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Old 16th September 2009, 03:03 PM   #1
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Default Preamp for Hiraga

I have Hiraga amp with 19V (1.3A quiescent current) and I try to connect my Dac with BB1794 and IV conversion with ne5534. When I connect my dac on Hiraga there is no sounding,only buzzing with no music. This Dac works well on my stereo integrated amplifier Menuetto and with techncs preamp and hiraga. Why there is no sound when dac is connected directly (there is no series capacitor in the signal path). What preamp do you sugest to me to build (simply and relatively cheap) because this passive combination dont work.
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Old 16th September 2009, 03:12 PM   #2
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you probably have offset on output of that I/V stage , resulting with mentioned problems

if I remember correctly from few pics , Menueto have input cap

place any cap on output of that I/V stage and try ;

without more details , I can't tell you more
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Old 16th September 2009, 03:25 PM   #3
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Yes Menuetto have input MKP cap and pot which form a passive preamp. I will try to connect DAC with series cap but i don't know if the output signal of that IV circuit is suitable for driving the hiraga?!
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Old 16th September 2009, 03:28 PM   #4
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Quote:
Originally Posted by Zen Mod View Post
you probably have offset on output of that I/V stage , resulting with mentioned problems

if I remember correctly from few pics , Menueto have input cap

place any cap on output of that I/V stage and try ;

without more details , I can't tell you more
IIRC that DAC is unipolar, meaning that the '0 signal' output current is maybe 2mA. That would mean that your I/V has 1.5V DC at the output, which will drive the Hiraga amp against the supply.
Put in a coupling cap and you should be fine (if the amp & speaker survived...).

jd
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Old 16th September 2009, 05:25 PM   #5
00940 is online now 00940  Belgium
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Originally Posted by janneman View Post
IIRC that DAC is unipolar, meaning that the '0 signal' output current is maybe 2mA. That would mean that your I/V has 1.5V DC at the output, which will drive the Hiraga amp against the supply.
Put in a coupling cap and you should be fine (if the amp & speaker survived...).

jd
Nah... "only" 4.65V of offset

(the pcm1794 0 is at -6.2ma)
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Old 16th September 2009, 05:28 PM   #6
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What kind of capacitor i do need to put in the signal path and which value if preferable ?
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Old 16th September 2009, 05:34 PM   #7
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Nah... "only" 4.65V of offset

(the pcm1794 0 is at -6.2ma)
Ahh. Hope the speaker survived.

jd
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Old 16th September 2009, 06:37 PM   #8
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Speakers are ok ;o))). I tryed with series capacitor (1uF MKP) and it works !. Now is a question if the passive preamp (potentiometer and series capacitor) better than some preamp for my DAC output and hiraga?!
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Old 18th September 2009, 11:55 AM   #9
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I decided for PoorSerbianManLightspeed preamp. I hope that this will sound great. Does any listen this combination (hiraga & lightspeed)
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