Swooshing sound on mc275vi

[seattlesounders]

I purchased a used mc275 vi and im finding:
1.It makes a swooshing sound when first turned on that lasts for around 4 seconds
2.Background noise from both speakers when input is on phono.

This repros with both a c46 and a c2300. Using XLR to RCA cables as interconnects. RCA into the amp. Any ideas?

[jameslrock]

Who can give advise regarding the tubes?

[Masterlu]

Originally Posted by jameslrock

Who can give advise regarding the tubes?

A good tube tester.

[Stahle]

I can’t comment on the phono issue because I don’t use a turntable but regarding the swooshing, can you elaborate? I think what you’re describing is this:

When the lights on the tubes go from amber to green, the sound turns on. At this point is the volume slightly lower and then increases for just a few seconds and then levels off? At the same time, does the signal first sound slightly distorted and then clear up along with the increase in volume during those first few seconds? If so, I believe your tubes just haven’t finished warming up in the time that the amp has allotted during the turn on sequence. Some tubes just take a little longer to warm up.

[seattlesounders]

Thanks for the willingness to help. I typically turn the preamp on then the MC275 and let them turn green. All seems well and no music is playing. Preamp can be on any input. Then I hear the swooshing sound which increases in volume and as I run over to turn the volume down it turns quieter and disappears.

The second issue: I assumed the MC275 background noise would be quiet but mine is audible when I put my ear to the speaker.

Note this unit was described as being in B1 condition, and all tubes light up green so not sure what the issue is.

[JMD]

Tube noise in the first couple of minutes is normal if it goes away and second if you have to put your ear up to the speaker to hear "tube noise" you don't have a problem. All tube gear makes noise if you put your ear up to the tweeter.

[JWJW]

Originally Posted by seattlesounders

I purchased a used mc275 vi and im finding:
1.It makes a swooshing sound when first turned on that lasts for around 4 seconds
2.Background noise from both speakers when input is on phono.

This repros with both a c46 and a c2300. Using XLR to RCA cables as interconnects. RCA into the amp. Any ideas?

A good tube tester or just upgrade to Gold Lions.

[ATC2]

Get a new tube, replace the tubes and see if you you can recreate the isssue. By processes of elimination you may determine which tube is defective. If it continues after checking them all then i would say it’s not the tubes. A bit tedious but it’s one way to do it, plus it’s always good to have a spare tube.
Just an idea...2cts

[seattlesounders]

Thanks guys. To those that have changed stock tubes on the 275mkvi, how did you find the sound quality and noise changed?

[crwilli]

I make a point of turning my PreAmp volume to zero before shutting my system down. I think it is a good habit to get into - especially in a system with tubes.