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Lamm LL2.1 Deluxe "DC Offset"?

Hi there,

Is there anybody who has a deep experiences with high fluctuated "DC offset" in Lamm LL2.1 Deluxe PreAmp?.

My Lamm LL2.1 Deluxe Preamp shows a highly fluctuated DC reading that reaching +-200mV even more. Last night measurement showed a flucuated reading and reached +-300mV.

A three weeks continuous observation shows that the preamp DC fluctuation seems higly affected by the swing/fluctuation of AC Volatage,day time and night time. I can see that even as small as 0.3V AC voltage abrupt swing will directly generate significant DC offset in the LL2.1.

Your sharing experience and advices are higly appreciated.
gr-gin

Showing 3 responses by jtimothya

jtimothya
612 posts
 
Lamm gave you a diagnosis and offered to supply the parts to your dealer to address the issue. Your dealer has a Lamm qualified technician.

This situation is either very simple or there is some information missing. Seems like it is up to you and your dealer to effect the factory recommendation and it appears odd that this has not happened and equally odd that you do not know why.

Work things out with your dealer to make happen the factory suggested change. Regardless of what you think or who you think should do what, until that happens there's little else to be done. If Lamm's advice is ignored or otherwise not taken, that moves them outside the resolution loop. Speculating about a design or conjecturing about motives on an internet forum will not change things. Fwiw, the LL2.1D is an excellent preamp that yields further enjoyment with NOS tubes. Good luck.
jtimothya
612 posts
 
This story does not appear to be happening in real time.

The dealer gets a lower measurement than you and Lamm states a lower measurement has been seen on one occasion which was diagnosed as leaking caps, which they offered to replace. You suggested the dealer's lower measurement was a function of AC conditioning.

What did you do to validate the accuracy of your meter? Have you taken your meter to the dealer to let them compare its reading with theirs in their context?

Have you taken your amplifier to the dealer to let them try it with another LL2.1 or different model Lamm preamp?

Have you observed the woofer problem replicated with any other amplifier?

Thus far it sounds as though Lamm is responsive and open in their correspondence and following their protocol. It is not unusual for them to supply repair parts to local technicians for installation.

Lamm sent a report of the build tests for your specific unit. Did you share those with the dealer? Does the dealer's test show a deviation from those results?

If your dealer has a Lamm qualified technician in their employ who can do the work and the unit is under warranty, what reason do they give for declining the repair?

Why is a third-party technician involved?
jtimothya
612 posts
 

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