2. amps-preamps
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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

Showing 2 responses by bifwynne

bifwynne OP
2,206 posts
 
Thanks Al. Easy enough to check. Next time I turn my rig on, I'll turn the linestage gain up to 80-85 clicks on phono setting, with the TT running -- but leaving the tone arm elevated off the record. That should be a good test to see how much noise is coming through the system.

On a different note, some months ago, I posted a thread about dedicated power lines for my rig. Haven't executed yet. But ... last night, I disconnected my amp's power cord from a lightening arrester extension cord and plugged the amp's power cord directly into the wall socket. The lightening arrester extension cord feeds the rest of my gear. Major difference! It's kinda' like the amp was gasping for breath before. Across the board improvement, especially improved lower end and better kick with dynamic transient responses. This morning, I did the same with my linestage. It will be interested to see if there will be similar improvements.

Thanks as usual.

BIF
bifwynne OP
2,206 posts
 
Ralph, sorry to sound dumb, but not sure what you mean when you say "how much noise there is when the needle is in a good silent groove." Does that imply when the record is spinning??

I ask because I checked the phono noise level with the linestage set to 80 clicks (out of 104) with the TT motor running, but with the tone arm lifted OFF the record. Is there noise?? Yes. I can hear hissing about 2 foot away from the speakers. The noise level is about the same out of both channels. Much beyond 2 feet, it's pretty quiet, or quiet enough.

My linestage is pretty quiet, about -109 db; the phono pre is fair, about -74 db, but not outrageous for a tube phono pre.

I'm not sure how to assess noise if the stylus is in a "quiet groove" while the record is spinning. If you are referring to a quiet passage, like a single instrument playing (e.g., a flute or violin), I don't think it's too bad. If anything, on some records, I'm probably hearing the stylus tracing the groove. On other records, very little groove noise.

Having grown up in the 70s, vinyl was notoriously "hissy." OTOH, I just bought a brand new 200 gram Mahler LP re-issue from Acoustic Sounds. It's very quiet.

Not sure all of this is responsive to the comments and suggestions offerred by you and Al. But that's all there is to report.

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.

Thanks

BIF

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