So here are the FR, GD, Z and THD plots.

 

 

 

 

 

 

now I have to hear it

 

any at carny this year? I'll try my best to get there

 

we can all have a busmans holiday and meet up?

 

as long as you don't mind me grinding some chicks up, mykey sandwich stylee 

 

I make it 102dB at 30Hz and 103dB at 31.5Hz.

 

The specs, which have to be updated, state -3dB at 34Hz, but that was for a prototype which got changed at the last moment. All production models are -3dB at 30Hz.

 

I expect there will be a few floating around somehwere at carnival this year .

 

 

*unless its run below ~25Hz

 

Alos have to say.. congrats man you must be chuffed with the results... I am soo looking forward to hearing these.

 

Thats what im thinking! its an incredible output for a port, usually you cant make the ports match the horn output, im amazed!

Lowest spike looks like damped Fs, then 50Hz spike dictated by 30Hz tuning and 230Hz spike due tuning of small chamber.

 

I notice this in Pro Sound News this month which uses an interesting alignment:

http://www.apg.tm.fr/telechargements_workflow/subwoofers/TB215S_APG_UK.pdf - http://www.apg.tm.fr/telechargements_workflow/subwoofers/TB215S_APG_UK.pdf

which looks like a 6th order bandpass with a horn loaded front chamber, and large vented rear chamber?

 

Rich

 

Also i was racking my brain to remember what the plot looked similar to...

... then i realised i was thinking about http://www.speakerplans.com/forum/forum_posts.asp?TID=14904&PN=6 - this ! I know its not very similar but there are certain characteristics that i recognised,

 

@Rog, do you take your plots in a warehouse 26 meters wide by any chance?

 

simple

 

The thing that really puzzles me is how you can have a rear chambers port matching the output of the horns, i dont know how thats done!

Theres 2 heat sinks on the rear, so the magnets are touching the back wall heat sinks.... theres already been a thread discussing this....

 

http://www.speakerplans.com/forum/forum_posts.asp?TID=11711 - http://www.speakerplans.com/forum/forum_posts.asp?TID=11711

 

Really its just a double 18" reflex cab with front loaded drivers. There is a clever cloaking device that makes it look like there are ports and horns.

 

tb mike is close with the port tuning at horn cutoff. Its about 28Hz for the port and about 57Hz for the horn. The pivital point of the whole design is 50Hz. You can see somthing going on at 50Hz in all the plots. Its the point where the ports output meets or takes over from the horns cutoff point. There is a small dip in the THD plot, a peak in impedance and a dip in GD.

 

Jake F said that the port output is as loud as the horns output. I would not argee. The frequency plot really gives away what is happening here. Above 60Hz the response averages 105dB with 106.5dB peaks. The plot shows a typical horns response of peaks and undulations. Below 60Hz the reponse smooths out. This is typical of the output from a port. Its also at an average of 103.5dB, so it not as loud as the horns output. Any port has losses, the longer the port the greater the losses due to there being a greater wall surface area. If you take a 4.5 meter port with its considerable losses and now make it only 45 cm long, you will have less losses and more output. Of course the new shorter port can never have the same tuning frequency as one thats 10 times longer, or can it, ha ha.

 

Yes peaks in the impdance plot are undamped areas, so the port/horn tuning lies at the lowest point between peaks. The highest small peak is due to a harmonic of one of the chambers resonances. Looking at the Z plot its quite an easy cab to drive, this is born out in reality as well.

 

Well no. The ultimate bass bin is the size of a small briefcase, weighs 3Kg has no moving parts and can do 140dB at 10Hz. Stasys X is quite a long way off from that, but I do think that Stasys X is at the edge of what can ever be achieved from its volume. There's no getting away from Hoffmans Iron Law and with the materials and technology we have at this time I think Stasys X is making as best use of the space it occupies as anything ever will. Its got to the point where thats it, you will never get anymore out in terms of SPL or frequency response from its size enclosure. It doesn't matter who tries or what they try with it can only ever be matched. Give me a bigger enclosure or materials from 200 years in the future and it can have more output and play even lower. But for now its reached 100%effeiciency of what you can ever get from what we have.

 

 

Thats what i meant, as you said, i cant see it getting any better for the size, unless better driver or cabinet technology is available.

 

Thats really interesting Rog, thank you, you've really got me thinking with these tit-bits of information.

 

Do you take your plots in a 26 meter long warehouse BTW?

 

Well i think its as near as damn it! when I play around with my design in hornresp (i know its a different league but the theory should still largely apply) i can never get the port output anywhere near as high as horn output (like ~8/10dB lower).

 

I had been thinking previously that as there are many ways to achieve the same tuning freq (using rear chamber, port length and area) i might get better efficiency from the port if it was tuned in such a way that it was a short as possible whilst having the biggest cross-sectional area as possible (which is what you seem to have done), this would result in a massive rear chamber though, unless i used your technique (which i fear i will never learn)

so Rog... do you get better efficiency with a bigger port or not?

