventionally but they also sound convincing when you hear them from outside the room. Piano, acoustic guitar, male and female vocal and acoustic instruments in general are all excellent. Bass heavy content and electronic dance is a struggle for them at higher playback levels.

Jeff Goldblum's excellent Capitol Studios Sessions jazz album sounded really special earlier today. The speakers do have a relatively limited maximum volume level and also relatively limited bass, however, used within their comfort zone, they are good...........very good.

Blue curve below is sample 1 on axis, green curve is 15 degrees off axis, red curve is the shorter 55mm port option. The high frequencies rise, on axis.....but as anticipated, the high frequency response is closer to flat when slightly off axis.


Factory measurement under anechoic conditions. The curves show response on axis, 30 degrees off and 60 degrees off. I didn't make any 60 degree off axis measurements.



The blue line below is sample 1 on axis, green is 30 degrees off axis, red is the 55mm port option. High frequency extension still holds up well even 30 degrees away from the centre line.



Blue below is sample 1 on axis, green is 45 degrees off axis, red is the 55mm port option. Still a reasonably extended high frequency response for a full range driver measured at 45 degrees off axis.



Blue is the second sample on axis, red is a smoothed response 15 degrees off axis, green is the slightly longer 65mm port option.

Edited by Crackie on Wednesday 3rd March 20:42

[Crackie]

This product may be of interest to anyone interested in building their own speakers.



249 Euro for this unit would be great value for just the 3 way digital crossover facilities...........the fact that is also be used a 4 input integrated amp with 2 digital and 2 pairs of analogue inputs or a DSP crossover / pre-amp to control an active system is incredible for the money. The only similar product I can think of is the MiniDSP 4x10 digital crossover / pre amp; it is approx. £600.00.........and the MiniDSP hasn't got any power amp stages.

Reckhorn have been around for years; I first noticed them about 10 years ago when looking at analogue subwoofer crossovers. I hadn't seen their digital units until recently though.

https://reckhorn.com/en/active-x-over/139/dsp-6-di...

Here is a review of the DSP-6 unit when the price was 349 Euros.
http://www.tnt-audio.com/sorgenti/reckhorn_dsp6_e....

Edited by Crackie on Saturday 12th June 06:02

[Crackie]

fiju said:

Could we have a a sub or something to fill the low end as your next project?

Hi Fiju, I finally got round to building a sub to complement the 'Bowl' speakers. Known to some as a SLOB ( Slot Loaded Open Baffle ) or a RIPOLE, the design uses a pair of drivers mounted face to face. The benefits of this loading method is that the drivers' mechanical forces cancel out and the air mass trapped between their cones lowers their resonance frequency. This is likely to result in them playing deeper bass, for a given cabinet size, than any other form of bass loading. Anyone who has heard well engineered open baffle bass knows just how much damage is done to low frequencies by sealed and ported bass loading. The Bowl speakers are exceptionally open and uncoloured with an almost electrostatic sound quality; a conventional ported or sealed sub woofer would just not be able to keep up............an open baffle type design might though

Another potential advantage of the open baffle family of designs is their dispersion pattern. Front and rear output cancels at the sides of the cabinet and consequently they do not excite the room modes and resonances the same way a conventional 'Omni' subwoofer does. Deep deep uncompressed bass at the listening postion ( and directly behind the cabinet too ) but almost nothing to the sides. A great solution if you love bass but can't indulge because of neighbouring flats, adjacent rooms, sleeping children etc etc.

Parts cost is approx £190 all in. It uses a pair of Peerless 830668 10" drivers https://www.falconacoustics.co.uk/drive-units-1/pe... . The cabinet is constructed from 4 x IKEA chopping boards costing £12 each https://www.ikea.com/gb/en/p/skogsta-chopping-boar...

If any PHers are interested in knowing more, I'll post some more details & measurements.

Edited by Crackie on Saturday 12th June 06:08

[TonyRPH]

Hi Crackie,

Is this sub tuned by the various apertures then?

Is it a bit like isobarik loading, but without the cabinet (as so to speak)?

[Crackie]

TonyRPH said:

Hi Crackie,

Is this sub tuned by the various apertures then?

Is it a bit like isobarik loading, but without the cabinet (as so to speak)?

Hi Tony, I see where you're coming from regarding the isobaric link i.e. the internal driver is used to approximate free air conditions for the 'external' unit. The internal driver always 'sees' an air compliance though and consequently the system has a resonance higher than the driver's free air figure. With the SLOB / Ripole loading the system resonance is significantly lower than the free air ( Thiele-Small ) result.

The SLOB/Ripole design is still closely related to a conventional open baffle; the cabinet folds / returns are used to increase the front to rear path length. Each driver has an individual opening to the rear and a single opening combines their front output.

The drivers I used have a free air resonance of 33Hz.............I haven't measured them in the cabinet yet when mounted face to face I'm expecting the resonance to go down into the mid 20's.

Conventional subwoofer drivers aren't ideal for open baffles, you need a driver with a relatively high QTS of approx 0.5 or above. The figure for the Peerless 10" units is 0.59............I already had a pair left over from a different project.

