# new mcIntosh amp owner



## file audio (Mar 12, 2013)

well yesterday I purchased a used mcIntosh amp model mc440, after the chase and the heat of the moment passed I realise that I cant get the righ sound of it,,, i connected the on" terminal to the remote from the head unit, even reading the manual I undestand that the "pg"terminal is only for a mcintosh head unit, I found here on diymobile audio that it can be grounded too.... can I ground it really? any advises here ??
I MUST confess that the amp is gettin very hot in a moment(hot to the touch) when I start the engine here comes a strong feed back high irritating noise that only goes off after I completly shut the engine and close the key, plase I need help.....here really


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## ATOMICTECH62 (Jan 24, 2009)

The PG terminal is to disable the power guard circuit.You dont have to have a Mac deck to use it.What speakers are you using?


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## file audio (Mar 12, 2013)

ATOMICTECH62 said:


> The PG terminal is to disable the power guard circuit.You dont have to have a Mac deck to use it.What speakers are you using?


im using focal krx3 3way pasive mid range and tweeter s & active woofers conectedto the 100rms channel s 5&6. Tnx for your help


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## file audio (Mar 12, 2013)

So how can i connect the pg .can I use a split signal from the remote fron head unit?


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## RNBRAD (Oct 30, 2012)

file audio said:


> So how can i connect the pg .can I use a split signal from the remote fron head unit?


The Power Guard goes to a ground, *not power*. Take the wire, run it to a small 2 prong switch and mount it somewhere. Wire one prong to ground, the other to the PG wire. Now you can turn the PG on and off as you like. When the PG wire is grounded, this defeats the Power Guard circuit allowing the McIntosh amp to deliver power beyond the PG distortion parameters.


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## ATOMICTECH62 (Jan 24, 2009)

I just read your other post on a different thread so I will try to help you on this one.

First off let me explain Mac amps .
If your amp has an MEQ module,it has been set up for the system of the previous owner and will not sound good with your install.There is no way you can change the settings without the controller.They are hard to find and will cost about $5-900 if you can.
The best thing to do is remove the module and put those small 2 pin jumpers on the amp plug to bypass the EQ module,its simple,I do it all the time.
2nd,Mac amps work best when run into 4 ohms stereo mode.The output sections are very overbuilt but the power supplies are not.
SO.When the switch's are set to bridged mode the power supply changes the rail voltage to run lower then in stereo mode.On your amp in 6 channel mode the amp is really putting out about 70x4 and 135x4 at voltages down to about 12volts.They are very tightly regulated.But when you set it at 5 or 4 channel mode the amp really does about 120 x2 on the 4 channels bridged into 4 ohms and about 250 x 1 on the 2 100 watt channels bridged into 4 ohms.
Do not bridge this amp into anything lower then 4 ohms or it will blow.They only use 8 mosfets in the power supply.AND they used a military grade PWM chip that is long obsolete.So if it goes the amp might not even be repairable.
Also when any channels are in bridged mode only the odd number RCA inputs are active.
1,3 and 5.The others will do nothing.
Its hard to say why you have motor noise coming from the amp but I have never had that problem with any of mine.I would say there is no ground on the RCA's,Gains maxed out on the amps or something else wrong.These are the quietest amps I have ever used.

I would NEVER use any of these multiple channel Mac's to run subs.And if the Power Guard indicator is lighting up that means you are pushing it past its limits.It should only flash briefly during loud peaks and if its on continues then its running full throttle and no matter how much the more the volume is turned up it wont get any louder.


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## vwdave (Jun 12, 2013)

Are you running it off your factory deck or aftermarket? What else is in your system?

I have the same amp (check my install thread) running off factory deck. If you get less than 12 volts of signal to turn it on the amp won't power up. I used a relay and when I did I had crazy engine whine. I since got the lc6i which has signal sensing turn on and no more noise.

Also when I got mine I heard a rattle inside. Opened the bottom and found one of the power supplies not connected. The rattle was an nut but I never found where it was from. The previous owner said that the amp was always working fine. Point being, check to make sure everything is kosher inside. Don't fully dismantle it, just take off the bottom cover and check the power supply cables.

It's also good advise to not run subs from this amp. Im Running a 12 off it and there's very little output. I'm planning another sub amp at some point.


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## file audio (Mar 12, 2013)

It was very helpful atomictech ..i read the manual i was using the 5 and 6 channels on 80hz cause im using the focal krx3 woofers there and after put on out the xover the engine noise went off... the manual said twice warnings hhehe..... i go active and the feedback went to but comeback. Im grounding righ now


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## ATOMICTECH62 (Jan 24, 2009)

I would remove the eq module and bypass it.When you take it out you will see 2 rows of pins.The in and outs for all the channels are directly across from each other.The little black jumpers (the kind that can be found on the back of your standard hard drive)can be found at Radio Shack.Simply placing them on each channel will run the amp at a flat response.
All crossovers will still work since the are on the main board.
If you want to try it I will dig up the service manual and let you know which ones to jump.


