Slight hum at all times

[bandade]

This is kind of a dumb post given that there are so many links for hum issues on this site but I can't find what I'm looking for.

I just finished a Liverpool build and it turn out awesome. My only remaining issue is a consistent low volume hum when the amp is powered on. The hum comes through the speakers when standby is on and off and does not change volume whatsoever. I've tried moving wires around and swapping OT primaries with no results.

You do not hear the hum when playing because it isn't very loud but annoying nonetheless. I am using an EDCOR PT and Heyboer vintage OT from RJ fyi.

I'm new to Trainwreck style amps. Is this normal??

Thanks

[paulster]

It's because Ken arguably put the transformers round the wrong way.

The magnetic flux from the power transformer makes a figure 8 if you look down on the amp, so the OT gets hit right with it and it magnetically couples.

The OT should be in the same orientation as it is now, but to the side of the power transformer.

So not a lot you're going to be able to do about it really!

[amplifiednation]

Are there pictures of the tranny layout? I got some florescents and a cpu monitor that even make my solid state PA hum. Im trying to get those lights replaced

[RJ Guitars]

Taylor has the right idea there, a few pictures might be a great help. This forum is a great place to get some quality help. Most issues with Trainwreck circuits have been seen and overcome by many of the folks here. Glad you have the amp together and working.

rj

[paulster]

This isn't one you'll solve without changing how the iron is arranged on the chassis, which then leaves you with other issues to deal with internally as regards the cable routing and the position of all the tubes.

This diagram (very roughly) shows the magnetic flux pattern you get from a transformer, so Ken has really put the PT and the OT completely round the wrong way.

Ideally the OT would go to the side of the PT (without changing the orientation of either), or you could rotate both the PT and OT in their current positions. This would leave the magnetic flux directed towards the preamp tubes though, so it's not as ideal as having the OT to the side.

Essentially, unless you want to consider laying everything out from scratch you're really stuck with this, and the amount of hum is easily dwarfed as soon as you're passing signal, despite not being an ideal solution from an engineering standpoint.

[bandade]

I set up my transformers like the attached ceriatone layout but the OT is on the side of the power tubes rather than behind them.

Has anyone tried shielding with an aluminum shield between transformers? Or been successful at moving the OT to the opposite end of the chassis? I'm just wondering if this is even worth trying. Its not a huge deal, as you guys have said, the hum is dwarfed when playing.

I can snap some pictures when I get home tonight. For those who have worked on the orientation of the trannies, what are you doing?

Thanks

[bandade]

One thing I forgot to address was the florescent light issue. I have one small florescent desk lamp in the room on my work bench but I disconnected it after reading some posts on here and the hum did not change. I also run a couple other amps and dont have the hum.

I may try reorienting the OT tonight just to see what happens.

[2tone]

Why don't the original Wrecks have the hum then??? I haven't noticed it..

It's because Ken arguably put the transformers round the wrong way.

The magnetic flux from the power transformer makes a figure 8 if you look down on the amp, so the OT gets hit right with it and it magnetically couples.

The OT should be in the same orientation as it is now, but to the side of the power transformer.

So not a lot you're going to be able to do about it really!

[paulster]

Why don't the original Wrecks have the hum then??? I haven't noticed it..

They do if you put your head against the cabinet, but you'll never hear it in any real world scenario, just as you won't hear the hiss either which is way louder than the hum. It'll also depend on the PT and how well its magnetic field is contained, which will vary from manufacturer to manufacturer, and from transformer to transformer.

About the only thing you can realistically do without drilling holes is to make sure your OT is pulled as far back as its mounting slots will allow, so it is as far away from the PT as possible. Millimetres can make a difference.

On your PT you can try sliding it left or right the tiny amount that's available and see if it makes any difference.

[2tone]

I know the hiss level is to be expected, but the low level of hum never bothered me in any of my origina lTrainwrecks. It might bother the hi fi guys. There are other reasins why Ken put the transformers that close and oriented like that, and not everyone may agree, but he diud it for a sonic reason..

[redshark]

I know the hiss level is to be expected, but the low level of hum never bothered me in any of my origina lTrainwrecks. It might bother the hi fi guys. There are other reasins why Ken put the transformers that close and oriented like that, and not everyone may agree, but he diud it for a sonic reason..

What original trainwrecks do you owned or still own 2tone? can we have her names?

[Lonely Raven]

I was about to ask the same thing. You got photos!?!

[M Fowler]

I remember posting to 2tone a while back about his TW amp.

https://tubeamparchive.com/viewtopic.ph ... c&start=45

[bandade]

I rotated my OT 90 degrees tonight and eliminated 95% of the hum. Now all I hear is the expected Trainwreck Hiss.

Was it a pain in the ass? YES

Was it worth it? Absolutely!

Thanks for the insight.

The picture is the final configuration with the OT secondary side closest to the PT. This is going to be inverted compared to your normal Trainwreck so that I can run it in a head w/ 212 cab or a 112 combo.

Thanks

[RJ Guitars]

OK - that helps. A little hum and maybe some hiss is reasonable but I was thinking that it really shouldn't be that noticeable. Nice work, you are almost there!

What output tubes are you using?

rj