Duo Omega G1 speaker hiss and amp hum

**haygeebaby** · January 19, 2019, 09:58 AM

Guys
Got a question - for those who have or had G1 Duo Omega horns - do you get a lot of "hiss noise" from the horn drivers even when the volume is at zero?
I'm running Pass XA30.8.

Also, do you get a lot of hum noise from the Sub225 unit?

Would be interested in your thoughts - and if its the same with the G2 and XD speakers.

TIA

**Mike** · January 19, 2019, 10:07 AM

Originally Posted by haygeebaby

Guys
Got a question - for those who have or had G1 Duo Omega horns - do you get a lot of "hiss noise" from the horn drivers even when the volume is at zero?
I'm running Pass XA30.8.

Also, do you get a lot of hum noise from the Sub225 unit?

Would be interested in your thoughts - and if its the same with the G2 and XD speakers.

TIA

Welcome to AS!

All quiet on my end. You have to work at it though. The G1 Duo Omega drivers are about 15 years old now? No?

Have you always had this hiss from this amp? Are other amps quieter?

**Paul** · January 19, 2019, 08:53 PM

Originally Posted by haygeebaby

Guys
Got a question - for those who have or had G1 Duo Omega horns - do you get a lot of "hiss noise" from the horn drivers even when the volume is at zero?
I'm running Pass XA30.8.

Also, do you get a lot of hum noise from the Sub225 unit?

Would be interested in your thoughts - and if its the same with the G2 and XD speakers.

TIA

So far I heard the XA160.5 and XA30.5 both made the hiss noise on Avantgarde and Legacy speakers he has. So it could be your amp.

**joeinid** · January 19, 2019, 10:38 PM

I’m afraid the Pass amps, except the First Watt series, seem to be a little too noisy for the Avantgarde speakers. I think some of the point 8 series are better but still.

I need dead quiet amps.

**Elberoth** · January 20, 2019, 04:45 AM

+1

It seems Pass amps are just too noisy for AG.

**Kuoppis** · January 20, 2019, 06:47 AM

Gentlemen, what would be the technical explanation for the hum from any amps. Care to elaborate?

Also, the speakers have an amp inbuilt themselves. And it is a 15 year old amp, if I understand it correctly. I think it might make sense to search a little closer to the problem.

Mike could test the Pass hypothesis easily, as he has both Pass amps and AGs in the store. Personally I think that statement is bollocks, as AGs love tube amps, especially 300Bs, and most of those are for sure more noisy than Pass transistor amps.

Typically speaker hum is a result of EMI caused by contact between signal and power cables.

**Elberoth** · January 20, 2019, 09:13 AM

Originally Posted by Kuoppis

Typically speaker hum is a result of EMI caused by contact between signal and power cables.

Errr, no. Hiss you can hear on high efficiency speakrs, is just the residual noise of the amp. You can hear it on less efficient sepakers too, but since their efficiency (measured in dB) is much lower, the hiss is just much less audible.

**Mike** · January 20, 2019, 10:12 AM

The 350.8 was quite noisy (hiss) on the AG’s. The quietest amp is the Viva 300b SET. Go figure. Strange. The VAC 200iq is also very quiet.

**harri** · January 20, 2019, 11:34 AM

It could be also preamp. i have used Trio G1 with Pass XA-30.5 and XA-60.5 and TVC. No audible hiss. then heard Burmester956 amp ( gain 32 dB low input impedance) -audible hiss.
Is the hum from bass unit electrical or mechanical from the transformer ? I have heard AG transformer humming.

**Kuoppis** · January 20, 2019, 12:13 PM

Interesting points, supporting the argument that there are many possible factors. Hence, based on the discussion, the conclusion might have been a bit premature.

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**haygeebaby** · January 20, 2019, 08:12 PM

Gents - good discussion.
When playing music - the sound is delightful with the Pass XA30.8 + ARC LS28 combo.
If I turn everything off and just have the amp powered - I get hiss.
My music room is heavily treated so its even more noticeable.
The hiss does bother me somewhat and it's helpful to see what the AG community experience with this is.

**Kuoppis** · January 21, 2019, 01:27 AM

Have you tried any other amps, than the two Pass models?

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**joeinid** · January 21, 2019, 01:34 AM

Pass Labs doesn’t publish conventional S/N ratios. I’m curious how they compare to other amps.

