Help please... how do I set the gains on my amp?

[lunchmoney]

My system is CD player-->EQ-->Preamp-->Amp

So how do I set the gains on my amp?

I’m really confused here. I recently heard from a few knowledgable folks here that I should probably have the gains wide open on my amp, and then let my preamp handle the volume control.

Obviously I’m letting my preamp handle the volume control… unless I’ve completely lost it, that’s what a preamp is for.

But what is absolutely bananas to me is the notion that the amp gains should be wide open.

From years of doing car audio, (which I assume has at least vaguely similar principles to home audio) I always assumed the following approach… many experts over on diymobileaudio.com (serious SQ guys, not silly SPL nuts) taught me this process:

1. Set the volume control of the source (dvd player, head unit in your car, etc) to approximately ¾ of it’s maximum output, in order to get a nice strong signal, but not so high in volume that it’s clipping… this of course will vary from unit to unit, but it’s a good starting point.

2. Now I assumed a similar approach with the preamp in my home system… set to approximately ¾ volume…

3. Then set the gains on the amp such that it’s about as loud as you’ll ever want to hear it.

The theory behind the above approach being that you’re starting with a nice strong signal, and then the amp isn’t working very hard to reach a given volume… thereby any distortion introduced by the amp is not amplified very much. It also means that the volume control on my preamp isn’t overly sensitive.

The notion that you would crank the gains on the amp is obviously completely backwards to this, as to reach the same given volume, you’d have the volume control on the preamp MUCH lower… so the amp would be taking a low signal, then working much harder to reach a given volume, therefore amplifying more of the amp’s distortion… also, the volume control on the preamp would be incredibly sensitive… a slight turn of the knob would result in a huge change in volume.

Am I correct in my approach? If not, then what little I thought I understood about how amps work goes right out the window.

Do the gains on car audio amps work differently than the gains on home audio amps?

What am I missing here?

What is the correct way to set the amp gains in a home stereo?

(Will I EVER learn even the SIMPLEST basics of this insane hobby? )

Thanks

[MSaturn]

Your method is fine. Assuming your equipment isn't faulty, you'll get the same output signal with whatever combination results in the same volume.

You'll always get the most range with the amp gains set to maximum, though - it doesn't mean the amp will "work harder", unless you choose to overdrive it from the preamp.

I never set gain at maximum in car audio for a simple reason: people are stupid and blow out speakers.

[lunchmoney]

Your method is fine. Assuming your equipment isn't faulty, you'll get the same output signal with whatever combination results in the same volume.

You'll always get the most range with the amp gains set to maximum, though - it doesn't mean the amp will "work harder", unless you choose to overdrive it from the preamp.

If this is true, then home amps must work differently from car amps

[MSaturn]

Car amps are really not built as well, and besides that, they're working on 12v mains .. there are many factors to consider, like the charging system, the car's environment, blah blah .. more than in home audio.

Also, an amp will always work "as hard" to get to whatever volume, seeing as the output stage will then be at the same operating level. The input stage? No, but that's not where big wattage comes from.

[lunchmoney]

Ok, well I guess I'll try opening the gains up on the amp... but I always assumed that the system would then just be crazy loud, with the preamp's volume control being incredibly sensitive.

I'm so fricking confused.

[Brent_S]

It depends on whether the level controls in your amp are gain circuits or attenuators. Many pro-amps actually use attenuators, so the gain structure is fixed and the level control is simply reducing the input signal before it is amplified, which is why many that use pro-amps with home gear are encouraged to set them to max. For gain circuit amps, the gain structure will be variable...this Emotiva has a 0-32dB range. Either way, I see no harm setting the gains to max as a competently designed amp should still have a suitable S/N ratio at this level and shouldn't be exposed to the EMF noise of the car environment. Car amp gains may also have ridiculous gain structures, similar to subwoofer plate amps that might produce 100 watts from only 100mV instead of needing 1v for 100 watts per THX's 29dB spec.

-Brent

[MSaturn]

Yeah, that's the more specific version, and he's right. Most good gear maxes out at 5V or so, but many car amps will be overdriving by 1 or 2V. If your preamp is very sensitive, you can adjust your amp's gain to match. That's the reason there's adjustment - there's no standard, per se, for output and input impedance, and therefore it's nice to have adjustable front ends on amps.

