Hiss at addition in system LAMM L2


Hiss (noise) from speakers at addition in system LAMM L2.

Three weeks ago, I have bought preliminary amplifier L2 reference
Improvement in sounding all system was huge!!!! The overall dynamics and scale of the music!!!
Illusion of a presence(finding) in a concert hall has appeared.

But I am disturbed with the following:
At addition in system L2 strong enough noise (hiss) has appeared from
speakers. At inclusion of toggle-switch MUTE hissing disappears, at deenergizing
Toggle-switch MUTE all room is filled with noise (hiss).
Even at listening music on silent passes or piano music
Such noise level it is normal or L2 demands repair?
anton9005
I have soft, low-level hiss in my system with the Lamm L2. Yes, it can be heard from the listening chair 8 feet away. It's very slightly more hiss than I heard with an Atma-Sphere MP1 MK III linestage or Audio Research Reference 3 preamp in the system. It's *less* hiss than was present when using the Atma-Sphere's phono section. The hiss is not audible during quiet passages of music playback (although obviously it's still present).

The hiss goes away when the L2 is muted.

I often wonder if some of us are more sensitive to hiss than others, and were we to listen to the same system at the same time if some of us would object to hiss we hear whereas others would not.

The question is, how do we compare in writing the loudness of the hiss we hear unless we each measure the decibel level with the same model sound pressure level meter, at the same distance from the drivers, and after having established a baseline test tone decibel level? IMO, this is nearly impossible.

To directly answer your question with a few suggestions...

Using the L2 in balanced mode with balanced amplifiers reduces hiss level, as does changing old tubes to new tubes and re-biasing the preamp. Re-biasing according to the owner's manual must be done after tube changes in the L2 power supply. A multi meter, and a small flat head screwdriver is required.

If you still have excessive hiss after you change the tubes, re-bias the preamp, and run it in balanced mode, then perhaps the issue is one of personal preference for less hiss and another preamp is in order.
I owned a L2 Ref 2 years ago. Had the same issue which drove me nuts. I did everything I could (bought new tubes, rebiased numerous times, changed cables, got balanced cables, moved my rack (thinking it might be and RF issue), took both isolated both pieces from the rack, swapped in another amp. You name it I tried it as I did love what it did in terms of musical presentation. Spoke to Lamm and on their advise shipped both crate "air express" from western Canada to NYC - OUCH at almost $500 return. They could not find anything wrong with it. Since it was there I had them upgrade all the toggle switches to the current version.

Got it back and still the noise but mine was more than a hiss it was more like a sizzle. Had my buddy John Wright of Museatex fame give it the once over - still the same problem.

While it bettered my resident Hovland preamp the Hovland was dead quiet in comparison. In the end I sold it. I could not justify its "issue" for what I had in it.

As Grant advises it may not be for you which was my case...
Hiss can be annoying, no doubt.

I will add that using different power conditioners and cords has affected the
L2's level of hiss in my system. It seems to be fairly sensitive to power cords
and power conditioning, IMO. You don't necessarily have to spend a fortune,
either. I'm presently burning in an Alan Maher Reference Power Center V2
that retails for $750 including a captive power cord. The hiss level is the
same, or slightly less, than when I was using a Shunyata Hydra 2.

In my system, the L2 is better (more transparent, alive, and lacking
coloration) than the ARC Ref3, despite the ARC being nearly dead quiet.
However, this is likely due to better impedance matching with my amplifiers
than anything else.

The only other balanced preamplifier I'm aware of that has an output
impedance somewhat close to the L2 is the Modwright LS36.5. I'd like to hear
one in my system since Modwright products are famously quiet, but the
price including the PS36.5 power supply puts it out of my comfort zone.
forgot to add that I threw mine on a BPT balanced conditioner and also ran it on its own dedicated 20A line - still had the problem. Got an email from a gent in Europe after I posted my findings and his L2 Ref had a similar problem. I would imagine what could be this preamp's "best" match is a Lamm amp(s) but that was not in the cards for me...
The L2 Reference is an outstanding match with Pass Labs XA-.5 series.

IMO.
The pre will hiss no matter what you do. The hiss comes from the mosfets in the circuit and higher gain amps on more sensitive speakers will hiss more than others.
You either live with it or sell it. For me, I chose to go a lower gain amp and it remedied the problem well enough for me.
Interesting about the mosfets.

