Amp Gain, input/output sensitivities.. Different advice everywhere.. Help!!

[BPM]

Hi everyone and Happy Easter!
Let me start with making clear that I'm swedish..so have some patience with my english.
Tomorrow I'll be installing a new system i my livingroom. It will consist of a Wiim Ultra, two Apart Champ-2 power amps where one will power a pair of Canton Ergo 620 standmounts from the preout-sockets and the other two Klipsch SPL-120 subwoofers that I have converted into passive subs since both of the built in amps have died.
I have some questions on amplifier gain och channel balance. The power amps are 1V/10kOhm at the rca inputs and the Wiim preout can be set to either 1V or 2V so my initial plan was to set the output to 1V and the amps gaincontrols to max as it would give what I've read is "unity gain". Then I started to read forums.. Some say that I'm right and thats the correct way. Others say definitely not since hiss will be elevated with gain on max. I've also read that if I dont use 2V from the Wiim pre out it will degrade performance significantly..
I know that many in here are close to experts so how would you set up a system such as mine?
I'm not to concerned about the subs. I'll just twist the knobs until I get the level I want and if right and left differs a little I probably wont here it. The fronts though.. If I'm not using the amp with full gain, how can I be sure that I get the channel balance right? I dont trust my ears more than I trust that the gain controls track perfectly so I'm a bit lost.. There are no steps in the controls so getting them identical wont be easy.
Should I play some white noise and measure in front of each speaker with a dB-app? Measure voltage with a multimeter at the speaker outputs?
Questions, questions.. Please help me make the most of my system.

 

[DVDdoug]

In the real world, Line level is loosely defined, home setups aren't calibrated, and sometimes there is a volume control, different sources have different volumes, and some recordings are louder than others.

Generally, outputs are "hot" enough and inputs have enough gain so that everything just "works together". But you'll probably have to "calibrate" the subwoofer level. I simply adjust the subwoofer by ear.

The rule for "gain staging" is to keep the highest possible signal (without distortion) for the best signal-to-noise ratio, and then attenuate at the last possibility. But for everyday volume control that's not always practical.

You can sometimes have issues with a "pro" amplifier with balanced XLR inputs. Pro line level is higher so they usually expect a hotter signal.

If I'm not using the amp with full gain, how can I be sure that I get the channel balance right? I dont trust my ears more than I trust that the gain controls track perfectly so I'm a bit lost.. There are no steps in the controls so getting them identical wont be easy.

You can make a test tone with Audacity or find one online that you can download. 400-500 Hz is probably about right. Strange things happen with reflections at high frequencies and there are other variables at low frequencies. Then you can use an SPL meter app on your phone to measure the acoustic loudness. The measurement doesn't have to be accurate, it just needs to be consistent-repeatable. You can also try pink noise or white noise but since noise is "random" it's harder to get a solid-stable reading.

 

[RandomEar]

Hi everyone and Happy Easter!
Let me start with making clear that I'm swedish..so have some patience with my english.
Tomorrow I'll be installing a new system i my livingroom. It will consist of a Wiim Ultra, two Apart Champ-2 power amps where one will power a pair of Canton Ergo 620 standmounts from the preout-sockets and the other two Klipsch SPL-120 subwoofers that I have converted into passive subs since both of the built in amps have died.
I have some questions on amplifier gain och channel balance. The power amps are 1V/10kOhm at the rca inputs and the Wiim preout can be set to either 1V or 2V so my initial plan was to set the output to 1V and the amps gaincontrols to max as it would give what I've read is "unity gain".

The way I know "unity gain" it literally means the signal level isn't changed at all, so 0 dB = factor 1.0. That's typically an option on preamps, not amps.

Then I started to read forums.. Some say that I'm right and thats the correct way. Others say definitely not since hiss will be elevated with gain on max. I've also read that if I dont use 2V from the Wiim pre out it will degrade performance significantly..
I know that many in here are close to experts so how would you set up a system such as mine?

If you set the Wiim to 2 V, you run the risk of clipping in the amp input buffer. It will depend on the volume you use on the Wiim. I would therefore set it to 1 V max - you loose some theoretical SNR, but you would equally loose that at 2 V output with the correct (lower) digital volume setting on the Wiim. It's a limitation of the amplifier which you can't really work around without getting one with a different input sensitivity.

I would then set the Wiim to max volume, play some music and slowly turn up the amps to the highest level you are comfortable with. You want the volume dials on the amps as low as possible to keep the tweeter hiss low and maybe to protect your speakers if they can't handle 350 W.

I'm not to concerned about the subs. I'll just twist the knobs until I get the level I want and if right and left differs a little I probably wont here it. The fronts though.. If I'm not using the amp with full gain, how can I be sure that I get the channel balance right? I dont trust my ears more than I trust that the gain controls track perfectly so I'm a bit lost.. There are no steps in the controls so getting them identical wont be easy.
Should I play some white noise and measure in front of each speaker with a dB-app? Measure voltage with a multimeter at the speaker outputs?
Questions, questions.. Please help me make the most of my system.

