Total system gain

werd · « **on:** 18 Jun 2012, 04:32 pm »

Here is an ambigous question...

How does everyone here rate their system gain in importance to individiual components? When system matching how do you look at system gain and is there is a total system gain that an individual tries to attain? I am talking personal gain preferences.

I have been currently interested in low gain preamps. Matched with my 14b (23db) i like to keep my total gain under 40db. My speakers are rated at 89db sensitivity at 8ohms there abouts.

Any thought would be appreciated in your own gain philosphies and how it helps to get your prefered sound. There is no right or wrong just prefences.

ptmconsulting · « **Reply #1 on:** 18 Jun 2012, 04:41 pm »

I'm a firm believer that each piece of music has an "optimum" volume level necessary to sound it's best. Yes, it can still sound good lower, and sometimes higher, but usually there's one level where it just gells.

That being said, to achieve that optimum level you have to consider:
- the efficiency of the speakers
- the volume level of the recording itself (and we all know that can differ dramatically)
- the dynamic of the presentation as well (peak to trough)

As such, I believe that I need sufficient gain to give me options to make those low volume recordings come to life on my highely inefficient speakers (83db). I therefore need power in my rig. Someone with 106db efficient Klipshorns can get away with 3 watt SET amps and probably have even more dramatic dynamic swings than I can achieve with my 1000 watt amp.

I guess there are just many different ways to skin the beast.

JohnR · « **Reply #2 on:** 18 Jun 2012, 04:44 pm »

How is speaker sensitivity factored into "total system gain"? Do you add it, or add the difference relative to some other reference like say 90 dB/W/m2?

Serous question, for the Lab.

werd · « **Reply #3 on:** 18 Jun 2012, 04:52 pm »

Quote from: ptmconsulting on 18 Jun 2012, 04:41 pm

I'm a firm believer that each piece of music has an "optimum" volume level necessary to sound it's best. Yes, it can still sound good lower, and sometimes higher, but usually there's one level where it just gells.

That being said, to achieve that optimum level you have to consider:
- the efficiency of the speakers
- the volume level of the recording itself (and we all know that can differ dramatically)
- the dynamic of the presentation as well (peak to trough)

As such, I believe that I need sufficient gain to give me options to make those low volume recordings come to life on my highely inefficient speakers (83db). I therefore need power in my rig. Someone with 106db efficient Klipshorns can get away with 3 watt SET amps and probably have even more dramatic dynamic swings than I can achieve with my 1000 watt amp.

I guess there are just many different ways to skin the beast.

Yes that is exactly where i am headed. That sort of "gel". I find that a lower gain preamp with a great volume control helps to dial in that "gel". You hit the nail on the head with that. There is no right or wrong but just personal prefences.

Is it worth getting a high gain pre amp matched with a lower gain power amp? What are the benefits?Assuming the speakers are not way out of line in sensitivity.

sts9fan · « **Reply #4 on:** 18 Jun 2012, 05:20 pm »

Have you seen this article?
http://www.diyaudio.com/forums/diyaudio-com-articles/186018-what-gain-structure.html
I am a firm believer that modern components have too much gain.
You do not need a pre with 14db and a power amp with 32db. Ymmv.

vortrex · « **Reply #5 on:** 18 Jun 2012, 05:22 pm »

I've asked this question before and couldn't really get a good answer. I'm interested too in how system gain, watts per channel, and speaker sensitivity all relate to each other. I have a very low gain system with 88db speakers. I can reach volume levels I am happy with, however I am going to be going to slightly less efficient speakers soon.

werd · « **Reply #6 on:** 18 Jun 2012, 05:32 pm »

Quote from: sts9fan on 18 Jun 2012, 05:20 pm

Have you seen this article?
http://www.diyaudio.com/forums/diyaudio-com-articles/186018-what-gain-structure.html
I am a firm believer that modern components have too much gain.
You do not need a pre with 14db and a power amp with 32db. Ymmv.

