Full Range?
Thanks for this thread. It's been a splendid read. I have a few questions; please forgive my various ineptitudes in this field.
About 15 years ago a friend and I, in a fit of late teenage bravado, built a speaker with something like 8 parallell ribbons, about 2 cm wide, about 1.5 meters long, using 6 micron aluminum. These were suspended in the middle of a large piece of particle board -- ca 2 meters high, 1 meter wide. There was no enclosure. We used several hundred ferrite magnets, 4 cm high, 2 cm wide, 0.5 cm deep. The whole thing ended up weighing so much it could just barely be physically moved.
The experiment was to see how close we could get to a full-range, transformer-free, crossover-free ribbon-only speaker. We ignored tons of aspets of loudspeaker design that, I suspect, in reality made the speaker quite a bad one... but the experiment was largely successful. To my virgin ears, music radiated from this creation sounding more or less like it was all there.
Many years later, living on a different continent, I am trying to figure out how successful we actually were. Is a 2x1 meter baffle actually sufficient to output any significant bass below, say, 50 Hz? Are multiple parallell long ribbons actually more linear than a single element of the same length, and if so, why?
I'm struck by an urge to duplicate this old experiment of ours. I think I could afford thin neodynium magnets this time; perhaps something like
http://www.kjmagnetics.com/proddetail.asp?prod=BZX082&cat=11
but I am stuck on the foil issue. There are several references to sources for foil in this thread, but none of them are fully satisfying me. Is there no place that stocks retail-style quantities of very thin gauge (I'd really prefer < 10 micron) foil tape? Sheets are too short. McMaster does not seem to go below 18 microns or so.
More than anything, I'd like to see somebody dismiss the whole idea as naive, so I don't have to build it to find out it doesn't really hold up under measurements! 🙂
What do you think?
Thanks for this thread. It's been a splendid read. I have a few questions; please forgive my various ineptitudes in this field.
About 15 years ago a friend and I, in a fit of late teenage bravado, built a speaker with something like 8 parallell ribbons, about 2 cm wide, about 1.5 meters long, using 6 micron aluminum. These were suspended in the middle of a large piece of particle board -- ca 2 meters high, 1 meter wide. There was no enclosure. We used several hundred ferrite magnets, 4 cm high, 2 cm wide, 0.5 cm deep. The whole thing ended up weighing so much it could just barely be physically moved.
The experiment was to see how close we could get to a full-range, transformer-free, crossover-free ribbon-only speaker. We ignored tons of aspets of loudspeaker design that, I suspect, in reality made the speaker quite a bad one... but the experiment was largely successful. To my virgin ears, music radiated from this creation sounding more or less like it was all there.
Many years later, living on a different continent, I am trying to figure out how successful we actually were. Is a 2x1 meter baffle actually sufficient to output any significant bass below, say, 50 Hz? Are multiple parallell long ribbons actually more linear than a single element of the same length, and if so, why?
I'm struck by an urge to duplicate this old experiment of ours. I think I could afford thin neodynium magnets this time; perhaps something like
http://www.kjmagnetics.com/proddetail.asp?prod=BZX082&cat=11
but I am stuck on the foil issue. There are several references to sources for foil in this thread, but none of them are fully satisfying me. Is there no place that stocks retail-style quantities of very thin gauge (I'd really prefer < 10 micron) foil tape? Sheets are too short. McMaster does not seem to go below 18 microns or so.
More than anything, I'd like to see somebody dismiss the whole idea as naive, so I don't have to build it to find out it doesn't really hold up under measurements! 🙂
What do you think?
Re: Full Range?
all foils is the only place I know of that sells it... they have 6.8 micron and it's $400 for 1000 feet at any width
Zell said:
all foils is the only place I know of that sells it... they have 6.8 micron and it's $400 for 1000 feet at any width
I think it comes down to suface driven surface area and excursion.
Two square meters is a huge suface area but I suspect only some fraction will be actual driven ribbon surface area. Assuming you can get a strong enough field across the ribbons I think you could get significant bass out of something like that. On other threads I've heard of at least one person going down to 200hz at very good levels with a single ribbon ~ 1 inch wide.
I don't know about multiple thin strips of aluminum being more linear but I do think it would not be very practical to try to get a significant field across a single ribbon a foot wide.
The magnets you show are interesting and it's certainly convenient to have them so long. I think if you look around you may be able to get magnets that will get you more field strength per linear inch per dollar - but they will also probably be shorter magnets.
