Fullest Sonic Potential

[AcuDefTechGuy]

Parasound Halo amps have Gain controls on the back panels. Kudos to Parasound. I think all amps should have gain controls.

If you look in the Parasound Halo manual, it says to turn the Gain knob all the way clockwise to the MAX gain level in order to "reach fullest sonic potential". This would be 28dB Gain .

An AVS member recently changed amp from a Rotel to Parasound Halo JC. He claims the Halo gives more PUNCH.

The Rotel has a gain of 26dB. The Parasound has a gain of 28dB. The ATI AT2000 & AT3000 amps have a gain of 34dB (unbalanced) .

I wonder which amps would have the most PUNCH if we did NOT level match? I wonder.

 

[slipperybidness]

Parasound Halo amps have Gain controls on the back panels. Kudos to Parasound. I think all amps should have gain controls.

If you look in the Parasound Halo manual, it says to turn the Gain knob all the way clockwise to the MAX gain level in order to "reach fullest sonic potential". This would be 28dB Gain .

An AVS member recently changed amp from a Rotel to Parasound Halo JC. He claims the Halo gives more PUNCH.

The Rotel has a gain of 26dB. The Parasound has a gain of 28dB. The ATI AT2000 & AT3000 amps have a gain of 34dB (unbalanced) .

I wonder which amps would have the most PUNCH if we did NOT level match? I wonder.

I think you probably know this, but I will throw it out there to avoid confusion with others on the forum.

The reason that parasound says to max out the gain is so that it is technically not in the signal path at all. They are signal attenuators. Those are there as a kind of last resort to get your levels matched up, or to match levels if you have a legacy pre/pro without the fancy room correction algorithms. I don't think they are saying that those should be maxed out to improve the gain, but rather to not choke it down.

 

[AcuDefTechGuy]

I think you probably know this, but I will throw it out there to avoid confusion with others on the forum.

The reason that parasound says to max out the gain is so that it is technically not in the signal path at all. They are signal attenuators. Those are there as a kind of last resort to get your levels matched up, or to match levels if you have a legacy pre/pro without the fancy room correction algorithms. I don't think they are saying that those should be maxed out to improve the gain, but rather to not choke it down.

Turning the gain to Max is the equivalent of all the amps without any gain controls - fixed gain level.

Turning the gain control to Max does not "improve" the gain. It makes the gain 28dB, instead of 20dB, 24dB, 26dB.

IOW, if you set the amp gain to 50%, the amp will never be able to produce the full power if ever needed.

 

[Irvrobinson]

I wonder which amps would have the most PUNCH if we did NOT level match? I wonder.

No question about it, the Mr. T amps.

 

[slipperybidness]

Turning the gain to Max is the equivalent of all the amps without any gain controls - fixed gain level.

Turning the gain control to Max does not "improve" the gain. It makes the gain 28dB, instead of 20dB, 24dB, 26dB.

IOW, if you set the amp gain to 50%, the amp will never be able to produce the full power if ever needed.

I think I covered that when I called the gain knobs "attenuators". Your statements are correct.

 

[AcuDefTechGuy]

No question about it, the Mr. T amps.

Mr. T amps?

I've never heard that expression.

Regarding gains/ level attenuating knobs, I think most of us equate the increased in gain to increased noise floor (hiss sound).

The fact that ATI amps can have a gain of 34dB and still have a SNR of -123dB and crosstalk of -100dB from 20Hz-20kHz is pretty good.

Since louder is "better" and "punchier" to some people who don't level match, and assuming the SNR & crosstalk can be great like -123dB 20Hz-20kHz & -100dB 20Hz-20kHz, respectively, why wouldn't all amps have a gain of 34dB or 36dB?

 

[Hocky]

Man your posts are like a broken record.

 

[AcuDefTechGuy]

Man your posts are like a broken record.

And your posts are like.................who cares?

 

[Irvrobinson]

Man your posts are like a broken record.

None of us are purfect.

 

[KEW]

Here is a Volume knob labeled to reflect how it actually functions. At "0" the control is (ideally) equivalent to a straight piece of wire.

 

[AcuDefTechGuy]

None of us are purfect.

He's just mad because I don't praise Martin Logan or Emotiva. So he stalks my posts.

I have so many fans.

I should change my name, don't tell anyone what I have, and say everything is just great.

And don't ask questions like why some amps have a 24dB gain and some have a 34dB gain. That's asking for too much.

 

[KEW]

And don't ask questions like why some amps have a 24dB gain and some have a 34dB gain. That's asking for too much.

I think it has to do with the sensitivity of the amplifier. If your preamp has a strong output the higher gain amp may get saturated by the incoming signal. OTOH, if your preamp has a relatively weak output signal you need the extra sensitivity of the higher amp gain.
The following is from Gene's review of the XPA-2:

I did some quick spot-checking on the XPA-2 amplifier gain structure to ensure it could be properly driven with a wide assortment of preamps or receivers. My personal criteria for amplifier gain structure is that it should be able to hit full power when driven with 2Vrms. The XPA-2 blew this notion out of the water with an unusually high voltage gain of 32dB (un-bridged) and 38dB (bridged). After confirming this twice via my measurements, I pinged Emotiva technical support and they informed me this was purposely done for end users using a budget receiver many of which tend to clip above 1Vrms output. I can certainly appreciate this as I have found this to be the case with many receivers even in the $1k price range. The XPA-2 reached its full power with only 1.2Vrms. Although the penalty of having such high gain is also higher noise, the XPA-2 remained very quite and yielded a SNR of 105dB at 319 watts (unweighted) which translates down to about 80dB at 1 watt. Emotiva informed me that part of the reason for such good SNR measurements is that all of the voltage and current gain is done in last stage of the amplifier.

