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What did i do to my amp?

107.215.54.238
Posted on May 13, 2015 at 19:41:03
mgm
Audiophile

Posts: 115
Joined: February 10, 2009
 After reading about mods to my amp (onkyo a9555), i went ahead and removed the small poly caps on two of the inputs. These inputs now sound much more open and extended in the highs. Just wondering why the caps were there in the first place.

 

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good question, I did the same when I had that amp, posted on May 14, 2015 at 00:29:14
bullethead
 I did the exact same thing when I had that amp.

by the way it is an awesome amp. I noticed extended highs and more air and detail in the recordings after removing the caps. I at the time didn't know what I was doing, but it was indeed good. It was a good choice to just do a few inputs, this way you can have some flexibility in the sound.

 

The caps were likely there for stability and RFI blocking -nt, posted on May 14, 2015 at 05:43:38
E-Stat
Audiophile

Posts: 37666
Joined: May 12, 2000
Contributor
  Since: April 5, 2002
 .

 

RE: good question, I did the same when I had that amp, posted on May 14, 2015 at 07:34:09
mgm
Audiophile

Posts: 115
Joined: February 10, 2009
 It is a nice upgrade. It takes some of the dark, veiled quality away. I like this amp better than your nad and cambridge types under 1k. What amp did you upgrade to?

 

RE: What did i do to my amp?, posted on May 14, 2015 at 07:57:32
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
 These likely were to keep DC off the inputs of the amplifier. Once you've done this, be sure to power up your preamp before powering on this amplifier.

 

RE: What did i do to my amp?, posted on May 14, 2015 at 08:24:13
mgm
Audiophile

Posts: 115
Joined: February 10, 2009
 Thank you, It is an integrated, so is it important to have sources turned on before amp? Also, it is quite amazing the detrimental effects it had on sonics.

 

RE: What did i do to my amp?, posted on May 14, 2015 at 13:02:25
airtime
Audiophile

Posts: 11287
Location: Arizona
Joined: February 4, 2003
 Sometimes safety does come first. It was an engineering compromise that a cap was put there for a reason! Sonics aside.

 

RE: good question, I did the same when I had that amp, posted on May 14, 2015 at 15:18:46
bullethead
 I eventually upgraded my entire system to Bel Canto. I use a Bel Canto REF500s amp now (also Class D), very nice upgrade for me.

Enjoy the new sound with the enhancements you made :) that is a very nice amplifier.

 

RE: What did i do to my amp?, posted on May 15, 2015 at 17:56:59
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
 Without looking at the schematic, it's hard to say much. Caps at the input on a solid state amp may be there because the first transistor driven has bias at its base, and that bias voltage is unwanted at the input.

If you have a FET at the input, this is less likely to be a problem, and even a standard BJT on a split rail can be set up for 0V on the base.

Most likely, the cap was there to block incoming DC, which is why removing it isn't super detrimental. Since you have an integrated, just leave the volume control down if you're powering sources on and off and you should never have a problem.

 

Maybe you should just try upgrading the caps....., posted on May 17, 2015 at 08:36:38
ABliss
Audiophile

Posts: 1482
Joined: March 16, 2001
Contributor
  Since: August 3, 2002
 just to be safe. Some better caps might yield the same improvements. If the designers could have saved a few dollars by leaving them out, I am sure they would have done it.

AB.

 

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