WHY oh WHY do monitors have hiss?!?

[ZolaIII]

I’ve been using cheap ‘studio monitors’ (Yamaha HS5) for years. I always tolerated the noise because I thought it was from the computer or ground loop. Turns out, yeah, they were just shite.
Recently I got a topping mini 300 amp and Dali Sonik 3 speakers. Dead silent.
There’s a lot of good reasons listed previously as to why this might be the case with studio monitors. But I also think that people buying cheap ish monitors aren’t into hifi (like I was) and just tolerate the noise. You can still make a decent mix with them, and they’re likely to be an upgrade from whatever was previously being used. Therefore there isn’t much incentive to put half decent amps in them.

Don't agree with you, Yamaha is above average regarding self noise and pitch ain't on highs side either. Older Neumann's where amoung quietest. I don't consider my self prone to it and I don't really like much to listen in near field when I don't have too and this day's that's not that often.
The noise flor of your current combo is - 18~20 dB and in the worst case important before soft clipping at 5 KHz stays under sensitivity of those speakers so silent as expected.

 

[JohnnyNG]

I've also wondered why this seems an insurmountable problem. I run a full active 3-way setup (4-way if you count a mono subwoofer) with the very inexpensive Fosi Audio V3 mono on mid and tweeter (SICA 5.5C1.5CP-8 coax tweeter rated at 93.5 dB) and I have to be within 6" to hear any hiss.

 

[LSPhil]

I set the input to the maximum level my source can deliver, and there’s no noise at all. When I reduce the gain on the active speakers, the system stays perfectly quiet and I can simply enjoy the music.”

 

[dfuller]

Passive crossover do not suppress noise. It has very little influence in pass band and outside speakers usually aren't efficient enough to make a difference.

Well, consider that most active speaker noise is called "hiss" - meaning it's mostly perceived at higher frequencies. Tweeters in passive circuits are usually heavily padded down to match the mid and especially woofer's sensitivity (which also reduces the noise), but this is not the case with an active circuit. They have the level turned down before any power amp circuits - where exactly varies.

 

[MAB]

Passive crossover do not suppress noise. It has very little influence in pass band and outside speakers usually aren't efficient enough to make a difference.

The passive crossover actually does. Agree, most drivers aren't efficient enough for people to notice outside of nearfield or in an extremely quiet room.

Is the entire audio industry a fraud?

What? Why would professionals not care about hiss? They usually will be seated closer than home listeners. I'm sure it is a cost saving measure and good enough, but barely. In more expensive monitors it really is unforgivable or at least quite unnecessary. People complaining about hiss in...

www.audiosciencereview.com

9dB in this example, which is why some monitors have negligible hiss, and even high efficiency passive speakers have little or no hiss even when they are used with noisy amps.

 

[Roland68]

Is there not hiss simply because self powered monitors must operate with their amps “wide open” to be able to give full output as attenuation is located upstream? You can replicate this if you have separate power amps on your passive speakers by turning the gain knobs wide open. You’ll get hiss.

It's been mentioned several times that users with amplifiers that measure well, such as Hypex, Purifi, and Topping PA5 (II), perceive absolutely no noise, regardless of whether they're using active or passive systems, and even at full volume.

I just tested this again myself, with my ear 10 cm in front of the tweeter, and the gain turned all the way up for both passive and active systems.
This should apply to all current amplifiers with measurements like those of the Mini300, PA5 II, 3E Audio A5/A7, etc.

 

[Bwaslo]

I see some hypothesis, which doesn't seem right. To summarize:
Passive crossover do not suppress noise. It has very little influence in pass band and outside speakers usually aren't efficient enough to make a difference.
Amplifier chips work the same in active and passive design. There is no reason to assume, that they generate more noise in active speaker.
Active crossover works similar as tone control in setup with passive speakers.
DSP is common in AVRs, which do not exhibit excessive noise.

IMO the main difference is position of volume control in the whole chain of electronics. With passive design volume control is usually after DSP and tone control, effectively supressing any noise at low volume.
With active speakers, volume control comes before active crossover (analog or digital) and generated noise is the same, regardless of volume or input signal level.

Usually active speakers have its own volume trimmer. It is worth checking if this control suppress noise.

A passive crossover also restricts upstream noise to the bands of the individual drivers. Take a look at typical raw curves of midranges and woofers and you will notice considerable sensitivity at tweeter frequencies (often more than at assigned frequency range) from sharp resonances. The large radiating area of a mid or wooder can radiate a lot of hiss if it is fed with it.

 

[Timcognito]

can radiate a lot of hiss

What is the transferring mechanism and why would passive be different than active? Curious.

 

[Bwaslo]

What is the transferring mechanism and why would passive be different than active? Curious.

