2. amps-preamps
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Lamm 1.2 tubes, power cable and slight one channel

Hi All. Well I have just (last week) had my Lamm 1.2s arrive (second hand via the local dealer) and they are ohhhh so nice to listen to. Fantastic detail and sound stage, I have an Antipodes DX into a Meitner MA1 Dac into the latest Concert Fidelity pre into the Lamms. For cables - mostly Antipodes Komako (IC) and am trialing Townshend SC into Harbeth Super 5s.

My tube questions are:
- Has anyone tried EAT (new - which appeals but are they any good) valves or CCA Philips yellow lables?
- What tubes would go best with these (2 or 3 choices in case I have avail. /cost issues)? What are the best few i should be saving/waiting for?
- Who are the most trusted tube sellers? i just hear so many bad stories.
- What should I be looking out for/asking when buying tubes?

Also should I be using any special power cables and/or a conditioner with the Lamms - and if so any recommendations?

Finally (sorry for all of the questions) I am using them unbalanced with the shorting cap on. However I get a very low level hum (audible from more than a few feet away) on one channel. That channel had no issues when running my Airtight previously. This is even when all of the local RF generating items are off and the pre is unplugged from the Lamm - and also when the pre is muted (but plugged in). I have tried swapping out the power cable with the other amp (which has no such noise), changing speaker cables, making sure power and sp cables are well seperated, changing where it is plugged in to (wall socket) but still... The tubes are a few months and 40 (or so) hours old. I am thinking of next swapping the two amps over to see if it's a very very localised RF issue - and then swapping the tubes over to see if one tube got damaged on the amps being delivered. Could a tube be creating a very low level hum? And is there anything else I should be thinking about or trying?

Thanks in advance - any and all thoughts and help really appreciated. Kind regards
Stu from NZ
colville12
3 responses Add your response
dkarmeli
334 posts
 
Disclaimer- I'm a Lamm dealer.

The dealer should be troubleshooting them for you!

My favorite replacement tubes are Telefunken, Mullard or Amperex, the sonic benefit is worth the money for these tubes.

Best sound with Lamm stock cords! They're black with a round molded plug don't change to audiophile cords, they'll just color the sound. Conditioners and other AC filters will degrade the sound of your amps, they already have built in AC filters.

The hum can have several reasons, troubleshoot in this order disconnected from the preamp.
- Check the fuses make sure that they're stock and not of the audiophile variety.
- Ground loop, try plugging it in to the same outlet as the quiet one and see what happens. Try a cheater plug(ground lifter) if you still have noise.
- Bad shorting plug, swap them out and if the hum persists change the tubes around with the new shorting plug in place, don't change back.

If none of the above works you need to have the amp serviced.
Good luck!
David
kurt_tank
1,189 posts
 
I too use Lamm amps, and have for ten years.
(Although, I use the M2.1 amps. But I am jealous, as I would love to upgrade to the M1.2 amps!)

I use Amperex pinched waist 6922 tubes now, (which are the best tubes I have heard, and very expensive), although I used to use some Amperex Orange Globe 6DJ8 tubes, (which were very good, and much less expensive).

I too just use the stock power cords, as Vladimir told me that he doesn't feel after market cords do much good.

I do use a power conditioner, but it is a minimal conditioner, (Shunyata Hydra 2), made for amplifiers. And I use this almost more because I needed to use an extension cord, and this worked out the best for me.

I will point out that I do use dedicated circuits, which are very important to use. (The transparency improved a bit and the bass response really got tighter and deeper when I installed them.)

As far as your hum issue, I can't help you as mine are dead quiet, but then I do run mine balanced.

My two cents worth,
Ag insider logo xs@2x
hotjacket
1 posts
 
I understand this is a very old post, I just spotted it now ... but I also have a pair of Lamm M1.2 Reference amps, which have always made a humming / buzzing noise (not through the outputs, but a physical noise emanating from both amps). What I find interesting, is that I also live in New Zealand... so I wonder if that is a contributing factor.

The only way I got rid of the noise was by running through a PS Audio PowerPlant 10 power regenerator... which is unfortunate, since Lamm recommend in the manual not to use such devices. I emailed Lamm but never heard back, so they’ve been gathering dust for some years now :-( I'd not thought about using a dedicated circuit though, so might give that a go, they are very musical amps but the buzzing always drove me nuts.
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