 

Hmmm, its just there is the same lump at ~13Hz on the stasys X plot and the rubic horn.... Do you know why?

Could be a generator or something in a near by factory that puts out 13Hz. Is it at the same level in both plots. Ummmm you got me worried now. Lucky its at 13Hz and out the way. Wonder what its doing to my head state to have this constant 13Hz around all the time.

 

Bigger ports are not louder than smaller ones, but ports with less losses are louder.

 

The loudest low sound I never heard was in a ship once. I was near the engine room in this narrow hallway. Don't know the frequency, but must have been 15 to 18Hz. So stange when you can't hear anything but you eyeballs are shaking.

 

My ears give up under about 26Hz. I can tell that its a note down to about 26Hz, but below that it doesn't make sence and isn't really there.

 

"Bigger ports are not louder than smaller ones, but ports with less losses are louder"

I'll have to work on that then!

 

Will the following things significantly help the ports output? (i assume all these points will affect it slightly)

Smoothness of edges

How round or slot like it is

Folded or non folded

flaired / non flaired

 

http://en.wikipedia.org/wiki/Binaural_beats - http://en.wikipedia.org/wiki/Binaural_beats

 

 

But actually the 13Hz bump is alot bigger on the rubic horn plot than the stasys, so unless you put the cabs and mic in different places with the tests i'd say its more of a boundry effect than a outside noise......? although i suppose the 13hz noise would just be adding to the output of whatevers being tested......  interesting though!

 

tbmike gave a link to a really good site that showed the different effects of port shapes etc. Do a search for the link, its a must read and saves me having to tell you the same stuf ha ha.

I looked at Impulse 5t, B15, Impulse 8t and none of them have that small peak at 13Hz. They all have a nice natrual rolloff. Must be conisidence that both Stasys X and Rubic horn have some output down that low.

 

Here is a plot of Impulse 5t that was taken around the time the Stasys X plot was made.

 

 

 

 

I've just looked at what I wrote and that the Rubic Horn has an output of 86dB at 15Hz. Wow, most home Hi Fi speakers are only 88dB sensitive from 50Hz upwards. The Rubic horn is nearly that sensitive at 15Hz.

 

 

 

Rog Mogale wrote: I've just looked at what I wrote and that the Rubic Horn has an output of 86dB at 15Hz. Wow, most home Hi Fi speakers are only 88dB sensitive from 50Hz upwards. The Rubic horn is nearly that sensitive at 15Hz.

 

Thats well good!

"You should take a plot outside with just a mic to see if anything funny is going on!"

 

I did once. I took a mic out and pointed it at Benny Hill.

 

There was nothing funny going on that day.

 

 

 

No, thats frightening.

Infact it could quite easily be a home, Would you consider renting out a spare section of rubic horn for me to live in as a trendy apartment?

 

Back on topic, whats the secret at 50Hz then?

 

I'll rent you the front chamber of the rubic house for a tenner.

 

Talking of speakers the size of a house.... Did anyone see a dub system one year at glastonbury festival. It must have been around 1983 -1984. The whole system was painted red with brick work patterns and each speaker made up a part of the house. Some speakers had windows painted on them and other looked like a roof. There was even a chimney and a white picket fence post around the front to stop people from getting too close. It was classic and I've never see anything like it since. It must have been about 20 feet high.

 

Talking of glastonbury, I must get those photos from the early days. I promised Ian JBL man that I would dig out the pics I have of the stage 2 martin system I used to mix on. I looked last september when I was in the uk but could not find them, hope they will turn up soon though. Also have pics of that white van in 1986-87 that got so stuck in the mud that only the roof was visible. And someone even tried to set fire to what was left of the roof ha ha. That was the same year that I saw this nutter on wednesday night spinning round and round in a circle on an old army bike. He had one leg down and was doing doughnuts with the bike. I kept walking past him for 5 days and everytime I did he was still going round and round in circles. It didn't matter if it was day or night he just kept going round. Pure art that is.

 

 

I cant tell if you're taking the piss by throwing me a red herring! or if its actually something to do with mains frequency....? 

 

Ha ha, I thought I was the one telling the jokes around here.

 

I've just pissed myself at what you said.

I dont know what you mean!?

 

 

 

 

They put the plyons out of phase to stop old women making cups of tea too quickly with there electic kettles. If you reverse the phase the kettle gets more juice and heats up more. The same with ya sound system. Its all to do with the earths magnetic fields and God. 

 

Cheers Rog, did you know if you reverse the phase of your pants you can wear them twice as long?

So you're saying that if I buy some kacks that are half as long as I need, I can then get them home reverse there phase and they will fit.

 

Its a good money saver mate.

