JH Audio stuffs

[cetoole]

On the topic of amplifier hum/hiss. I do get a low level hum/hiss from the B22 with my JH13. It is not volume dependant so I've chalked it up to dirty AC power (from the line or the UPS I have plugged into the same circuit).

Why dirty AC power? I would think it much more likely that you are running into issues with either EMI from the transformer or simply amplifier noise floor due to the level of voltage regulation being used.

[veloaudio]

Why dirty AC power? I would think it much more likely that you are running into issues with either EMI from the transformer or simply amplifier noise floor due to the level of voltage regulation being used.

Mainly due to the horrible wiring in my 1940s house. EMI is a possiblity. Moving wires etc doesn't change it. Although I need to do more troubleshooting. I guess I could try shielding the transformer?

[n_maher]

IIRC Matt's beta is a two box design so it should be pretty free of EMI at least from the perspective of the beta22 trafos. Depending on what the amp is sitting on there may be some other component contributing though. The hiss is probably just due to the gain of the amp and could also be source related. In fact, it'd be worth trying it without a source attached.

[cetoole]

Moving the amp would be a good idea too, especially if the amp is sitting on top of the PS box. Seems though the beta is fairly apt to picking up EMI though, so it could definitely be some other equipment nearby, like a monitor or something.

[The Monkey]

The hum issue is interesting. I tried my UE5c out of my B22 (which Nate knows rather well) and got some serious hum, but not hiss, although that could be due to the hum volume. It sounded almost like a ground loop hum (I don't think that's it, just describing the sound). The amp is dead silent with all other headphones.

[guzziguy]

There's a measurable benefit to replacing the cable in these IEMs, if you get 4 wires all the way to the jack. The stock cables join the ground wire at the Y-split which reduces stereo separation. Enough to hear, probably not, but it will be there. This change is at least a billion times greater than what kind of wire is used ...

What if it's made from milspec wire with magical energy? Surely that makes a difference?

Edited December 1, 2009 by guzziguy

[n_maher]

The hum issue is interesting. I tried my UE5c out of my B22 (which Nate knows rather well) and got some serious hum, but not hiss, although that could be due to the hum volume. It sounded almost like a ground loop hum (I don't think that's it, just describing the sound). The amp is dead silent with all other headphones.

That's pretty strange Dinny since I tested your amp with my ETY ER4Ps and it was silent. I wouldn't have though the 5cs were that much more sensitive, but I just checked and the 5cs are rated at 119db/mW and the 4Ps @ 108db/mW. Just goes to show you what assuming something will do...

[Beefy]

FWIW, I have used my M3 with UE SuperFi 5Pro, and at a gain of 2 it was dead silent at normal listening volumes (though began to hiss loudly as the volume went up with nothing playing). I very rarely used them together though, because normal listening volumes was about 15 degrees of pot rotation, and even the slightest bump upwards would be enough to give serious hearing damage.

I suspect you really need something unity gain, and/or with a VERY good attenuator.

Edited December 1, 2009 by Beefy
Dig up, stupid

[The Monkey]

Is it possible the cable is the culprit?

[n_maher]

Is it possible the cable is the culprit?

For the hum/buzz? Unlikely.

[veloaudio]

IIRC Matt's beta is a two box design so it should be pretty free of EMI at least from the perspective of the beta22 trafos. Depending on what the amp is sitting on there may be some other component contributing though. The hiss is probably just due to the gain of the amp and could also be source related. In fact, it'd be worth trying it without a source attached.

It is a two box version.

Moving the amp would be a good idea too, especially if the amp is sitting on top of the PS box. Seems though the beta is fairly apt to picking up EMI though, so it could definitely be some other equipment nearby, like a monitor or something.

The amp sits on top of the Cary. The PS is 20" below the Cary on my desk. I'll post a picture later (I did post a crappy picture in the post a pic of you rig thread)

And to clarify, it is a hum. No hiss.

[Salt Peanuts]

FWIW, when I had a two-box B22, I detected some hum when it was plugged directly into a wall. When I plugged it into my ZeroSurge unit, the hum went away almost completely.

[Beefy]

FWIW, when I had a two-box B22, I detected some hum when it was plugged directly into a wall. When I plugged it into my ZeroSurge unit, the hum went away almost completely.

Sounds like a ground loop.

[Salt Peanuts]

Sounds like a ground loop.

Possibly. Though there's no way for me to test it now since that was at my last place and I also don't own the B22 anymore.

[cetoole]

It is a two box version.

The amp sits on top of the Cary. The PS is 20" below the Cary on my desk. I'll post a picture later (I did post a crappy picture in the post a pic of you rig thread)

And to clarify, it is a hum. No hiss.

Might want to try moving it away from the Cary, just to see. The Cary almost certainly has transformers in it.

[veloaudio]

IIRC Matt's beta is a two box design so it should be pretty free of EMI at least from the perspective of the beta22 trafos. Depending on what the amp is sitting on there may be some other component contributing though. The hiss is probably just due to the gain of the amp and could also be source related. In fact, it'd be worth trying it without a source attached.

I did disconnect the Cary and hum was still there.

Might want to try moving it away from the Cary, just to see. The Cary almost certainly has transformers in it.

I'll try that after work.

