Yamaha HS5/HS6/HS8 Monitors Limiter Mod.

I've been trying to perform the limiter mod on the HS7 but I have not been able to find schematics or detailed instructions on the process other than that of the HS50/80.

Although they are similar circuit boards, there are some updates that make me doubt what to remove, since there are no schematics on the internet for the HS5/7/8.

I was able to find the old schematics and comparing both I was able to make a wild guess as to what resistance to remove.

I did a pretty nice search across multiple search engines and forums and found no photos or information whatsoever on the new HS models.

So here are a few pictures I took of my HS7 pair along some notations.

I would greatly appreciate if someone with more electronics expertise gave their advise and opinion. And if someone could finally pinpoint the resistance that would be awesome as you will be helping not only me but a lot other people that are handy enough to do repairs/mods like these but don't have the expertise to find the components.

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Is the limiter only on the woofer?

Are you trying to defeat the limiter so you can go louder?

I see R409 C417 echoing R424 C429. I suspect these are RF loads on the power amps (look at the chip data).

What I see different on Woofer may be (hard to tell with the blue nail polish) a thin trace from left end of R409 up past screw to an R417. This may trace through to D408 and C420, which from here smells like rectifier smoothing. Further it does something to Q403, which wanders off to Q402, which may come far-right to small pins which may be the input connector.

You are a brave soul for messing with SMD without a clear plan.

I had preformed this back when I had a pair of HS80's. The limiter removal was a simple jumper snip and was only on the woofer. It really opened up the sound and seemed to allow for lower bass extension.

Thanks a lot for your input guys.

Yes, actually disabling the limiter opens up the woofer and reduces the muddled sound adding clarity.

On the older HS80/50 model the mod was done by clipping or removing the R622 jumper which leads me to believe it is done in a some sort of same way on the new HS/5/7/8 models.

Here are some comparison photos where you can see that the circuit board is very similar between HS50/80 and HS5/7/8.

Left is HS80 and right is HS7.



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This one is the actual HS80 Schematic.

did you end up doing it monolith? im a HS8 owner. cant find any service manuals

Older thread, but I stumbled across it searching for info on the HSx series, and I thought the question deserved an answer.

The resistor/jumper to remove to disable the limiter is R417.

Unlike the HS80m, the jumper on the HS8/7/5  is an actual 0-ohm resistor which needs to be removed. On the HS80m, it is as simple as cutting a jumper wire.

It was easy to identify since it is the only 0-ohm resistor in the limiter section.  You can verify by tracing one end of the resistor to the 1.2K resistor in series with the limiter (R416 on the HS7, R621 on the HS80m).  The other side of R417 can be traced back to pin 4 of the speaker connector and pin 3 of the woofer amplifier IC.