our family grows
enter the Dragon: Field coil version of the 5 inch with Urushi treated phase plug and special treatment to the cone material. and a few other little inspired touches, courtesy of Teramoto-san. standing next to the D5nf.
right now I'm powering them with our DC filament supplies. We can get a maximum of 13.5 V out. And field coil draws a little over an amp. We will do a higher voltage version of the supply especially for powering field coil motors.
I know, you can't take your eyes off those boxes! I think I can claim the highest driver to box cost ratio in the world. I'm still thinking about their final resting places.
Not able to take any measurements of the field coil version has we had a break-in and someone took my notebook which is what I use to measure. Replacement coming this week, then will do some measurements. But I may need to wait until we have the high-voltage filament supply as I understand 15 V is optimum so would be nice to compare a different voltages.
will post some listing impressions later.
Regards
Brian
enter the Dragon: Field coil version of the 5 inch with Urushi treated phase plug and special treatment to the cone material. and a few other little inspired touches, courtesy of Teramoto-san. standing next to the D5nf.
right now I'm powering them with our DC filament supplies. We can get a maximum of 13.5 V out. And field coil draws a little over an amp. We will do a higher voltage version of the supply especially for powering field coil motors.
I know, you can't take your eyes off those boxes! I think I can claim the highest driver to box cost ratio in the world. I'm still thinking about their final resting places.
Not able to take any measurements of the field coil version has we had a break-in and someone took my notebook which is what I use to measure. Replacement coming this week, then will do some measurements. But I may need to wait until we have the high-voltage filament supply as I understand 15 V is optimum so would be nice to compare a different voltages.
will post some listing impressions later.
Regards
Brian
Attachments
Dave,
I started building mine, but I'm on hold at the moment while I finish up the tube amp I'm building concurrently. I'll pick it up again as soon as I finish my amp.
The design might be changed slightly based on feedback from those who have built it and are now listening to it . . . .
Mike
I started building mine, but I'm on hold at the moment while I finish up the tube amp I'm building concurrently. I'll pick it up again as soon as I finish my amp.
The design might be changed slightly based on feedback from those who have built it and are now listening to it . . . .
Mike
Re: dragon close-up
Crikey, a red cone! Now I know why he needed to obtain a supply of "dragon's blood." And that looks like a different frame too. Doesn't that guy ever sleep? Or did you put him up to it so you could have a 10th "dragon" for Kowloon? (I should think nine dragons ought to be plenty . . .)
If that motor is like other Feastrex field coil motors, I would want a power supply that could be adjusted all the way up to 24V, at least for experimentation purposes. Probably 24V is "wasted" insofar as the gap flux density ceases to rise long before you get anywhere near 24V, but I think remember reading on the president's blog that the sound continues to change as the voltage is increased, even though the gap flux density remains unchanged.
I definitely want a run-down on what they sound like because I think that's probably the sole pair of Feastrex drivers using dragon's blood. The red glow of those translucent phase plugs is a nice match . . . a "dragon green" frame to complete the "draconic" imagery would have been an interesting touch.
-- Chris
bcherry said:
Crikey, a red cone! Now I know why he needed to obtain a supply of "dragon's blood." And that looks like a different frame too. Doesn't that guy ever sleep? Or did you put him up to it so you could have a 10th "dragon" for Kowloon? (I should think nine dragons ought to be plenty . . .)
If that motor is like other Feastrex field coil motors, I would want a power supply that could be adjusted all the way up to 24V, at least for experimentation purposes. Probably 24V is "wasted" insofar as the gap flux density ceases to rise long before you get anywhere near 24V, but I think remember reading on the president's blog that the sound continues to change as the voltage is increased, even though the gap flux density remains unchanged.
I definitely want a run-down on what they sound like because I think that's probably the sole pair of Feastrex drivers using dragon's blood. The red glow of those translucent phase plugs is a nice match . . . a "dragon green" frame to complete the "draconic" imagery would have been an interesting touch.
-- Chris
it was a case of one thing leading to another. The basket is machined so that it can flush mount into the front baffle. With the D5nf a wide baffle really affects the sound positively. so I'd like to find out if anything is to be gained by removing the diffracting edge of the basket frame on the front baffle. and then there was some discussion on cone treatment and a few other details and Hal then just took the ball and kept on running....
the thing is that even at 13.5 V we are dissipating about 15 or 16 W. I measured the basket increasing about 18°C above ambient temperature. At 24 V we'd be dissipating about 48 W. I hate to think how much that will drive up the temperature. I think our supplies will have an adjustment limit of about 20 V.
I'll need to get them out of those MDF boxes first. That's just to let them run in and to give our DC supplies a shake down. IMO it is a total waste of these drivers to put them anywhere near MDF. I can hear the MDF-muffled-decay sound right away, especially with these drivers. I plan to make some cabinets from a material more familiar to the dragon -- solid bamboo wood.
Next step will be to do some measurements.
regards
Brian
bcherry said:
Yeah, the D5e and D9e series drivers are usually used in the 15-17V range and I don't think they have ever been used for any extended period of time at 24V. (Maybe never -- although I am sure they have been used beyond 20V.) I remember Hal joking about putting a 19-21V setting on the power supplies as an undocumented "Warp Drive" setting . . . sort of like overclocking a computer chip, although probably a lot less potentially dangerous to the product than overclocking.
bcherry said:
Given the stiffness of bamboo, that is VERY interesting indeed.
