Low-level listening problems with 102/180 combo

Posted by: Gavin on 10 September 2002

I posted this in another thread a while ago, but it seems to have been passed by! Still wonder if anyone can help...

I'm hoping somebody might be able to shed some light on a minor quibble I have with my 102/180 which is as follows:

7 o'clock on the 102 is zero (almost!). If I turn the volume up slightly, I get only the l/hand channel. It's only when I get toward the 8 o'clock mark that the r/h channel decides to make music. Sometimes it's not practical to have my music at volume I want(ie low), and there is a minimum volume I have to hit before things 'even up'.

I never noticed it with the Kef Concertos, only since I got the Celestion A2s, which are 4 ohm imp, sensitivity = 96dB, where the Kefs were about 88dB I think, and also an 8 ohm load. Are things just getting louder quicker because of the speakers? Is there a fault with the setup? Most importantly, what can I do to sort it?

I have tried powering down and giving the volume pot a brisk up/down to see if there is dirt or dust on the inside, but to no avail...

Gav confused
Posted on: 10 September 2002 by Simon Crosland
quote:
I never noticed it with the Kef Concertos, only since I got the Celestion A2s, which are 4 ohm imp, sensitivity = 96dB, where the Kefs were about 88dB I think, and also an 8 ohm load. Are things just getting louder quicker because of the speakers? Is there a fault with the setup? Most importantly, what can I do to sort it?


The more sensitive speakers result in you using a lower position on the volume control for the same absolute audio output level from the system. Higher sensitivity equals more audio from less signal. Note also that sensitivity is in dB - i.e. it is a logarithmic ratio - so adding 3dB to the value is the same as a doubling of the sensivitiy (assuming that I have remembered my maths correctly). The jump of 8dB will have been quite significant to the output.

What can you do? Not a lot apart from getting less sensitive speakers.

The mis-match in the volume pot is also a common feature - it is very difficult to make a volume pot that is perfectly matched along the entirety of its travel, and the beginning is where it is usually noticable. The NAC112 and Nait5 should be better because of their discrete resistor ladder networks in place of the volume pot.

Simon
Posted on: 10 September 2002 by David Stewart
Might be worth borrowing a pair of minimum 5 metre long NACA5 cables from your local dealer just to make sure it isn't an output matching problem they could fix. Just a thought confused

David