I owned a Moscode 401HR amp that used mosfets. It's a high gain amp, and I can't say I heard any appreciable hiss.

Not arguing your point. Just making an observation.
I had BAT Rex in my system recently, paired with BAT 75-SE, and it was "dead silent"- I could only hear very low level ground loop- type cycling humm with my ear literally 1" from the tweeter, which I'm positive, was related to my power lines, rather then Pre/Amp themselves.
So, I guess hiss is a byproduct of less, then perfect design, and not inherent to tubes or mosfets for that matter.
Considering the bad user experiences and opinions being
expressed, I suppose there'll be a glut of used L2 Reference preamps in the
listings soon. Mine won't be one of them, however.

It might be helpful to know the sensitivity of everyone's speakers who are
experiencing excessive hiss with the L2 Reference. Mine are 93dB, and as I've
already written, the hiss is normal, IMO, and certainly within the range of hiss
I've heard in my system in several iterations with other gear and speakers
(89dB).

I have had a few iterations where there was zero hiss...and I mean none. The
amps were NuForce, Bel Canto, and Leben. Preamp was Atma-Sphere.
However, none of the systems were as musically satisfying as the one I have
presently.
Just for reference, I had the lamm pre in a system with Coincident Total Victory, Revel Studio and Verity Parsifal. There was some degree of small hissing with all but none really annoying except one combo: Coincicent TV with Antique Sound Labs 1009 60 watt monos. The hiss was very audible.
I had a 200 watt Edge NL 10 in that system that was fairly silent, surprising considering the power difference.
Currently the Lamm M1.1 are paired with the Verity and the hiss is only audible if you put your ear to the tweeter.
So in my experience it appears to be a amp gain speaker sensitivity issue.
The lamm pre is the longest surviving component in my system and is the last one that will leave.
My system:
Mark Levinson ML-390S
Preamplifiers LAMM L 2
amplifiers LAMM M 1.2
Dunlavey SC-V
Purist Audio
I always thought, that Preamplifiers and amplifiers one manufacturer
Will well incorporate …
However hisses strongly … even on distance 15.
Can change L 2 on LL 2???
What Preamplifiers LAMM L 2 or LL 2 hisses less??
In response to Tvad's comment:

"I often wonder if some of us are more sensitive to hiss than others, and were we to listen to the same system at the same time if some of us would object to hiss we hear whereas others would not."

Absolutely true.
I am one of those that can not stand hiss, (usually introduced via tubes), that is audible from one's listening position. I have sold all of the tube preamplifiers (and tube phono preamps), that I have tried becasue of this. That eventually led me to use the (solid state) Ayre K-1xe preamplifier, and its phono boards, in order to get as deep, dark blackground as posible. (FYI: I am very happy with the results, and doubt I will ever go back to a tube preamp.)

And what is funny is that I can ignore pops and ticks from records, which is how I listen to 90% of my music, but not low level hiss. (Well, a limited amount of pops and ticks anyway. Too much of course spoils it for me.)

However, I do realize that I like how tubes make the music sound, so I have managed to interject a nice touch of tubes via my Lamm M2.1 monoblocks. They only use one 6922 tube in the driver section of the amp, but it is enough to make the music come alive. (I will state that I use NOS Amperex pinched waist tubes, because I want the absolute best of the tube sound, and since I only need two, the exorbident cost of these tubes is somewhat mitigated.) And yes, it does introduce a very small touch of hiss, audible only by putting one's ear to the speaker, but it's not audible from my listening position.

If you can find that you can live with the hiss, you're probably better off in the long run, as the Lamm L2 reference is a wonderful preamp, and incredible musical, and one of the better preamps around. (Assuming you can live with the hiss, and its lack of a remote, (which was the deal breaker for me).

Good Luck!
FWIW In various tubed preamps I have had good luck reducing hiss by using Rothwell Atennuators at the amps input(s) also they have elimated AM radio leaking through my speakers.
I owned a LL2 Deluxe, which was one of my favorite preamps. In some
respects, I prefer it to the L2 Reference. However, it does not allow for balanced
operation.