Because the active filter is before the amplifier (and DAC if dsp), so all their noise bandwidth goes to the driver. With passive crossover, the out of (assigned) band noise doen't make it to the drivers

 

[popej]

Because the active filter is before the amplifier (and DAC if dsp), so all their noise bandwidth goes to the driver.

IMO active crossover suppress own noise outside pass band too. At least to some degree.

 

[KSTR]

What I can say, as a former designer of active studio monitors, is that many, typically low-cost all-analog designs of the day I've analyzed suffered from non-optimized circuit structures, using lots of simple and independent building blocks for all atomic circuit functions, like input circuits --> volume control --> EQ --> XO filters and driver EQ --> limiters (sometimes) --> power amps, with each of these blocks using one or more opamps (also often not chosen wisely), and many times without optimized gain structures. This way, all the noise from the active and passive parts in the preamp sections add up and are passed to the power amp. Using a low noise power amp does not help.

When one really tries to optimize and minimize the whole preamp circuitry to just two or three opamps, and further also uses the (linear chip-based) power amps for filter functions then the self noise can be kept very low.

But a professional studio monitor always has to handle more variety with regard to input levels and output levels. You want to be able to feed a +24dBu signal and acheive a playback level of like below 70dBSPL, and with the same circuit and preferably only one volume control / level setting element in you want to achieve full output, say, 115dBSPL with just 100mV or so. This is an extremely wide range of internal gain/attenuation range and requires effort to realize without side-effects like excess self noise, clipping setting in too early etc, within in all possible ranges of user settings.

 

[Bwaslo]

IMO active crossover suppress own noise outside pass band too. At least to some degree.

To some small degree, but if it's done actively to small signal ahead of the power amp, the power amp's own noise (boosted by its 20ish dB gain) completely ignores the active crossover filter that precedes it.

Ideally, band limiting should occur we within the power amp's circuit, but that requires a custom power amp for both bandlimiting and for keeping it stable with the much added hf feedback. Easier might be a single fixed LC passive filter between amp and mid/woofer, with rest of crossover shaping done actively before the amp.

 

[popej]

the power amp's own noise (boosted by its 20ish dB gain) completely ignores the active crossover filter that precedes it.

This is the same noise that passive speaker gets from an amp. It can be quiet enough.

Ideally, band limiting should occur we within the power amp's circuit, but that requires a custom power amp for both bandlimiting and for keeping it stable with the much added hf feedback.

Probably standard tricks for opamps would work. Class D chips could be problematic.

 

[Jcrow]

Don't agree with you, Yamaha is above average regarding self noise and pitch ain't on highs side either. Older Neumann's where amoung quietest. I don't consider my self prone to it and I don't really like much to listen in near field when I don't have too and this day's that's not that often.
The noise flor of your current combo is - 18~20 dB and in the worst case important before soft clipping at 5 KHz stays under sensitivity of those speakers so silent as expected.

Maybe mine were faulty, because they were very noisy

 

[Bwaslo]

This is the same noise that passive speaker gets from an amp. It can be quiet enough

No, it's not. Passive crossover will block most out of band amplifier noise, actve one before the amp will not.

For instance, here's a typical decent quality midwoofer response --

The power amp noise in a typical active crossover setup will play out noise shaped only by the blue curve above. But a passive crossover between amp and driver would block out the noise energy above the crossover point.

 

[theREALdotnet]

lol any amp that is noisy during pauses in the music is borked

Like the ones in the active monitors this thread is about?

 

[Timcognito]

No, it's not. Passive crossover will block most out of band amplifier noise, actve one before the amp will not.

For instance, here's a typical decent quality midwoofer response --
View attachment 516956
The power amp noise in a typical active crossover setup will play out noise shaped only by the blue curve above. But a passive crossover between amp and driver would block out the noise energy above the crossover point.

Novice question, there are two variables passive vs active crossover and before vs after amplification, so which is a bigger contributor to the hiss. sorry if I'm missing something.

 

[solderdude]

Depends on the design of the amplifier, sensitivity of the used drivers and design of the (active) filter.
It's a budget/design decision/compromise.

Just look at S/N ratio measurements of various amplifiers and sensitivity numbers of drivers and you will have to draw the conclusion that it is all design dependent (as well as budget dependent).

It is possible to design active speakers that do not show audible hiss even at close proximity but some (often cheaper designs) can have pretty audible hiss.

 

[Timcognito]

Depends on the design of the amplifier, sensitivity of the used drivers and design of the (active) filter.
It's a budget/design decision/compromise.

That's true in all engineering but OP seems to think its universal to active systems and others say it's not it's design and component quality. But is it universally HF "hiss"

 

[solderdude]

Noise in electronics is usually 'white noise' and as humans are much more sensitive in the 2 to 8kHz range such hiss is often heard as 'high pitched noise'.