2. amps-preamps
  3. 1109824073

Volume level mystery - can you solve it?

I recently replaced a pair of Linn LK power amps (85 and 140, in passive biamp mode) with the much more powerful Linn 2250 amp (just one). My preamp is a Linn Kairn. I have noticed that in order to achieve the same volume levels with the 2250 as I was getting with the 85/140 combo, I need to crank the Kairn volume setting much higher. By way of example: on a scale of 1-100, 50 used to be my normal listening level, but to achieve that level I now need to turn the Kairn up to 70 or higher. The Kairn only goes up to 100, but with the new amp, everything below 60 or so is very, very quiet. After 70, the volume ramps up pretty quickly, whereas with the 85/140, the distribution seemed more of an even straight line graph. Does anyone have any idea what this is all about? Are amps just calibrated differently? If anything, I would have expected the 2250 -- a more powerful amp -- to produce higher volume at lower settings, but the reverse seems to be true. Any thoughts about this would be much appreciated. I am a little worried that something is wrong with the amp, but aside from the volume issue the sound seems good. Thanks.
kdl6769
gregm
3,405 posts
 
Bigtee wrote:
Some preamps like more load, some less...
No, not really. Lowering the load's impedance always makes things more difficult for the source. The higher the destination impedance and the lower the source impedance, the better.

If all Linn amps have identical input impedance across the FR spectrum, the single 2250 should be a MUCH easier load (twice as high in fact).

Maybe you should follow Lugnut's advice, pronto!
bigtee
803 posts
 
Maybe so, but I haven't always found this to be the case in real life as for actual levels(few other factors envolved.) I don't know about Linn equipment and the type of input configuration it has ( Jfets or whatever) I do know a lot of preamps like a certain load and I based my statement on that ( a generic one at best) and I agree, most preamps like a higher impedance load (especially tubes without a buffer)
I also concur, call the factory.
lugnut
1,190 posts
 
Bigtee might be right. I have no experience with passive bi-amping. The tech people might be able to shed some light on this. In my experience they are slow to respond. Expect up to a week to get an answer.
kdl6769 OP
23 posts
 
Here are some gain, impedance and other stats. For those who know about these things, perhaps they help answer the question. Gain looks approximately similar across the board, but input impedance looks different, although I can't interpret the information.

Please let me know what you think.

1. 2250 Amp (which I am using now and which requires me to jack up the volume dial on my preamp):

Gain
Unbalanced 28.3dB
Balanced 22.3dB [NOTE -- I use unbalanced]

Input Impedance
Unbalanced 7K8ohms
Balanced 7K8ohms

Input Level for Clipping
Unbalanced 1.2V rms
Balanced 2.4V rms

Output Power
230W rms into 4 ohms
115W rms into 8 ohms

Maximum Input Power
1000W

Typical Operating Input Power
44W

2. LK 140

Gain
x27 (28.6dB)

Input impedance
10Kohm

Input signal for maximum output
870mV rms

Maximum input power
570W

3. LK 85

Gain
x27 (28.6dB)

Input impedance
10Kohm

Input signal for maximum output
685mV rms

Maximum input power
350W
gunbei
2,327 posts
 
I agree, it could be that running the two older amps in passive biamp may have had the effect of summing their input impedances, which is greater than the single new amp, and thus presenting a different load to the preamp.

To test this theory out just run one of your older amps full range and see what kind of gain issues you have then.
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