Hey Casey-
Very Amazing job here. . . I'm frikin jeolous
One thing that you might consider experimenting with is horn loading em. If you test the directivity in the higher frequencies you can use a horn with low density open cell foam lining the outsides to match the directivity/minimize defraction above the throat frequency.
I've been doing some experiements with Neo8 arrays and am getting much more LF extension this way. Even in smaller horns, with only two neo8's I can get down to 150 at loud levels with an active 36dB/oct XO.
I still have much more to do try though. . .
You could probably give it a shot fairly easily with some 4x8 sheets of drywall, clamped to the horn to make the angle on the horizontal axis. Carpet padding worked well in my smaller ones, and foam better. But if you like what you hear, it could be worth looking into.
The foam also seems to lower the effective freq on the horn, so they might not have to be as huge as you might think.
My thinking is that it is much eaiser to transition a ribbon to a woofer below 100hz if possible.
Very Amazing job here. . . I'm frikin jeolous
One thing that you might consider experimenting with is horn loading em. If you test the directivity in the higher frequencies you can use a horn with low density open cell foam lining the outsides to match the directivity/minimize defraction above the throat frequency.
I've been doing some experiements with Neo8 arrays and am getting much more LF extension this way. Even in smaller horns, with only two neo8's I can get down to 150 at loud levels with an active 36dB/oct XO.
I still have much more to do try though. . .
You could probably give it a shot fairly easily with some 4x8 sheets of drywall, clamped to the horn to make the angle on the horizontal axis. Carpet padding worked well in my smaller ones, and foam better. But if you like what you hear, it could be worth looking into.
The foam also seems to lower the effective freq on the horn, so they might not have to be as huge as you might think.
My thinking is that it is much eaiser to transition a ribbon to a woofer below 100hz if possible.
OK..my bad for not updating sooner. It's been a flurry of activity and I've had a hard time stopping progress in order to write about progress 😀
RyanC-
I've thought about it, but since I can go down to around 100hz without loading them the idea is in the back of the cue of things to try for now.
Turns out my transformers are not that great. I found that on certain material they had a rather obnoxious ringing problem. At first I believed it to be an interaction with the output transformers of my Fisher..but it's not. I'm back to using the power transformers for now. Thats not as bad as it sounds..they actually work amazingly well. I will be attempting another pair soon though.
I decided it was time to flesh out my electronics needed for development, so I set out to finish my crossovers, and put together some amps for bi-amping. I gutted a Kenwood KA-7200 and used it for a case and volume control. I then built the variable crossover in it...
On the bottom is the high pass that I built earlier, and at the top of the photo is a single pole passive high pass that I added. This gives me a total of 5 poles. In the middle is a 4-pole low pass that feeds a 12 dB amp. The knob next to it adjusts the bass level out.
Next up is my "Amp On A Stick " collection. My dual mono UcD400 amp...
...and my 250 watt NHT mono blocks...
Top cabin all the way 😉 Now that I have a bi-amp setup I wanted to try out the Extremis drivers OB before i went to work on the TL's. I didn't put a whole lot of thought into this baffle. Basically I just ripped the boards I had in half, folded it at a right angle, glued a bunch of ribs in, and filled the voids with urethane foam...
This is what I see from my chair now (the SpeakerLab sub is acting as a makeshift tv stand only)...
I currently have the passive 6 dB high pass set to 200hz and the active 24 dB high pass set to 100 hz. The 24 dB low pass is set to 200 hz. This overlays the ribbon for an octave before the sharp cut off.
Even though this is truly a "hack" setup right now it sounds great. So much so that I have had a paradigm shift in thinking and am going to go OB with the bass instead of a transmission line. I may still do a line, but only as a sub. The Extremis runs out of steam way sooner than the ribbon though. I'm currently considering my options, but I'm pretty sure I'll be going to 15" for the 200 hz down duties.
I'll try to post more frequently in the future..no promises though😀
RyanC-
I've thought about it, but since I can go down to around 100hz without loading them the idea is in the back of the cue of things to try for now.
Turns out my transformers are not that great. I found that on certain material they had a rather obnoxious ringing problem. At first I believed it to be an interaction with the output transformers of my Fisher..but it's not. I'm back to using the power transformers for now. Thats not as bad as it sounds..they actually work amazingly well. I will be attempting another pair soon though.
I decided it was time to flesh out my electronics needed for development, so I set out to finish my crossovers, and put together some amps for bi-amping. I gutted a Kenwood KA-7200 and used it for a case and volume control. I then built the variable crossover in it...
On the bottom is the high pass that I built earlier, and at the top of the photo is a single pole passive high pass that I added. This gives me a total of 5 poles. In the middle is a 4-pole low pass that feeds a 12 dB amp. The knob next to it adjusts the bass level out.
