# why dont amp companies make amps that automatically adjust the output ?



## JAX (Jun 2, 2006)

What i was trying to say is why cant they make an amp that senses the voltage at the input and adjust the ouptut for what it is getting.

wouldnt that take all the guess work out of improperly setting the gains?

I have installed lots of stuff and I honestly will not say that by ear I have always set the gains right.

seems like this day and age they could make an amp that knew what the input voltage was and make the amp perfom to its max unclipped ouput.

smart amp I guess it would be called


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## danssoslow (Nov 28, 2006)

Or better yet, through the many companies that make headunits and amplifiers, a system by which full voltage is always present between the headunit and the amp; and the volume is adjusted at the amplifier's output stage.


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## 07azhhr (Dec 28, 2011)

danssoslow said:


> Or better yet, through the many companies that make headunits and amplifiers, a system by which full voltage is always present between the headunit and the amp; and the volume is adjusted at the amplifier's output stage.


^^^^ this is the only way this vvvvv work since the HU's output voltage changes as the volumn is changed. 


JAX said:


> What i was trying to say is why cant they make an amp that senses the voltage at the input and adjust the ouptut for what it is getting.
> 
> wouldnt that take all the guess work out of improperly setting the gains?
> 
> ...


Otherwise we would never get any more volumn. It would be full tilt or OFF lol.


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## JAX (Jun 2, 2006)

07azhhr said:


> ^^^^ this is the only way this vvvvv work since the HU's output voltage changes as the volumn is changed.
> 
> 
> Otherwise we would never get any more volumn. It would be full tilt or OFF lol.



makes sense


somehow couldnt amp know when the deck is putting out max output? maybe learn it somehow?


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## 07azhhr (Dec 28, 2011)

JAX said:


> makes sense
> 
> 
> somehow couldnt amp know when the deck is putting out max output? maybe learn it somehow?


Sure it could but then it would need some kind of chip based processor to self learn and even then you would have to be involved by turning the deck up when prompted. 

There are a few amps that have clipping indicators built in now. Some line drivers have it on both the inputs and the outputs to help with tuning. Perhaps those will be the baby steps to this. I actually wish they all had these clipping indicators both on the inputs and outputs.


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## danssoslow (Nov 28, 2006)

Even if the amp could know the radio's max output voltage, the source material whould throw another wrench into the mix. 

To simplify this whole deal, and keep it out of the realm of proprietary, how about the amplifiers provide the D/A conversion, keep the volume control at the amp's ouput stage, and all radios provide volume adjustment via a phone jack that runs straight to the amplifier. All processing anyone wishes to use stays in the digital domain, wiring would be simplified, and gain would no longer be an issue. Plus, volume would remain constant ( or predictable, if you'd rather) no matter the source or material.

I'm sure I've oversimplified this, but good idea?


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## MarkZ (Dec 5, 2005)

JAX said:


> What i was trying to say is why cant they make an amp that senses the voltage at the input and adjust the ouptut for what it is getting.
> 
> wouldnt that take all the guess work out of improperly setting the gains?
> 
> ...


So, play a calibration tone (e.g. 0dB sine wave) and have the amp automatically calibrate its gain? Sure! That would work, and would be easy to implement. Amp manufacturers probably don't do this because they know it's a bad idea to calibrate to 0dB.


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## t3sn4f2 (Jan 3, 2007)

Anyone ever heard of a home A/V receiver? If you have, have you ever noticed the volume setting that they start to distort with most speakers and most music? Yeah around half of full. Why is that? Hmmmmm


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## danssoslow (Nov 28, 2006)

t3sn4f2 said:


> Anyone ever heard of a home A/V receiver? If you have, have you ever noticed the volume setting that they start to distort with most speakers and most music? Yeah around half of full. Why is that? Hmmmmm



Don't know, never used anything beyond what the television came with as far as sound goes. Care to share? Something to do with dynamics?


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## Victor_inox (Apr 27, 2012)

t3sn4f2 said:


> Anyone ever heard of a home A/V receiver? If you have, have you ever noticed the volume setting that they start to distort with most speakers and most music? Yeah around half of full. Why is that? Hmmmmm


walmart special HT in a box? sure. go try top of the line Denon, maranz or premier Elite- no distortion at 0 db db least `i can't hear any. Denon and harman kardon can be preset to start at any volume desired 0db or anything you want. I set mine starting at -25 ' I'm capable of adjusting my own volume what a big freaking deal?