I also suspect Emotiva boosted the gain to make their amplifiers sound more impressive (remember the predilection for people to associate louder with better) when a newbie hooks up their amplifier for the first time. Personally, I’d prefer to see a +3, 0, -3dB toggle switch on the backpanel for those who have preamps with plenty of drive to further lower the noise floor.

 

[Hocky]

He's just mad because I don't praise Martin Logan or Emotiva. So he stalks my posts.

I wouldn't praise those companies, either. Well, certainly not Emotiva, anyway. lol. But if the discussion comes up and my opinion is relevant, I will post what I think about my own hardware. I think it is a bit more appropriate than trolling around regurgitating the same things over and over about what I own.

edit: And for the record, I don't intentionally stalk your posts - you just post a lot and it is fairly frequent that they make me face palm.

 

[AcuDefTechGuy]

I wouldn't praise those companies, either. Well, certainly not Emotiva, anyway. lol. But if the discussion comes up and my opinion is relevant, I will post what I think about my own hardware. I think it is a bit more appropriate than trolling around regurgitating the same things over and over about what I own.

edit: And for the record, I don't intentionally stalk your posts - you just post a lot and it is fairly frequent that they make me face palm.

So....I'm trolling because I own ATI amps and I mentioned ATI amps in my post?

So when Irvrobinson says he thinks he Salon2 in piano black looks great, he was trolling since he owns these $22000 speakers?

It's no wonder you have all those red chicklets.

Please, for the love of god, place me on your IGNORE list. Please.

And if you start a thread, any thread, I will be sure to ignore.

 

[mike c]

good idea. place each other on 'ignore' (it's a forum function, you'll love it)

 

[Irvrobinson]

Since louder is "better" and "punchier" to some people who don't level match, and assuming the SNR & crosstalk can be great like -123dB 20Hz-20kHz & -100dB 20Hz-20kHz, respectively, why wouldn't all amps have a gain of 34dB or 36dB?

This is not a simple matter. The gain at each stage is best determined at the system level. For example, most high quality pre-amps seem to be optimized for amps with about 26db of gain, assuming speakers that have sensitivities of 85-90db @ 2.83v. So at a typical lively listening level the volume control will be somewhere in the range of the 11:00-1:00 position. If the amp is too sensitive you won't be to adjust the volume with fine granularity at low listening levels. This can also happen with very sensitive speakers.

Of course, 26db of gain with a 300W amp means that you are assuming the pre-amp can provide a clean output of 2V or more to the amp. Most good pre-amps have no problem with this, and many pre-amps will put out well over 5V into relatively low input impedances (e.g. 10K ohms), but I'm told a lot of cheapo receivers can't. I've read in several posts that some receivers clip at 1V. Yuck.

IMO one reason these amps need to have higher gain is that they fudge the input impedance of their inputs, and these receivers wouldn't have these problems if they provided an input impedance of at least 50K ohms. I remember when 100K ohms was a common spec. As you might imagine, it is cheaper to build an input stage with lower impedance than higher. And the receiver guys don't seem to want to use high current driver stages, because that would throw off more heat, and my guess is that most of these receivers already have a hope and a prayer thermal budget. (My Benchmark pre-amp, for example, that will output a lot of volts and has to padded down for home use, runs *hot*.)

There's also a question of noise and how you want to manage it with multiple gain stages. 34db of gain means that your upstream device had better have very low noise, and that you're not using highly sensitive speakers, or the net result may be one hissy mess.

 

[markw]

IOW, if you set the amp gain to 50%, the amp will never be able to produce the full power if ever needed.

Yes, it will. As far as I recall, gain controls control the level of the incoming signal. If the input signal is high enough, it should drive the amp to it's maximum rated output regardless of the attenuation. I believe Kew said something like this as well.

 

[AcuDefTechGuy]

Yes, it will. As far as I recall, gain controls control the level of the incoming signal. If the input signal is high enough, it should drive the amp to it's maximum rated output regardless of the attenuation. I believe Kew said something like this as well.

If the amp gain is set to Zero (for example the Crown XLS 2500), there is no volume even when I crank the Denon master volume to -0.0.

So explain how the amp will produces 300 Watts into 8 ohms when there is no volume?

There is such a thing as a silent 300watts?

 

[slipperybidness]

If the amp gain is set to Zero (for example the Crown XLS 2500), there is no volume even when I crank the Denon master volume to -0.0.

So explain how the amp will produces 300 Watts into 8 ohms when there is no volume?

There is such a thing as a silent 300watts?

I would want to agree with ADTG, but this section from my amp makes we think that mark may be right

Level Controls
Each channel has a separate input level control. The HCA-1206 will sound best with its level controls
set to maximum, where they are effectively out of the audio signal path. However, if your preamplifier
has very high gain, and its volume control cannot track properly for left-right channel balance near its
minimum position, it may be necessary to reduce the input level control settings on the HCA-1206. We
deliberately have located the controls on the rear panel, so they can be set once and forgotten.

Interesting, makes me want to read up on this more.

 

[markw]

If the amp gain is set to Zero (for example the Crown XLS 2500), there is no volume even when I crank the Denon master volume to -0.0.

So explain how the amp will produces 300 Watts into 8 ohms when there is no volume?

There is such a thing as a silent 300watts?

You're kidding, right?

When it's not making any volume at all, it's not producing any watts. Its got the potential to produce 300 watts given a large enough input signal.

Of course, if you attenuate the input signal to zero on the power amp, none of that input, no matter how strong is is, will make it to the amp. You're not really saying that, are you? Nobody here would be that stupid, I hope.