I noticed there is a limiter in the block diagram of the HS80m monitors for the LF Driver, and I'm curious if anyone has any insight as to when and how the limiter becomes active: when it's affecting the output, and by how much, essentially. I noticed that the MSP7/10 do not have limiters in their block diagrams, and they are also lacking the Room Control switch, making me think that the limiter is possibly controlled by that switch on the HS80's, considering that it attenuates only frequencies below 500Hz, and the limiter exists only on the LF Driver. That's just a guess though. Any input on this would be great! I've asked Yamaha, but support doesn't seem to have any technical data in this area.

I got more information from Yamaha, and they confirmed that the Room Control switch is not related to the limiter, but they still could not provide any info on when/how the limiter works as implemented in the HS80m's.

when, how, how much, or "how do i bypass it"?

And also, is there a visual indication? That white light on the logo blinking?

I'm gonna write Yamaha an email as well, maybe if they receive a lot of those they might spill the beans! heh

ripple_fx1: Any one of those things would be nice. I figure if I know when/how, then it can be avoided, or I could just bypass it altogether. The latter is out of the question according to Yamaha though.

diogo_c: As far as I can see, the white light is only an indication of power, nothing else. Thanks for joining in!

It's really just out of curiosity that I would like to know. I imagine the limiter is probably some sort of overload protection, in which case no one is probably running them that hard, but you never know. Did I mention that they sent over a service manual for the HS80's, and it has all kinds of diagrams of the circuitry. That may be of use, so I've attached it. I can't be certain if I'm reading it correctly.

visual indication of limiting would be nice to have - but might be a constant reminder that 75 watts of "dynamic power" isn't a lot of headroom and woofer beware. but these are nearfields, so if you're using them that way, you'll have no worries. if p.20 isn't talking to you, probably best avoid the bypass.

ripple_fx1: Thanks. Again, it's curiosity my need to learn anything and everything, and not necessarily putting any of this to practical use. I don't plan on killing my HS80's. If I'm being completely honest, not too many of those pages were speaking to me at all, due a relative lack of circuit knowledge.

I may not know exactly how much I'm asking here but can you expound on this statement: "but might be a constant reminder that 75 watts of "dynamic power" isn't a lot of headroom and woofer beware." Maybe a mini-lesson on power to output ratios or something?

honestly, I'm not aware of how typical the inclusion of a limiter is in similar boxes, but I've got no use for one in a studio monitor system. To my way of thinking, it means this: there's not enough amp to drive the woofer cleanly. distressed amps kill speakers. tame the amp, save the speaker. operated as nearfields they should get louder than required without getting into the limiter.
The use of the term "dynamic power" in the specs means "embarrassed to use established rating methods". Way too much to cover between amp in and acoustic watts out. If the sound of the monitor is put aside, lots of power amp, with low impedance, high sensitivity and power handling drivers is what you're trying to achieve. Hey, you got a whole monitor system for less than a grand, it probably sounds great and won't blow up easily - enjoy!

That makes sense. I've found that I can't hear a limiter even when pushing them a little beyond comfortable mixing levels, but it's not something I'm worried about, more than something I just wanted to understand. I love my HS80m's, and they see a lot more use than my MSP7's. I will keep what you've said in mind, should I decide to look into something fancier in the future, if that's ever necessary. Thanks again.

Looking at the schematic, that limiter circuit is a very poor piece of design IMO, and I reckon it is probably adding distortion at low volumes. They are using transistors as the control element to limit input signal once the output from the power amp exceeds a certain level. The transistors are very non linear, not what I would expect from Yamaha.

The limiter circuit occupies the typical gain setting position - an output to input feedback loop - on an amp. so the woofer loop/gain is dynamic. eventually, the more you turn it up, the louder it wont get. if you have a meter and slowly turn up a low tone you can watch the voltage increase at the woofer leads flatten off. input & tone control options probably made a limiter based on power delivery much simpler. have a tech rig a bypass switch and alt this dynamic circuit with a static circuit if it starts to itch.

Tim: What is it about transistors that makes them non-linear?

I bet a blown speaker cone is even more 'non-linear'...

There is no linear - within limits and with much compromise you can fake it if you stand way back and squint your eyes.

So, I have another question and I figured it was relevant enough to just add to this thread. It specifically has to do with the MSP7 monitors, but more to do with just damage as a result of clipping. I was fooling around with the TotalMix control system for a Fireface UC that I have, and I accidentally tapped one of the output level controllers to the top, sending an ear-splitting signal straight to my MSP7s, flat out clipping them for about a second. Is it likely that they or any typical monitor would be damaged as a result of this? Also is there a good way to test a monitor for damage, besides something like checking for distortion during a sine sweep. Thanks!

wow. just look at all those 4558's.

i wonder if these can be modded and if it's worth it.

care to ellaborate? heh

wondering about swapping 4558's with cleaner opamps like lme49720... but then again, some people say that mixes on yamaha hs80 translate very well because they(the hs's) don't sound too good...
I know my mixes do translate almost perfectly to a great variety of systems, both the lousy and the good.

Indeed!

I've been working for quite a long time with the HS80, and so far so good. I will be upgrading monitors this year, and as the HS's value is not high I'm not considering selling them so I'd consider a mod.

Not to divert the conversation you guys are having, but would you guys have any answers to my post on 18th June 2010 02:14 PM above?

there's no way of knowing - the most gawdawful ruckus may leave speakers intact while something unheard kills 'em dead. between amp design and fault mode and duration, crossover design and driver construction there's lots of "what if". do the sweep on each and compare your RTA curves, stick your nose in there and give everything a good sniff, or surgically remove the voicecoils and do a forensic analysis.

If they still sound OK, then they have probably survived. Speakers can handle a bit of clipping for a short duration until the voice coils heat up and break, but it does not take long to cook them.

R622 is a jumper actually; unsolder one leg and the limiter is off.

To make real human beings from 4558 I usually add a couple of 7k5 resistors per chip: from outputs to + rail. Such a way they are loaded asymmetrically and biased in class A, that increases as well base currents of output emitter follower making them a bit faster and more linear on fine details.

Hi, I'm trying to remove the limiter on the HS8, but there's not any R622 jumper to remove like on the HS80m, so how do i do it??