No not really. Why have you done that?
I haven't built or heard any of Dave's designs. If I did, and found something I didn't like, I'd ask Dave about it thinking I had done something wrong. He's that kind of guy. Also, I'm sure he'd be interested in your feedback.
They are 2 different approaches. By stuffing the port, it will take on an aperiodic nature, and kill the qualities of the Onken.
It would be nice to pull my stuffing, and end up with an Onken.
Talk to Dave.
Cheers,
Geoff.
I haven't built or heard any of Dave's designs. If I did, and found something I didn't like, I'd ask Dave about it thinking I had done something wrong. He's that kind of guy. Also, I'm sure he'd be interested in your feedback.
They are 2 different approaches. By stuffing the port, it will take on an aperiodic nature, and kill the qualities of the Onken.
It would be nice to pull my stuffing, and end up with an Onken.
Talk to Dave.
Cheers,
Geoff.
Thanks for your feedback Geoff.
I stuffed the ports as I found that the bass was swamping the other frequencies.
I think I'll take your advice and get in touch with Dave.
Thanks again,
Regards, Lee.
I stuffed the ports as I found that the bass was swamping the other frequencies.
I think I'll take your advice and get in touch with Dave.
Thanks again,
Regards, Lee.
I always though for AP that the rear-wave (through the membrane) must be totally isolated from the front, such as outside the listening space... where is my misunderstanding?
Hello Pulse-R. I think your thinking is close to the mark, not a misunderstanding. I questioned it because I was getting sound from the port, and it sounded pretty good.
But the idea is to flatten out the z curve, making the speaker more efficient around it's natural resonance. If that is achieved, there should be no need to augment the front wave with the reversal of the rear.
I have now filtered all sound from the port. It still needs work to try to get the z rise flatter. Bigger holes, more stuffing. More stuffing around measuring z. And as GM said, probably have to go past optimum to realise where optimum is.
This system is sounding real nice, I could easily sit back and say that will do. What we learn from this, I want to try on a few other drivers.
The problem is that there doesn't appear to be much information about it. So we need to create it.
Thanks for the interest.
Geoff.
But the idea is to flatten out the z curve, making the speaker more efficient around it's natural resonance. If that is achieved, there should be no need to augment the front wave with the reversal of the rear.
I have now filtered all sound from the port. It still needs work to try to get the z rise flatter. Bigger holes, more stuffing. More stuffing around measuring z. And as GM said, probably have to go past optimum to realise where optimum is.
This system is sounding real nice, I could easily sit back and say that will do. What we learn from this, I want to try on a few other drivers.
The problem is that there doesn't appear to be much information about it. So we need to create it.
Thanks for the interest.
Geoff.
Greets!
What kind of info? I have Jordan's 1956 article where he explains (with math) how he designed the Goodmans' ARU cabs as well as some scanned pages from either Kinsler or Everest (can't remember).
GM
What kind of info? I have Jordan's 1956 article where he explains (with math) how he designed the Goodmans' ARU cabs as well as some scanned pages from either Kinsler or Everest (can't remember).
GM
G'day GM. Any info really. I have collected some off the web. Haven't collected any math based stuff though.
I am not after shortcuts for this project, but the more data the better.
I think you'll understand where I'm coming from. That is big drivers in big enclosures being the recipe for big efficient bass.
I am getting close to matching the good old 411s as far as bottom end goes. Cleaner in the 200 - 500 region. I don't know if the 10 inchers can push as much air at 20. The shortened coils will be the limiter there I think.
One myth that has been dispelled is low efficiency in this style of cab. No probs making the RS SPL meter hover in the mid 90s at 3 1/2 metres.
I have another problem now. There's a W12RS on fleabay. And it's got the big red magnet:
http://cgi.ebay.com.au/Wharfedale-1...ryZ50597QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
I haven't got room for it. I don't need it. It looks nice. How long is a 3000B Horn? I could make an Altec-Wharfedale.
BTW thanks for urging me to round out the cutouts. The treble no longer beams. It's letting the energy coming from the apex sneak out behind the whizzer and combine with the big dome.
Cheers,
Geoff.
I am not after shortcuts for this project, but the more data the better.
I think you'll understand where I'm coming from. That is big drivers in big enclosures being the recipe for big efficient bass.
I am getting close to matching the good old 411s as far as bottom end goes. Cleaner in the 200 - 500 region. I don't know if the 10 inchers can push as much air at 20. The shortened coils will be the limiter there I think.
One myth that has been dispelled is low efficiency in this style of cab. No probs making the RS SPL meter hover in the mid 90s at 3 1/2 metres.
