Hi everybody.
I have a pair of Ciare CH 250 (single magnet) drivers from an old open-baffle project...
Impedance: 4 Ohms.
Sensivity (1w/1mt): 96 db.
Qts: 1,36.
Vas: 52 l.
Xmax: 0,5 mm.
and I think that would be interesting to make a pair of aperiodic boxes with ScanSpeak´s 130 mm flow resistors...
http://www.tymphany.com/products_ScanSpeak.html
I don´t have any experience with aperiodic boxes, so any advice is very welcome.
My doubts are:
-dimensions (a big floor-stander is prefered).
-number and best location of flow resistors.
-box material (normally I use finland birch but maybe MDF is better for this “hot” driver).
-best type and location of stuffing material.
...so, at this point, I need a lot of help.
Power-amp: EL84 single push-pull, around 10 Watts.
Many thanks.
I have a pair of Ciare CH 250 (single magnet) drivers from an old open-baffle project...
Impedance: 4 Ohms.
Sensivity (1w/1mt): 96 db.
Qts: 1,36.
Vas: 52 l.
Xmax: 0,5 mm.
and I think that would be interesting to make a pair of aperiodic boxes with ScanSpeak´s 130 mm flow resistors...
http://www.tymphany.com/products_ScanSpeak.html
I don´t have any experience with aperiodic boxes, so any advice is very welcome.
My doubts are:
-dimensions (a big floor-stander is prefered).
-number and best location of flow resistors.
-box material (normally I use finland birch but maybe MDF is better for this “hot” driver).
-best type and location of stuffing material.
...so, at this point, I need a lot of help.
Power-amp: EL84 single push-pull, around 10 Watts.
Many thanks.
some thoughts.
look here..
No first hand experience here, but I do own a set of original Dynacos. You can also make your own restrictive vents, see the link.
Basically an aperiodic acts like a "leaky" sealed box. The real benefit is the peak impedence and smoothed, and reduced.
Seas sells a driver suitable. Anthing that will work in a vented enclosure (Qts approc .4)
look at World Audio Designs, and not the price!
You will need to be able to measure impedence of the loudspeaker, to adjust the resistive layer in the "vent". Looking further, I am pretty sure a variovent or resistive port is not suitable with the driver you have .
Here's a floorstanding version
here's the specs
that's about all I can add.
look here..
No first hand experience here, but I do own a set of original Dynacos. You can also make your own restrictive vents, see the link.
Basically an aperiodic acts like a "leaky" sealed box. The real benefit is the peak impedence and smoothed, and reduced.
Seas sells a driver suitable. Anthing that will work in a vented enclosure (Qts approc .4)
look at World Audio Designs, and not the price!
You will need to be able to measure impedence of the loudspeaker, to adjust the resistive layer in the "vent". Looking further, I am pretty sure a variovent or resistive port is not suitable with the driver you have .
Here's a floorstanding version
here's the specs
that's about all I can add.
With the Qts on that, the receipe boils down to:
1/ figure out how big a box you can live with -- if one dimension is a fair bit longer than the others that is good
2/ mount the drive at one end and start playing with ports and port resistance at the other end. use GM's click test, or use an impedance jig to tune until you have flatest impedance.
3/ making your own "resistive vents" is much more versatile than buying the scan vents.
dave
1/ figure out how big a box you can live with -- if one dimension is a fair bit longer than the others that is good
2/ mount the drive at one end and start playing with ports and port resistance at the other end. use GM's click test, or use an impedance jig to tune until you have flatest impedance.
3/ making your own "resistive vents" is much more versatile than buying the scan vents.
dave
Hi
here's an example of another way to build an aperiodic enclosure.
It's for an Onmes Audio L8 data sheet , in ca. 40 Liter and 120 holes (8mm dia.) in the back.
The old Saba tuberadios with the famous greencones in them, where build like that.
best,
LC
here's an example of another way to build an aperiodic enclosure.
It's for an Onmes Audio L8 data sheet , in ca. 40 Liter and 120 holes (8mm dia.) in the back.
An externally hosted image should be here but it was not working when we last tested it.
The old Saba tuberadios with the famous greencones in them, where build like that.
best,
LC
Attachments
Here is an enclosure modelled with MJKs ported box worksheets.
