cdwitmer said:
And i'm not sure how really good it is... the 1st time i heard them i said they sounded like they might have potential in a room that didn't bury so much detail, the next time i heard them they were set up by themselves (and not a great room) and the system was painful... those drivers have since been relegated to a "closet" and someone could well rescue them for a pittance.
dave
Joe,
I think Mr. Teramoto was planning to implement various changes anyway, but the 9-inch Type I (i.e., all-iron one-piece integral yoke + pole piece) field coil driver for William's friend reflects changes in the manufacturing process (such as a different annealing process) along the lines recommended by Aleksandar Radisavljevic' of RAAL at RMAF. I still don't know all the details about what Feastrex has started to do differently with their Type I field coil drivers. They had a hard time finding someone who would even attempt some of the things that they wanted. Finally one of Mr. Teramoto's suppliers developed some new equipment that could be used to do the necessary work, but even Mr. Teramoto does not have all the details on that: people in the metalworking industry are very secretive about proprietary annealing and machining processes that give them a distinct advantage over their competitors. (These tiny, specialized companies can't afford to get and defend patents so they keep their secrets to themselves.)
From what Mr. Teramoto tells me, your Type II drivers with their Permendur pole piece and top plate still have a significant edge, but the Type I drivers did get a definite performance boost from the assorted changes that have been implemented. Looking at the assembled motor from the outside, aside from a different color (due to the different annealing process) there are not a lot of differences that are immediately obvious to the eye. The tolerances are all even tighter than before -- so tight that the assembly of parts which abut each other ends up removing some of the electroplating at the interface. Mr. Teramoto is still in the process of assembling the drivers, but he did find that the new motors run cooler. He has to bump up the voltage by about 2V to get the temperature up to where it was with the previous version of the motor. When he put the lower voltage into them, the motors remained so cool to the touch that at first he doubted they were even getting power. I'm not sure just what that means in terms of performance, but improved operating efficiency can only be a good thing, I should think.
The proof is in the playing . . . I think these new drivers will start testing their lungs next week. I very much doubt I'll have an opportunity to hear them before they are shipped out but I'll pass on any comments I get from Mr. Teramoto. Beyond that I think we'll have to depend on William to give us a report on how they sound in their final home.
Note to William: be sure to have a "designated non-listener": someone remaining safely outside the listening room who can throw the power breaker switch and release everyone in the room from the D9e's spell. Otherwise we may never hear from any of you again . . .
-- Chris
P.S. I am seriously considering getting a 5-inch version of the above driver for myself, maybe as early as the new year. I have long been fascinated by field coil technology and I'm starting to seriously salivate as I hear about these developments and extrapolate from what I have heard in various listening sessions in the past. The 9-inch are out of the question for me, but maybe a pair of the D5e-I could be manageable.
I think Mr. Teramoto was planning to implement various changes anyway, but the 9-inch Type I (i.e., all-iron one-piece integral yoke + pole piece) field coil driver for William's friend reflects changes in the manufacturing process (such as a different annealing process) along the lines recommended by Aleksandar Radisavljevic' of RAAL at RMAF. I still don't know all the details about what Feastrex has started to do differently with their Type I field coil drivers. They had a hard time finding someone who would even attempt some of the things that they wanted. Finally one of Mr. Teramoto's suppliers developed some new equipment that could be used to do the necessary work, but even Mr. Teramoto does not have all the details on that: people in the metalworking industry are very secretive about proprietary annealing and machining processes that give them a distinct advantage over their competitors. (These tiny, specialized companies can't afford to get and defend patents so they keep their secrets to themselves.)
From what Mr. Teramoto tells me, your Type II drivers with their Permendur pole piece and top plate still have a significant edge, but the Type I drivers did get a definite performance boost from the assorted changes that have been implemented. Looking at the assembled motor from the outside, aside from a different color (due to the different annealing process) there are not a lot of differences that are immediately obvious to the eye. The tolerances are all even tighter than before -- so tight that the assembly of parts which abut each other ends up removing some of the electroplating at the interface. Mr. Teramoto is still in the process of assembling the drivers, but he did find that the new motors run cooler. He has to bump up the voltage by about 2V to get the temperature up to where it was with the previous version of the motor. When he put the lower voltage into them, the motors remained so cool to the touch that at first he doubted they were even getting power. I'm not sure just what that means in terms of performance, but improved operating efficiency can only be a good thing, I should think.