Next up is my "Amp On A Stick " collection. My dual mono UcD400 amp...
...and my 250 watt NHT mono blocks...
Top cabin all the way 😉 Now that I have a bi-amp setup I wanted to try out the Extremis drivers OB before i went to work on the TL's. I didn't put a whole lot of thought into this baffle. Basically I just ripped the boards I had in half, folded it at a right angle, glued a bunch of ribs in, and filled the voids with urethane foam...
This is what I see from my chair now (the SpeakerLab sub is acting as a makeshift tv stand only)...
I currently have the passive 6 dB high pass set to 200hz and the active 24 dB high pass set to 100 hz. The 24 dB low pass is set to 200 hz. This overlays the ribbon for an octave before the sharp cut off.
Even though this is truly a "hack" setup right now it sounds great. So much so that I have had a paradigm shift in thinking and am going to go OB with the bass instead of a transmission line. I may still do a line, but only as a sub. The Extremis runs out of steam way sooner than the ribbon though. I'm currently considering my options, but I'm pretty sure I'll be going to 15" for the 200 hz down duties.
I'll try to post more frequently in the future..no promises though😀
Sick. Just sick....
The commitment and engineering involved here leaves me speechless...
I am -VERY- glad I don't have metalworking as a skillset. I might be tempted to take on a "little project" the "W" would make me regret very much.....
Now to go find my jaw....it fell of the desk a couple pages back....
The commitment and engineering involved here leaves me speechless...
I am -VERY- glad I don't have metalworking as a skillset. I might be tempted to take on a "little project" the "W" would make me regret very much.....
Now to go find my jaw....it fell of the desk a couple pages back....
Having that much engineering skills I have one idea for you:
Swap transformer and power amplifier.
Result is a kind of customized current amplifier. Operating voltage is just few volts but maximum current like is like 100A or so. Ideal for a ribbon.
No problems due transformer design since it´s before PA and PA works as a buffer which gets feedback over extremely small resistor in series with the ribbon.
Haven´t seen such a design before.
Swap transformer and power amplifier.
Result is a kind of customized current amplifier. Operating voltage is just few volts but maximum current like is like 100A or so. Ideal for a ribbon.
No problems due transformer design since it´s before PA and PA works as a buffer which gets feedback over extremely small resistor in series with the ribbon.
Haven´t seen such a design before.
Hi ruerose-
Guilty as charged 😉
APi-
I'm not sure I understand what your suggesting here. A low voltage current amp ? Truth is all that "sand" in my audio chain is giving me hives 😀. I went this route simply because of ease and expense. Once I finalize my crossover points/slopes I plan on building a triode push-pull amp with the high pass elements integrated passively between stages.
Casey
Guilty as charged 😉
APi-
I'm not sure I understand what your suggesting here. A low voltage current amp ? Truth is all that "sand" in my audio chain is giving me hives 😀. I went this route simply because of ease and expense. Once I finalize my crossover points/slopes I plan on building a triode push-pull amp with the high pass elements integrated passively between stages.
Casey
Yep. A current amp that can push/pull signal as a (high) current into any load. Even 0 ohm. Power don´t need to be that big due low voltage.
Anyway... Lorentz force is F=I x B. To reproduce audio signal with a ribbon as pure as possible you must control current, not voltage. Normal amplifier and impedance transformer can be good enough but not as hifi as the rest your system 🙂
A voltage amplifier is not perfect due cable/ribbon reactances and EMF because the ribbon move in the strong magnetic field. Trefefore EMF cause distortion. The stronger field and more sensitive ribbon, the more distortion.
Just an idea to be even more hifi. 🙂
Anyway... Lorentz force is F=I x B. To reproduce audio signal with a ribbon as pure as possible you must control current, not voltage. Normal amplifier and impedance transformer can be good enough but not as hifi as the rest your system 🙂
A voltage amplifier is not perfect due cable/ribbon reactances and EMF because the ribbon move in the strong magnetic field. Trefefore EMF cause distortion. The stronger field and more sensitive ribbon, the more distortion.
Just an idea to be even more hifi. 🙂
remember V=IR,
So substituting in the Lorenz equation gives
F=(V/R)*B
The primary advantage of ribbons is the reduced back EMF into the amp, that enables the amp to control displacement of the ribbon.
Doesnt matter two hoots if it is current or voltage.
Owen
So substituting in the Lorenz equation gives
F=(V/R)*B
The primary advantage of ribbons is the reduced back EMF into the amp, that enables the amp to control displacement of the ribbon.
Doesnt matter two hoots if it is current or voltage.
