Re: 91DB
I worried that confusion concernng this might be an issue. The numbers Feastrex was quoting were based on measurements that came from a respected measurement company in Japan, but I suspect that the method of testing they were using may have different from that used overseas. Add in the factor that we are talking about 16 ohm voice coils and there is plenty of room for "95dB" to "equal" 91dB. Especially when you keep in mind that with fullrange drivers the generally rising frequency response curve means you might have a nominally higher sensitivity rating than in the area of most concern with a low-wattage amplifier -- the bass region.
I wonder if it would make any difference if you ran your amp into one of the Nelson Pass amps and then into the Feastrex drivers.
-- Chris
Phil Townsend said:
I worried that confusion concernng this might be an issue. The numbers Feastrex was quoting were based on measurements that came from a respected measurement company in Japan, but I suspect that the method of testing they were using may have different from that used overseas. Add in the factor that we are talking about 16 ohm voice coils and there is plenty of room for "95dB" to "equal" 91dB. Especially when you keep in mind that with fullrange drivers the generally rising frequency response curve means you might have a nominally higher sensitivity rating than in the area of most concern with a low-wattage amplifier -- the bass region.
I wonder if it would make any difference if you ran your amp into one of the Nelson Pass amps and then into the Feastrex drivers.
-- Chris
First Watt
Chris thank you...I am quite sure that if I were to use Nelson's First Watt F4 amp that it would do a very fine job.
However I believe it sits at about $3000. USD.
But The 845 amp is something I can build with relative ease. Plus I have most of the parts required. ( Well, I don't that big Mike output Iron) Tubes, caps, resistors, wire, low DCR supply etc. Check the photo for BIG IRON power supply. One of these for the left and one for the right....42 pounds each 1000volts at the center tap at 1.5 amps...YES! These will run a 845 and make them scream.
Joe has agreed to push the smoke back into my lifeless form should the need arise.
Now if some soul is willing to pass on a F4 my way...I would of course send many happy prayers/chants to the do gooder.
Chris thank you...I am quite sure that if I were to use Nelson's First Watt F4 amp that it would do a very fine job.
However I believe it sits at about $3000. USD.
But The 845 amp is something I can build with relative ease. Plus I have most of the parts required. ( Well, I don't that big Mike output Iron) Tubes, caps, resistors, wire, low DCR supply etc. Check the photo for BIG IRON power supply. One of these for the left and one for the right....42 pounds each 1000volts at the center tap at 1.5 amps...YES! These will run a 845 and make them scream.
Joe has agreed to push the smoke back into my lifeless form should the need arise.
Now if some soul is willing to pass on a F4 my way...I would of course send many happy prayers/chants to the do gooder.
Attachments
Re: First Watt
So build one using the full schematics Nelson published for about $200. Like a good friend did. Dead-easy build about sums it up. If you still can't cope yourself, get a local radio-ham or similar to make it for you, for a suitable commission (a few 6 packs is usually a good offer).
Phil Townsend said:
So build one using the full schematics Nelson published for about $200. Like a good friend did. Dead-easy build about sums it up. If you still can't cope yourself, get a local radio-ham or similar to make it for you, for a suitable commission (a few 6 packs is usually a good offer).
Hi Christopher,
I recently found out that Feastrex now also distributes Alexander's Raal Ribbons. Apparently Mr. Teramoto formed a friendship with Alex at the recent RMAF.
Nov. '07 news
It would be intresting if there would be a future joint-project between the two... A D9 permendur whizzerless version + custom Raal on top maybe? In MLTL or BLH etc...
How efficient are those monster D9's?
Anyway, I could never afford such drivers, but one could dream.
I recently found out that Feastrex now also distributes Alexander's Raal Ribbons. Apparently Mr. Teramoto formed a friendship with Alex at the recent RMAF.
Nov. '07 news
It would be intresting if there would be a future joint-project between the two... A D9 permendur whizzerless version + custom Raal on top maybe? In MLTL or BLH etc...
How efficient are those monster D9's?
Anyway, I could never afford such drivers, but one could dream.
fred76 said:
You know, I'm not sure. I could be wrong but if I recall correctly they have so far built and shipped just one pair of the D9 drivers and I don't think they measured them. However, the D9 uses the exact same motor as the D6, which Feastrex never brought to market as they concluded the motor was actually too powerful for a 6.5-inch driver. The D6 was measured to be 104dB, but that's into 16 ohms, so 101dB might be more like it. As I wrote a few posts back, Feastrex had the measurements taken by a reputable company with very advanced equipment, but for some reason there is a discrepancy between those measurements and what Joe Cohen came up with when he took measurements of some drivers recently.
-- Chris
More bullets into my tortured soul
As long as we're crossing the bridge of sighs, we might as well go the whole way. Here are some more of Feastrex's latest bullets into my tormented soul.
First up is a new one-off pair of Phosphor Bronze phase plugs coated with a traditional Japanese red Urushi lacquer. I have not heard these but people who have were quite shocked that simply painting this Urushi lacquer on a pair of phase plugs could have such a pronounced effect on the sound. I'm not even going to bother trying to describe the sound of something that I have not heard, but will simply leave it at relaying the fact that people who heard them were deeply impressed. Traditonal red over phosphor bronze is shown on the left; unpigmented urushi over plastic resin is shown on the right.
Next up are the parts that will become the all-Permendur D9e-III field coil drivers using milled Phosphor Bronze frames.
Note the square wire used in the coil. Only the certifiably insane, or people with a determined wish to join the merry ranks of the certifiably insane, need apply.
