03-01-2010 Post does not mapped to Knowledge Tree cv Derby, United Kingdom Posts 158 Joined on 09-15-2004 Post #: 81 Post ID: 13050 Reply to: 13042 New Site Posts End of the project pl Another Stupid Lamm L Reading an official a Random Subjects Dukane 5A540 Compress A good young conducto The GoodSoundClub’s ‘ Balanchine’s “Patheti The Nimbus' Prima Voc More on the field coil damping - and an easy way to adjust it Hello chaps, Firstly, something I forgot before was that the high impedance coil will have more turns... so the DCR etc will be stepped down as seen by the voice coil. My guess is that overall it will still provide slightly less damping, due to imperfect transformer action and perhaps a lower copper/insulation ratio with the high voltage wire, but don't hold me to that. Romy - I'm not sure a tapped coil is the way to go; there's only one optimal design and you may not get the flux required without full turns utilisation. But there's an easier way of varying the damping - which I'll get to in a moment. Bud - high current CCS are a bit more difficult but shouldn't be a problem - a simple single mosfet based one should suffice. Doesn't need to have spectacularly high impedance of 200M across the audio band after all! That said, say we have a CCS (or series inductor), we can make the damping variable by putting a variable resistor across the field coil, with DC blocking capacitor in series. You could even play with the damping at different frequencies (EQ the damping network), which I'm sure only Romy would have the patience to explore and master. Another way to do it is to undamp the amplifier - have some unbypassed cathode resistance on the output tube to raise the output plate impedance... This will give you more predictable "undamping" across the bandwidth compared to the less predictable behaviour of a speaker motor masquerading as a transformer...

03-01-2010 Post does not mapped to Knowledge Tree Romy the Cat Boston, MA Posts 6,241 Joined on 05-27-2004 Post #: 82 Post ID: 13054 Reply to: 13050 Random Subjects Better chassis design Samuel Feinberg's Wel Software for collecti The field-coil loading vs. plate loading. Yes, CV, I thought about it myself and I fine that this might be VERY interesting to play with. Unfortunately, or fortunately, I am months away from the position when I will be able to do it. The subject is devilishly interesting however. I think it would be possible to tap field-coil by tapping off external layers. This would keep the filling of the magnetizing surface even but juts reduce the turn/ampere ration. I will not break my mind on it as I do not know how it needs to be engendered properly. I will ask the people who know how it need to be done and I am sure if it doable then it will be done. I do feel that in the end the plate loading and sort of speaking the field-coil loading will have different effect. The plate loading give to us harmonics vs. transients balance but I think the field-coil loading will firm just transients character with less influence to harmonics. I however do feel that by acceleration of transients by field-coil we would consider to load the plates harder with all obvious advantages. Of course the validity of this presumption and how it might be used practically will be possible to assess only during the practical experiments. The caT "I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

07-26-2010 Post does not mapped to Knowledge Tree audiofilofine Posts 21 Joined on 02-26-2010 Post #: 83 Post ID: 14113 Reply to: 13054 New Site Posts End of the project pl Another Stupid Lamm L Reading an official a Silbatone and WE in G Srajeans Waterloo ….and a few follow up Koshka behaves like s Random Subjects Multiple Tracks, Each Streophile show 2007 A great production of My new favorite " What is interesting a The Softer Side of a The loudspeakers for Another driver altec 806

07-26-2010 Post does not mapped to Knowledge Tree Romy the Cat Boston, MA Posts 6,241 Joined on 05-27-2004 Post #: 84 Post ID: 14115 Reply to: 14113 I do not like those drivers. audiofilofine, I do not like when they just remove the magnet and to replace it with electromagnet coil. I do feel that in this configuration the coil is not vented well and either the driver has too much thermal stress or it will run only at very low magnetic force. The last one is not a problem for Altec 806 as it has reduced magnet side compare to Altec 808/802. What I would like those people who do conversions to do is to cut some sluts across the driver back path allowing the coil to breathe in open air. Or preplans to have own custom-made naked cylinder back path, the way how Cogent do. The caT "I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

07-26-2010 Post does not mapped to Knowledge Tree audiofilofine Posts 21 Joined on 02-26-2010 Post #: 85 Post ID: 14117 Reply to: 14115 New Site Posts End of the project pl Another Stupid Lamm L Reading an official a Silbatone and WE in G Srajeans Waterloo ….and a few follow up Koshka behaves like s Random Subjects Khachaturian anyone? Incorporating active Roger Waters' Ça A phenomenal find: Ga Flac 16bit/48Khz stre Audio Quality Matters TU-X1 setup 806 I have not made any measurements on these drivers, I've just heard. at 100 volts the sound is similar to the original Alnico magnet, at 130 volts instead of the original seems to be more shrill and personally I find it more pù piacevole.sembra dettagliato.li I tried with horns altec 811 to have a reference with a that are well remembered. The next test will be made on mounting them with trumpets tactrix profile internal law as these  trumpets of the photo. unfortunately the time is little evidence to do ee endless. as the cooling coil do not think is a problem, even after several hours of high-volume sheet and the driver then I do not think the coil may be damaged. The idea is to get as high as possible frequency response (I am using diaphragms of 902) in order to use a system only 2 streets. this work is just fun to make my sound, without any claim to do extraordinary things.