Here is some additional information about slot loaded open baffles and also a comprehensive build guide for a ripole.

http://enjoythemusic.com/diy/0911/slot_loaded_open...

https://jazzman-esl-page.blogspot.com/2011/01/ripo...

Edited by Crackie on Thursday 17th June 07:05

[TonyRPH]

Interesting, cheers!

[RSTurboPaul]

Crackie said:

TonyRPH said:

Hi Crackie,

Is this sub tuned by the various apertures then?

Is it a bit like isobarik loading, but without the cabinet (as so to speak)?

Not quite, the design is still closely related to a conventional open baffle; the cabinet folds / returns are used to increase the front to rear path length. Each driver has an individual opening to the rear and their output combines to increase pressure at the front.

The drivers I used have a free air resonance of 33Hz.............I haven't measured them in the cabinet yet when mounted face to face I'm expecting the resonance to go down into the mid 20's.

Conventional subwoofer drivers aren't ideal for open baffles, you need a driver with a relatively high QTS of approx 0.5 or above. The figure for the Peerless 10" units is 0.59............I already had a pair left over from a different project.

Here is some additional information about slot loaded open baffles and also a comprehensive build guide for a ripole.

http://enjoythemusic.com/diy/0911/slot_loaded_open...

https://jazzman-esl-page.blogspot.com/2011/01/ripo...

Interesting!

Stick a board across the back of that, reverse one of the drivers so it's basket-out, and you've got yourself a PPSL sub

[Crackie]

RSTurboPaul said:

Crackie said:

TonyRPH said:

Hi Crackie,

Is this sub tuned by the various apertures then?

Is it a bit like isobarik loading, but without the cabinet (as so to speak)?

Not quite, the design is still closely related to a conventional open baffle; the cabinet folds / returns are used to increase the front to rear path length. Each driver has an individual opening to the rear and their output combines to increase pressure at the front.

The drivers I used have a free air resonance of 33Hz.............I haven't measured them in the cabinet yet when mounted face to face I'm expecting the resonance to go down into the mid 20's.

Conventional subwoofer drivers aren't ideal for open baffles, you need a driver with a relatively high QTS of approx 0.5 or above. The figure for the Peerless 10" units is 0.59............I already had a pair left over from a different project.

Here is some additional information about slot loaded open baffles and also a comprehensive build guide for a ripole.

http://enjoythemusic.com/diy/0911/slot_loaded_open...

https://jazzman-esl-page.blogspot.com/2011/01/ripo...

Interesting!

Stick a board across the back of that, reverse one of the drivers so it's basket-out, and you've got yourself a PPSL sub

https://linkwitzlab.com/woofer.htm

[Crackie]

Here is the impedance measurement for the open baffle sub. The 'system' resonance i.e the combined impedance measurement when the drivers are loaded by the cabinet / enclosure, has reduced. This was expected; in this case resonance reduced from 33Hz in free air to 26.65Hz in the 'cabinet'.

The smaller resonance in the trace, at approx 285Hz is caused by the cavities in front of and behind the drivers. This is not an issue, subjectively, because the the sub isn't being used to cover that part of the bandwidth.



Measuring the lowest frequencies is difficult to do accurately and consistently 'in room' at home. The following graph shows 3 measurements of the sub overlayed; the variations below 20Hz could have many causes. Vehicles passing, wind pressure changes outside, someone moving or closing a door in another room etc etc. The SPL amplitude curves below show the raw measurements without any smoothing; the results are as expected with a gradual 6dB per octave rolloff as a consequence of the front and rear output meeting and cancelling. This is close to ideal because boundary loading can be used to generate a 6 dB per octave lift When optimally placed in relation to walls / corners the design has the potential to produce a very flat response down to 23Hz and a -3dB point of 19Hz. The open baffle allows it to still make useful output into the low teens but cone excursion would be a limitation.




The graph below is a zoom in showing the the same three curves as above but in more detail. The important part of the curves is below approx 65Hz..... the bowl satellites will be handling everything above that. Very happy with the measured and subjective performance.

Edited by Crackie on Wednesday 9th June 20:10

[Ambleton]

I've been looking at getting a small Bluetooth speaker for the bit at the back of our garden where we have outdoor sofa/pergola/bbq/chiminea. It's under cover, so although outside it should remain dry.

Whilst looking I came across these on thingiverse. Looks like reasonable reviews with quite a few builds...

https://www.thingiverse.com/thing:4750820

So I've ordered a little Bluetooth amplifier, power source and a pair of drivers and ill make a stereo pair. Total spend so far is £44. The plan is to mount them high up, as close to the roof as possible to ensure they stay dry. The 3d printed housing will be fine, I'll need to modify the design a bit to include a cover to stop and bugs getting into the horn etc.

JBL 424 4" full range drivers:
https://amzn.eu/d/6PMrAWO

2ch amp:
https://www.ebay.co.uk/itm/175298770133?mkcid=16&a...

Plan at the moment is to make a passive pair of speakers and then sort out some kind of waterproof/semi waterproof housing for the amp to tuck out of the way, what's the worst that could happen



I have a tonne of filament hanging around that i could do with using up.

