Tube preamp hum

rubin

I added the Jolida Envoy preamp (their best offering) hummmmmmm.The SS pre was dead quiet. The hum does not increase when turning the gain up, even all the way. It cannot be heard while playing music. It's not loud, it reminds me of the humming heard at electrical transformer stations.The tubes look good, the pins and sockets are clean, the tube connection is tight. The tubes and preamp have low mileage. So is this normal for a tube pre?

heiney9

Sometimes this is just a byproduct of running tubes. I think all my tube gear has a very slight hum which I have to go up to the speakers to hear, so it's not distracting at all. You could try a different power cable or consult Jolida about some fixes to lower or get rid of it. I even borrowed the well liked Dodd ELP and it had a slight hum.

I assume it's coming through the speakers and not the actual transformer itself.

H9

thsmith

Have you tried using ground cheater plug?

You may have a ground loop. I had a SS pre that would do the same thing but my tube pre does not.

fishbones

I'm no tube expert, but from what I've learned - these are some things that can also make that happen:

-First off it could be exactly what H9 said. Many times it's the nature of the beast. It really depends on how loud it is?

-All tubes have different noise levels. Some are better than others (even within the same production run I believe). You could have a noisy tube? You could try tube rolling if there's not too many tubes in it?

-Are you using different outlets than before? If you're using a different outlet that is linked to other outlets in the house, it could be picking up the RF noise from other appliances in the household?

rubin

fishbones wrote: »

I'm no tube expert, but from what I've learned - these are some things that can also make that happen:

-First off it could be exactly what H9 said. Many times it's the nature of the beast. It really depends on how loud it is?

-All tubes have different noise levels. Some are better than others (even within the same production run I believe). You could have a noisy tube? You could try tube rolling if there's not too many tubes in it?

-Are you using different outlets than before? If you're using a different outlet that is linked to other outlets in the house, it could be picking up the RF noise from other appliances in the household?

The entire system runs on 2 separate 15 amp supplies, via 2 panamax line conditioners/protectors.

rubin

heiney9 wrote: »

Sometimes this is just a byproduct of running tubes. I think all my tube gear has a very slight hum which I have to go up to the speakers to hear, so it's not distracting at all. You could try a different power cable or consult Jolida about some fixes to lower or get rid of it. I even borrowed the well liked Dodd ELP and it had a slight hum.

I assume it's coming through the speakers and not the actual transformer itself.

H9

It has 3 transformers, all are quiet.The humming is about as loud as the ballast box in a fluorescent light fixture. I'm not worried about it, doesn't seem to be hurting anything. As mentioned, the ss pre made no speaker hum and I'm using the same outlet. The only difference is the ss is a 2 prong the tube pre is 3 prong.

Ricardo

Try a different pair of interconnects if you have one.

HB27

I ended up having to use a cheater plug on my Comcast box to get rid of the hum on mine. I've chased hum issues and ground loop problems for decades and it's just a matter of unplugging one thing at a time until I find it.
My cell phone charger was an issue once and I just had to unplug the charger when not in use.
I had a DeWalt cordless drill gave me a hum when the charger was in use too. Usually it's just something simple if it's a loop issue but can be a P.I.A. to find. One plug at a time.
Harry

rubin

I added a 2 prong extension cord, no difference. The noise stops when the pre is off while amp and source equipment is on.

rubin

HB27 wrote: »

I ended up having to use a cheater plug on my Comcast box to get rid of the hum on mine. I've chased hum issues and ground loop problems for decades and it's just a matter of unplugging one thing at a time until I find it.
My cell phone charger was an issue once and I just had to unplug the charger when not in use.
I had a DeWalt cordless drill gave me a hum when the charger was in use too. Usually it's just something simple if it's a loop issue but can be a P.I.A. to find. One plug at a time.
Harry

As mentioned, with the ss pre no noise, same outlet.

punk-roc

I have a Dodd ELP tube pre and I've found the hum distracting.. I've tried cheater plugs and different outlets, etc as well. I haven't monkey'd around with IC's or power cords yet though, I hadn't thought of that.

I like my current IC's though!

