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My MC275 has a clueless sound-change...

I just moved my MC275 from the ground to on top of my rack. Same system and same cables, but the sound changed from musical, well tonal balanced... to thin, noisy, sharp, bottom-less... Anyone of you had such experience and can explain why would this happened? I have the amp sitting close (approx within 2-3 feet from the speakers' mid range section, can the magnetic field affects the operation of the tube amp? or is it that the cables needs to break in again after a few new bends... I am clueless, I switched my interconnect from my Pre to Amp... although it added weight on the bottom end, the mid to the top is still noisy, sharp and forward... please help...
infinity_audio
lapierre
547 posts
 
Examine 12 type tubes and double check the fuse.
Double check connections to loudspeaker and amplifier.
infinity_audio OP
186 posts
 
The 12 type tubes were mostly new.
Mine is the V generation. The current production.
V1 I left the original tube, because im using single end.
V2 and V5, i upgraded to a new pair of RCA 5751.
V3 and V6, V4 and V7, I installed a matched quad of RCA black plate 12AT7 which all tested around 75-90.

It is very hard to believe that the tubes are out.

Can it be the power tube?
I am interested in changing the tube to the Gold Lion reissue. How are they compared to the stock tubes?

My connections are as tight as they get...
cyclonicman
693 posts
 
I had a similar experience and moved my amp back to the lower rack. Could not explain it, but rationalized that maybe the lower rack offered better vibation control.
lapierre
547 posts
 
Do you have dedicated AC for the MC275?

Tubes like stable power.

My fuse blew in the first couple of weeks which really bothered me so I ended up upgrading the fuses first. Later I added Mullard 12A7T and 12X7A along with Genalex KT 88/6550.

Expect more depth and bottom end with the Genalex Gold Lion KT 88/6550. Brings your power rating closer to 90 to 95 watts a channel. Since I have oversized bookshelf speakers I could really tell the difference.

If we need to talk offline just send me an email.
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