More than anything else it's an interesting little project. Worst case I have something functional for the summer. Best case is it sounds half good and lasts...

[paulrockliffe]

Can you let me know how you get on with them?

Having started this thread in - checks notes - 2019 I'm finally about vaguely ready to swap my various black boxes for the final speakers.

By vaguely ready I mean my wife has made her first complaint about the front speakers, "Those big speakers aren't staying are they?" Luckily she's right as they're floor-standers and they're stood next to some shelving on both sides, so I do need smaller speakers. But I don't have time to make something nice at the moment, so something my printer can print would be really helpful!

[Ambleton]

paulrockliffe said:

Can you let me know how you get on with them?

Having started this thread in - checks notes - 2019 I'm finally about vaguely ready to swap my various black boxes for the final speakers.

By vaguely ready I mean my wife has made her first complaint about the front speakers, "Those big speakers aren't staying are they?" Luckily she's right as they're floor-standers and they're stood next to some shelving on both sides, so I do need smaller speakers. But I don't have time to make something nice at the moment, so something my printer can print would be really helpful!

I sure will.

I'm not expecting anything too exciting from them to be honest. My bass line for acceptance is pretty low.

Basically if it's as good or better than an equivalently priced BT speaker then I'll be happy. So similar to an anker soundcore thingy and that'll be fine. Anything better will be a Brucey bonus.

As the drivers and power consumption in those type of products is limited on size and battery then I'm hopeful it'll be better, I just don't know by how much.

My concern with 3d printed enclosure is that it's very hard and reflective.

Anyways, I'll keep you posted.

[dhutch]

On the other side, it's amazing how good the little Bluetooth speakers actually sound!

[Ambleton]

dhutch said:

On the other side, it's amazing how good the little Bluetooth speakers actually sound!

Exactly. I've ummed and arrd about it for about 6weeks.

Nearly bought a Sony SRS XB33, then changed my mind for a soundcore jobby, nearly bought a JBL flip. My dad has an older bose one (must be 6yrs old now) and that's really good for a small thing.

But then thought, it's £50, it's only for the garden/bbqs, and its a cool little project as much as anything else. Doesn't REALLY matter.

Let's see

As an aside I have a few Yamaha Musiccast devices inside (kitchen, garage, dining room) and they really are very impressive.

Edited by Ambleton on Friday 10th June 12:00

[TonyRPH]

dhutch said:

On the other side, it's amazing how good the little Bluetooth speakers actually sound!

They sound good because of DSP.

Without DSP they sound tinny and lifeless, so if building your own, you do need some kind of signal processing to optimise the sound.

[Crackie]

Ambleton said:

I've been looking at getting a small Bluetooth speaker for the bit at the back of our garden where we have outdoor sofa/pergola/bbq/chiminea. It's under cover, so although outside it should remain dry.

Whilst looking I came across these on thingiverse. Looks like reasonable reviews with quite a few builds...

https://www.thingiverse.com/thing:4750820

So I've ordered a little Bluetooth amplifier, power source and a pair of drivers and ill make a stereo pair. Total spend so far is £44. The plan is to mount them high up, as close to the roof as possible to ensure they stay dry. The 3d printed housing will be fine, I'll need to modify the design a bit to include a cover to stop and bugs getting into the horn etc.

JBL 424 4" full range drivers:
https://amzn.eu/d/6PMrAWO

2ch amp:
https://www.ebay.co.uk/itm/175298770133?mkcid=16&a...

Plan at the moment is to make a passive pair of speakers and then sort out some kind of waterproof/semi waterproof housing for the amp to tuck out of the way, what's the worst that could happen



I have a tonne of filament hanging around that i could do with using up.

More than anything else it's an interesting little project. Worst case I have something functional for the summer. Best case is it sounds half good and lasts...

There are some great speaker designs on Thingiverse

Back loaded horn designs like the one you linked to will play very loud with little power but won't ( can't ) make any bass; the horn path is short and the mouth area is too small to work at low frequencies. This reduced bandwidth coupled with the plan to mount them high up is likely to give a bass light sound balance. clearly everyone has different tastes and this may not be a big factor for you. The amp you linked to has bass and treble controls so may be able to compensate for the relatively low bass from the horn design and roof mounting.

If the original back loaded horn design doesn't deliver enough bass for your taste, you could try a transmission line design. It will make a significant contribution / improvement at lower frequencies.

TL https://www.thingiverse.com/thing:4972779

Good luck.

[Ambleton]

Thanks for the input crackie, they won't be "listening" loudspeakers, only playing low level background music whilst sat out in the garden having a bbq etc.

Even so, if there isn't enough bass I'll look at a small sub like the one you've suggested. There are a few 3d printed isobaric designs too which look neat. Any thoughts/impressions on any of those?

Edited by Ambleton on Sunday 12th June 23:32

[anonymous-user]

HexiBase on YouTube is worth checking out for 3D printed speaker designs - e.g. https://youtu.be/4_4tu4rAtgI