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## TrickyRicky (Apr 5, 2009)

I figure for it to sense the voltage of the HU, the HU would need to play a few seconds of sinewaves (either 100hz for sub duty or 1khz for upper duty) in order for it to detect the output voltage of the HU. And even after that music cannot be compared to sinewaves, so lets say if the amp is to adjust to the output every nano-second the fhz changes or output of the HU. So it would be pretty much worthless to do so.


But I know where you going on this Jax. It would be nice, especially for those that cannot set a gain in the first place, lol. For me it doesnt bother me that amps dont have the auto-sense.


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## MarkZ (Dec 5, 2005)

If you don't know how to set gain, you have no business trying to install an audio system in the car with the expectation that it will sound better than stock.


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## JAX (Jun 2, 2006)

Something I do think all amps should have and that's clip indicators. 

Just a great tool when setting an amp as long as its accurate. I have had amps with that. Seems like it should be on all amps. 

That would be fairly simple. 

I do like the idea of a smart amp though. 

Was just a thought. Lol.


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## JAX (Jun 2, 2006)

MarkZ said:


> If you don't know how to set gain, you have no business trying to install an audio system in the car with the expectation that it will sound better than stock.


That's like saying if you can't set points on a car you shouldn't do a tune up but yet now there is no such thing as points in a car since the tech was there to eliminate the need.


To say people shouldn't install if they don't know how to set gain is silly since we all know there are plenty of people ****ing up **** setting it wrong. 

There is a need for improving how it's done. 

Myself never broke anything by setting gain wrong. Doesn't mean I don't wish it was improved. 

Without tools you are talking about setting things with your ears . The same ears that hear things differently with each person.


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## MarkZ (Dec 5, 2005)

I'm not saying people shouldn't try. It's a DIY site, I'm a big fan of people DIYing. But most aftermarket installs sound like garbage, and if your goal is truly to improve the sound beyond what your stock system can provide, then you've got a LOOONG way to go if setting gains is presenting a difficulty.

If your goal is to have fun, take on a project, learn something, etc, I'm all for it.

By "you", I don't mean you, Jax.


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## JAX (Jun 2, 2006)

Ok then


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## TrickyRicky (Apr 5, 2009)

JAX said:


> Something I do think all amps should have and that's clip indicators.
> 
> Just a great tool when setting an amp as long as its accurate. I have had amps with that. Seems like it should be on all amps.
> 
> ...


Making clip indicators is pretty easy. Depends on how deeep you want to get into on the clip indicators (barely clipping, slightly clipping, clipping, clipping hard, okay you've been warn clipping). But its not worth the time and components for a simple on time use (or only checked once in a while)...you see where am going. Music is different, so while on song may be louder than the other it may clip slightly on that song, but not at all on the other, those that mean your going to adjust it on every song/genre?


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## ChrisB (Jul 3, 2008)

I've said it before and I'll say it again, when it comes to clipping, 12v manufacturers should implement Peavey's DDT circuit.


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## JAX (Jun 2, 2006)

TrickyRicky said:


> Making clip indicators is pretty easy. Depends on how deeep you want to get into on the clip indicators (barely clipping, slightly clipping, clipping, clipping hard, okay you've been warn clipping). But its not worth the time and components for a simple on time use (or only checked once in a while)...you see where am going. Music is different, so while on song may be louder than the other it may clip slightly on that song, but not at all on the other, those that mean your going to adjust it on every song/genre?


they have it on line drivers like that. audio control does anyhow.

I can see why they will not, cause it would keep people from destroying their stuff but it would be nice.


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## TrickyRicky (Apr 5, 2009)

JAX said:


> they have it on line drivers like that. audio control does anyhow.
> 
> I can see why they will not, cause it would keep people from destroying their stuff but it would be nice.


Yeah but if you stop them from destroying their stuff, how are they going to stay in business. Most companies want idiots to destroy their amps so they come back and buy new ones (oh I forgot they have Jimi's warranty).


A clip indicator is not hard to make, but most amplifiers are already crammed packed inside, but it doesnt take much space to include in the circuit.


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## evo9 (Jul 6, 2005)

t3sn4f2 said:


> Anyone ever heard of a home A/V receiver? If you have, have you ever noticed the volume setting that they start to distort with most speakers and most music? Yeah around half of full. Why is that? Hmmmmm


Sorry not totally true! Yeah my $2500.00 Onkyo from the 90s had that problem. My $2500.00 Denon form 2 years ago dont. 

On the Onkyo anywhere between 9 & 12 position on the knob would be enough to damage things. The Denon has a digital volume & I can go close to 0.