Owen
Casey, my brain is out of town for the day, so I'm not sure if we discussed this before at the small audio gathering last year (have there been anymore?), but have you reconsidered using Magnepan panels for bass duties? I've had very good experience using Tympani bass panels with my pseudo-true ribbons (despite the less than satisfactory crossover setup) and if you're now considering OBs, maybe you'd prefer going all the way to planars and avoid any pointsource to linesource disconnect in coherence? Do you still have those MG-IIs? If so, it might be fun to set them up beside your ribbons, using your crossover and giving the combination a listen to hear how you like it.
- JP
APi-
owen-
I'm siding with owen on this one😉 I have looked at direct drive for the ribbon simply to eliminate the need for a transformer. Even though from a theoretical standpoint it would seem like the better option, the real world limitations of the available output devices (namely non linear "on" resistance) realizing the promised performance would be very dificult. Besides..I'm a toob guy 😀
JP-
Nope..I no longer have any Maggies. My preliminary experimenting has bolstered my belief that going line to point sources at the frequency I'm attempting is doable. Besides ,the tall baffle converts the point source into a faux line to some extent.
I'm looking at this driver as an option...
http://www.aespeakers.com/phpbb2/viewtopic.php?f=3&t=536
Email me JP..I need to get you over to have a listen.
Casey
owen-
I'm siding with owen on this one😉 I have looked at direct drive for the ribbon simply to eliminate the need for a transformer. Even though from a theoretical standpoint it would seem like the better option, the real world limitations of the available output devices (namely non linear "on" resistance) realizing the promised performance would be very dificult. Besides..I'm a toob guy 😀
JP-
Nope..I no longer have any Maggies. My preliminary experimenting has bolstered my belief that going line to point sources at the frequency I'm attempting is doable. Besides ,the tall baffle converts the point source into a faux line to some extent.
I'm looking at this driver as an option...
http://www.aespeakers.com/phpbb2/viewtopic.php?f=3&t=536
Email me JP..I need to get you over to have a listen.
Casey
I've tried emailing you three different ways, but I believe the email addys I had for you are out of date.valveitude said:
Anyways, if you wish to try Maggie panels, I can use my backup Tannoys and spare my panels for a couple of weeks worth of experimentation.
As for those 15" woofers, are you aware of the DPL-15?
Have you thought about showing off your ribbons at
The Puget Sound! DIY speaker contest ?
Hey JP-
My email client has been wacking out and tossing my email into the "Spam" bin from time to time...I found yours last night.
I'll email you when I get off work.
Casey
My email client has been wacking out and tossing my email into the "Spam" bin from time to time...I found yours last night.
I'll email you when I get off work.
Casey
Nice baffles 😀
Have you thought about basing your triode amp on an OTL-type design, with an autoformer or transformer for impedance matching? I would imagine that it would make finding, or winding, a suitable transformer easier - the lower output Z would need a lower turns ratio.
There are several designs out there - or you could design something yourself. I think that for a low output z amplifier, the huge 6c33c would work nicely.
James
Have you thought about basing your triode amp on an OTL-type design, with an autoformer or transformer for impedance matching? I would imagine that it would make finding, or winding, a suitable transformer easier - the lower output Z would need a lower turns ratio.
There are several designs out there - or you could design something yourself. I think that for a low output z amplifier, the huge 6c33c would work nicely.
James
Building up steam
Valveitude
I got me hooked again. I have begun scouting for magnets....
I curious- how much movement do you get in the middle of the ribbon ? On my commercially made ribbons crossing over at plus minus 1000 Hz I can hardly see movement but on my 1 meter long DIY ribbon I can easily get 10mm movement.
The problem is that the movement stretches the foil and it eventually breaks. This time I am going to use a Behringer digital crossover to adjust the slopes but it still remains a concern.
Regards
Jozua
Valveitude
I got me hooked again. I have begun scouting for magnets....
I curious- how much movement do you get in the middle of the ribbon ? On my commercially made ribbons crossing over at plus minus 1000 Hz I can hardly see movement but on my 1 meter long DIY ribbon I can easily get 10mm movement.
The problem is that the movement stretches the foil and it eventually breaks. This time I am going to use a Behringer digital crossover to adjust the slopes but it still remains a concern.
Regards
Jozua
jrevillug-
Aren't they a beaut 😀. I'm amazed at how good they sound in spite of how "wrong" they are. Thats been the main reason I haven't posted any progress of late...there hasn't been any to speak of. I can't seem to pull myself away from listening to them.
The progress that has been made is in the future design. I've been working on a new baffle design, here is the plan view (from the top)...
