McIntosh Power Guard lights up in rhythm with music

mpitogo

Wow, I haven't been here in a while and I like the new forum look.

It seems I can get McIntosh Power Guard to light up in rhythm with music. BTW we're in the process of moving, hence grills on, on the L800's and ignore the clutter.

https://youtu.be/XnjkeajqYAM

BlueFox

mpitogo wrote: »

Wow, I haven't been here in a while and I like the new forum look.

You are deep, deep inside the minority with that opinion.

motorstereo

Lighting up the pg lights like that is a sure fired way to destroy something expensive.

mhardy6647

Hmm.
I thought the purpose of the Power Guard was to prevent "destroy[ing] something expensive"...?

EDIT: That said -- I would think that a condition that makes those lights flicker more than very occasionally suggests 1) there is something quite wrong in the chain -- perhaps the match of the amplifier and the load impedance and/or 2) the SPL is very dangerous.
I guess there's also an option 3), which is that the amp is way underpowered (e.g., at least 3 dB; which is a factor of two in output power into the load) for the application.

DaveHo

Not that hard to clip a 100 WPC amp. But yeah, I'd say you need more amp if you like to listen loudish.

motorstereo

mhardy6647 wrote: »

Hmm.
I thought the purpose of the Power Guard was to prevent "destroy[ing] something expensive"...?

Yes occasionally lighting up the pg's won't do any harm. But when it becomes a steady flicker the overdriven amp will take out tweeters and or damage crossovers.
I agree with what was mentioned about either turning it down or buying a more capable amp.

mpitogo

The MA5200 without autoformers is ~150WPC into 4ohms. more power is on order for the treble/SDA section, ~320WPC into 4ohms. Bass already fed with 450WPC and fairly easy for the amp.

mhardy6647

mpitogo wrote: »

The MA5200 without autoformers is ~150WPC into 4ohms. more power is on order for the treble/SDA section, ~320WPC into 4ohms. Bass already fed with 450WPC and fairly easy for the amp.

Well, that's all well and good -- but if the Power Guard lights are flickering more than occasionally, you're asking more of the amplifier than its designers are happy with it giving. That's what the circuit is there for, and the lights are there to tell the end user it is woking.
The fault may lie in the amp, the load, or the volume.
The easiest to test: turn the volume down just a hair (2 or 3 dB more attenuation) -- should be barely audible (one may check the delta with an SPL meter at the listening position if one is curious enough) but should take the amplfier out of its danger zone. If there is any audible impact, it should be beneficial.

mhardy6647

I just looked at the manual for the MA5200: it calls for "8 ohm" loudspeakers.
https://www.musicdirect.com/documents/pdf/AMCHMA5200.pdf




The L-800 isn't nominally 8 ohm, IIRC.
EDIT: Occam's Razor and all that... my guess is the load impedance is stressin' the little MA5200 past whatever its Power Guard" figures it should be safely giving.

mhardy6647

Mac doesn't seem too concerned with "momentary illumination", though.

tratliff

Never seen my power guard!