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## Chapman (Oct 3, 2012)

According to me Amp Acoustic Control Corporation,Behringer,Carvin A&I these company are good for amp and speakers.


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## Candisa (Sep 15, 2007)

I have 4 Genesis Dual Mono's waiting to be installed, 2x150W RMS at 4ohms and 0.1%THD with running car in reality...
I will use these on midbass (no problem there), but also on midrange and tweeters, no way I would EVER want to put full power on mids'n'tweets (do these play softer versions of guns'n'roses songs?)... Not even while calibrating the amps...

If Genesis Series 3 amps had this kind of technology, I'd probably had to get a Stereo60 on the tweeters (and still blow them, but that's the lightest amp they have!), a Stereo100 on midrange and still get a Dual Mono Extreme, bridged Four Channel or maybe even a pair of Monoblocks to make the midbasswoofers sound in balance to the mids and tweeters...
- I'd still be deaf way before my volume-dial comes even close to it's maximum...
- I'd spend crazy money on powering the midbasswoofers, while the tweeters and mids would still be overpowered and have less stereo-separation (no dual-mono-topology in the ST60 and ST100) on them...
- I'd have 3 different size amps in my trunk -> harder to create a nice design
- If I'd swap my midrangers by more efficient ones, I'd have to sell that ST100 to get a ST60 for them and rebuild my trunk... Wait, spending a lot of time to get and install a *less* powerfull amp???

A simple clip-indicator is all what's needed: tune the levels by ear and make sure none of the clipping-indicators are (severely) flashing...
Want full output on your subs: set the gains so the clipping indicator lights up at 0dB signal, but doesn't at -1dB... Easy, isn't it?


I wouldn't want to pay for technology that is intended to use only once everytime I change drivers or amps (auto-gain) and still have quite a bit of downsides, if a much cheaper technology (clipping-LED) does the job too and doesn't come with these downsides...

A volume control at amp-level would solve a few downsides, but if you have way overpowered amps like me, you'd still have to buy/build dummy loads to calibrate the amps without blowing your speakers...


PS.: Calling Behringer amps good really made my day :laugh:

Isabelle


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## minbari (Mar 3, 2011)

this has been done already. company called BBE made an anti-clipping circuit. it would detect when the output got near the rail voltage and would turn the gain down for you. 

so you could set the gain all the way up and crank sine waves all you want, it would not clip. best part is it really worked! worst part is, it really worked! it took out all the dynamics of music since it wouldnt allow any clipping. beleive it or not, we listen to clipping all the time and cant hear it until it gets to ridiculous levels.

bottom line, it didnt sound very good and only low end amplifiers used it.


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## robert_wrath (Apr 24, 2011)

I remember BBE from the early Pro Logic days in A/V receivers. Completely shattered sound stage in 5 Ch & Stereo.


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## minbari (Mar 3, 2011)

robert_wrath said:


> I remember BBE from the early Pro Logic days in A/V receivers. Completely shattered sound stage in 5 Ch & Stereo.


ya, it did exactly what it said. just did it a little too well, lol. took all the dynamics away and made everything sound dead. I guess my point was, it has been done and it doesnt work very well.


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## SuMb0dY (Oct 23, 2012)

This is a little different from what you guys are talking about but maybe still relevant. Doesn't JL Audio produce amps (I think their HD Line uses this) that detect resistance and voltage and adjust their output accordingly? So you can use them with 2 ohm or 4 ohm speakers and still see x wattage that they are rated for?

Their technology makes no mention of clipping or clip protection but seems to help ensure you get the rated wattage at your speakers regardless of their resistance (within a certain range of course).

What are some opinions/thoughts about this technology? I am hesitant to purchase something that unique, almost seems fishy to me but JL is a name I trust.


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## tnaudio (Mar 4, 2012)

The best way to fix this would be to standardize output voltage on decks. Make them all the same. Then in turn, you would remove the gain knob all together on the amp since they would know what the input voltage is going to be.


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## TrickyRicky (Apr 5, 2009)

tnaudio said:


> The best way to fix this would be to standardize output voltage on decks. Make them all the same. Then in turn, you would remove the gain knob all together on the amp since they would know what the input voltage is going to be.


So if your music happens to be recorded at lower or higher volumes.....what would happen? Music is recorded different in every genre. I just cant see why you (not you, in general) can't match the gains, it's real simple but many can't resist the sound of clipping. Lol.