Good luck rubin

Jason

Ricardo

Sometimes different IC's will produce more/less hum. Some are directional and have the ground lifted in one side, and I've had good results with them. Outlawaudio IC's are like this.

punk-roc

I've got some Kimber Hero ICs that i really like; but I do remember using the Dodd ELP without near as much hum when I first got it (before the Kimbers) and I did add a Pangea PC.. I will try with different cords.. Thanks Ricardo

Jason

Ricardo

From Outlaw's web page:

We are firm believers in the use of twisted, twin conductor construction for analog audio interconnects. This type of construction is superior due to the natural hum and noise reduction when twisted pairs are used, something not possible when coax type construction is used for audio applications. In addition, the use of twisted pair construction allows us to build semi-balanced style cables, where the ground is lifted at one end. This allows for a further degree of noise immunity not possible when coax style cables are used for audio applications.

The whole thing:

http://outlawaudio.com/products/cab_about.html

reeltrouble1

impedance mis match between pre and amp.

RT1

fishbones

reeltrouble1 wrote: »

impedance mis match between pre and amp.

RT1

That brings up a question I've had before...How close should they be?

rubin

punk-roc wrote: »

I have a Dodd ELP tube pre and I've found the hum distracting.. I've tried cheater plugs and different outlets, etc as well. I haven't monkey'd around with IC's or power cords yet though, I hadn't thought of that.

I like my current IC's though!

Good luck rubin

Jason

Can you hear the hum during music playback?

hearingimpared

Ricardo wrote: »

Try a different pair of interconnects if you have one.

That's what fixed my hum problems when I was using a step-up transformer.

punk-roc

rubin wrote: »

Can you hear the hum during music playback?

No, its drown-out during playback, but during quiet parts, its there.. and it can be heard from my listening position if no music playing (I.E. fairly loud)

Jason

rubin

reeltrouble1 wrote: »

impedance mis match between pre and amp.

RT1

Possible, I also have a MF buffer I could add .

reeltrouble1

its not a matter of proximity, there are many variables, its gets into the whole hum/hiss thing, given the cables establish ground then the problem is in the reluctance of the signal to travel its path, particularily if the impedance output from the pre does not see an input impedance at the amplifier it likes, that said, balanced is better, that though is another tale from the Rabbit Hole.

the Anthem hybrid amplifier plays nice with Dodd, maybe Lou will sell you his....or not.

RT1

rubin

Preamp input impedance= 100Kohms, output impedance= 600 ohms

Amp input impedance= 22Kohms.

reeltrouble1

does the amp use a stacked transformer or a toroid???

RT1

rubin

reeltrouble1 wrote: »

does the amp use a stacked transformer or a toroid???

RT1

toroid, distance between the amp trans. and the preamp trans is about 21" horizontally. The components are not stacked.

reeltrouble1

well, if you want to use that gear then the cable change suggestion is valid but its hit/miss and most are miss, maybe somebody has the same stuff.

You can try putting the buffer in, fact is this sound is normal for the Dodd with ss amps and it varies by amp. Gary Dodd was able to build some units isolating the power supply in a different box which others have said helped, but that wont help you and he is not doing it any longer.

RT1

rubin

Swapped cables, bypassed ground plug, all ic's are shielded, no difference.So it just must be the nature of the component.

heiney9

rubin wrote: »

.So it just must be the nature of the component.

That or synergy with your associated gear. It happens all the time and more frequently when tubes are in the mix.

EX. My brother wanted to buy a very nice Granite Audio tube pre-amp from a friend. Nice, well built, expensive piece. Sounded fantastic at the friends house. My brother brought it home to see how it sounded in his rig. It hummed like a ****. He swapped everything out, cables, tubes, etc. Bought 2 different power conditioners and humbusters, etc. Nothing helped. He returned it, reluctantly, because he couldn't get it to stop humming.

That's the way it goes sometimes. Synergy is a ****!!

H9

thsmith

Do you have someone else's system you could try the pre in ? The pre may have problems that need addressing.

fishbones

Does it exist in both speakers if you walk up to each and listen?

quadzilla

Something no one has mentioned, tube gear is also more succeptable to induced hum from other components than SS gear is. Have you tried simply moving the pre around? You can also try moving your hand around the outside of the pre and see if the hum gets less with your hand in a particular position. If it does that, look in that direction, as whatever your hand is between is what's inducing the hum.

doctorcilantro

Is it a humming, or a buzzing? You comment about a ballast box made me think of a buzz.

In my experience, 60hz gum doesn't have that buzz, whereas a ground loop has all kinds of weird harmonics....and a BUZZ.

You said something about two separate outlets. Have you tried:

-grounding the chassis of pre and amp together with a solid wire
-checking for DC current on chassis'
-trying everything on same outlet/ground