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My 30 Watt class A is louder than my 100 Watt Class AB?

Curious observation…

I had just done some work on my DIY Hiraga 30 Watt Class A amp, and decided I would do an A/B comparison with my Adcom GFA 545.

To my great surprise, when I switched from the Hiraga to the Adcom, leaving everything else in the set up the same, and when I turned the music back on, it needed to be turned up to play at the same volume.

Input impedance is different, and I’m wondering if this is what could be causing this counter intuitive finding? Hiraga is around 33K and the Adcom around 100K.

Wondering if anyone has any thoughts as to why this is what I’m experiencing.

Thanks

 

perkri
sgreg1
612 posts
 

Watts per channel are only the out put measurement ( horse power). There is so much more (torque) inside the an amp that produces the watts per channel. They did not name the company “First Watt” because it was catchy!

cey's avatar
cey
257 posts
 

gain and input sensitivity ...man, how about my conrad johnson preamp:

Gain:

Phono stage 47dB

Line Stage 31dB

is is sometimes too loud at 9 o clock. i use inline attenuators on amplifiers that dont have a volume knob. man this thing has a lot of gain.

perkri OP
906 posts
 

Heard back from Stanton re: the Hiraga specs

Input sensitivity is .5v

30db of gain - not 26 as I had thought.

That would explain the volume increase!

The Cary SLP-30 I am driving it with has variable gain, so I gave some wiggle room to play w that adjustment.

jjss49's avatar
Ag insider logo xs@2x
jjss49
6,612 posts
 

That would explain the volume increase!

haha... when seemingly weird stuff happens there is ALWAYS an explanation, it is just that sometimes it takes us a while to figure it out!

perkri OP
906 posts
 

Very much appreciate the input/information!

This surprise, sent me down a rabbit hole of “research”.

Now, I have more questions than I had prior to this observation :)

 

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