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Summary of Contents for Fredenstein HD Reference
- Page 1 REFERENCE Operating Manual...
- Page 2 The HD Reference also has a few added features, such as a display that shows gain in dB next to the knob that allows one to set gain in accurate 1dB steps, which is great for setting up stereo pairs. We also added more choices to the High Pass Filter (Off, 39Hz, 82Hz) and more choices to the Input Impedance (200K, 1K, 300, 232).
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Page 3: Installation
, 1AT 250V, slow blow (1 Amp) in the IEC socket on the Commander. The HD Reference does get hot. This is a result of it using 4 Class A amplifiers on 48 Volt rails, which, in terms of heat generated, is like having a 15 watt light bulb in a 1U box. - Page 4 Phantom powered output amplifiers of microphones do not have a lot of voltage or current to work with and is part of the reason why using the HD Reference to drive the long line is preferred. Another reason is that a line level signal is more immune to RF and interference than a much lower level mic level signal.
- Page 5 EQ, but were intended to be simple problem solvers. We might characterize the high pass filters in the HD Reference as relatively gentle and safe. The filters are 6 dB/oct types with minimal phase shift and low group delay distortion. Steep filters tend to introduce more phase shift which basically means the low frequencies may arrive milliseconds later than mid frequencies.
- Page 6 Only the +60 dB gain setting (red line) shows any visual departure from the others (-0.5 dB at 5 Hz, -2.5 dB at 2Hz). With 40 dB gain, you can see the HD Reference measured as flat as the AP within 0.1 dB from 2 Hz to 80 kHz, which were the frequency limits of the AP.
- Page 7 +20 dBu and +25 dBu, then rise suddenly and sharply as the device nears hard clipping. Notice the gentle rise in the HD Reference. Tube circuits also often tend to have this kind of curve. Fredenstein HD Reference Manual V1.0 Feb 5, 2016 Page 6...
- Page 8 OK, that is enough of geeky graphs, but sometimes a picture is worth a thousand words. Even though the frequency response goes amazingly high, don't expect that the HD Reference will be “bright” because the frequency response is also very flat, but it may be brighter than a preamp with a rolled off top end.
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Page 9: Controls And Operation
Note: With P48 engaged 200K becomes approximately 13 Kohms. Low Cut 39 reduces the lower frequency response to 39 Hz Low Cut 82 reduces the lower frequency response to 82 Hz Fredenstein HD Reference Manual V1.0 Feb 5, 2016 Page 8... - Page 10 There is also an indicator called LOCK STATUS, which lights up if the LOCK button is pushed on the Commander. If this is lit, all controls on the HD Reference are frozen and can only be controlled from the Commander. This is to prevent tampering.
- Page 11 4 true Class A amplifiers capable of driving 600 ohms. Class A amplifiers dissipate the same heat whether there is no signal or the signal is fully driven. In the case of the HD Reference, this means about 16 watts (8 watts per channel) of heat, so there are heat-sinks inside, ventilation slots in the top and bottom panels and a serious recommendation in the beginning of this operating Fredenstein HD Reference Manual V1.0 Feb 5, 2016 Page 10...
- Page 12 GREEN or near clipping (+24 dBm) when RED. Generally, if the LED is lit GREEN and not flashing RED, you are probably in the safe zone as far as the HD Reference, but you still probably want to avoid overloading the recording device, so those meters are worth watching. However, the best thing is to use your ears and if it is seeming like there may be some unwanted warmth and mid range build up, probably turning the Gain down will help.
- Page 13 Contact Info: Fredenstein Professional Audio by Orion Communication 7F-1, No. 582, Ruei Guang Rd. Neihu District Taipei 114 Taiwan Phone : + 886-2-2657-2618 Email : info@fredenstein.com www.fredenstein.com...
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