Dodd ELP with a transformer hum and the PS Audio Humbuster III

mmadden28

Anybody have any thoughts or experience with the PS Audio HumBuster?
http://www.psaudio.com/ps/products/detail/humbuster-iii?cat=accessories
http://www.audioadvisor.com/prodinfo.asp?number=PSHBIII
Sells new for about $300. Looks to have been released in 2008. Actually after reading through a few threads here, it appears that this is a new version of previously no longer available models.
It promises to reduce transformer hum by reducing DC voltage that may be present on the AC line which is what causes transformer hum or buzz. This is not a device to eliminate ground loop hums.

My Dodd ELP has a moderate transformer hum that is apparently common with this pre. Its been suggested to me to send it to Gary Dodd to get the hum reduced, perhaps with an outboard power supply mod/upgrade, however that may or may not completely reduce the hum. At a minimum it may only reduce but not eliminate the hum. (this is not a ground loop hum).

I just saw this Humbuster thing and was intrigued whether it might actually do a better job at reducing the hum in the Dodd, rather than sending it out to get modded. While at the same time gaining the possible benefit of its hum reducing capability for any other connected equipment (thus better investment of my money overall). I'm just not really sure what the cause of the hum is, whether it has something to do with the proximity of the transformer to the circuitry or the tubes, or if its actually a power source issue that the Humbuster might resolve.

FYI, I have no plans to sell the Dodd, so I'm not concerned about resale value, so that is not a determining factor in my final action to resolve the hum.

Or can anybody suggest any other comparable products that might also help with this transformer hum. They would have to be reasonably priced. Eventually we'd reach the point of diminishing returns where buying a new pre would be the better option.

Thanks
-Madden

Ricardo

I use a humbuster (the original). All the amps I've owned since I moved to the dedicated room (with dedicated line) have had a toroidal hum; no idea why. The humbuster completely eliminated it.

unc2701

Ricardo- you have DC in your AC & get toroidal hum- sounds like the humbuster is doing exactly what it should.

mmadden28, I don't know what you have going on. The humbuster fixes mechanical hum coming from the actual gear, NOT the speakers (well... occasionally it's bad enough to create a field that you can hear through the speakers). This only applies to toroidal transformers; EI transformers usually don't get DC hum. I thought the ELP had a EI tranny, so the humbuster won't fix your issue.

unc2701

Good comparison of transformer types here:
http://bryston.com/newsletters/85_files/vol8is5.html

BTW, AA has a 30day return, right? Doesn't hurt to see if the humbuster does the trick. If it does work, you may think about building your own circuit... There are some threads over at diyaudio.

Ricardo

unc2701 wrote: »

Ricardo- you have DC in your AC & get toroidal hum-

Right; the weird thing is that it started happening only when I moved everything into this room, with a dedicated line; not sure why I didn't have it before...though there's also the possibility that I never heard it, given that the gear was in a very big room.

In any case, the humbuster does work for toroidal hum

mmadden28

unc2701 wrote: »

...

mmadden28, I don't know what you have going on. The humbuster fixes mechanical hum coming from the actual gear, NOT the speakers (well... occasionally it's bad enough to create a field that you can hear through the speakers). This only applies to toroidal transformers; EI transformers usually don't get DC hum. I thought the ELP had a EI tranny, so the humbuster won't fix your issue.

I can hear the hum even without the amp on. If I put my ear close to the transformer-I can hear it. So I would imagine that it may be a mechanical hum? When the amp is on I hear the same hum, only amplified thru the speakers.

unc2701

Well, give Gary a call & see if it's an EI or a toroid. EI's hum (it's just in their nature), but not due to DC.

Systems

unc2701 wrote: »

Ricardo- you have DC in your AC & get toroidal hum- sounds like the humbuster is doing exactly what it should.

Like they did on your 4B Bryston incororate a DC filter in the neutral leg of the AC in each of their amps.I have duplicated their simple circuit (bridge rectifier, 2 big capacitors) for use on a noisy toroid ,it solved the problem.

mmadden28

unc2701 wrote: »

Well, give Gary a call & see if it's an EI or a toroid. EI's hum (it's just in their nature), but not due to DC.

It's an EI.

heiney9

mmadden28 wrote: »

It's an EI.

Electromagnetic Inductor. It's the "old" style Iron Core tranny's

A transformer in which laminations of iron or other magnetic material make up part or all of the path for magnetic lines of force that link the transformer windings.

george daniel

heiney9 wrote: »

Electromagnetic Inductor. It's the "old" style Iron Core tranny's

A transformer in which laminations of iron or other magnetic material make up part or all of the path for magnetic lines of force that link the transformer windings.

Say that fast three times,,, iron core,iron core,iron core;)
It's got a nice ring to it

Iron core:)

unc2701

GV#27 wrote: »

Like they did on your 4B Bryston incororate a DC filter in the neutral leg of the AC in each of their amps.I have duplicated their simple circuit (bridge rectifier, 2 big capacitors) for use on a noisy toroid ,it solved the problem.

Yep. I know they've got the schematic on their website somewhere... I'll look for that.

unc2701

mmadden28 wrote: »

It's an EI.

Given it's an EI, the humbuster is _probably_ not your solution, but it's not a really heavy device, so return shipping from AA wouldn't be that bad if it doesn't work. It's also a $300 fix for a $350 piece of gear...

Anyhow, the solution could be a a fun DIY project. Pull that tranny out, put it in it's own box... maybe fill that box w/ sand to take care of the mechanical hum. Getting it away from the tubes would probably fix the hum you're getting through the speakers.

Or it could just need to be replaced with a better quality transformer. Quality iron isn't cheap and Gary had to figure out some way to sell those ELP's for so little. Probably the biggest issue would be getting it in the chassis AND if that doesn't fix your problem, that's not going to be something you can return.