Yes, get a multimeter, put on some hearing protection and play a test tone at 400 Hz. Don't use white noise. Measure the AC voltage on the outputs of one channel, then switch the multimeter to the other channel and dial in the same voltage. Done.

 

[staticV3]

The power amps are 1V/10kOhm at the rca inputs and the Wiim preout can be set to either 1V or 2V so my initial plan was to set the output to 1V and the amps gaincontrols to max as it would give what I've read is "unity gain".

Unity gain means input voltage = output voltage.

When the Champ-2 is set to maximum volume, then it will amplify the input voltage by 32x, which means it would output 32V, definitely not unity gain.

Others say definitely not since hiss will be elevated with gain on max.

Ideally, set the WiiM to 2V and 100% volume, turn down the Amp all the way, then play a few tracks which you know need the volume knob turned up the most out of your library.

Finally, turn up the Champ-2 slowly until it's as loud as you'll ever need and leave the volume knob there.

Then during regular use, control volume with the WiiM Remote, WiiM Home App, or WiiM volume knob.

I've also read that if I dont use 2V from the Wiim pre out it will degrade performance significantly..

No it won't, but there's also no disadvantage to leaving it at 2V.

I'm not to concerned about the subs. I'll just twist the knobs until I get the level I want and if right and left differs a little I probably wont here it. The fronts though.. If I'm not using the amp with full gain, how can I be sure that I get the channel balance right? I dont trust my ears more than I trust that the gain controls track perfectly so I'm a bit lost.. There are no steps in the controls so getting them identical wont be easy.

I don't understand. You use a single Champ-2 to power both of your Canton standmounts, right?
Why would you expect channel imbalance unless the Champ-2 is turned up to full volume? Is the potentiometer behind the volume knob that bad?

 

[Wayne A. Pflughaupt]

I don't understand. You use a single Champ-2 to power both of your Canton standmounts, right?
Why would you expect channel imbalance unless the Champ-2 is turned up to full volume? Is the potentiometer behind the volume knob that bad?

The amplifier has separate gain knobs for each channel, hence the potential for channel imbalance.

Regards,
Wayne A. Pflughaupt

 

[BPM]

Thanks for all the answers.
"staticV3"
I will use identical power amp to drive the subs. In 4ohm it will deliver more than enough power (the Cantons are 8ohm..).
I dont "expect" channel imbalance. It's just that since there are no steps it is difficult to get them exactly the same (the controls) and small differences in rotation can bring on pretty big differences. If one of the subs play 1dB or so louder than the other I wont hear it. That kind of imbalance with the fronts would be audible.. I havent tried the amps yet so I really dont know what to expect. I just want to have warm shoes on when I start.

What about all the power amplifiers out there that lack any means to adjust gain? Are they always on a "max" setting?

 

[DVDdoug]

What about all the power amplifiers out there that lack any means to adjust gain? Are they always on a "max" setting?

Yes... But you can't say "maximum" or "minimum" since there's no adjustment. It's fixed... "It is what it is." And of course, different amps have different gain. But like I said above, most can go to full power with "line level" from most sources.

 

[Wayne A. Pflughaupt]

BPM, I didn’t have any luck finding the specs you mentioned for the Wiim output voltage or the amp’s input sensitivity at the company websites. However, I noted that neither company publishes SNR specs for these pieces. IMO that’s a red flag. In that situation, my go-to is to assume the piece is not all that quiet, until hands-on evaluation shows otherwise.

Yes, maxing out the amp’s gains can cause noise. However, switching the Wiim output from 1 to 2 volts will also increase noise. The maximum noise level the Wiim generates for either output setting will be at the highest master volume setting.

Since you claim the amp’s input sensitivity is 1V (meaning 1V is sufficient to drive it to maximum output), I’d start with that setting on the Wiim. Since it’s possible the Wiim will clip at the max master volume setting for either output voltage setting, I’d start with the master volume at 3/4. Play a music source, and gradually increase the amp’s gain controls. Hopefully by the time the amp’s gains are at max, you’ll have all the in-room volume (read SPL) you need. If not, switch the Wiim to 2 volts and try again. You can level-match the main-speaker channels with an SPL meter, if you find the need.

As noted, without hands-on evaluation, I’m suspicious of the background noise levels of both these pieces of equipment. What saves the day, potentially, is that the speakers aren’t especially efficient. High efficiency speakers are brutally unforgiving of equipment with unacceptable noise levels.

I put together a piece on gain structure when mixing residential and pro gear some years back that you can access in my signature. However, since you’re not using any processing equipment between the preamp and amp, it might not be of much practical use in this situation.

What about all the power amplifiers out there that lack any means to adjust gain? Are they always on a "max" setting?

Generally, those are home audio amps. Gain structure is typically a non-issue when residential equipment is used top to bottom. It usually only gets to be a problem with combining home and pro gear.

