Quick Question on Adcom 545

K-amps · 30th July 2005, 04:07 PM

Chris or anyone else who has a schematic for the older 545 not the 545ii.

Is it truly DC coupled? i.e. does it have any input coupling caps in the signal path?

Better yet can anyone post the fromt end schematic?

thanks!

anatech · 30th July 2005, 06:16 PM

Hi K-amps,
I will have a look around. I see the 555 is direct coupled, no caps. It is very likely the 545 is the same. I personally don't like that since the variable input resistance will vary the base offset voltage in the diff pair. That and you may someday get a DC offset into the amp. yuk.

-Chris

K-amps · 30th July 2005, 10:06 PM

Yup,

But there's one good thing, the sound does not deteriorate after 20 yrs as does in the 545ii and 555ii that need input cap replacement...

anatech · 30th July 2005, 10:12 PM

I can't see where that's an incredible expense. Components are always improving and equipment needs maintenance. Besides, other parts will need attention too.

Take my car ... and fix it - PLEASE.

-Chris

K-amps · 30th July 2005, 10:54 PM

I'll refer you to Jacco on the car,

GEirin · 31st July 2005, 12:14 AM

Hello

K-amps. Here Adcom GFA 555.

Guillermo Eirin

K-amps · 31st July 2005, 01:14 AM

Thanks!

Whats the second schematic... looks like a regulated PS but where is it used?

anatech · 31st July 2005, 02:07 AM

That's an option. I have never seen it installed. It regulates the main supplies. Reduced the power but it was supposed to sound better. As you can see, your raw 80 VDC went down to 62 VDC.
-Chris

30th July 2005, 04:07 PM	#1
K-amps diyAudio Member Join Date: Nov 2003 Location: Indiana	Quick Question on Adcom 545 Chris or anyone else who has a schematic for the older 545 not the 545ii. Is it truly DC coupled? i.e. does it have any input coupling caps in the signal path? Better yet can anyone post the fromt end schematic? thanks!

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30th July 2005, 06:16 PM	#2
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi K-amps, I will have a look around. I see the 555 is direct coupled, no caps. It is very likely the 545 is the same. I personally don't like that since the variable input resistance will vary the base offset voltage in the diff pair. That and you may someday get a DC offset into the amp. yuk. -Chris

30th July 2005, 10:06 PM	#3
K-amps diyAudio Member Join Date: Nov 2003 Location: Indiana	Yup, But there's one good thing, the sound does not deteriorate after 20 yrs as does in the 545ii and 555ii that need input cap replacement...

30th July 2005, 10:12 PM	#4
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	I can't see where that's an incredible expense. Components are always improving and equipment needs maintenance. Besides, other parts will need attention too. Take my car ... and fix it - PLEASE. -Chris

30th July 2005, 10:54 PM	#5
K-amps diyAudio Member Join Date: Nov 2003 Location: Indiana	I'll refer you to Jacco on the car,

31st July 2005, 01:14 AM	#7
K-amps diyAudio Member Join Date: Nov 2003 Location: Indiana	Thanks! Whats the second schematic... looks like a regulated PS but where is it used?

31st July 2005, 02:07 AM	#8
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	That's an option. I have never seen it installed. It regulates the main supplies. Reduced the power but it was supposed to sound better. As you can see, your raw 80 VDC went down to 62 VDC. -Chris

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