In my system, the LL2 Deluxe hissed about as much as the L2 Reference, from
what I recall, and to be fair my system has completely changed in the interim,
so the comparison is not apples to apples.
FWIW In various tubed preamps I have had good luck reducing hiss by using Rothwell Atennuators at the amps input(s) also they have elimated AM radio leaking through my speakers.
Faziod (Threads | Answers)
Depending on the system's resolution, this may not be an ideal solution, IMO, because the Rothwell device adds a layer of resistor that reduces system transparency. The better solution is to have the preamp manufacturer reduce the output gain of the preamp by swapping an internal resistor. I had Lamm do this with my LL2 Deluxe, and the result was perfect.
Prior to acquiring my L2 Ref I also auditioned the LL2 Deluxe and loved it. It bettered my Hovland HP-100 and did everything well. Funny enough it was as quiet as the Hovland and both were dead quiet as compared to the L2-Ref! The only reason I jumped on the L2-Ref was I thought (and maybe foolishly) it would be that much better than the LL2 deluxe which in my case it was not. Based on typical used prices IMHO the LL2 Deluxe is the darling of the Lamm line-up...
how could u possibly deal with a piece of equipment that introduces a hiss to your system? i dont care how good the soundstage is. i would junk it or sell it. it would be a good idea to let the poor potential buyer know about the issue.
Tvad , I am thinking about lowering the gain on my LL2 Deluxe
If you recall,how much gain in db did you reduce.
Many thanks
ed
Tvad agreed on the loss of transparency with the Rothwells but its the only thing I have found to work to eliminate the AM radio leaking through to the speakers. Shielded cables help but the Rothwells completely eliminate it. Strange as it may sound.
Based on typical used prices IMHO the LL2 Deluxe is the darling of the Lamm line-up...
Rgd (Threads | Answers)
I absolutely agree. If I did not require balanced operation, I'd likely own another one.

09-26-08: Goldeneraguy
Tvad , I am thinking about lowering the gain on my LL2 Deluxe
If you recall,how much gain in db did you reduce.
As I recall, it was reduced to 12dB.

09-26-08: Faziod
Tvad agreed on the loss of transparency with the Rothwells but its the only thing I have found to work to eliminate the AM radio leaking through to the speakers
Understood.
09-26-08: Flyin2jz
how could u possibly deal with a piece of equipment that introduces a hiss to
your system?
I am certain that no answer I, or
others, will provide will be satisfactory to you based on your obvious
predilections. However, I will offer my perspective.

I have heard several highly regarded, universally well-reviewed components
in my system that have been as silent as a corpse, but the music they
produced was sterile, lifeless, and basically sounded like crap.

For me, choosing some hiss over the alternative is an easy choice.
Rgd and Tvad, I agree with your assessment of the Lamm LL2 preamp. Especially at its resale price it is a screaming steal and a wonderful musical preamp that flat-out danced with my ML 2.1s. I found the musically to hiss trade-off to be extremely positive...and the hiss to be sort of a small attention getter setting the stage for what was to come.
RGD your experience sounds like a nightmare to me...
It was and I still maintain that the L2Ref is a wonderful preamp that did not work out for me. It was my first foray into a big ticket expense (at least according to my level of disposable income) that left me gun shy on making further commitments at such an expense level. I have found that an ARC LS-26 (acquired at a really great price) has fit the bill nicely. My aural memory, like many people, is short so I cannot say what differences there are between these 2 preamps as there were months between them being in my possession but the LS-26 has been a solid performer from day 1 and is not on my list of components to upgrade.
I've had both the LL2 DLX & currently the L2 Reference! I'm using it with Lamm ML1's & Wadia 861 cdp. Connected with Nordost Vahalla balanced IC's & Klipschorns! If any system should have hiss this should be the one "dead quiet"!! Considering 581ise.
Today, I tried connecting the L2 Reference to my Pass Labs XA-60.5 amps using
the L2's single ended outputs with XLR/RCA adapters. I am still using the Pass
Labs' balanced inputs. I find the sound to be more natural this way. Less
mechanical. I don't discern any additional noise or hiss as a result. In fact, it
may be even quieter.

I did not expect this result, and I'm wondering if any other L2 Reference owners
who run the preamp balanced have tried this experiment.

Does the L2 Reference's signal pass through additional circuitry to convert it to
balanced?

Based on what I hear today, I am likely to convert my interconnects to
RCA>XLR cables thereby eliminating the adapters.
Has anyone solved the hiss issue?
I would like to know this too.