If this is a proof of concept, I would not worry too much about starting out with the thinnest foil. The thickness affects the weight which really only affects efficiency. I would suggest you start out with something available and cheap and then go for the skinny stuff after you've proven the concept of a ribbon subwoofer 😉
I say go for it but make sure you keep us informed. It would great to have another person actually building DIY ribbons.
Regards,
Denis
Two square meters is a huge suface area but I suspect only some fraction will be actual driven ribbon surface area. Assuming you can get a strong enough field across the ribbons I think you could get significant bass out of something like that. On other threads I've heard of at least one person going down to 200hz at very good levels with a single ribbon ~ 1 inch wide.
I don't know about multiple thin strips of aluminum being more linear but I do think it would not be very practical to try to get a significant field across a single ribbon a foot wide.
The magnets you show are interesting and it's certainly convenient to have them so long. I think if you look around you may be able to get magnets that will get you more field strength per linear inch per dollar - but they will also probably be shorter magnets.
If this is a proof of concept, I would not worry too much about starting out with the thinnest foil. The thickness affects the weight which really only affects efficiency. I would suggest you start out with something available and cheap and then go for the skinny stuff after you've proven the concept of a ribbon subwoofer 😉
I say go for it but make sure you keep us informed. It would great to have another person actually building DIY ribbons.
Regards,
Denis
random question to dhenry:
I just ordered 2 of those ferrite cores for xfrmers that you used and I have a few questions before I start winding
this is sort of a dumb question but how exactly do you wire a transformer?
I understand all that trifilar stuff and will do that with mine... but I don't understand the primary and secondary thing
from what I can gather you simply wrap the series trifilar primary around say 51 times like you did (18 per turn) and the entry wire is postive the out wire is negative and this is hooked up to the high voltage line from the amplifier?
and with the secondary is 9 paralleled wires now this is wrapped our say 9 turns like what you did (or whatever for me using those equations) and the start of the wire is positive and the other is the negative to the speaker?
I don't see how this would work but it's the only thing that makes sense...
I just ordered 2 of those ferrite cores for xfrmers that you used and I have a few questions before I start winding
this is sort of a dumb question but how exactly do you wire a transformer?
I understand all that trifilar stuff and will do that with mine... but I don't understand the primary and secondary thing
from what I can gather you simply wrap the series trifilar primary around say 51 times like you did (18 per turn) and the entry wire is postive the out wire is negative and this is hooked up to the high voltage line from the amplifier?
and with the secondary is 9 paralleled wires now this is wrapped our say 9 turns like what you did (or whatever for me using those equations) and the start of the wire is positive and the other is the negative to the speaker?
I don't see how this would work but it's the only thing that makes sense...
Re: Re: Re: Full Range?
I could go for that... if it was thinner 🙁
I can start one if you like
we can actually get a 10 foot wide roll of it for $400 too if someone knows of somewhere to cut it .... cutting from them costs as much as the whole roll would which I think is ridiculous
dhenryp said:
I could go for that... if it was thinner 🙁
I can start one if you like
we can actually get a 10 foot wide roll of it for $400 too if someone knows of somewhere to cut it .... cutting from them costs as much as the whole roll would which I think is ridiculous
Re: Re: Re: Full Range?
honestly I was thinking about this... and it's a really good idea to do this...
I'm thinking that we could easily sell this for $20 per 100 feet if we get a place to cut it...
100 feet will last us all a long time
you think 20 people would be interested in this?
I emailed them about maybe a 5000 foot roll of 1" and .5" widths... they quoted me awhile back that it's $400 for a .5" and 2000 feet (just looked at the email).... but he was saying that it's actually more expensive to cut it to that width than to just buy a 20" wide roll ... and I know everyone would want a different width
maybe get that 20" cut into .5", .75", 1", 2", and any other widths that seem popular...
I'm willing to chip in $20 for such a rare item, heck even $60 to have like some 2", 1" and .5"
dhenryp said:
honestly I was thinking about this... and it's a really good idea to do this...
I'm thinking that we could easily sell this for $20 per 100 feet if we get a place to cut it...
100 feet will last us all a long time
you think 20 people would be interested in this?
