Lamm LL2.1 Deluxe "DC Offset"?

Lamm suggested that it could be a leaking capacitor. I'd accept the offer to have your dealer install them and see if this solves the problem.
Regards,

Hi Charles1dad,

Following that Lamm suggestion, about ten days ago I dropped the unit to the dealer for observation and necesary repair by their technician.

Amazingly, what they did and feed back me after having their own observation are as follows:

1). There is no repair or parts replacement required to the Lamm. They said this is new unit and no need any repair, only small tightening by reinforcing some solder has been made in and to the power supply area (I am not sure whether this is necessary)

2). The DC Offset fluctuation on the preamp that caused by AC voltage swing is naturally common in Lamm as this is the natural design of Lamm. In other words, the Lamm design will allow such AC swing, even as small as 0.3-0.5v AC, and pass it through the circuitry, to generates high DC milliVolt.

3). They suggesting me to use another power amp that may compatible with the Lamm. They also suggesting me to use stabilizer.

Learning from the above:

1)Should I push the dealer and technician to change the capacitors while they are very confidence that there is nothing wrong with the unit?

2) To my understanding, installing stabilizer and using other power amp is not the right way in solving the root of the problem, it's only curing the symptom while the real problem still exist, beneath. This only creating a time bomb.

I urged the dealer to contact Lamm about this, but they asked me to bring back the unit isntead. They very confidence the unit will be just fine. I can imagine, once the unit back to my system the problem will still exist, and do know what should be the next thing to do except to sell it

Gr-gin,
Well,it appears that the Lamm has this inherent design issue and will require a more compatible power amplifier. Or keep your amplifier and sell the Lamm, as there's no repair for this situation(design choice).

Charles1dad,

Welll, that actually a statement coming from the dealer free-lancer technician and His statement is contradictory with Lamm statement.

if we learn from the Lamm email, as a manufacturer who design and pruduce the unit, it's clear that this not their natural design. They said that the measurement of AC fluctuation causing high DC fluctuation was PUZLING them and they never had that experince on such case. They also said that even if there is a leakage on the caps, it will never exceed 50-100 DC milliVolt. So, there are two big questions that they themselves dont have the answer.

I believe they can find the answer, only if they deeply and sincerely and honesty listen, learn and dedicated their time to observe the unit. Further, if I were them, I will have myself to look back and learn the design and then have one or two comparison units put in the bench to be tested. And I believe those unit will perform well, contrary to mine.

If that is the design, does a highly fluctuated +-200 milliVolt DC offset common and acceptable to the industry? Secondly, does the small swing of 0.3-0.5 AC voltage that generates a fluctuated hundreeds DC Offset also aceptable to the industry?. If that the case, then Lamm will have extreem difficulty in finding a matching power amp in the market. They can only be paired with Lamm power amp, which is notbthe case.

There is also the fact that for the first 4 weeks the Lamm work well with my entire system, we did have microphonics problem in one of the tubes but we replaced it by new one and things back to normal.

There is also the fact that before I bought the unit, I firstly contact Lamm whether their preamp will be matching with my system, their answer is: the Lamm LL2.1 will work well with any power amp as long as the input impedance is 10k-ohm or more.

Again, the answer is depend on how serious the dealer, technician and Lamm trying to solve the problem. Not shifting the issue or blamming other products.

I would go with option 1 and have the dealer replace the caps. That way you will have shown Lamm a good-faith effort on your part to see if that was the problem.

And who knows, maybe that will fix things. If not, then it's time for either a full replacement or your full money back.