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Old 22nd December 2009, 02:03 AM   #491
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as far as i understand it the subjectivist claim that distortions exist that can not be measured with a distortion analiser but i see rarely an attempt to come up with a measurement or method how they measure their secret mechanism. another issue is, and i have said that before that the programm material is flawed and a subjectively optimised circuit "enhances" the listening experience maybe. 25 years ago we analised the original Linn and found that it ran slghtly fast and added some "reverberation". Studios do that. My friend Allen has a small and very controlled voice. With the right microphone and some reverb added on his Digidesign Pro Tools system he sounds like a Pop star. That is also the reason i record sometimes on a 2MHz DSD system with Microtech Gefell ORTF mics without mixing board directly into the AD converter. When i have the musicians in my home they are very mesmerised about the sound. It´s importand that we do not loose contact to the unamplified life experience. I am more your type and apreciate good measurements. On the other hand i accept if other people have different ears or another frame of reference. This double blind is silly. We can spare that. You have such a transparent and clear view that i trust your choices. I learned a lot from you. I really apreciate your generosity of sharing your high tech designs with us.
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Old 22nd December 2009, 07:49 AM   #492
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Thorough and careful investigations concerning my bastel-bin unburied two unused INA103. It already contains the nodes for a more local loop desgin. So, during christmas time, I might set up a basic gain block à la your proposal.

I don't think that the instrumentation amp ist the problem dc-wise, but the imbalances of the 2sk389/2sj109 pairs which are not that small one would hope.

Rüdiger
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Old 22nd December 2009, 10:37 AM   #493
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Hi Rüdiger, that sounds exiting.
Have you tried to use trimmers on the Fets ? I usually use trimmers and when i found the right value i substitute with fixed resistors. Anyway, i have no doubt you find a solution.
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Old 22nd December 2009, 04:21 PM   #494
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I use this IA in front of a sound card for some measurements. Min gain is >2 but otherwise it is pretty good. You could use any single op-amps and play with bias currents too. I leave it as an exercise to see how the intermingled CM and gain loops work out.
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Old 22nd December 2009, 09:14 PM   #495
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Scott, interesting how you ashure stability. That could help Rüdiger.
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Old 22nd December 2009, 09:49 PM   #496
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Finally i have some vacation before i go to Vegas. Today we set up my phono system at a friends house. The vinyl trampled the CD in 80% of the cases and that was my most simple stage, the Hiraga Optime Transimpedance stage i have described here. His CD system is not bad at all. An updated Audio Aero directly into the Audionet Max2 Monoblocks. He has a good tonal balance even on the warm side. His speakers are Sonics Allegria S2 with RAAL Ribbon with an active 400W Breeze subwoofer. His room is big and proportioned after Feng Chui. The CD had very good staging and even a measure of microdetail. Were it was better then Vinyl was in bass definition and tightness. Everything else was better then CD. Instruments sounded more typical, treble extention and resolution was better and there was an udeniable sense of presence with the musicians in the room. I show you some photos. From left to right:
The Spiral Groove SG1 with Triplnar arm and Lyra Titan i on my DIY stand. My chaos-fractal cable into the Hiraga Optime into the Transimpecance RIAA. Interconnects are from Wire-World and speaker cables were a double 7m run of Spiral Groove speaker cable.
I have also good news for fellow audiophiles concerning cartridge loading. I talked half an hour today on Skype to Stig Björge of Lyra. Jonathan Carr has gone through the pain of simulating his cartridges plus capacitive loading of cable and Pre. The results will be published in recent setup instructions of Lyra cartridges. Stig will also send the information to me and i will publish it here. As far as i understand it has to do with capacitance and ultrasonic resonance and varies with the cable and stage you use.
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File Type: jpg Phono only 2.jpg (175.0 KB, 376 views)
File Type: jpg SG1 Phono 1.jpg (175.4 KB, 364 views)
File Type: jpg Total system 1.jpg (173.7 KB, 356 views)
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Old 22nd December 2009, 10:53 PM   #497
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Quote:
Originally Posted by Joachim Gerhard View Post
Scott, interesting how you ashure stability. That could help Rüdiger.

C1/C2 can be bigger, stability was not a big issue with something like AD823. Resistors can be tweaked for very good low gain performance on noise so relatively good to excellent noise performance is available for G = 10dB to 70dB.
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Old 23rd December 2009, 12:49 AM   #498
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This is good news. I never used the AD823 before and that bias servo is new to me too.
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Old 23rd December 2009, 02:50 AM   #499
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After a lot of head scratching i designed a subsonic filter. The starting point was the ESP filter but i wanted to optimise the time domain, lower the amount of caps to the minimum and do it aproximatly complimenting my arm-cartridge combination. My low frequency resonance is at around 10 Hz with a 8dB overshot so i put the -8dB there. I tried to optimise groupdelay as much as possible and ended up with a modified 6th order Linkwitz response. I do this with 2 op amps and 4 caps only. I think this could be useful to get more SPL without cone bottoming and as i learned from the ESP website it could be useful for digital transfer to optimise dynamic range of the A-D converter.
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File Type: pdf 6th order Linkwitz Subsonic FRD.pdf (42.6 KB, 67 views)
File Type: pdf 6th order Linkwitz Subsonic Schem.pdf (42.8 KB, 77 views)
File Type: pdf 6th order Linkwitz Subsonic Step Response.pdf (43.0 KB, 58 views)
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Old 23rd December 2009, 02:52 AM   #500
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Here is the rest. Happy listening !
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File Type: pdf 6th order Linkwitz Subsonic 50Hz quare.pdf (75.0 KB, 54 views)
File Type: pdf 6th order Linkwitz Subsonic Group Delay.pdf (33.8 KB, 55 views)
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