About 85 Liter with stuffed port (Density 0.99lb. ft^3) - see yourselfs - this way, Martin once explained, aperiodics can be modelled with his worksheets.
As you might see, the port still adds some impact in the LF and the woofer displacement is reduced, but the response is relatively flat and the impedanz peak around zero. I think the most critical point is to find the right material and amount of stuffing for the port.
BTW, I own a pair of Dynaco A25 and I kind of like the bass they offer - although I have to say, it's a shame to use such a great woofer in a way too small enclosure and give away all the deep bass it could deliver. For high Q drivers, like the ciare, aperiodic loading seams a good thing though.
ciare.pdf
best, LC
About 85 Liter with stuffed port (Density 0.99lb. ft^3) - see yourselfs - this way, Martin once explained, aperiodics can be modelled with his worksheets.
As you might see, the port still adds some impact in the LF and the woofer displacement is reduced, but the response is relatively flat and the impedanz peak around zero. I think the most critical point is to find the right material and amount of stuffing for the port.
BTW, I own a pair of Dynaco A25 and I kind of like the bass they offer - although I have to say, it's a shame to use such a great woofer in a way too small enclosure and give away all the deep bass it could deliver. For high Q drivers, like the ciare, aperiodic loading seams a good thing though.
ciare.pdf
best, LC
Hi everybody.
Many thanks, Nanook and Dave, for your comments and suggestions.
According to "Audionutz on AP Enclosures" article (thanks for the link) it seems that drivers with Qts higher than 0,45 aren´t good for aperiodic boxes.
The idea of aperiodic boxes came to my mind after reading about the Omega A8´s on ...
http://www.6moons.com/audioreviews/redwine3/system.html
Given that Visaton B200´s Qts is on the high side (0,75), I thought It would be a good idea trying something similar with my Ciares. But what is good for a certain driver could be less than optimal for another.
Equally, many things that couldn´t work (on paper) are offering surprisingly good results.
What attracts me of aperiodic boxes resides in their potential for clean bass, with a soft decay in response, and that you don´t need a lot of internal stuffing (with the consequent loss of life and transparency).
Please, any information is very welcome.
Best regards.
P.D: Dave, sorry for my poor understanding of english. What does "GM's click test" and "impedance jig" means?
Many thanks, Nanook and Dave, for your comments and suggestions.
According to "Audionutz on AP Enclosures" article (thanks for the link) it seems that drivers with Qts higher than 0,45 aren´t good for aperiodic boxes.
The idea of aperiodic boxes came to my mind after reading about the Omega A8´s on ...
http://www.6moons.com/audioreviews/redwine3/system.html
Given that Visaton B200´s Qts is on the high side (0,75), I thought It would be a good idea trying something similar with my Ciares. But what is good for a certain driver could be less than optimal for another.
Equally, many things that couldn´t work (on paper) are offering surprisingly good results.
What attracts me of aperiodic boxes resides in their potential for clean bass, with a soft decay in response, and that you don´t need a lot of internal stuffing (with the consequent loss of life and transparency).
Please, any information is very welcome.
Best regards.
P.D: Dave, sorry for my poor understanding of english. What does "GM's click test" and "impedance jig" means?
foniton said:
Maybe not ideal, but if you have to put a driver that would prefer to be in an open baffle into a box, aperiodic is your best bet. I did a quite nice speaker, with a driver with Q>1. I took a set of old boxes (close to floorstander height), slapped some scrap MDF to the front, mounted the driver on the side, drilled a bunch of holes (simillar to the picture above) and tuned the cabinet by ear by adjusting the amount & density of the foam i placed over the holes on the inside. My mom enjoyed these for quite a while, before i found something littlier that would squeeze in beside the TV.
I'm hoping GM comes by and describes clik test....
Impedance jig, is kit to measure the impedance of your speaker.
dave
One of the few papers on aperiodic boxes (by Ted Jordan):
http://p10hifi.net/tlinespeakers/TLS/downloads/TedJordanAperiodic.pdf (4.6 MB)
dave
http://p10hifi.net/tlinespeakers/TLS/downloads/TedJordanAperiodic.pdf (4.6 MB)
dave
Hi everybody.