 

 

Rog Mogale wrote: The pivital point of the whole design is 50Hz. You can see somthing going on at 50Hz in all the plots. Its the point where the ports output meets or takes over from the horns cutoff point. There is a small dip in the THD plot, a peak in impedance and a dip in GD.

 

Whats going on @ 50Hz regarding the Stasys X?

 

I thought this site was about discussing the design and theory of loudspeakers / PA... not simply stacking products without understanding how they work... this is what makes SP great!

 

I do agree tho, Rog has been more than generous with the info, and in the wrong hands the stuff he has posted could probably be used to create a rival product.. BUT, I have a feeling Rog's coming news is so big that he's not hat bothered about this old tech stuff any more.

Thats exactly it.

 

Josh: you are completely wrong, quote me information from this thread that Rog has given, that has not been mentioned before. I bet you cant find alot, also Rog is not slowly but surly telling us more, he knows how much information he's willing to give out, he's not daft, its not like if i keep asking he's going to eventually give me the plans.

 

I think we should seperate in our minds, understanding the concept is not the same as being able to build a copy... the Stasys-X will sell, not because it sounds superb  / puts out more SPL etc... but because of the backup the buyer gets from VOID, the rider friendlyness of the products, reliability etc etc.

 

An analogy might be... I expect you could build me a really fast PC... I wouldn't buy it cos next year, when it goes wrong I might not find you again, if I buy a Dell / HP I know they will help me out.

 

Exactly, its easy to know the rough physical layout, but no one knows the specifics. If you have the ability to work out the specifics then im sure you can invent your own rough physical layout and design your own cab with equal technology, hence, theres no need to copy if you can.

 

josh wrote: jake im not compleatly wrong, i am more than happy to talk about this technology, listen and learn from someone more knowledgable than me and i am gratefull. However all i am saying is id hate for rog to get f**ked over at the end of the day.

 

I dont want to start an argument on a thread as brilliant as this but unless you can "quote me information from this thread that Rog has given, that has not been mentioned before", then your argument doesnt really make sense....

 

This is the best thread I have ever been involved in IMO, and the main reason was because of what it made me do outside of the forum. It has made me step up my hornresp modeling alot and experiment with loads of different enclosures, and I'm not just looking at the spl & displacement anymore, I'm looking at impedance and group delay as well.

coincidentally, I was trying to see if it was possible to get a stasys X like response from a 5 chambered ported horn........ It is very achieveable to hit 40Hz at about 103-105dB efficiency from a dual driver setup in a cabinet about the same size as a lab horn, IN SIMULATION.

 

When you start getting custom made drivers, and the engineering EXCELLENcE that Rog taled about with his Resonance Mapping, months of CAD to fit more enclosure into less volume, a great knowledge of materials, etc that the final 10Hz extension of the stasys X becomes achieveable, I think.

 

I think with custom drivers,

 

 

I think the secret could be in the designing and testing rather than modeling, hence the thousands of accelerometers!

 

The chamber in (Fig. A) will obviously act as spring of air, and will be compressed, this would NOT act as a longer port.

 

The chamber in (Fig. B) could possibly act as a longer port as there would be more mass inside the port yet the air in the chamber wont compress too much, the air would circulate in the chamber but could still act like a port. Just like blowing across the top of a bottle

 

Sorry, i dont get you? When i drew those pics I was just picturing a blast of air and whether or not it would compress.

 

 

 

 

 

Is this not correct?

 

Volume of air in cabinet = spring (compliance)

Volume of air in port = mass (inductance)

 

Picture something like an 8th order bandpass design with 2 chambers (one on each side of the driver) and both chambers are ported into a 3rd chamber, are you saying that (as compression is only at the source) the air in the 3rd chamber does not act as a spring of air?

 

(this conversation is very quickly rising above my head )

 

All i was thinking is that a chamber acts as a spring and a port acts as a mass (is that right or wrong?) so to make a port have the same mass as a larger port you would need an intermediate chamber (to add mass) but somehow stop it from adding any "spring"/compliance....

 

....oh i dont even know what im on about anymore

 

I`ve found this thread on a research we are doing at the moment to get benchmarks concerning subwoofers, their freqeuncy responses, spl etc. Have you measured the Stasys X subwoofer with 2.83V ot 2V as an impedance correction due to 1W@1m. Do you have a waterfall or burst decay plot for the subs?

An answer would be really nice, either here as a pm.

Thank you in advance, greetings Marcus

This is a 14 year old thread aswell.

Lammbock wrote: Hallo Rog, I`ve found this thread on a research we are doing at the moment to get benchmarks concerning subwoofers, their freqeuncy responses, spl etc. Have you measured the Stasys X subwoofer with 2.83V ot 2V as an impedance correction due to 1W@1m. Do you have a waterfall or burst decay plot for the subs? An answer would be really nice, either here as a pm. Thank you in advance, greetings Marcus