[shellylh]

Why dirty AC power? I would think it much more likely that you are running into issues with either EMI from the transformer or simply amplifier noise floor due to the level of voltage regulation being used.

Interesting discussion.

I have a very low level hum with some of my headphones and my Woo Audio WA5-LE (low hum with HD800 out of the high jack - low level hum and maybe a little hiss with the JH13s in the low jack for example) - even with no source. In fact, every tube amp I have owned has had some hum (DV 336SE, DV 3322, SP Extreme), some more than others. I always thought that it was because of the 1940 wiring in my house and the fact that tubes amps weren't perfectly quiet. I asked Jack of Woo Audio about the low level hum and he said that low level hum is perfectly natural for a tube amp. Do you agree?

Of course, the B22 isn't a tube amp....

[n_maher]

I asked Jack of Woo Audio about the low level hum and he said that low level hum is perfectly natural for a tube amp. Do you agree?

Translation: it is difficult to remove all of the hum from a tube amp and most people won't notice/care unless someone else points it out the them. And yes, I'm being serious, it can be next to impossible to get a tube amp with a dead quiet background and in most cases (for a man'f) it isn't worth it to do so since it's just wasted effort easily blamed on the tubes.

[cetoole]

Interesting discussion.

I have a very low level hum with some of my headphones and my Woo Audio WA5-LE (low hum with HD800 out of the high jack - low level hum and maybe a little hiss with the JH13s in the low jack for example) - even with no source. In fact, every tube amp I have owned has had some hum (DV 336SE, DV 3322, SP Extreme), some more than others. I always thought that it was because of the 1940 wiring in my house and the fact that tubes amps weren't perfectly quiet. I asked Jack of Woo Audio about the low level hum and he said that low level hum is perfectly natural for a tube amp. Do you agree?

Of course, the B22 isn't a tube amp....

You can definitely have a tube amp with no audible hum. Requires both sufficient filtering of the B+, as well as any fixed bias references if present and filaments if DHT. Also, you have to worry about EMI on the OPTs. My tube amp has a bit of audible hum with headphones more than about 98dB/mW sensitivity, which goes away if you move the OPTs an inch or so further away from the PS transformer and choke, at least listening with 109dB/mW sensitive Shure E4. There are certainly noisy tubes due to construction faults or damage, h-k leakage, but with good tubes and a well designed amp, it is definitely possible to have a tube amp that is dead silent, even with IEMs like dinny was talking about. Its just a real pita.

Edit: what Nate said.

[shellylh]

Translation: it is difficult to remove all of the hum from a tube amp and most people won't notice/care unless someone else points it out the them. And yes, I'm being serious, it can be next to impossible to get a tube amp with a dead quiet background and in most cases (for a man'f) it isn't worth it to do so since it's just wasted effort easily blamed on the tubes.

Thanks for the translation Nate. I keep hoping that by changing tubes that the low level hum will go away and become like my GS-1 (haha) but I suppose I am just stuck with it this way. It doesn't bother me with music playing and to be fair the level of noise is similar to the hum that I can hear in the background from other sources - like my refrigerator, air conditioner, etc. I think it may be slightly louder in the left channel though.

[The Monkey]

Do tube dampers do anything in this regard or is that just so much moar snake oil?

[cetoole]

Thanks for the translation Nate. I keep hoping that by changing tubes that the low level hum will go away and become like my GS-1 (haha) but I suppose I am just stuck with it this way. It doesn't bother me with music playing and to be fair the level of noise is similar to the hum that I can hear in the background from other sources - like my refrigerator, air conditioner, etc. I think it may be slightly louder in the left channel though.

Yeah, very possible it could be louder in one channel than the other. That is how my amp is too, left channel, which is closer to the input choke in the power supply, is quite a few dB louder hum than the right.

Do tube dampers do anything in this regard or is that just so much moar snake oil?

Tube dampers can help reduce microphonics in some cases.

[shellylh]

You can definitely have a tube amp with no audible hum. Requires both sufficient filtering of the B+, as well as any fixed bias references if present and filaments if DHT. Also, you have to worry about EMI on the OPTs. My tube amp has a bit of audible hum with headphones more than about 98dB/mW sensitivity, which goes away if you move the OPTs an inch or so further away from the PS transformer and choke, at least listening with 109dB/mW sensitive Shure E4. There are certainly noisy tubes due to construction faults or damage, h-k leakage, but with good tubes and a well designed amp, it is definitely possible to have a tube amp that is dead silent, even with IEMs like dinny was talking about. Its just a real pita.

Edit: what Nate said.

Do you think it may help to try and move the amp farther away (a few inches) from the power supply? Here is how it is situated right now:

When the Fedex woman delivered the amp/power supply the boxes were on top of one another. My partner watched her slide one box off the other and let it drop to the ground (so it dropped about a ft or two). Could this have caused a problem or caused something to come loose enough to cause some hum? The amp/ps were packed pretty well - lots of foam and wooden crates.

I want a dead silent tube amp.

[cetoole]

Oh, you have the one with the 300Bs? Yeah, those are DHTs, which are even harder to get quiet. Not only do you have to worry about hum coming from the B+ and EMI, but the filament is also directly in the signal path, so any noise on it is multiplied by the gain of the 300B and injected into the output. I wonder how that amp is heated.

[The Monkey]

That rig is full of all sorts of win.