I emailed them about maybe a 5000 foot roll of 1" and .5" widths... they quoted me awhile back that it's $400 for a .5" and 2000 feet (just looked at the email).... but he was saying that it's actually more expensive to cut it to that width than to just buy a 20" wide roll ... and I know everyone would want a different width
maybe get that 20" cut into .5", .75", 1", 2", and any other widths that seem popular...
I'm willing to chip in $20 for such a rare item, heck even $60 to have like some 2", 1" and .5"
I have several rolls of 5.8 micron thick, 0.7" wide, pure Aluminum foil. The original cost was about $50/pound... guessing about 60,000 inches (5,000 ft) long per pound.
I am willing to sell 1 of the smaller rolls at cost + ship to help diyAudio folks experiment.
I gave about 20 ft to dhenryp to experiment with, and you can get his feedback on using 5.8u Al foil.
I am willing to sell 1 of the smaller rolls at cost + ship to help diyAudio folks experiment.
I gave about 20 ft to dhenryp to experiment with, and you can get his feedback on using 5.8u Al foil.
Maybe a person could get the roll and take on the responsibility of mailing lengths to all interested. This would have to be one of the simplest group buys !
Variac said:
I'm picking up a roll tomorrow from a capacitor site someone pointed me to.... anybody interested post here
also a roll of 3 micron metallized mylar...
I'll send the lengths for free to anyone actually.... only shipping if it's a large amount or to another country
I did try out the foil linesource sent and it ceratinly improved efficiency. Measured with an RS sound meter, it was at least 3db better and maybe as much as 4-5db. I didn't notice a change in frequency response but given I can't hear much above 15-16k you can take that with a grain of salt. I did find it quite a bit more difficult to handle. I'm sure I would get the hang of it if I spent more time at it. I went back to my thicker foil until I was sure I needed the efficiency. Initial measurements with my ribbon show the ribbons ,with the thick foil, to be just about a perfect match to the lmid/woof ine source efficiency. I've put aside the thinner foil for now. I would be interested in getting some wider foil (1 inch +-) because Paul's beautiful speaker has got me thinking about trying for something wider range.
I can send you some Dhenry I just ordered some...
just pay post if you want alot...
I have 4.3 micron and 5.8 micron
the 4.3 micron is 1 5/16" inch wide
the 5.8 micron is 1 1/8" wide
both are pure aluminum
I think I'm getting 2 lbs of each... which is roughtly 10000 feet each 😱
just pay post if you want alot...
I have 4.3 micron and 5.8 micron
the 4.3 micron is 1 5/16" inch wide
the 5.8 micron is 1 1/8" wide
both are pure aluminum
I think I'm getting 2 lbs of each... which is roughtly 10000 feet each 😱
Thanks, that's very generous. I'm happy to pitch in on the cost as well as postage. Please send me an e-mail so I can respond and work out the details.
Regards,
Denis
Regards,
Denis
Re: Re: Re: Re: Full Range?
If you really think they'd be up for cutting a 20" roll into lots of different rolls of different widths without charging an enormous amount of money for it, I'd happily take a total of 4" or so at various widths... I think we'd have a better chance selling off full rolls of e.g. 2000 feet at certain widths than trying to spool off a few hundred feet at a time.
For what it's worth, I just got this email from all-foils:
So, err, if I read that right, she wants to sell me $2,900 worth of 2" foil. Your offer is better. 🙂
Audiophilenoob said:
If you really think they'd be up for cutting a 20" roll into lots of different rolls of different widths without charging an enormous amount of money for it, I'd happily take a total of 4" or so at various widths... I think we'd have a better chance selling off full rolls of e.g. 2000 feet at certain widths than trying to spool off a few hundred feet at a time.
For what it's worth, I just got this email from all-foils:
So, err, if I read that right, she wants to sell me $2,900 worth of 2" foil. Your offer is better. 🙂
Re: Re: Re: Re: Re: Full Range?
lol yes... I got that quote as well...
since I found foil all I have is 5.8 microns at 1 1/8"
and 4.3 microns at 1 5/16".... if you want any of this... it's free besides postage...
I think I'm ending up with over 10,000 feet of each
also that foil from them is around 28.5 gauge or 6.5 microns
Zell said:
lol yes... I got that quote as well...
since I found foil all I have is 5.8 microns at 1 1/8"
and 4.3 microns at 1 5/16".... if you want any of this... it's free besides postage...
I think I'm ending up with over 10,000 feet of each
also that foil from them is around 28.5 gauge or 6.5 microns