Lovechild,
thanks for your post. Very interesting design for the Omnes Audio driver. I´m also thinking on a much wider than deeper cabinet and I like the idea of holes, but I don´t know if I must combine them with some form of foam or similar.
From past experiences with Ciares in open-baffle I know is not easy to get reasonable bass from this drivers. In open baffle (with same panel dimensions) they are a lot more bass-light than the 215 Supravox drivers, for example. So, I´m convinced a big box is needed and I´m thinking about 100-120 liters. It sounds a bit excessive but with this project I want a big and visceral sound for my Motown, Stax or Trojan albums. Detail and delicacy is needed too, of course, but with a big and cohesive presentation. After years of precise but bass-light monitor speakers I want to indulge myself with a more "high-calorie" speaker for modern music.
I´ve seen the MJK´s worksheets but I must confess they are too technical for me. Thanks anyway.
Dave,
thanks for the clarification about the impedance jig. I´d like to thoroughly examine Ted Jordan´s article about aperiodic boxes. It´s dense and quite technical but very promising.
Nanook,
very interesting articles from World Design. I like the dual chamber with aperiodic loading concept but it´s too complex for me. At my present home I have minimal wood-working possibilities. Thanks anyway.
Henkjan,
Please, could you explain more the series condensator to smoothen the bass frequency curve?. I´m interested. And I´m interested too in a passive correction circuit to put before the power amp. Many thanks.
Best Regards.
Lovechild,
thanks for your post. Very interesting design for the Omnes Audio driver. I´m also thinking on a much wider than deeper cabinet and I like the idea of holes, but I don´t know if I must combine them with some form of foam or similar.
From past experiences with Ciares in open-baffle I know is not easy to get reasonable bass from this drivers. In open baffle (with same panel dimensions) they are a lot more bass-light than the 215 Supravox drivers, for example. So, I´m convinced a big box is needed and I´m thinking about 100-120 liters. It sounds a bit excessive but with this project I want a big and visceral sound for my Motown, Stax or Trojan albums. Detail and delicacy is needed too, of course, but with a big and cohesive presentation. After years of precise but bass-light monitor speakers I want to indulge myself with a more "high-calorie" speaker for modern music.
I´ve seen the MJK´s worksheets but I must confess they are too technical for me. Thanks anyway.
Dave,
thanks for the clarification about the impedance jig. I´d like to thoroughly examine Ted Jordan´s article about aperiodic boxes. It´s dense and quite technical but very promising.
Nanook,
very interesting articles from World Design. I like the dual chamber with aperiodic loading concept but it´s too complex for me. At my present home I have minimal wood-working possibilities. Thanks anyway.
Henkjan,
Please, could you explain more the series condensator to smoothen the bass frequency curve?. I´m interested. And I´m interested too in a passive correction circuit to put before the power amp. Many thanks.
Best Regards.
well, the principle of the series condensator is to both smooth out the bump caused by the high Q, and to extend the f3 downward to approx the same as if it were a Q=0.7. this effect is caused by a lowering of the system impedance due to a resonance with the voicecoil.
the general formula for the series condensator is:
Cs = (265000*Qts)/(Re*fs) [uF]
source: Hobby Hifi 1/2006 p.48
this is based on a Qtb=0.9 - 1.0, sa some adjustment might be required for the very high Q of the Ciare.
while digging for this, I came across a design (HH 5/2006) for the Ciare in a closed box, 20 liters with a variovent... and 4 (four) correction RCL's.... and without series C.....
the general formula for the series condensator is:
Cs = (265000*Qts)/(Re*fs) [uF]
source: Hobby Hifi 1/2006 p.48
this is based on a Qtb=0.9 - 1.0, sa some adjustment might be required for the very high Q of the Ciare.
while digging for this, I came across a design (HH 5/2006) for the Ciare in a closed box, 20 liters with a variovent... and 4 (four) correction RCL's.... and without series C.....
Thx. Henkjan.
I'm in the same situation...but with qts.=0,53---Fs.=52hz..Supravox 215rtf bicone.
In the end I choose a big enclosure with a little port help in MLTL design...still looking.
