Lowering amplifer gain to reduce hiss? (1 Viewer)

[Aaron Cooke]

I recently upgraded a lot of my equipment and am experiencing a lot more hiss than i'm used to. I'm not blaming any of my components, I don't really care where the hiss is coming from. If i lower the gain on my amplifer and compensate by raising the levels the speakers are set at coming from the pre/pro, the hiss diminishes My question is, is there any disadvantage/danger in doing this. I'm running a B&K 7270 amp, Outlaw 950 and Klipsch RF-7/RC-7 For what it's worth, I don't notice an abnormal hiss coming from my surrounds which are def tech BP2X's so I'm assuming it has a large part to do with the higher efficiency of the Klipsch.

 

[Martice]

I'm running a B&K 7270 amp, Outlaw 950 and Klipsch RF-7/RC-7 For what it's worth, I don't notice an abnormal hiss coming from my surrounds which are def tech BP2X's so I'm assuming it has a large part to do with the higher efficiency of the Klipsch.

Uh Oh. Red flag!! If I were you, I'd check this thread out because the Outlaw 950 has a short history of having a "Hiss" problem. I don't know if that is your problem but it won't hurt to start with the piece with the known history of that particular problem.
Here's one of the many threads on the 'Hiss' problem.
Good Luck

 

[Bill Polley]

I have very little (next to none) hiss with my 950 and Parasound amp. The amp had a blown channel (I only used it for 2 channel, when I went to surround I noticed it) and the dealer is fixing it under warranty. The loaner Yamaha I got hissed very loudly when I hooked it up as an amp. By turning the volume down on the Yamaha, effectively lowering the gain, and raising the volume on the 950, the hiss went away.

 

[Kevin C Brown]

The Outlaw does tend to exhibit more hiss in systems with more sensitive speakers, and amps with more gain.

Hey, stupid question here:

More gain = ... more power?

(I have 2 Acurus 200 per channel, 3 channel amps. Before this I had a Nakamichi 2 channel 150W/channel + 1 Acurus 100W per channel, 3 channel amp. The Acurus 200W/channel definately had more hiss than the Nak at 150W/channel. All of those hisses though were only audible at the tweeters.)

 

[Aaron Cooke]

More gain = ... more power?

I guess this is kind of what i'm wondering too. If i turn the gain on my amp way down, am i running the risk of underpowering my speakers. I specifically got an amp with a lot of power so i wouldn't have to worry about running into clipping and i don't want to negate that by lowering the gain. I would rather live with the hiss than have to worry about damaging my speakers every time i crank it up.

 

[BruceD]

In the latest replies on the Outlaw forum, it appears a consumer comparison to the Atlantic P-2000 finds:
. . . . results = exactly the same sound as the 950.
Also, it appears (comments from an owner) that Outlaw told him hiss from 4'feet is normal.
read here

 

[Saurav]

I guess this is kind of what i'm wondering too. If i turn the gain on my amp way down, am i running the risk of underpowering my speakers.

If you turn the gain on your amps down, your pre-pro will have to send a stronger signal to the amp. Let's say your pre-pro normally sends around 2V, and your amp is set to X dB gain. If you cut the gain by half, your pre-pro will now need to send double the voltage, i.e. 4V, to reach the same overall SPL level. As you turn the gain down, eventually you'll reach a point where your pre-pro cannot supply the voltage required to reach the original SPL, so in that sense you'll be "under-powered".
Check your amp's specs, it should tell you what input signal voltage it needs to reach full power (this is called the amp's input sensitivity). Ideally, it should give you two numbers, for both ends of the gain control's range. Then check your pre-pro's specs, that should tell you the peak output voltage it is capable of producing. As long as the pre-pro is capable of producing more than what the amp needs, you're fine. If the pre-pro's output is less than what the amp needs, you have a situation where you won't be exercising the full power capacity of your amp (which isn't necessarily a bad thing - depending on your speakers' sensitivity, you might not need the amp's full power capacity anyway).
I hope that made some sense

 

[Aaron Cooke]

thank you saurav, that was exactly the information i was looking for.

 

[Kevin C Brown]

Saurav- Cool, thanks. Hey, have you been following the Outlaw 950 hiss issue at all?

For me, the hiss is volume independent, doesn't depend on source or source type (coax digital, 2 or 5.1 channel analog), and goes away when I turn the 950 off but leave my amps on.

I'm convinced the problem is in the 950's analog output stage, but that's just a big fat guess...

 

[Saurav]

Saurav- Cool, thanks. Hey, have you been following the Outlaw 950 hiss issue at all?

Nope. I'm not really interested in a home theater processor, my DVD player hooked up to my stereo is good enough for me now

 

[Craig Ball]

I just sent my 950 back yesterday. I have Klipsch speakers and Acurus amps, these were hooked up to a H/K 520 used as a pre-pro and had no hiss issue at all. In comes the outlaw and HISS is awful. Needless to sy the H/K's back and the hiss gone.

Craig

 

[Russell _T]

The H/K 520 employs muting circuitry that kicks in when there is no signal from the source. You will most likely get hiss when it receives a signal, but you probably can't hear it over the music or dialogue. It's too bad Outlaw didn't employ this feature.