. . . Sigh . . .
-- Chris
As long as we're crossing the bridge of sighs, we might as well go the whole way. Here are some more of Feastrex's latest bullets into my tormented soul.
First up is a new one-off pair of Phosphor Bronze phase plugs coated with a traditional Japanese red Urushi lacquer. I have not heard these but people who have were quite shocked that simply painting this Urushi lacquer on a pair of phase plugs could have such a pronounced effect on the sound. I'm not even going to bother trying to describe the sound of something that I have not heard, but will simply leave it at relaying the fact that people who heard them were deeply impressed. Traditonal red over phosphor bronze is shown on the left; unpigmented urushi over plastic resin is shown on the right.
An externally hosted image should be here but it was not working when we last tested it.
Next up are the parts that will become the all-Permendur D9e-III field coil drivers using milled Phosphor Bronze frames.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Note the square wire used in the coil. Only the certifiably insane, or people with a determined wish to join the merry ranks of the certifiably insane, need apply.
. . . Sigh . . .
-- Chris
Re: Re: First Watt
Chris, that really looks cool. That's a lot of copper replacing a lot of iron from the nf model. I can see how the flux in the gap goes way up.
Scott, I think Phil gets hives if he even touches an IC. Wood, glass, iron and litz only, right Phil?
But thanks for the tip, I would like to see the F4 plans (thanks to Nelson for publishing too.) An amp designer friend has been threatening to build current source amps for me to use with these, but alas they haven't arrived yet - imagine that!
I'm pretty darn happy with 100wpc PP Manleys on the D5nf. They are as fast as the speakers, so all the thrill comes through easily, and plenty of power. No tubey goo. I think it's a good match. Agon used for about $3k. Lots of 100w tube amps out there, ripe for tweaking.
I still wanna try the autoformers on the Altmann. I think it is the Feastrex of amps, but very weird little thing.
The 5" don't really need a tweeter. Toe is like a treble control, and there is plenty of headroom if you're a little deaf - just aim it straight on. That's too much for me. But it is still pure and natural highs.
Rich
Chris, that really looks cool. That's a lot of copper replacing a lot of iron from the nf model. I can see how the flux in the gap goes way up.
Scottmoose said:
Scott, I think Phil gets hives if he even touches an IC. Wood, glass, iron and litz only, right Phil?
But thanks for the tip, I would like to see the F4 plans (thanks to Nelson for publishing too.) An amp designer friend has been threatening to build current source amps for me to use with these, but alas they haven't arrived yet - imagine that!
I'm pretty darn happy with 100wpc PP Manleys on the D5nf. They are as fast as the speakers, so all the thrill comes through easily, and plenty of power. No tubey goo. I think it's a good match. Agon used for about $3k. Lots of 100w tube amps out there, ripe for tweaking.
I still wanna try the autoformers on the Altmann. I think it is the Feastrex of amps, but very weird little thing.
The 5" don't really need a tweeter. Toe is like a treble control, and there is plenty of headroom if you're a little deaf - just aim it straight on. That's too much for me. But it is still pure and natural highs.
Rich
cdwitmer said:
Rubbish. You can never have too much motor power.
(Assuming the rest of the damned thing doesn't fly apart, but that's the job of the designer).That's only partly tongue in cheek. Looking at the measurements of the D5nf & D9nf, their relative motor power does not seem to be especially remarkable. Personally, I tend to like slightly lower Q units as you have more flexibility.
Scottmoose said:
Rubbish. You can never have too much motor power.
Well, since I have never built a fullrange driver, I won't presume to speak with any authority, but from what I hear, the decision was not based purely on the strength of the motor per se (and therefore I apologize if my way of putting gave the wrong impression), but also on the diameter of the voice coil and other factors, taken together. After having built several 6.5-inch prototypes, they thought the motor would be more successful as a 9-inch driver, and they feel the results have affirmed the correctness of their decision.
Also, that motor was originally designed by someone who is no longer associated with Feastrex, and who left very early on. (Several of the 6.5-inch drivers that he built on the motors in question did literally fly apart, by the way.
That's one of the reasons why Feastrex let him go. If I recall correctly those drivers had a Qts of about 0.13 -- perhaps not unprecedented but definitely on the powerful side.) -- Chris
Scottmoose said:
Perhaps not a perfect analogy, but listening to some of those early 6.5-inch drivers could have been compared to this:
http://www.youtube.com/watch?v=MoqhfrOq5uQ
Plenty of power, yes, and an experience you're not likely to soon forget. The ones with two drivers in a single enclosure were especially so.
-- Chris
talawalla said:
Joe,
It has come to my attention that the sensitivity of the field coil drivers can vary by as much as 2dB depending on the various combinations of field coil polarity and voice coil polarity that are possible. (A total of four combinations are possible.) Did you try all four polarity combinations in your sensitivity tests for the field coil drivers? Thanks,
-- Chris
gelatomonster said:
What model are we talking about here? What size listening room, what kind of music and what volume levels?
If you want to use the D5nf in a large room to reproduce at realistic volume levels the Great Gate of Kiev from the orchestral version of Mussorgsky's Pictures at an Exhibition, those amplifiers are not the ones to be using.
However, there are circumstances under which they would be quite acceptable. So it really comes down to the specifics of your situation.
You may recall my friend is very happy with his 5-inch Feastrex drivers powered by the WE205D, which also has quite a small output.
http://www.diyaudio.com/forums/showthread.php?postid=1462946#post1462946
But it is also true that he is not listening in a large room, nor at high volume levels.
-- Chris
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