That's why I ask about series capacitor.
Look another design here and the performance of that enclosure ...maybe it work for my Supra and also for you....
The Manger driver have qts=0,88.
Any thoughts?
http://www.cooltune.ch/index.html
http://www.cooltune.ch/Projects/Menhir01.htm
I'm in the same situation...but with qts.=0,53---Fs.=52hz..Supravox 215rtf bicone.
In the end I choose a big enclosure with a little port help in MLTL design...still looking.
That's why I ask about series capacitor.
Look another design here and the performance of that enclosure ...maybe it work for my Supra and also for you....
The Manger driver have qts=0,88.
Any thoughts?
http://www.cooltune.ch/index.html
http://www.cooltune.ch/Projects/Menhir01.htm
Hi everybody.
Nannok and Henkjan, I greatly appreciate your help.
The SEAS drivers employed by World Design (in their dual chamber aperiodic design) are electrically and mechanically quite different to my Ciares, so I presume that a minimal experience with this kind of loading is required to successfully translate the dual chamber concept from one design to another.
More info about multichamber aperiodic boxes...
http://www.northcreekmusic.com/MAPD1.htm
By the way, despite the aperiodic-box potential for bulk saving, in my case a compact box or slimline floorstander is not a priority. Great results can be achieved with compact monitors playing small scale acoustic music but, in my humble opinion, "bigger is better" for amplified music.
I´m thinking about 100-120 liters (100hx50wx25d. aprox). I don´t have any box calculation software, so this dimensions are purely intuitive. Please, any help on this matter is very welcome.
At this point, and I´m just trying to put in order my ideas, some things are reasonably clear about the aperiodically damped loading technique...
- Aperiodic loading reduces the impedance peak and box resonances at Fs.
- Less internal stuffing is needed for aperiodic boxes than for sealed boxes. Bitumen pads can be used for panels resonances.
- Aperiodic ports ("acoustic resistors", "air springs", etc) can be made of many shapes and materials, being fiber-glass or any low-density high-porousity foam the most accesible. Commercial examples are FLOW RESISTANCE VENTS by ScanSpeak...
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=296-546
and VARIOVENTS by Dynaudio.
Materials, shapes and quantity of aperiodic ports is a question open to experimentation. About location, in the back panel just behind the main or bass driver it´s a good starting point.
I wonder if could be beneficial using aperiodic ports (or just little
"holes") in other locations (like high pressurized places in the box) and their impact on bass performance.
Best regards.
Nannok and Henkjan, I greatly appreciate your help.
The SEAS drivers employed by World Design (in their dual chamber aperiodic design) are electrically and mechanically quite different to my Ciares, so I presume that a minimal experience with this kind of loading is required to successfully translate the dual chamber concept from one design to another.
More info about multichamber aperiodic boxes...
http://www.northcreekmusic.com/MAPD1.htm
By the way, despite the aperiodic-box potential for bulk saving, in my case a compact box or slimline floorstander is not a priority. Great results can be achieved with compact monitors playing small scale acoustic music but, in my humble opinion, "bigger is better" for amplified music.
I´m thinking about 100-120 liters (100hx50wx25d. aprox). I don´t have any box calculation software, so this dimensions are purely intuitive. Please, any help on this matter is very welcome.
At this point, and I´m just trying to put in order my ideas, some things are reasonably clear about the aperiodically damped loading technique...
- Aperiodic loading reduces the impedance peak and box resonances at Fs.
- Less internal stuffing is needed for aperiodic boxes than for sealed boxes. Bitumen pads can be used for panels resonances.
- Aperiodic ports ("acoustic resistors", "air springs", etc) can be made of many shapes and materials, being fiber-glass or any low-density high-porousity foam the most accesible. Commercial examples are FLOW RESISTANCE VENTS by ScanSpeak...
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=296-546
and VARIOVENTS by Dynaudio.
Materials, shapes and quantity of aperiodic ports is a question open to experimentation. About location, in the back panel just behind the main or bass driver it´s a good starting point.
I wonder if could be beneficial using aperiodic ports (or just little
"holes") in other locations (like high pressurized places in the box) and their impact on bass performance.
Best regards.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.