The proof is in the playing . . . I think these new drivers will start testing their lungs next week. I very much doubt I'll have an opportunity to hear them before they are shipped out but I'll pass on any comments I get from Mr. Teramoto. Beyond that I think we'll have to depend on William to give us a report on how they sound in their final home.
Note to William: be sure to have a "designated non-listener": someone remaining safely outside the listening room who can throw the power breaker switch and release everyone in the room from the D9e's spell. Otherwise we may never hear from any of you again . . .
-- Chris
P.S. I am seriously considering getting a 5-inch version of the above driver for myself, maybe as early as the new year. I have long been fascinated by field coil technology and I'm starting to seriously salivate as I hear about these developments and extrapolate from what I have heard in various listening sessions in the past. The 9-inch are out of the question for me, but maybe a pair of the D5e-I could be manageable.
This just in from Pure Music Group's Warwick Freemantle, who is using the Feastrex D5 driver in a new prototype loudspeaker currently debuting at the Guangzhou AV Show:
Day 2 at Guanzhou and our room was full for most of the day. The word seems to have gone around the show that there is a new loudspeaker worth listening to and many of the other manufacturers are coming to listen. I have received some very good compliments from competitor companies. They are particularly impressed with the full range sound quality and level of technical expertise displayed by our loudspeaker in such a compact package.
I was invited to attend an industry dinner hosted by Shuguang the Chinese valve manufacturer. It was attended by Chinese valve amplifier manufacturers and a number of loudspeaker companies. I was extremely humbled when a toast was proposed in recognition of our loudspeaker in which they expressed great respect for our product and it's creators and wished us well for the future. I took it as a great compliment for our team and responded accordingly. It is unusual for such expressions of support to be made in China for a foreign product and I think our team should be justly proud of their achievement.
Last day tomorrow.
Warwick
-- Chris
Day 2 at Guanzhou and our room was full for most of the day. The word seems to have gone around the show that there is a new loudspeaker worth listening to and many of the other manufacturers are coming to listen. I have received some very good compliments from competitor companies. They are particularly impressed with the full range sound quality and level of technical expertise displayed by our loudspeaker in such a compact package.
I was invited to attend an industry dinner hosted by Shuguang the Chinese valve manufacturer. It was attended by Chinese valve amplifier manufacturers and a number of loudspeaker companies. I was extremely humbled when a toast was proposed in recognition of our loudspeaker in which they expressed great respect for our product and it's creators and wished us well for the future. I took it as a great compliment for our team and responded accordingly. It is unusual for such expressions of support to be made in China for a foreign product and I think our team should be justly proud of their achievement.
Last day tomorrow.
Warwick
-- Chris
For myself I really like the D5nf with the PB9s.. Hopefully Mr Teramoto can start on the field coil version of D5nf soon.... should be more affordable plus I can still use it with my current spk cabinets.. Re: Matt came over to my house
Phil, that really struck a chord with me. I feel the same way. Listening to these D5nf drivers simply makes me feel happy. Sometimes I even literally get a smile on my face when I hear something beautiful I've never heard before in a recording I've listened to many times before. It's a wonderful feeling.
I don't know what it is about them that does that to me, but I'm thinking that it's their fine resolution or their "organic/natural/real" sound quality.
And I'm still just listening to mine in corrugated cardboard boxes! I can hardly wait to listen to them in the new Maiko cabinets.
Mike
Phil Townsend said:
Phil, that really struck a chord with me. I feel the same way. Listening to these D5nf drivers simply makes me feel happy. Sometimes I even literally get a smile on my face when I hear something beautiful I've never heard before in a recording I've listened to many times before. It's a wonderful feeling.
I don't know what it is about them that does that to me, but I'm thinking that it's their fine resolution or their "organic/natural/real" sound quality.
And I'm still just listening to mine in corrugated cardboard boxes! I can hardly wait to listen to them in the new Maiko cabinets.
