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stupid question about sources, amps, and loudness

Okay, so I really should know this, but I don't, so your help is most appreciated.

My speakers are a fairly tough load to drive 86db efficient, 6 Ohms nominal.

That suggests that I need reasonably powerful amplifier(s). Currently I use solid state amps rated at 100 WPC.

The amps are Kharma MP150s. They drive the speakers quite loud, although they do start to "flatten out" at 95 db (which is much louder than I typically listen, even when I've turned it up).

I have some issues with not having enough range of volume control either with a pre-amp or with a CPD with a volume control -- that is to say, if I turn the volume control much past 10 or 11 it is too loud.

I know that I can use attenuators to fix the volume control problem, but that they also can have sonic consequences.

Here's the question: less powerful amps are NOT the answer right? It's input sensitivity. Right?

So, if for example, I am thinking of trying tube amps, I still need to be mindful of the difficult to drive speakers and thus need to get some pretty beefy tube amps (i.e., 100 WPC+). Because less powerful tube amps won't have enough current to drive the speakers effectively.

BUT: I would want amps with a lower input sensitivity?

Do I have this right?

Thanks for clearing the cobwebs for me.

--dan
dgaylin
xti16
1,525 posts
 
I had a similar problem when I use balanced ic's. Except I could not even get to 11 o'clock which is why I bought the rca version.

As far as tube power I had a Bryston B100 rated @ 100w into 8ohm and 180w into 4ohm. My speakers are Dyn C1's rated at 85 db but a steady 4ohm. Then I bought the Octave V70SE rated at 70w into 4ohm. The Octave has everything all over the Bryston especially the control of instruments and vocals. 2 things I would consider when looking at a tubes is a soft start to make the tubes last longer and a good output protection circuit (all tubes will eventually fail) and you don't want to have to have it repaired after a tube failure.
charles1dad's avatar
charles1dad
10,250 posts
 
Great comments from Onhwy61! I agree that you need to know the voltage out put of your digital sources as they can often exceed the 2.0 volt standard. Preamp gain plays major role also. I had rhis same issue a few months ago. My DAC has 3.1 volt output,preamp had 20db of gain, amp input sensitivity=0.7v and speakers are 94 db sensitivity. I solved the problem by having Coincident reduce rhe preamp gainfrom 20 to 10db, problem solved completely.
Good Luck,
dgaylin OP
255 posts
 
All --

Thanks for the many helpful comments.

Specifics are as follows: speakers are Wilson Benesch Curves; pre-amp is Nagra PL-L. Sources are EAR Acute CD player (yes very high 5V output) but also Northstar DAC (2 volt ouput).

Here's the experience:

with the Northstar into the Nagra, volume on the Nagra was at 8-10 o'clock. Over 10 too loud. When I changed the jumpers on the Nagra to -20db, the volume needed to be at 3-6 o'clock (7 is maximum). But the sound was noticeably less clear -- sort of compressed sounding.

with the EAR into the Nagra, the EAR's volume is set at 12 o'clock, and the Nagra then has a nice range of volume control (10 o'clock to 2 o'clock). Seems good. BUT...

The very best sound of the system, despite the fact that the Nagra is an absolutely wonderful pre-amp, is to connect the EAR directly to the amps. Surprisingly much better: more details, greater warmth, greatly improved soundstage.

In this set-up, the EAR's volume control is between 8 and 11.

Sebrof -- the problem is that fine volume control is difficult with such a small range, and as I understand it with volume controls, using them at the extreme range is not good in terms of sonics.
ckoffend
684 posts
 
I don't know the steps in volume control for the EAR CDP. But my question is when the EAR is running into the PLL preamp, why don't you have the EAR's volume/output set to fixed (is this not possible with the EAR?)?

I have heard very good things about the EAR Acute and have owned the Northstar DAC (good, but not better than the EAR from what I have heard). Doesn't the EAR have digital inputs?

Are you running balanced or SE? Maybe try a pair of Attenuators (either RCA or Balanced) running at negative 10dbA. I think this may help give you what you are seeking.

Finally, the EAR Acute is supposed to be pretty warm. Unless you are looking for a lot of warmth I would definately try it with a tube amp before buying one.
dgaylin OP
255 posts
 
Yeah the EAR has no fixed volume option. Yes it does sound warm, which I like, and while the Northstar is good, the EAR is substantially better. Agree that tube amps may be too much of a good thing. Also agree that maybe I have less of a problem than I originally thought. Will probably try some attenuators since it is an easy and relatively low cost experiment.

thanks all!
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