I have another problem now. There's a W12RS on fleabay. And it's got the big red magnet:
http://cgi.ebay.com.au/Wharfedale-1...ryZ50597QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
I haven't got room for it. I don't need it. It looks nice. How long is a 3000B Horn? I could make an Altec-Wharfedale.
BTW thanks for urging me to round out the cutouts. The treble no longer beams. It's letting the energy coming from the apex sneak out behind the whizzer and combine with the big dome.
Cheers,
Geoff.
Hi All 😀
I'm just finished experiments with the Aperiodic Enclosure.
I have a pair of Wharfedale SUPER 12 RS/DD
T/S for this pair:
Parameter Value Description
-------------------------------------------------------------------
fs 21,2 Hz free air resonance frequency
Zmax 65,9 Ohm impedance at resonant frequency
Rdc 12,5 Ohm DC-resistance
Qms 0,99 mechanical Q of the speaker
Qel 0,23 electrical Q of the speaker
Qts 0,19 total Q of the speaker
Mmd 26 mass of driver's cone
Cms 2.2 compliance of driver's suspension
Rms 3,5 The mechanical resistance of the driver resulting from its suspension losses.
Vas 682 liter compliance volume of the speaker
9cu.ft DP (distributed port) recommended for this kind of drivers by G.A. Briggs. (cabinet handbook by Wharfedale 1963)
DP is aperiodic Distributed Port. 12 slots 9" X 1/4" lined with soft woolen cloth (this kind of cloth named usually Cashmere in Russia)
Results attached.
Blue - slots without cloth
Green - with cloth
AP not only reduced the impedance peak, but also provided lowering resonance frequency. All the tests passed in 4cu.ft cabinet, so I hope that in real 9cu.ft bass will be deep and loud 🙂.
I'm just finished experiments with the Aperiodic Enclosure.
I have a pair of Wharfedale SUPER 12 RS/DD
T/S for this pair:
Parameter Value Description
-------------------------------------------------------------------
fs 21,2 Hz free air resonance frequency
Zmax 65,9 Ohm impedance at resonant frequency
Rdc 12,5 Ohm DC-resistance
Qms 0,99 mechanical Q of the speaker
Qel 0,23 electrical Q of the speaker
Qts 0,19 total Q of the speaker
Mmd 26 mass of driver's cone
Cms 2.2 compliance of driver's suspension
Rms 3,5 The mechanical resistance of the driver resulting from its suspension losses.
Vas 682 liter compliance volume of the speaker
9cu.ft DP (distributed port) recommended for this kind of drivers by G.A. Briggs. (cabinet handbook by Wharfedale 1963)
DP is aperiodic Distributed Port. 12 slots 9" X 1/4" lined with soft woolen cloth (this kind of cloth named usually Cashmere in Russia)
Results attached.
Blue - slots without cloth
Green - with cloth
AP not only reduced the impedance peak, but also provided lowering resonance frequency. All the tests passed in 4cu.ft cabinet, so I hope that in real 9cu.ft bass will be deep and loud 🙂.
Attachments
Thanks Lamer! Very interesting. Your aperiodic port seems to be working well.
BTW, what is the software/harware you are using?
BTW, what is the software/harware you are using?
Hi
some more info...
here is a link to Ted Jordans article on aperiodic enclosures,
ARU Article (4.5 MB dwonload!!!)
And below is a messured FR from my Dynaco A25, only the woofer. Blue with closed aperiodic port, pink with open ap-port. As you can see, you will lose bass with the ap but therefore reduce the bass-peak due to the highish Q of the system.
(made with ARTA on a uncalibrated system)
Unfortunately I've lost the impedance graphs, but the impedance peak at resonance frequency was significanly reduced in the ap version.
Here's a link to the enclosure plans of the Dynacos
Dynacos at t-linespeakers.org
hope that helps,
martin
some more info...
here is a link to Ted Jordans article on aperiodic enclosures,
ARU Article (4.5 MB dwonload!!!)
And below is a messured FR from my Dynaco A25, only the woofer. Blue with closed aperiodic port, pink with open ap-port. As you can see, you will lose bass with the ap but therefore reduce the bass-peak due to the highish Q of the system.
An externally hosted image should be here but it was not working when we last tested it.
(made with ARTA on a uncalibrated system)
Unfortunately I've lost the impedance graphs, but the impedance peak at resonance frequency was significanly reduced in the ap version.