Regards,
Wayne A. Pflughaupt

 

[BPM]

"Wayne A. Pflughaupt"
The info is taken from the amplifiers manual. It says that the rca input is 10kOhm/1V 0dBv. S/N better than 100dB. The Wiim is tested on this site but I cant remember the exact figures. It came out recommended though so it cant be too bad. Regarding the wiim output voltage I just happend to se the option to switch between 1V and 2V in the app.
I read somewhere that using 1V instead of 2V in the Wiim will cost just over 6dB of SNR. If its like 120 dB from the beginning I doubt that I can hear that difference..
Not sure what noise really is.. Hiss I understand so it would be easy to test how bad it gets with the controls set to max. 1V seems to be a comparatively low input sensitivity so with 1V from the Wiim it shouldnt necessarily hiss that bad.
I rarely listen at high levels. I've used a Wiim amp pro with the speakers before and never came close to run out of power. The Champ-2 delivers much more so clipping either output stage, distorsion the input or running out of power is probably never going to happen. I just want the cleanest sound possible at the rather modest levels I listen to..
In AVR-terms I can say that even on Disney + which have a rather low output i rarely exceed -20 on my marantz sr7011 receiver. Spotify connect usually lands at -25/30. I think volume makes out somewhere around +20..

 

[staticV3]

I dont "expect" channel imbalance. It's just that since there are no steps it is difficult to get them exactly the same (the controls) and small differences in rotation can bring on pretty big differences.

I see now, my bad for assuming there's one volume knob for both channels

You can precisely match the volume controls using just a basic multimeter.

Plug out the speakers, play a 60Hz sine wave into the Amp, then set the multimeter to V AC and measure the output voltage of each output channel separately. Then adjust the volume until they match.

What about all the power amplifiers out there that lack any means to adjust gain? Are they always on a "max" setting?

Yes. Power Amps usually have fixed gain, or just a few gain steps like Low/High or L/M/H.

The actual volume control is done upstream, just like you will do with the WiiM Ultra.

 

[Sokel]

Plug out the speakers, play a 60Hz sine wave into the Amp, then set the multimeter to V AC and measure the output voltage of each output channel separately. Then adjust the volume until they match.

Some amps don't like open load, he has to check on that first.

 

[staticV3]

Here's an alternative method that requires neither multimeter nor open load, and that also takes into account potential differences in sensitivity for each speaker:

Palmer ORBIT 11 Cardioid Coaxial 3-way studio monitor (MSRP 799€/899$)

thank you for sharing! one question, at what spl did you measure the distortion? It's the same measurement as shown above with the spl graph.

www.audiosciencereview.com

 

[Mnyb]

There are also inline attenuators you can buy if the amp is to sensitive . It can be a bit messy if mix different eras of consumer products to I had a classe power amp that only needed 0,5v for full power and I’ve seen lower .

In this case . Inline attenuation is an idea. 6dB seems right.

But if OP uses the room fit function and or EQ and already limits the volume to avoid clipping. I would simply try both settings and se if observed any problems with any of them possibly sticking to 1 volt if that gave the most usable volume range and no noticeable noise problems.

 

[BPM]

 

[BPM]

Was easier than expected.. The gain controls really had steps..but the effect is much smaller than what I thought. With 1V out from the Wiim I could easily have hade the gain knob at it's minimum setting. The difference between minimum and maximum is almost negliable. It sound really good. Much better than the 2.2K$ Marantz SR7011 that this gear replace. More dynamics, more detail, overall clarity is improved and I get that nice feeling of sound just wanting to bounce out of the speakers instead of being dragged out.. The taughtness and definition in the base is amazing.
The amps are dead silent even at full gain. No hiss. No pops or crackles on turn on/off.
It seems that 1V out doesn't give the amps all the beans but it is more than enough. I tried to light the clip indicator led on the bass amp by setting the volume on the wiim to max, amp gain to max och play a 30Hz tone. I could see, not just hear and feel, things moving in my 45m2 livingroom and the drivers looked like the were going into orbit.. No light, just an amazing power. It was rediciously loud..
Ended up with bass amp on full, front amp five clicks down (from there it makes no difference to the bottom) and I'm happy. No need for all the experimenting I thought I had to go through.
With 2V out I hear no difference other than difference in volume at any given setting. Maybe, just maybe, 1V sounds slightly calmer and 2V a bit more dynamic but since I have to recalibrate my ears and change the volume to what I think is equal it's hard to say for sure.
One strange note.. With a wiim amp pro I owned a while back, same speakers but a different amp for the subs, I ran the roomfit roomcorrection and settled on Harman curve and correction between 20-400Hz. With this stuff I've ran the correction several times in a number of different settings but I still prefer the sound with roomfit turned off..

I want to thank everyone for taking the time to read and even respond.

 

[DVDdoug]

Maybe, just maybe, 1V sounds slightly calmer and 2V a bit more dynamic but since I have to recalibrate my ears and change the volume to what I think is equal it's hard to say for sure.

The higher output simply louder. And when we turn-up the volume, it sounds like you've turned-up the bass more (Equal Loudness Curves).