-- Chris
Bamboo
Brian/Chris: FWIW, I've found with enclosures for 2 different designs using "the other F" drivers, that 3/4" bamboo plywood makes a huge improvement in that ineffable "tonality" of the enclosure vs any of the more conventional sheet goods (i.e. MDF/PB/ BB ply)
A very noble material indeed, and with a cost ratio that attempts to show more respect to the Feastrex.
Brian/Chris: FWIW, I've found with enclosures for 2 different designs using "the other F" drivers, that 3/4" bamboo plywood makes a huge improvement in that ineffable "tonality" of the enclosure vs any of the more conventional sheet goods (i.e. MDF/PB/ BB ply)
A very noble material indeed, and with a cost ratio that attempts to show more respect to the Feastrex.
Bamboo ply
Poinz,
What made bamboo ply a "bummer" to work with?
Building a basic fullrange speaker box now, and have decided on ply, but not sure which kind to pick up. Leaning towards pine on the recommendation of Common Sense Audio, who sold me the drivers (Audio Nirvana Super 12s). But the mention of bamboo ply caught my attention. Thoughts?
-Roscoe
Poinz,
What made bamboo ply a "bummer" to work with?
Building a basic fullrange speaker box now, and have decided on ply, but not sure which kind to pick up. Leaning towards pine on the recommendation of Common Sense Audio, who sold me the drivers (Audio Nirvana Super 12s). But the mention of bamboo ply caught my attention. Thoughts?
-Roscoe
Re: Bamboo ply
Well, I'm not Poinz or Pano, but I do have some experience using it for speaker enclosures that require more than simple butt joinery.
It's considerably heavier and harder than most plywoods (certainly more so than pine), so it can be rather tough on tools/bits, and your toes if you drop it. With appropriately sharp tooling, it can hold a machined edge such as a bevel sharp enough to do some serious damage to your flesh. On the 3/4" material, rabbeting very deeply in the long grain direction can weaken the thinner top ply layer to the point of splitting.
It's also been my experience that staining can be very problematic.
In the general neighborhood of $300 for a 3/4" 4x8' sheet, you want to make sure your cut plan is well thought out.
But we must suffer for our art, no?
roscoeiii said:
Well, I'm not Poinz or Pano, but I do have some experience using it for speaker enclosures that require more than simple butt joinery.
It's considerably heavier and harder than most plywoods (certainly more so than pine), so it can be rather tough on tools/bits, and your toes if you drop it. With appropriately sharp tooling, it can hold a machined edge such as a bevel sharp enough to do some serious damage to your flesh. On the 3/4" material, rabbeting very deeply in the long grain direction can weaken the thinner top ply layer to the point of splitting.
It's also been my experience that staining can be very problematic.
In the general neighborhood of $300 for a 3/4" 4x8' sheet, you want to make sure your cut plan is well thought out.
But we must suffer for our art, no?
roscoeiii said:
Don't take my earlier post as an attempt at dissuasion: I'd use it again without hesitation.
With only a bit more planning and patience than normal, it's possible to make darn purdy boxes
An externally hosted image should be here but it was not working when we last tested it.
Re: Bamboo
thanks, very helpful to read about your experience and was encouraged to note your observation about tonality of the material.
Bamboo anything is a very big thing in Asia now (for about the last year and a half). you can get bamboo fiber underwear, bamboo wood chopping blocks, bamboo charcoal deodorizer bags. bamboo sheet not available on the open market according to one cabinetmaking factory here. The factory owner was telling me that it had to be purchased from the manufacturer on a contract basis, agreeing to take a certain quantity delivery each month for 12 months. about a year ago I was at his factory and he had a bamboo board sitting in a tub of water for three weeks; it hadn't absorbed any moisture at all.
I haven't seen bamboo plywood here. Here we have two kinds of bamboo wood, both are laminations. The one has a center of rectangular strips about the width and height of parquet flooring except the strips are much longer, between two quarter-inch skins of solid bamboo wood. The other kind I've seen here uses single thickness of those bamboo strips laminated widthwise. the wood is extremely hard and a sheet of it isn't actually that heavy to lift. hopefully that means it won't store energy and will give a nice clean decay that follows the music.
regards
Brian
chrisb said:
thanks, very helpful to read about your experience and was encouraged to note your observation about tonality of the material.
Bamboo anything is a very big thing in Asia now (for about the last year and a half). you can get bamboo fiber underwear, bamboo wood chopping blocks, bamboo charcoal deodorizer bags. bamboo sheet not available on the open market according to one cabinetmaking factory here. The factory owner was telling me that it had to be purchased from the manufacturer on a contract basis, agreeing to take a certain quantity delivery each month for 12 months. about a year ago I was at his factory and he had a bamboo board sitting in a tub of water for three weeks; it hadn't absorbed any moisture at all.
I haven't seen bamboo plywood here. Here we have two kinds of bamboo wood, both are laminations. The one has a center of rectangular strips about the width and height of parquet flooring except the strips are much longer, between two quarter-inch skins of solid bamboo wood. The other kind I've seen here uses single thickness of those bamboo strips laminated widthwise. the wood is extremely hard and a sheet of it isn't actually that heavy to lift. hopefully that means it won't store energy and will give a nice clean decay that follows the music.
regards
Brian
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