They will have an effective width of around 45" giving me an Fp of about 300 Hz, and an Fe in the neighborhood of 100 Hz. I'm hoping I can be clever and have the x-over start early taking care of the baffle step and highpass at the same time.
For the bottom end I have purchased 4 of these (two for each side)...
http://www.audiocircle.com/circles/index.php?topic=47277.0
I experimented with bass placement using my Paradigms and discovered that due to the low x-over point placement wasn't that critical. I plan on having one on each side at the bottom at 45 deg. This way I can have a curved grill cloth that matches the baffle contour. The sims predict they will have an F3 at 25 Hz.
As for the OTL approach, I have looked into basing my amp around a low impedance tube. Currently the 6AS7 is in the cue.
Jozua-
At normal levels I have very little movement, but they can get a little squirrely at high volumes. I found that felt "bump stops" controls this though.
Casey
Aren't they a beaut 😀. I'm amazed at how good they sound in spite of how "wrong" they are. Thats been the main reason I haven't posted any progress of late...there hasn't been any to speak of. I can't seem to pull myself away from listening to them.
The progress that has been made is in the future design. I've been working on a new baffle design, here is the plan view (from the top)...
They will have an effective width of around 45" giving me an Fp of about 300 Hz, and an Fe in the neighborhood of 100 Hz. I'm hoping I can be clever and have the x-over start early taking care of the baffle step and highpass at the same time.
For the bottom end I have purchased 4 of these (two for each side)...
http://www.audiocircle.com/circles/index.php?topic=47277.0
I experimented with bass placement using my Paradigms and discovered that due to the low x-over point placement wasn't that critical. I plan on having one on each side at the bottom at 45 deg. This way I can have a curved grill cloth that matches the baffle contour. The sims predict they will have an F3 at 25 Hz.
As for the OTL approach, I have looked into basing my amp around a low impedance tube. Currently the 6AS7 is in the cue.
Jozua-
At normal levels I have very little movement, but they can get a little squirrely at high volumes. I found that felt "bump stops" controls this though.
Casey
6C33C ...
Watts, mo music 😉
Drive the sucker(s) using an EL34's, and a nice big interstage transformer...
Have fun
Owen
Watts, mo music 😉
Drive the sucker(s) using an EL34's, and a nice big interstage transformer...
Have fun
Owen
Re: Building up steam
I am crashing my head against the wall about that one too. It seems to me ribbons move so much because we let them do so, by means of corrugation and improper highpass crossovering. I would still say 1 m long ribbons are pretty much mid high transducers, not at all usable below cca 600 Hz, or so. From my experience with shorter corrugated ribbons which I later converted to flat foils, after modification they calmed down a lot (no wonder). RAAL and Perfect8 don`t use corrugated (pleated) diaphragms at all (only some sort of printed pattern on the foil), yet seem to achieve excellent results nonetheless.
Here is a short excerpt on corrugated vs noncorrugated ribbons:
http://www.purebits.com/ribbonloudspeakers.html
Jozua said:
I am crashing my head against the wall about that one too. It seems to me ribbons move so much because we let them do so, by means of corrugation and improper highpass crossovering. I would still say 1 m long ribbons are pretty much mid high transducers, not at all usable below cca 600 Hz, or so. From my experience with shorter corrugated ribbons which I later converted to flat foils, after modification they calmed down a lot (no wonder). RAAL and Perfect8 don`t use corrugated (pleated) diaphragms at all (only some sort of printed pattern on the foil), yet seem to achieve excellent results nonetheless.
Here is a short excerpt on corrugated vs noncorrugated ribbons:
http://www.purebits.com/ribbonloudspeakers.html
owen-
I'm looking at that one as well..just don't know if I need the heaters in my living room 😀
fivestring-
It is an issue, however there are means to control it. First, as you point out, a proper high pass. I found that a dual slope with a very steep second pole an octave or so below the x-over point does wonders. The majority of the ribbon movement is caused by infra-sonic garbage. I also found that when playing loud and the ribbon wanted to pull out of the gap I could barely touch it to push it back in. This led me to the conclusion that the force on the ribbon was very small indeed. I found that felt "bump stops" cured the problem with no noticible sonic side effects.
Casey
I'm looking at that one as well..just don't know if I need the heaters in my living room 😀
fivestring-
It is an issue, however there are means to control it. First, as you point out, a proper high pass. I found that a dual slope with a very steep second pole an octave or so below the x-over point does wonders. The majority of the ribbon movement is caused by infra-sonic garbage. I also found that when playing loud and the ribbon wanted to pull out of the gap I could barely touch it to push it back in. This led me to the conclusion that the force on the ribbon was very small indeed. I found that felt "bump stops" cured the problem with no noticible sonic side effects.
Casey
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