Here's a link to the enclosure plans of the Dynacos
Dynacos at t-linespeakers.org
hope that helps,
martin
Lamer, those test boxes are similar to my fathers when I was a kid. We only had the tens.
Thanks for posting the results. They are similar to my findings, and confirm a few things. The little bump at about 100 is most likely the box/port resonance.
That makes sense, it's where you want the dampening action to start.
Looking at the dampening effect I wouldn't be surprised if your test cabs went down to 20.
I noticed on the T/S data, there is no Xmax. Place a 1.5 volt battery across the speaker terminals and the cone will move about 3/8 inch.
You could try this. With your test gear, run a 5 hz square wave, and observe the output on a good mic and cro. Adjust the dampening for the best rise/fall times. You should hear a series of clicks.
Then listen to some music with lots of percussion, and a tympani.
I've enlarged the holes, going out to 3/8", but no measurements yet. On listening, hasn't changed the bass level much, but seems to have more detail.
Looking forward to hearing how they sound.
Geoff.
Thanks for posting the results. They are similar to my findings, and confirm a few things. The little bump at about 100 is most likely the box/port resonance.
That makes sense, it's where you want the dampening action to start.
Looking at the dampening effect I wouldn't be surprised if your test cabs went down to 20.
I noticed on the T/S data, there is no Xmax. Place a 1.5 volt battery across the speaker terminals and the cone will move about 3/8 inch.
You could try this. With your test gear, run a 5 hz square wave, and observe the output on a good mic and cro. Adjust the dampening for the best rise/fall times. You should hear a series of clicks.
Then listen to some music with lots of percussion, and a tympani.
I've enlarged the holes, going out to 3/8", but no measurements yet. On listening, hasn't changed the bass level much, but seems to have more detail.
Looking forward to hearing how they sound.
Geoff.
Hi Martin
Thanks for the links. I have the article re TJ and the ARU. Forgot to save where it came from! I think that's the one GM referred to earlier. And the info on the A25 is useful.
I have been asked by Freddi in another thread what I thought of the Beyma 12CX Coaxial in an AP.
http://www.diyaudio.com/forums/showthread.php?threadid=93656&goto=newpost
Looking at the specs I think it would be a good candidate.
http://www.diyparadiso.com/datasheets/speaker/beyma/12cx.pdf
Unfortunately I haven't heard this driver, does anyone have an opinion on it. It may help Freddi with his decision.
Cheers,
Geoff
Thanks for the links. I have the article re TJ and the ARU. Forgot to save where it came from! I think that's the one GM referred to earlier. And the info on the A25 is useful.
I have been asked by Freddi in another thread what I thought of the Beyma 12CX Coaxial in an AP.
http://www.diyaudio.com/forums/showthread.php?threadid=93656&goto=newpost
Looking at the specs I think it would be a good candidate.
http://www.diyparadiso.com/datasheets/speaker/beyma/12cx.pdf
Unfortunately I haven't heard this driver, does anyone have an opinion on it. It may help Freddi with his decision.
Cheers,
Geoff
OK, just got off the calculator. Results with the 5/8 holes.
160 Hz 7.1 ohms
126 hz 8.03 ohms
100 hz 10.5 ohms
rising to
63 hz 13 ohms (peak)
50 hz 11.4
20 hz 10.62 ohms.
The same material was stuffed back into the holes. The 16x0.625 holes would have lifted the cab resonance to 102 hz.
And they do go deep. The double bass on JBT sounds like it's in the room, with no sign of boom or one noteness.
If the vintage speaker buffs blink twice, I listened to some Black Eyed Peas earlier. The guys in the car parks on Friday nights don't know what they are missing.
I have noticed a slight harshness in vocals at high level. I suspect the extra load on the amp is pulling the rails down - less headroom.
Next up is a 10" bass driver in 2 cub ft cab.
Cheers
Geoff.
160 Hz 7.1 ohms
126 hz 8.03 ohms
100 hz 10.5 ohms
rising to
63 hz 13 ohms (peak)
50 hz 11.4
20 hz 10.62 ohms.
The same material was stuffed back into the holes. The 16x0.625 holes would have lifted the cab resonance to 102 hz.
And they do go deep. The double bass on JBT sounds like it's in the room, with no sign of boom or one noteness.
If the vintage speaker buffs blink twice, I listened to some Black Eyed Peas earlier. The guys in the car parks on Friday nights don't know what they are missing.
I have noticed a slight harshness in vocals at high level. I suspect the extra load on the amp is pulling the rails down - less headroom.
Next up is a 10" bass driver in 2 cub ft cab.
Cheers
Geoff.