I was hoping you would answer and i wouldve come calling if you hadn't... I know your amp is under 10db right? Is it noise that gets you into this low gain amp?. idk. How about the dynamic swings, could be brainswashed but wouldn't it suffer from a loss of dynamic power?. Don't know just asking.

going to read that article tonight at work on my ipad when i have a chance.

ptmconsulting · « **Reply #7 on:** 18 Jun 2012, 05:35 pm »

I guess it all depends on the noise floor of each component. For instance, I think you would want to pair a higer gain SS device with a lower gain tube device, just so you can get the most gain with the quietest piece of equipment (tubes generally being noisier with tube rush).

*Scotty* · « **Reply #8 on:** 18 Jun 2012, 05:52 pm »

I don't have a "system gain philosophy"? The gain a component has, if properly engineered, should have no bearing on how well it performs or sounds.
In my system I have a roughly 3600cu.ft. space to fill. My preamp has zero gain, the power amp has 26dB gain with 1volt in sensitivity and my speakers have about 96dB sensitivity.
The problem I have had with preamps with more than 7dB of gain has been related to the ability to use the volume control to achieve a desirable SPL in my room. A preamp with 14dB gain cannot be used because it is either too loud or turned all of way the down. There is no usable area of the potentiometer's travel. Obviously this is the worst case scenario, if the speakers had 89 to 90dB sensitivity the problem would be solved. This is only kind of problem with gain that I have had to deal with.
Depending on the loudspeaker's design I can see all sorts of thermal compression problems cropping up with speakers rated at 83dB and using conventional cone based drivers.
I confess that I don't understand werd's preference for staying under 40dB gain for his system.
Scotty

werd · « **Reply #9 on:** 18 Jun 2012, 05:54 pm »

Quote from: JohnR on 18 Jun 2012, 04:44 pm

How is speaker sensitivity factored into "total system gain"? Do you add it, or add the difference relative to some other reference like say 90 dB/W/m2?

Serous question, for the Lab.

The speakers are where it all ends up so ultimately i believe its where you start in system matching. For me its playback volume level when i look at sensitivity. Is that speaker going to perform in my room at the playback volume i like.? Its interesting how they don't refence into db/w/m2 or even m3. These are more real scenarios. It kinda adds to the confusion at m1. It might be a m1 where the room plays no role in the measurement. Idk.

werd · « **Reply #10 on:** 18 Jun 2012, 06:04 pm »

Quote from: *Scotty* on 18 Jun 2012, 05:52 pm

I don't have a "system gain philosophy"? The gain a component has, if properly engineered, should have no bearing on how well it performs or sounds.
In my system I have a roughly 3600cu.ft. space to fill. My preamp has zero gain, the power amp has 26dB gain with 1volt in sensitivity and my speakers have about 96dB sensitivity.
The problem I have had with preamps with more than 7dB of gain has been related to the ability to use the volume control to achieve a desirable SPL in my room. A preamp with 14dB gain cannot be used because it is either too loud or turned all of way the down. There is no usable area of the potentiometer's travel. Obviously this is the worst case scenario, if the speakers had 89 to 90dB sensitivity the problem would be solved. This only kind of problem with gain that I have had to deal with.
Depending on the loudspeaker's design I can see all sorts of thermal compression problems cropping up with speakers rated at 83dB and using conventional cone based drivers.
I confess that I don't understand werd's preference for staying under 40dB gain for his system.
Scotty

Well i have found that its gets way to noisy at the playback volumes i listen to. The internal noise of the components somehow get amplified which brings in noise imo. This seems to be a general rule of thumb i have found on all gear with this type of over all system gain. ymmv. On my Max bella pre set to 23db and my 14B set to 29 db its just way to much buzz from my pre amp. It does give you a great in your face soundstage when turned up though. I dont listen like that so i have my 14B set to its lower 23db setting and my max bella set to its 16 db setting. Here the noise is reduced substantially and i still get tons of dynamics.