**Jerome W** · January 21, 2019, 01:45 AM

Originally Posted by haygeebaby

Gents - good discussion.
When playing music - the sound is delightful with the Pass XA30.8 + ARC LS28 combo.
If I turn everything off and just have the amp powered - I get hiss.
My music room is heavily treated so its even more noticeable.
The hiss does bother me somewhat and it's helpful to see what the AG community experience with this is.

Hello,

High Eff speakers in theory need very quiet amps.
In theory only. Because this hiss will actually decrease
the S/N ratio, adding noise to the signal played.
In practice, only the result counts.
I have 2 different pairs of 300B monoblocks. One pair is very sophisticated, with a huge power supply. It gives a little hum in the woofer and very little hiss in the horn when no music is playing. The other one is dead silent : uses a very simple and less powerful power supply. When music plays, most people prefer the noiser amp : better dynamics, attacks, speed and resolution. The silent one is more euphonic and sweet.
So I would tell you “don’t be bothered” by the hiss. As long as you do not hear it when music plays, and you like the music a lot, who cares for the hiss when no music is played ?
Moreover, many recordings have been made with a hiss/ hum that you can clearly hear when listening to the music. The brain is able to cancel it when you focus on the music.
We should always try to stay focused at listening the music. Not the gear.

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**haygeebaby** · February 11, 2019, 07:58 AM

Gents
Just want to close this topic off and say thanks for the feedback.
It looks like this amp speaker combo does have hiss then.
FYI - I changed back to a XLR cable between pre and power amp - hiss level went down slightly.
That being said - the Pass Avantgarde combo is wonderful when playing music.
The Pass Quad 57 combo - is amazing.
Anyway - more questions to come for you horny guys.
Regards
Ken

**joeinid** · February 11, 2019, 08:46 AM

Hi Ken,

Sorry for the hiss, I totally understand. It’s the nature of the beast. My First Watt, Valvet and McIntosh gear, for example, are dead quiet. Everything else I have has varying levels of hiss or even a little hum depending on the combination. Even some components proximity to each other can affect hum to a certain degree.

**Kuoppis** · February 11, 2019, 11:17 AM

I agree, it’s a problem with the AGs. I didn’t hear any noise at all with Magicos, when I had a Pass amp.

Most probably the noise floor increases gradually, the more powerful the connected amplifier is. This is due to the size of its transformator. Should not be any problem with the flea watt amps usually used with horns.

My question would however be, why would anyone attempt to drive a loudspeaker with 107 db sensitivity with an amp with several hundred watts power output?

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**joeinid** · February 11, 2019, 01:07 PM

Originally Posted by Kuoppis

I agree, it’s a problem with the AGs. I didn’t hear any noise at all with Magicos, when I had a Pass amp.

Most probably the noise floor increases gradually, the more powerful the connected amplifier is. This is due to the size of its transformator. Should not be any problem with the flea watt amps usually used with horns.

My question would however be, why would anyone attempt to drive a loudspeaker with 107 db sensitivity with an amp with several hundred watts power output?

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Regarding my experience, using the McIntosh MC452 with 450wpc or the MC303 with 300wpc on my Duo, they sound great and are dead quiet. These amps may not ultimately have the same 3D of either tubes or some other solid state amps but they are smooth, sweet and dynamic as all heck. Even the amps Avantgarde sells are pretty powerful. I know recommended power is greater than 10wpc. They want or appreciate the voltage swing of powerful amps.

**Kuoppis** · February 11, 2019, 01:55 PM

Sure, usually something’s gotta give

.

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**Elberoth** · February 11, 2019, 06:33 PM

Originally Posted by joeinid

Pass Labs doesn’t publish conventional S/N ratios. I’m curious how they compare to other amps.

They are on the low side compared to other SS designs.

**rubato** · February 21, 2019, 02:02 AM

Joe how does your Valvet E2 sound? I know sensitive speakers are essential, but other than that, any suggestion for pairing?

**joeinid** · February 21, 2019, 04:06 AM

The Valvet E2 is truly outstanding. I cannot believe how wonderful it sounds. Compared to the SIT3, it’s a little livelier, a little more open on top, I would have to say a little more neutral but none of what I’m saying is in anyway a bad thing.

I don’t think I’d miss the SIT3 if I had the Valvet E2 or never heard the SIT3. I’m trying to decide which I like better and I just can’t make up my mind. The E2 runs hot on the bottom because it’s fully class A and that’s where the output devices are mounted, so I use a little fan to keep air moving underneath. It’s probably not necessary but makes me feel better. I’m using Belden 8402 rca interconnects.

http://10audio.com/valvet-e2.htm

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