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AUDIO FORUMS >> General Discussion and Support >> Mini Torii hum with headphones
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Message started by chalun823 on 10/05/16 at 08:49:45

Title: Mini Torii hum with headphones
Post by chalun823 on 10/05/16 at 08:49:45

My Mini Torii doesn't have a headphone jack, so Steve made an adapter where a jack is connected directly to the speaker binding posts.

However, the hum is so obvious when using headphones (Sennheiser HD650 600ohm) that it makes listening impossible.

When using speakers (93db sensitivity) there is hum when I place my ears about a foot away and it never bothered me.

I actually moved to another home recently, and the result is the same. I have tried swapping the 6v6 tubes with no changes. I don't have other tubes to try swap out.

Any tips guys? Should I explore other tube changes or get the transformer checked out?

Title: Re: Mini Torii hum with headphones
Post by BadWolf on 10/06/16 at 18:57:39

Could be the input tubes. I've had that happen with mine, changing them made a huge difference.

Title: Re: Mini Torii hum with headphones
Post by jorgen on 10/07/16 at 09:40:17

I have a MT with headphone out, ordinary wired, and I too have a hum, also same with speakers, they are 94dB sensitive and the hum is hearable up close. We might be a little different in the sense that i am not bothered with hum, using LCD 2.2 cans I hear this hum in between tracks, but not a problem when Music is playing, of course unless the quiet. The hum im hearing is not affected by volume. I hav tried a few different input and a lot of ouput tubes and there is no difference

Title: Re: Mini Torii hum with headphones
Post by chalun823 on 10/10/16 at 05:03:04

Thanks guys for all your input!

The hum when using headphone actually gets louder than the music when listening to moderate music such as vocal jazz.

This has been going on for the past 9 months, but there was a new development last night. The speakers made a pop sound and the whole room was filled out burnt electrical smell. The left transformer was very hot to the touch compare to the right one. The fuse blew, and continues to blow fuses after changing them.

I sent Steve a message to see if it needs to be sent in. Hope it gets sorted out soon!

Title: Re: Mini Torii hum with headphones
Post by Steve Deckert on 10/10/16 at 05:25:52

I haven't checked e-mails yet, but your problem is a shorted rectifier tube. Only way to know if it has damaged the amp is to replace it with a good one and change the fuse and see what the result is.

This is likely the cause of some or all of the hum as well. If it turns out to be unrelated then your hum issue can be solved by putting a resistor in series with the headphone jack. 50 ohms is the starting point. Higher value, lower hum.

Title: Re: Mini Torii hum with headphones
Post by chalun823 on 10/11/16 at 02:44:11

Hi Steve,

Thanks for jumping into the discussion!

Actually, I have swapped out both EZ81 and OA3 before blowing the 2nd fuse.

What should I try next?