*Scotty* · « **Reply #11 on:** 18 Jun 2012, 06:43 pm »

The 1 meter measurement is an industry wide standard that takes the room gain variable out of the equation. It's up to the loudspeaker manufacturer to provide any room specific interaction information if they deem it necessary. The one meter sensitivity is also optional and it is frequently meaningless due to over optimism.
I usually listen at under 85dB SPL average, transient peaks not considered. It is interesting that we are both happy with the overall system gain we have and there a 7dB difference in total gain between our two systems. It just goes to show how the total system gain is unique the the room and equipment involved.
Scotty

sts9fan · « **Reply #12 on:** 18 Jun 2012, 11:07 pm »

I am still wrapping my head around this stuff. It seems to me that the power amp is where the attention needs to be paid. You want to be able to drive it to maximum power. So you look at the source output and then you should know how much gain is needed. I could be wrong.

Freo-1 · « **Reply #13 on:** 19 Jun 2012, 12:20 am »

Quote from: sts9fan on 18 Jun 2012, 11:07 pm

I am still wrapping my head around this stuff. It seems to me that the power amp is where the attention needs to be paid. You want to be able to drive it to maximum power. So you look at the source output and then you should know how much gain is needed. I could be wrong.

Well, one then gets into wattage vs. gain. For example, a Class A/B amp that outputs 150 WPC and a 50 WPC Class A both have 26 db of voltage gain. Most Threshold/Pass Lab amps have 26db of voltage gain. The difference is how much db per watt, which is different.

stereocilia · « **Reply #14 on:** 19 Jun 2012, 12:49 am »

I would think it's perfectly fine to have a high-gain amp as long as the noise floor of the input is low enough and the maximum output before clipping were high enough. A lower gain amp with a higher noise floor would only solve the problem of an annoyingly sensitive volume knob. right?

sts9fan · « **Reply #15 on:** 19 Jun 2012, 01:16 am »

Well, we are talking gain not watts right?
I guess if you are quiet upstream then I guess 32db is fine for the power amp.
Remember the noise is not being attenuated from the pre.

Freo-1 · « **Reply #16 on:** 19 Jun 2012, 01:42 am »

Actually, db per watt provides a measure of how much power one gets out of the amp.

Voltage gain in and of itself does not provide the same level of detail. Kind of need to know both.

*Scotty* · « **Reply #17 on:** 19 Jun 2012, 02:09 am »

Actually, I would look at the input sensitivity of the power amp. For example, 1 volt in equals the full rated output, what ever that might be. If I have control of my source's output voltage I can set it up to have slightly less than 1 volt output into the power amp to prevent clipping.
In my case one of my digital sources has only slightly more than 1 volt out. When fed into
my buffer based preamp with zero gain and thence into my amp with 1v. input sensitivity for 110watts full rated power output, I am almost guaranteed to be free from clipping and this has proven to be the case so far.
Scotty

Davey · « **Reply #18 on:** 19 Jun 2012, 02:27 am »

Quote from: Freo-1 on 19 Jun 2012, 01:42 am

Actually, db per watt provides a measure of how much power one gets out of the amp.

Voltage gain in and of itself does not provide the same level of detail. Kind of need to know both.

"db per watt" is a meaningless "specification" since voltage gain has no correlation to power capability of an amplifier. You correctly (sort of) noted this in your previous posting....but I think there still might be some confusion? Of course, with speakers, it is completely meaningful.

The main issue/problem with identifying a (nominal) total system gain is the varying levels of source material. It's not unusual for me to select settings of my system volume control anywhere in a 15db range. Obviously, your system gain would need to be sufficient to allow proper listening levels for the lowest output recordings in your collection without having to max the system volume control.

A common conclusion I see from some users is to assume that since the typical CD player (or other source) probably has a maximum output of around two volts and the typical power amplifier will deliver its rated output with 1 volt input, that a preamp with gain is not required. It's seems a logical conclusion, but in the real world it's nice to have a preamp with a line amp gain of at least 6db to accommodate the aforementioned large range in source material level.

Cheers,

Dave.

*Scotty* · « **Reply #19 on:** 19 Jun 2012, 03:10 am »

Davey is correct. In my case about 1volt peak output from my USB DAC in a system with 26dB gain and 96dB speakers can be insufficient. I have a few CDs ripped to wave that could another use another 6dB of gain even when I have my volume pot at maximum. Rather than look for another preamp, I will probably have a friend re-record the CDs with 6dB more gain.
Scotty