2. amps-preamps
  3. 1376189207

Preamp Headroom Question

Just bought a "lowish" output MC cartridge -- Lyra Kleos.

Background info: The Kleos' rated output is .5 mV. My phono pre is an ARC PH-8 which has rated gain of 58 db. The PH-8 is tied into an ARC Ref 5 SE which has rated gain of 12 db.

In most cases when playing vinyl the rig produces plenty of gain when the Ref 5 cranked up to 65 to 75 clicks out of 104 maximum clicks. But in a few cases, usually when playing some classical LPs, I have to turn the Ref 5 up to 85+ clicks to achieve acceptable gain levels.

The question: If the Ref 5 is cranked up to 85+ clicks, will I lose headroom in cases when the music hits dynamic passages? Also, I think playing the Ref 5 at such high levels increases the noise floor. That is I hear a lot of record hiss. Does all of this make sense?

I suppose the only solution is to insert a SUT, but it will come with its own cost. Probably need only another 5 to 10 db.

Any thoughts or suggestions.

Thanks.

BIF
bifwynne
almarg's avatar
Ag insider logo xs@2x
almarg
8,673 posts
 
Ralph, I'm not sure I understand your comment either, especially the part about "in the latter case the noise should be less than that of the groove." Can you clarify? Did you mean "in the former case"?

Also, why would playing an essentially silent groove say anything more about the noise performance of the phono stage than an assessment that is made with the stylus lifted off of the record?

Best regards,
-- Al
jjrenman
279 posts
 
My main Q was about dynamic headroom if I crank the linestage up. Per Al, shouldn't be a problem. If it is, it's likely happening on classical records which generally present large dynamic swings in volume. Less so on compressed rock

How you word your question suggests that you are thinking in terms of how an amplifier is set up. Specifically amps are almost always set up to achieve full output before you run out of volume control, anything farther causes overload/distortion. Preamps on the other hand are typically set so that as long as you do not overload the input you will not reach full output (before overload/distortion) even with the volume control all the way up.

IOW, in properly set up preamp/amp set up you never drive the preamp into overload and distortion no matter how much you open up the volume control. The overload is in the amp.

This is why the other posts are discussing noise levels/issues as that is the major concern when having to turn the volume control up all or nearly all of the way.

HTH
atmasphere's avatar
atmasphere
7,068 posts
 
Ralph, I'm not sure I understand your comment either, especially the part about "in the latter case the noise should be less than that of the groove." Can you clarify? Did you mean "in the former case"?

Also, why would playing an essentially silent groove say anything more about the noise performance of the phono stage than an assessment that is made with the stylus lifted off of the record?

In most cases the noise floor of the LP is going to be higher than that of the phono stage. Since the noise of the phono section will be masked by the LP surface, it is only important for the phono section to be quieter than the LP. That is why lifting the needle off the spinning LP surface really isn't telling you much.

Now if the phono section proves to be the noise you hear when you set the needle down in the spinning groove, that is when you know you have a problem.

Silent grooves can be found at the beginning of LPs, and also between cuts.
almarg's avatar
Ag insider logo xs@2x
almarg
8,673 posts
 
Thanks Ralph. Yes, that makes sense.

Best regards,
-- Al
More to discover