📄 preamplifier_modular_eng.htm
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<title>High-End Audio Modular Preamplifier</title>
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<td width="100%" bgcolor="#BB0000"><p align="center"><font color="#FFFF00" face="Bangle"><em><strong><big>High-End
Audio Modular Preamplifier</big></strong></em></font></td>
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<td width="100%"><font color="#000000" face="Tahoma"><small><strong>Generally</strong></small></font></td>
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<td width="100%"><p class="MsoNormal" style="text-align:justify"> <small><font
face="Tahoma"><span lang="EN-GB">This preamplifier is requirement result of many friends
to give a high quality preamplifier, capable to drive high quality power amplifiers with
good sound, it's not however difficult to making, it combines simplicity and handiness. It
does not allocate a lot of facilities and various filters, but is drawn so the acoustic
signal follows the smaller course without it's influenced by </span><span lang="EN-US"
style="mso-ansi-language:
EN-US">stages</span><span lang="EN-GB"> they do not need, with
result the coloration of reproduced sound. It follows the modular philosophy that gives
the possibility of changing each module and adapted in yours acoustic taste. Thus it will
constitute the base for long-standing listening and experimentations. Use relay in the
input selection ensures the smaller way and the better possible quality, because the relay
contacts are not influenced easily by temperature changes and environment, offer smaller
ohmage and parasitic resistance in the signal course. This of course depends also from the
relay quality that you will select; I propose choice of relay small size and very high
quality. Enough companies they manufacture such relays. Exists different possibility of
choice for the Listen inputs and different for the analogue recording. Thus we can listen
other sound source and other recording. Exists the possibility, for those who they judge
of suppressing Balance potesometer [RV1], the recording selector and proportional relays
making the manufacture simplest and more economic. In the each place module we have big
variety of choices. Certain you I will give I below, but can make also your choices. As
you will observe exist somebody "facilities" as monophonic [MONO] operation etc.<span
style="mso-spacerun: yes"> </span></span></font></small></td>
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<td width="33%" bgcolor="#FFFF80"><p align="center"><font face="Tahoma" color="#800000"><small><strong>Input
selector</strong></small></font></td>
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<td width="100%"><p align="center"><img
src="preamplifier_modular_sel.gif" tppabs="http://users.otenet.gr/~athsam/Circuits/preamplifier_modular/preamplifier_modular_sel.gif" width="458" height="848"
alt="preamplifier_modular_sel.gif (15674 bytes)"></p>
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<td width="33%" bgcolor="#FFFF80"><p align="center"><font face="Tahoma" color="#800000"><small><strong>Main
Preamplifier</strong></small></font></td>
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<td width="100%"><p align="center"><img
src="preamplifier_modular_main.gif" tppabs="http://users.otenet.gr/~athsam/Circuits/preamplifier_modular/preamplifier_modular_main.gif" width="1063"
height="1021" alt="preamplifier_modular_main.gif (47659 bytes)"></td>
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<td width="100%"><small><font face="Tahoma"><strong>Discription</strong></font></small></td>
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<big><span lang="EN-GB" style="font-size:10.0pt;mso-ansi-language:EN-GB">The choice of
acoustic signal follows two streets [Fig.1A]. First with the selector S1 that is 1 contact
12 places, from which I use five. Exists the possibility to using also the remainder
places adding to them proportional relay and Led. Each place supplies the proportional
relay and Led that it shows whom input has been selected. The supply becomes with + 12V
[+V4]. Selector S2 functions with the same way as the S1, supplying them proportional
relays and Led, so that becomes the source choice that recording. Afterwards recording
relay exists the buffer unit round IC1 [Fig.1B]. In the part list exist certain choices
for opamp. that will undertake this role, but exists the possibility of selecting somebody
of your choice. All the inputs are high level apart from input PHONO [RIAA Filter] that is
directed in proportional module PHONO [J11] and by his exit return again in the block
selector relay. He is alone module that has stereophonic structure and the two channels
that abut to connector [J11].<span style="mso-spacerun:
yes"> </span><span
style="color:black">Those who do not allocate the old turnable [pick-up] and disks
collection of 33 turns, they will not need PHONO module. It can easily they change him in
line, suppressing connector J11 and you connect the corresponding inputs J1-2 in
proportional contacts P1-2 relay RL1-6. </span>The relay team of listening direct the
stereo acoustic signal from some input in Buffer module [J12-13]. The gain of this unit is
X1, does not provide no gain in the signal. They follow potesometer BALANCE [RV1a-b] and
VOLUME [RV2a-b] that regulates the balance and the level of acoustic signal respectively.
These two Potentiometers should be high quality also from acquaintance constructor.
Afterwards the Potentiometer VOLUME exist the MUTE stage that is constituted by a divider
R21-22 and the contacts of relay RL11 that are found parallel with the R21. In normal
operation the contact jumper the R21, the signal pass without fall. If it close switches
S3, turns on the D22, the RL11 arms, the contact opens and the R21 with the R23 they
configure an divider which create a fall of level in acoustic signal [-20dB]. The same
logic is also for the other channel where exist the resistors R23-24. In the continuity
the acoustic signal enter via the J16-17 in Line module what offers the suitable gain in
the signal and this drive all the goods power amplifiers. Then exist the contacts of RL12
that the operation of is described in the delay circuit.</span><span lang="EN-GB"
style="mso-ansi-language:EN-GB"><o:p></o:p></span></big></font></td>
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<td width="25%" bgcolor="#FFFF80"><font face="Tahoma" color="#FF0000"><small><strong>硼殡镢蒡
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