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Accession MM Capacitance/Loading Settings |
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Graham Slee
Admin Group Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
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Correct! It is 460mH but my eyesight at 66 has trouble telling 6's from 8's and vice versa. As for hearing, I cannot hear up to 21kHz like I could at 15, and I'm now down to 13kHz. Neither can I hear floor stander bass because I use mini-monitors, but I can do a little maths and still have a good idea what things are going to sound like for others, and I'm happy that still works. So, corrected peaks are at 16.193kHz and 22.374kHz. Roll-off after peaks is always -12dB per octave with LC's. The 47k resistive load serves as damper to prevent excessively high peaks, and is generally less than 0.5dB at these sorts of turnover frequencies. With larger inductances like on some Stanton's the peaks are larger and of lower frequency (and can be quite nice). The formula is exactly the same for resonant frequencies of any parallel LC circuit (inductor capacitor), and isn't exclusive to this application. The median or average inductance of MM's is 0.5H ('alf an 'enry) and 200pf +/- 50pf takes it to or past the old hi-fi upper response of 15kHz - as near as damn it. The upper frequency extension of frequency response with MMs to achieve 20kHz, is mechanical tuning, as per tuning fork, which just happens to be the same technique as used in oscillator crystals. It is dependant on the stylus tube. Much of what you hear is highly dependent on other things never discussed in hi-fi circles, so I tend not to bother explaining as few want to know. |
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Fatmangolf
Moderator Group Joined: 23 Dec 2009 Location: Middlesbrough Status: Offline Points: 8998 |
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If it helps Paul I used to do the calculations and graphs to see what was correct. Now I try the options and go with the best sounding one.
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Jon
Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
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paulsmith048j
New Member Joined: 08 Apr 2021 Status: Offline Points: 21 |
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Hi Jon,
Many thanks to you and Graham for all your help and advice on this; I`ve learned a lot. The Accession MM has now safely arrived and is connected into my system and powered up. It will NEVER be powered down now. I have selected a loading of 100 pf as my starting point in order to provide a more `valid` aural comparison with my old Reflex M which has now found a new home. I`m going to let it `cook`/bed in until Sunday morning before I listen to it in anger for the first time. I`m very excited about what I `m about to experience Best wishes, Paul
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Fatmangolf
Moderator Group Joined: 23 Dec 2009 Location: Middlesbrough Status: Offline Points: 8998 |
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You are most welcome Paul. I am just passing on the advice others gave me and some trial and error. I remember the first listening session with my Accession so can imagine your pleasure this weekend!
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Jon
Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
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paulsmith048j
New Member Joined: 08 Apr 2021 Status: Offline Points: 21 |
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Thanks for that Jon,
I couldn`t resist having a quick listen to the Accession this evening. I didn`t have the discipline to wait until Sunday! It`s very early days of course, and the unit is nowhere near fully `burned in` yet. Initial impressions are of a much more detailed and tighter bass and much more musical information in general. I have settled on the loading option of 100 pf for my Audio Technica AT 760SLC The only thing I`m perplexed by, however, is that with no record playing, the Accession clearly generates much more background `hiss` at my standard listening volume setting on my Naim amplifier, compared to the Reflex M, even though both pre-amps have the same gain of approx` 41dB. I listen to my music on headphones (Sennheiser HD600). Although the hiss isn`t obtrusive when I`m actually playing music, should I be concerned there is a possible fault, or is this normal for the Accession? I was hoping the background hiss was going to be LESS than that of the Reflex M.
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Graham Slee
Admin Group Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
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You wouldn't buy an F1 racing car for the early morning commute, as you'd wake everybody up. In all areas of physics there are penalties for gains, that's how physics is. Therefore we have both the Reflex and the Accession offerings. The Reflex isn't the last word in low noise either, but is the more acceptable of the two if you're offended by hiss. The Accession is the next development, it has more reflexes than a Reflex, it is very fast. Physics has its penalties in that speed in the form of (true) high slew rate is penalised by noise. It is understandable that most listeners will not have the knowledge of an electronics engineer, but this is something I've tried to point out over many years. Most of the unplayable vinyl is actually playable, and one example is Santana's Moonflower album, where all four sides go off into frenzied high speed playing complete with deep lead guitar fuzz in the live recordings. To the Accession M it's a walk in the park, and that's due to speed over noise. It all depends on what you value the most.
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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Fatmangolf
Moderator Group Joined: 23 Dec 2009 Location: Middlesbrough Status: Offline Points: 8998 |
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I feel silly commenting after Graham's expert advice but here goes. In my system it is normal to have a soft background hiss, well below surface noise on the LP's as Paul said. Whether I notice it without music playing depends on the ambient noise and if I forgot to turn the volume back down afterwards...
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Jon
Open mind and ears whilst owning GSP Genera, Accession M, Accession MC, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC. |
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