What's the Best Way to Reduce Gain in a Preamp

[Bigun]

I dob’t get it, why use a preamp with gain if you don’t want gain, just get rid of the preamp from the signal path or swap it with a buffer.

 

[rayma]

Agreed, I use a simple switched resistor control for a line stage.

The feedback resistor cannot be reduced without increasing the distortion significantly.

 

[WBCHUM]

thank you TOny I will try....the "feed back 22K " means the one to pin#7 (just to ensure my understanding), correct ?

Hi Rayma, so do you mean just use a resistor control (like a VR) between the CD & the power amp ? Thanks for adv.

 

[JMFahey]

I m using a 100K volume, just 2 steps from the beginning already too loud

You are describing a linear pot behaviour, use 100k Audio or Log and everything will be fine.
No need to mod preamp.

 

[WBCHUM]

Hi JF, pls excuse if i m not clear (poor in the audio terms), the 100K volume is a step attenuator , the second step is @390R : 100K. thanks

 

[JMFahey]

OK, 100K:390 attenuation is whopping 48dB

IF that is already too loud, you have WAY too much gain, and that´s an understatement.

Get rid of that 20dB gain preamp and even so I am not sure it will be enough.

Go fully passive, or, if driving a LONG cable, add a buffer.
Tube type if you wish, but the point is unity gain.

Not really needed with, say, under 1 meter cables.

By the way, bigun said the same and rayma hinted at it.
Maybe there´s a reason we all agree on diagnostic.

 

[TonyTecson]

yes, there are a lot of options, first one being the volume control, but you can still set that line stage to unity gain if you just need buffering....a switch will come in handy....no guaranties you will like it better than if you just use a passive volume control preamp...

 

[TonyTecson]

i will even go as far as reducing the plate load resistor of the input voltage amp to 82k, with the next stage grid resistor increased to 100k...

my reasoning, decreasing the plate load resistor increases plate voltage therefore increasing ac output swings...