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## file audio (Mar 12, 2013)

I HAVE THE MEQ451 installed righ now from previuos owner i guess cause i found it used just like you said, yesterday I un plug the meq451 and the 1-4 channels doesnt give any sounds maybe because the jumpers missing that you mentioned on your post... I cant find the manual for the meq451 in the whole web.. if you have one for the meq 450 452 i guess is the same features only more or less bands and channels ..i would appeciate if you can tell me wich jumpers.. i have to buy some or take it from some boston pro xovers I have...


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## ATOMICTECH62 (Jan 24, 2009)

OK.I will start looking.Hang in there I have a few hundred manuals.


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## file audio (Mar 12, 2013)

I did 2 things i go active with the mids and tweeters still passive now the sound from tweeters is too low and clipping 
Maybe i need to go totally active those krx3 xovers gave me some trouble with a helix amp i have..
ground it the pg terminal and the tweeters
still trying to check all those things until my wife let me go to my truck again shes jealousy righ now.. and finally excuse my bad english spell


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## ATOMICTECH62 (Jan 24, 2009)

Are you saying that you grounded the the PG terminal to the tweeters?


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## ADCS-1 (Dec 14, 2011)

Have had a few (still have) McIntosh amps, never connected the PG terminal. My 420 got a little hot when bridged to 2 MTX 10 4 ohm, but was cold as ice when running 4 channel on front set. 

OT, Atomictech62, looks like you have a real killer system.


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## file audio (Mar 12, 2013)

Noup i ground the pg* to the -neg- of a gel battery in the truck, less feed back but still having problems maybe i need to put the tw without xovers. Or why not consider my amp failing (failure) i must say it is getting so hot but it never turn on the clipping pguaard light inly when it is turning on.tnx mates


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## ATOMICTECH62 (Jan 24, 2009)

Thanks.
Yeah,I never bypass the PG circuit.Thats the main feature of these amps.
When cranking 1500 watts on highs with zero clipping is incredible and reassuring at the same time.Then adding another 1200 on subs is total audio bliss.My neighbors hate me.


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## ADCS-1 (Dec 14, 2011)

IIRC, the clipping indicator only ligth up if the amp`s connected to a McIntosh hu. Is the fans blowing? I now use a 431 bridged to a pair 6" JBL GTi midbasses, gained and eq`ed like crazy and its not getting hot, maybe 35-40 deg celsius. But, man the fans is shifting air inside the amp...


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## ATOMICTECH62 (Jan 24, 2009)

The KRX3 manual states that running all 3 drivers on the crossover will cause the amp to see a 1 ohm load.
This cant happen.
Use your 880 in 3 way active to the mac.


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## ATOMICTECH62 (Jan 24, 2009)

The PG indicators light up with any source.I watch them in my rear view mirror.
BTW I know a guy that has an ADCS-1 NIB he wants to unload.


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## ADCS-1 (Dec 14, 2011)

Hmmm, one more Adcs....... I`ll be killed SLOWLY by my missus, as i have one, ans a Sony XES. If a single DPAA blowing by, thats a different case. I have the Toshiba laptop, but not the Dpaa. 
Back to topic, if the amp sees 1 ohm, its far beyond its limits.


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## ATOMICTECH62 (Jan 24, 2009)

Ok.I found the manual.
Look at the amp with the RCA's facing you.
There is 2 rows of 7 pins.
The 2 pins on the left are ch 1.Jump them.
The next 2 pins are GND and -15 volt.Leave them alone.
The next pins are ch 2.Jump them.
The next 2 are GND and +5 volts.Leave the alone.
The next 2 are ch 3.Jump them.
The next 2 are GND and +15 volts.Leave them alone.
The next 2 are ch 4.Jump them.
With the jumpers in place it should look this.

l:l:l:l

Channels 5&6 dont go to the EQ module.


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## file audio (Mar 12, 2013)

My mcIntosh is probably faulty or i need to go active in tweeters too.. cause its getting hot and that feedback is weird ...the focal xovers are a little bit trouble cause can be used at 1ohm i know I have to maintainbtje 4ohms inbthe mac to a better performance.. and the ground was connected to the gel battery


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## ATOMICTECH62 (Jan 24, 2009)

I would disconnect the speakers,Remove the ground from the PG terminal and see if it still gets hot.It could be faulty.


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## file audio (Mar 12, 2013)

I notice one cooling fan is not working..only one... is normal?