Hi guys. Pic shows the holes stuffed with polyester fibrefill.
One of the reasons I found for AP not being used much these days, was due to the added complexity of the vent. Nothing complex about this.
I just have to provide a front to apex brace, probably a length of 1" round hardwood, fitted to rebates on the baffle and rear cleat.
I tried to export a pink noise test last night. RTA crashes for some unknown reason. It will do that if I change freq too fast.
Down a few dB at 30hz, and showing reasonable energy between 20-30Hz. I need to check the fr of the spl meter to get true results.
Listening to a wide range of music, from Enya to Joe Satriani via Peer Gynt - Berlin Phil. I have not felt the need for more bass. If anything, a bit more headroom in the amp for JS, and The Eagles - Get over it.
On the next job, I might make the holes smaller, to more accurately control the amount of dampening material. Cigarette (rollies) filters could be useful. My first method was a little short of scientific.
Cheers,
Geoff.
One of the reasons I found for AP not being used much these days, was due to the added complexity of the vent. Nothing complex about this.
I just have to provide a front to apex brace, probably a length of 1" round hardwood, fitted to rebates on the baffle and rear cleat.
I tried to export a pink noise test last night. RTA crashes for some unknown reason. It will do that if I change freq too fast.
Down a few dB at 30hz, and showing reasonable energy between 20-30Hz. I need to check the fr of the spl meter to get true results.
Listening to a wide range of music, from Enya to Joe Satriani via Peer Gynt - Berlin Phil. I have not felt the need for more bass. If anything, a bit more headroom in the amp for JS, and The Eagles - Get over it.
On the next job, I might make the holes smaller, to more accurately control the amount of dampening material. Cigarette (rollies) filters could be useful. My first method was a little short of scientific.
Cheers,
Geoff.
Attachments
I have found this is usually due to the actual tuning frequency being off a bit or excessive port noise/distortion. Have you verified the tuning?
I understand the flatten of the Z-curve, but I Don’t understand why a flatter Z-curve results in better sounding music.
Hi Zach,
Re your first query. That's why I referred him back to Dave at Planet Hi-FI. Dave probably has the answer.
Re your 2nd query. The effect of the lower z would appear to only effect conditions below (in this case) below about 100 hz.
However, cone excursion is more like that of a well tuned BR, ie much reduced to that from a sealed enclosure. So less dopler, phase, and cone break-up issues. There may also be an effect on the amp, it's now driving a more resistive load, rather than reactive.
Where it is noticeable is the lower registers of Gretsch White Falcon and Gibson F355 hollow bodied guitars and viola.
Cheers,
Geoff.
edit: the first query relates to an Onken, not an aperiodic.
Re your first query. That's why I referred him back to Dave at Planet Hi-FI. Dave probably has the answer.
Re your 2nd query. The effect of the lower z would appear to only effect conditions below (in this case) below about 100 hz.
However, cone excursion is more like that of a well tuned BR, ie much reduced to that from a sealed enclosure. So less dopler, phase, and cone break-up issues. There may also be an effect on the amp, it's now driving a more resistive load, rather than reactive.
Where it is noticeable is the lower registers of Gretsch White Falcon and Gibson F355 hollow bodied guitars and viola.
Cheers,
Geoff.
edit: the first query relates to an Onken, not an aperiodic.
Hi Geoff - here's one patent on the subject including math (and use of "Rayls") which went along with a commercial product
J.J. Baruch US2766839 "Loudspeaker System" Filed March 16th 1953, granted Oct. 16th 1956
Freddy
J.J. Baruch US2766839 "Loudspeaker System" Filed March 16th 1953, granted Oct. 16th 1956
Freddy
Thanks Freddi. I'll look into that later. Ted Jordan went public in Feb 56, stating a patent had been applied for.
Heck, J.J. Baruch's took 3 1/2 years to be accepted. That time frame would be useless these days.
I think I have established a starting point. 1/2 the min vol rec for BR. Tune the cab to 2 to 3 times the fr of the driver, then stuff the port.
It's the last bit that needs refinement. Good thing I have a few systems laying about to experiment with. I can reduce box vol with bricks.
Cheers,
Geoff.
Heck, J.J. Baruch's took 3 1/2 years to be accepted. That time frame would be useless these days.
I think I have established a starting point. 1/2 the min vol rec for BR. Tune the cab to 2 to 3 times the fr of the driver, then stuff the port.
It's the last bit that needs refinement. Good thing I have a few systems laying about to experiment with. I can reduce box vol with bricks.
Cheers,
Geoff.