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## bhammer (Dec 9, 2011)

Victor_inox said:


> walmart special HT in a box? sure. go try top of the line Denon, maranz or premier Elite- no distortion at 0 db db least `i can't hear any. Denon and harman kardon can be preset to start at any volume desired 0db or anything you want. I set mine starting at -25 ' I'm capable of adjusting my own volume what a big freaking deal?


Yes, my Denon can go all the way without distortion. I haven't been able to withstand -10 without ear foamies and headphones for ear protection. Even then it is screaming load and the every window in the house is shaking. I think my bass speakers can go to 12 Hz so that you also feel those frequencies that you cannot hear. It's too bad that most audio logics cut it off at 20 or so....


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## 14642 (May 19, 2008)

Interesting thread. 

First, you want to allow some clipping. Calibrating at 0dB means that you'll never clip the amplifier and that costs a bunch of perceived loudness. In addition, it's helpful to alloow clipping because recordings vary a great deal in their average volume. Set your gains so that the amp reaches maximum undistorted output at 0dB and it'll be fine if you listen to Death Magnetic, but listen to a well recorded and dynamic album (Try van Morrison's Too Long in Exile) and it won't sound loud enough. 

I find that setting the amplifier gain to clip at -10dB wofks great. Your sub ampifier will have to be set much higher in order for you to perceive the right balance between sub and the rest, depending on the amp's power and the efficiency of the subs. 

Setting gains is the most misunderstood of all setup procedures. Electronic potentiometers are pretty expensive and the process only needs to be performed once when the system is set up. Adding electronic pots and a microprocessor and a UI of some kind just for gain setting would make for an expensive amp.

All of the new JBL amplifiers (MS-Series and GTO-Series) include a feature we call Simple Setup. The amplifiers have gain LED that are calibrated to light at -10dB and the amps come with a setup CD. Since the MS-Amps include a DSP, a micro and a UI already, they include a setup mode that mutes the output so you can make the adjustments without destorying speakers. You simply put the amp in setup mode, insert the CD, turn the volume of the radio up (ideally to the maximum undistorted output), turn the pot and flup the range switches until the green check mark lights up. There are additional indicators that tell you to turn the gain up or down until you get it right. Then, there's an output control in the DSP that allws you to adjust the output of the amp in relation to the other amps in the system.

The GTO amps are less expensive, so we use a similar analog circuit. The CD is recorded at a much lower level (-29dB), so that the setup signal isn't loud through the speakers. There are red, green and amber lights that indicate the same thing as the display in the MS-Amps. When the green light is on, you're good to go. Because the GTO amps don't include an additional output level control, the noise is shaped so that subwoofer amplifiers get an additional 9dB or gain to set balance between sub and the rest of the system.

For both amps, the RCA inputs are differential and will accept anything from 50mV to about 15 volts. No need to determine the voltage of the head unit. Just flip the range switch and adjust the pot until you get the green light. 

For cars that include OE amps that require a load to turn on, there's an additional position on the switch that provides a load. 

Given the experience with all of these DSPs with autocalibration, I can just imagine the phone calls and emails about not being able to set the gains manually if they were automated. 

One last point--all of this chatter about volume controls at the output stage of the amplifier, whether to preserve a high-voltage transfer of analog signals to the amplifier or to preserve the resolution in a digital signal is slpitting hairs and implementation would either cause you to have a seriously limited choice of amplifiers for your head unit, add ridiculous cost and complexity to your system or have to find an additional place to mount a control. We provided this in MS-8 and the VAST majority of users just want to use the factory control. The real advantage of high voltage signal or digital signal is the reduction in the possibility of noise. Floating outputs and differential inputs with high CMMR makes ground loops virtually impossible. This is what the OEMs use and they NEVER have noise. If we could just eliminate the silly connection between audio ground and chassis ground at the radio, all would be solved, but the RCA cable companies would cry like babies and an industry designed to sell ******** at astronomical prices that defraud customers would be destroyed. Ahhh...wouldn't that be a shame.


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## Topdown (Aug 12, 2009)

why not just add a piece of firmware that monitors the input from the RCA's, and if/when it senses a clipped signal, adjusts the sensitivity to prevent the clipped signal? that way the amp is always at its most sensitive giving the most output, volume up/down still works... Thats not hard to do or test and its been done over and over in other consumer audio electronics.


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## MarkZ (Dec 5, 2005)

Oh great. Andy said -10dB. Now everybody is going to break out their DMMs and oscillscopes to make sure that theirs is set to -10dB... not -9.9dB, not -10.1dB. 10dB.


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