Mackie 808M overheating? HELP!
MidiVeg
these amps shutting themselves off? Seems to happen when the band is
playing loud and for a long period of time. After giving them time to
cool off, they always come back to life. This has happened in the
past, but Last night I had 2 of them shut down. The mixer section was
still working (I could tell because the subwoofer was still being
driven from the mixer) but no sound went from the amp to the speakers.
Is this common with this unit? Is there a way to address the problem?
Direct email appreciated.
Neil
Phil Allison
"MidiVeg" <newatt...@bellsouth.net> wrote in message
news:1165198039....@16g2000cwy.googlegroups.com...
** Groper alert !
** The unit has no internal fan.
So get an ordinary room fan of your own and blow it on the heatsink at the
back.
Simple.
...... Phil
Erich
You might also want to make sure that you have plenty of room around
the air vents. I had an old Yamaha powered mixer about 15 years ago
that would shut down because I covered the air holes on the bottom by
placing it on a smallish, but tall round bar table.
Erich
Phil Allison
"Erich"
>
> You might also want to make sure that you have plenty of room around
> the air vents. I had an old Yamaha powered mixer about 15 years ago
> that would shut down because I covered the air holes on the bottom by
> placing it on a smallish, but tall round bar table.
>
** Here is a nice internal view diagram:
http://www.mackie.com/home/showimage.html?u=/products/ppmseries/images/3DPPMImage_lg.jpg
Appears to have NO ventilation slots in the plastic case.
If that toroidal tranny trapped inside there has a thermal sensor inside it
( like the other FR series amps do ) then it may well be the cause of the
shutdowns.
SFA you can do about it if that is the case.
....... Phil
Sl...@sarasotaslim.com
How many speakers are you driving with it?
Have you checked your speaker wires lately?
Rupert
Since you're running subs with these relatively weak heads, you should
consider inserting an inexpensive 2-way analog crossover between the
"Mixer Out" and "Amp In" jacks so you're sending a high passed signal
to your tops. If you're running full range signals to your tops, the
amp is going to generate a lot more heat, not to mention you're going
to have some phasing issues with the overlapping frequencies between
the sub and the tops. Use a crossover with a mono sub output and feed
the sub with that. The only scenario where this won't work is if you
happen to have the 1st generation 808 where Mackie had the Mixer Out
jacks half-normalled to the Amp In so the connection to the amp wasn't
completely broken when you wanted to insert something.
Also keep in mind that the lower the impedance of speaker load you run,
the hotter the amp gets. Mackie claims you can go down to 2 ohms, but
I'd recommend no lower then 4 ohms with that passive cooling, and even
then staying at 8 ohms is probably best. One other issue to be aware of
is that Mackie had a run of those things with improper biasing of the
output transistors that would cause them to overheat even at low levels
and run warm at idle. Lastly, while they have a lot of hype about that
unit in their advertising, it really is IMO just a vocal only PA for
lounge acts or wedding bands. I would never recommend it for much more,
especially anything where high output is required, especially with low
impedance loads.
Rupert
Phil Allison
"Rupert"
>
> Lastly, while they have a lot of hype about that
> unit in their advertising, it really is IMO just a vocal only PA for
> lounge acts or wedding bands. I would never recommend it for much more,
> especially anything where high output is required, especially with low
> impedance loads.
>
** Bet the Mackie Stick Man is running away and hiding himself after
hearing that one !!
....... Phil
Erich
Yup. I did a RTFM on it... it says keep 6" of space behind it and use
a fan on it for cooling. So there you go OP. Give it room to breath
and use a little floor fan behind them... and definitely don't try to
run 2 ohm loads. (I've friggin sworn OFF 2 ohm loads.... not worth the
hassle.)
E
Kevin T
Maybe you need to replace 1 or 2 with a real Power amp ?
Kevin T
Sl...@sarasotaslim.com
I just re-read that original post more carefully and also noticed the
"3" mixer setup. I hate to admit it but I think Phil may be right
about the groper alert. I suspect that some members of this and other
forums have multiple identitys for the express purpose of setting up
and bashing various products and brands.
IF 3 808M mixers were used - they could not be used as a single unit
like a 24 channel board. There is no way to link them together with a
common master volume. (If there is a way - please somebody tell me
how?!) So if I read the post correctly - the amps get hot - that means
all 3 amps that can and do run at 2ohms per side had shut down. That
also means they were driving at least 2 if not 4 speakers per side x 3
units = 6 to 12 speakers to make them get too hot - that's in adition
to the subs which apparently had there own power because they were
still working. I don't think so. If this is a real post by a real
person with a real thermal problem I would look at the speaker wires as
the cause.