[djg]

FWIW, I set my Yamaha Stereo power amp for the main speakers all the way up, no apparent strain or distortion. Yamaha HT receiver as preamp. Outlaw M-Block for center has no level control.

[lunchmoney]

It depends on whether the level controls in your amp are gain circuits or attenuators....

Car amp gains may also have ridiculous gain structures, similar to subwoofer plate amps that might produce 100 watts from only 100mV instead of needing 1v for 100 watts per THX's 29dB spec.

-Brent

Okay... now THAT makes some sense... I'll try it when I get home, and cancel my admission to the local psychiatric ward.

Thanks guys

[MSaturn]

I notice something interesting around here; no one seems to be in to esoteric amps/preamps. (and I'm not talking about the brand!) lots of guys with yamaha and H/K gear.

[biff]

A couple of ideas for ya -

play with the gain on the amp to get your system where the gain on the preamp is most usable, as in lets you get fine control over your working range. Sometimes small adjustments to me can really hit the sweet spot, so if I could make good use of the 9 to 3 range I'd be happy.

or..

set the amp at maybe half staff and play with the preamp gain with everything powered up and no CD spinning and find where on the pre's gain you get noise. (Preamps usually have more noise than amps IME) Back down a touch and make some music. using the amp gain control crank until you are at the top of your listening preferences and leave it there. Now you should have maximum control with the pre with the least noise introduced in the sytem.

or...

If you have kids, open up the preamp, then set the amp for your max listening level. Don't even hint to anyone that it has control. Now if they crank the pre to 11 your ears, their future, and your drivers should be safe.

[djg]

I am a big Yamaha fan, including my motorcycle. Never had a piece of Yamaha gear fail.

[MSaturn]

They make a fine piano, too.

Now, if Boesendoerfer would start making amplifiers ..

[Deward Hastings]

Now, if Boesendoerfer would start making amplifiers ..

Or Fazioli, if you really want "high tech" perfection . . .

[lunchmoney]

play with the gain on the amp to get your system where the gain on the preamp is most usable, as in lets you get fine control over your working range. Sometimes small adjustments to me can really hit the sweet spot, so if I could make good use of the 9 to 3 range I'd be happy.

That more or less describes the method I've been using... in a roundabout sort of way...

It goes back to the question of whether they are gains, or just attenuators. If they're gains, that makes sense.

If they're attenuators, leaving them wide open makes a sense.

I'll find out tonight.

[evilskillit]

I'll just parrot out what is printed in the manuals for my Parasound separates.

It says to set the amp gain so that your happy listening volume on the pre-amp volume knob is between 40 and 60 percent. Their reasoning is that you want a nice strong signal from the pre amp that is not too weak and easily interfered with, but at the same time not so high as to possibly be distorted at that stage in the chain. Seemed sensible to me so that is usually how I try to set things myself.

[billfitzmaurice]

My system is CD player-->EQ-->Preamp-->Amp

So how do I set the gains on my amp?

I’m really confused here. I recently heard from a few knowledgable folks here that I should probably have the gains wide open on my amp, and then let my preamp handle the volume control.


What am I missing here?

Time was most power amps did not have attenuator pots at all, which was the equivalent of running an amp with attenuator pots wide open.

[Dirk]

I am a big Yamaha fan, including my motorcycle. Never had a piece of Yamaha gear fail.

I have. Two receivers, by lightning strikes. One was repaired (fully functional again) and the other just lost its subwoofer out (acceptable loss, it's my office measurement / playback amp now).

I don't really blame the Yammys, though. I blame the crappy grounding scheme of the house at the time.

[djg]

Yes, lightning. I have had a few things get ruined by that. Hopefully, my Yamaha motorcycle will not suffer such a fate. With me on it.

[ampnation]

I've had lots of Yamaha equipment and only one failure. A stereo receiver I bought in the late 80's finally gave up the ghost after over 20 years of regular use. If memory serves on the price, that amounts to about $10 per year of service. Can't complain. I hope my current HT receiver lasts that long for whomever I sell it to. I'm going to upgrade to get more HDMI inputs.