Lamm LL2.1 Deluxe "DC Offset"?

Jtimothya

If you learn my previous posts, you may see that the measurement also taken in the dealer's show room. This is to prove and get both side agreements on the method to be taken as well as to get both sides admittance on the result that there is a real problem with the unit. Although they are using power conditioner in the system, the measurement clearly showed a highly fluctuated reading, and the dealer admit it, no arguments.

All measurements was taken using 3 different devices in several different occasions. We are using 2 Sanwa CD800a and 1 Fluke 87V multimeters, those are a well-recognized brands that being used by professionals and audio hobbyist. The dealer itself using local made multimeter (Heles) in comparison to mine.

The dealer does not have another Lamm preamp and power in their stock. So we cannot make any comparison. This is actually what I asked to the dealer.

The suspect is my speakers woofer? or may be my other equipment?. I have 3 other preamps (SFL-1 Signature/Modified & upgraded, Mark Levinson 380 and Graaf, and did comparison test by inserting each of them to the system, one in a time. The result was? Only the Lamm that generates highly fluctuating DC Offset and causing woofer movements. Others showed a very low and steady DC reading, under 2mV DC. I did also connecting my amp with other speakers and in other occasion connecting my speaker to other system, both system work very well.

Yes, Lamm sent that build test report and I immediately sent it to dealer. Unfortunately the dealer did not show their own test result, but I did the measurement and sent the result to Lamm. However, I have to wait more than a week before they finally respond to my email, that might be caused by my attack of suspecting their lack of QC when the unit leaving the manufacturer.

Why using third-party technician? He is actually a dealer's technician and Lamm very well trusted on him, according to their email. But he is not a full-timer or employee which dedicatedly works for the dealer. He is independent and takes work order from others. I only contact with them under dealer consent.

Whart & Charles1dad

Yes, I have already done most of your advices.

The dealer is the only channel I can communicate with. Lamm reject me to directly contact them. They never respond to my email anymore. If I send the unit to Lamm directly, I am afraid they will ignore it. Sending the unit without their consent will even get me into worse situation. In the other hand, I have to agree with Whart about the attitude of dealer, pretending as if my problem.

I did visit the dealer and talk about arrangement to ship the unit to Lamm (yes the unit still under warranty), that also include the shipping cost arrangement, but it seems not workable for them. I also insist dealer many many times to communicate with Lamm and explain our finding, not only my finding. I don’t know how their communication being conducted.

Lall,

I agree with you.
This is not only a technical matters of the unit. Not also a commercial matters. This is more about mentality.

Gr- It sounds like the bottleneck is the dealer- I agree that you should not ship the unit to Lamm without a return authorization and some idea of turnaround time. It seems odd to me that the dealer wouldn't handle this, or at least arrange it for you.
Can you tell me what city/country you are in? (I don't necessarily want you to name the dealer here, but perhaps I can help). You can send me a PM or email if you like.

Whart,

I dont thing the probelm is in the dealer alone. The tone of manufacturer's email responses was unbelievable. I can say that, both of them, in the way they responding to my case is similar. They are very defensive and tried to shift the issue to somebody else fault.

Iam not realy sure, but I guess something strange on the way they build and arrange the business which refrain the dealer to conduct intensive and frank communication with the manufacturer.

I live in Jakarta, Indonesia.

What reason does your dealer give for declining to replace the capacitors that Lamm offered to supply?

Jtimothya

I am not sure why.

Perhaps, the Lamm statement itself did not really confincing about the real problem that cause when they said "But even in cases like this the voltage at the preamp’s output never exceeds 50-100 mV."

I can understand if the dealer and thier technician in doubt to change the Caps. Based on my personal observations, the question should be addressed to the power supply system. Why an abrupt small AC swing (as small as 0.3-0.5v) can generate highly fluctuated DC output? shouldn't it be a tollerance range? says +-2v before this kind of AC swing hits the circuitry and manifested into high preamp DC output?

In this case a full technical support and detail instruction from Lamm is definetly required, they are the only one that really know about the design and topology/circuitry, so that it will not drive dealer and technician to perform a trial and error repair.