Mike
William,
Previously you had asked me in an email sent to my office about the recommended input voltage for the new field coil motor and whether any mods to the current P/S were necessary . . . Mr. Teramoto told me that he recommends sticking with the current P/S specs for the following reasons:
1) The current P/S top voltage setting (17V) is already quite "hot" in terms of performance . . . it gives a pretty low Qts. (It varies according to the model, but I believe that with some of the drivers 17V will take you to below 0.2.) 17V is possibly already a higher setting than you would want to use with a ported enclosure.
2) Previously, 17V in some models would tend to get rather warm, especially when you're really blasting at high volumes for an extended period, because you get the warming up of the voice coil and the field coil combined. Of course, even if the ambient temperature was also high, you'd still be safe, but the new motor gives you an extra margin of safety . . . you could leave it on continuously with no heat buildup, apparently.
-- Chris
P.S. Mr. Teramoto has, to my knowledge, never prototyped a field coil "Naturflux" driver but I think eventually he would like to . . .
Previously you had asked me in an email sent to my office about the recommended input voltage for the new field coil motor and whether any mods to the current P/S were necessary . . . Mr. Teramoto told me that he recommends sticking with the current P/S specs for the following reasons:
1) The current P/S top voltage setting (17V) is already quite "hot" in terms of performance . . . it gives a pretty low Qts. (It varies according to the model, but I believe that with some of the drivers 17V will take you to below 0.2.) 17V is possibly already a higher setting than you would want to use with a ported enclosure.
2) Previously, 17V in some models would tend to get rather warm, especially when you're really blasting at high volumes for an extended period, because you get the warming up of the voice coil and the field coil combined. Of course, even if the ambient temperature was also high, you'd still be safe, but the new motor gives you an extra margin of safety . . . you could leave it on continuously with no heat buildup, apparently.
-- Chris
P.S. Mr. Teramoto has, to my knowledge, never prototyped a field coil "Naturflux" driver but I think eventually he would like to . . .
I need a better job......... Anyone in need of a slightly pickled 42 year old kidney? Dave
Hi Phil,
Can you give a brief rundown on the disadvantage/possible danger (if any) of running these speakers at 8 ohms. My factory amp only offers 4-and 8-ohm taps.
If you recall from our phone conversation I'm electronically illiterate and am likely to build a set of new speakers before I venture into amp building. If those priorities are screwy, it won't be the first time. . . .
Thx
Mark
First, No possible danger using a 16 ohm driver on an 8 ohm amplifier tap.
There are some disadvantages however...
Power is the first. For an 8 ohm speaker, an amplifier needs to deliver 2.83VRMS to develop 1-watt of power. For a 16 ohm load the same amplifier needs to deliver 4.00VRMS to develop 1-watt of power. Bottom line, you get half power as the 16 ohm speaker is only half the load of an 8 ohm speaker.
With a vacuum tube amplifier (and assuming an output transformer) there are some some other disadvantages, mainly due to improper loading of the output tube(s). The output transformer "reflects" the impedance from the primary winding (output tube side) to the secondary (speaker side) and is designed to match the impedance of the output tube to the load (speaker). When you double the impedance of the load (8 ohms to 16 ohms), you double the impedance reflected to the output tube(s), ie, it doubles as well (in a 45 amp the load impedance would go from 5K to 10K which is half the load) so you get less power, less damping factor but more distortion.
So... best move is to get proper matching of your amplifier(s) to your speakers.
Regards, KM
There are some disadvantages however...
Power is the first. For an 8 ohm speaker, an amplifier needs to deliver 2.83VRMS to develop 1-watt of power. For a 16 ohm load the same amplifier needs to deliver 4.00VRMS to develop 1-watt of power. Bottom line, you get half power as the 16 ohm speaker is only half the load of an 8 ohm speaker.
With a vacuum tube amplifier (and assuming an output transformer) there are some some other disadvantages, mainly due to improper loading of the output tube(s). The output transformer "reflects" the impedance from the primary winding (output tube side) to the secondary (speaker side) and is designed to match the impedance of the output tube to the load (speaker). When you double the impedance of the load (8 ohms to 16 ohms), you double the impedance reflected to the output tube(s), ie, it doubles as well (in a 45 amp the load impedance would go from 5K to 10K which is half the load) so you get less power, less damping factor but more distortion.
So... best move is to get proper matching of your amplifier(s) to your speakers.
Regards, KM
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