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## vwdave (Jun 12, 2013)

nope both should be working. the one thats working might also be faulty. it should be pretty strong.

it could be disconnected. if ones working the other should be. Open the bottom and check all connections like I suggested earlier.


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## ATOMICTECH62 (Jan 24, 2009)

Im sure it needs recapped.I just had one of my 431's shut down a few weeks ago.It started making a pop in one speaker so bad I thought someone hit my car with a rock at first.But it then started doing a lot,then a different channel started making weird screeching sound when the amp was first turned on.It finally got to a point where the amp would go into protect every time it came on.


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## RNBRAD (Oct 30, 2012)

My fans are always on and they speed up the warmer the amps get. Hottest I've ever seen is 120 degrees from a 443 running subs at 1ohm but the fans will be moving some serious air. If a fan goes down, your going to have a heat issue even at 4ohms.


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## ATOMICTECH62 (Jan 24, 2009)

Yes.The fans are always running on every Mac Ive seen.If they are plugged into the board then they should be running.


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## file audio (Mar 12, 2013)

vwdave said:


> nope both should be working. the one thats working might also be faulty. it should be pretty strong.
> 
> it could be disconnected. if ones working the other should be. Open the bottom and check all connections like I suggested earlier.


Thank you you and atomictech62 had helped me alot.. i never got so many reaoinses here and help because i dont speak well english.. appreciate it and and im grateful 
Im going toi check the amp fans and the fedback is happening when the music is playing and starting the engine here comes the noise.. maybe the eqx is causing that


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## file audio (Mar 12, 2013)

Done the noisy feedback is gone! The problem Was the meq451 strange tuned maybe for my system. I purchased the pins jumpers stack 4 in the suggested places and Voala .. lucky me the fan that fáil is now working it was struck with the net i pull it out and release the fan... now the system is sounding so much better....today was a good I purchased and installed a jl audio hd750 to move my pair of 10w6v2 ..is enough power? Im concerned about SQ. Looking for it.. thinking about an idmax10 ..which sub is the most clean and nice sounding outthere?


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## ATOMICTECH62 (Jan 24, 2009)

Glad to help.Now try using the Mac without grounding the PG terminal.


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## file audio (Mar 12, 2013)

ATOMICTECH62 said:


> Glad to help.Now try using the Mac without grounding the PG terminal.


Ungrounded i mean detached ,, no need to use it now... I know im very unexperienced amateur audiophile and musician ..wanting to hear music in the best posible way even I know its imposible to reach perfection..so Im thankful with your help


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## file audio (Mar 12, 2013)

Well.. anybody know hows this amp considerated in front of a audison lrx5.1 a helix . A jl 900/5 hd, zapco ref 650. Or arc audio. . Cant find so many feedback and reviews here of this mcintosh mc440 any advises?


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## RNBRAD (Oct 30, 2012)

I'm sure there are several great amps out there that can match the level of transparent sound of the McIntosh. Longevity and quality is the question? This winter I will start on my 19th year with McIntosh amps, one having run 1 ohm load the entire time. How many amps can match that? The McIntosh rep at a show told me to send them in at 30yrs old and have them benched, said they are guarantee'd for 30yrs to match it's original performance specifications. If they don't they will be fixed till they do. Who else does this? Who's going to be around in 30yrs, lol. I bet McIntosh will. I wouldn't say these are the best sounding amps in the world, but I would say there are non better. When you factor in all of the other aspects of design, features, quality of components, that's when you can say you have the best amplifier money can buy. As a whole, I'd be hard pressed to find a better car amplifier anywhere at any price.


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## file audio (Mar 12, 2013)

RNBRAD said:


> I'm sure there are several great amps out there that can match the level of transparent sound of the McIntosh. Longevity and quality is the question? This winter I will start on my 19th year with McIntosh amps, one having run 1 ohm load the entire time. How many amps can match that? The McIntosh rep at a show told me to send them in at 30yrs old and have them benched, said they are guarantee'd for 30yrs to match it's original performance specifications. If they don't they will be fixed till they do. Who else does this? Who's going to be around in 30yrs, lol. I bet McIntosh will. I wouldn't say these are the best sounding amps in the world, but I would say there are non better. When you factor in all of the other aspects of design, features, quality of components, that's when you can say you have the best amplifier money can buy. As a whole, I'd be hard pressed to find a better car amplifier anywhere at any price.


thanks for tour response and knowledge! any advise to get to a new level? do you recomend a dsp processor , like arc audio ps8 , audison bitone, jbl ms8, as im considering to buy a stereo high end cause I sold my 880 psr to get the mcintosh, p99rs would be a great expensive risky choice in my car,, so im considering to add a dsp to my system but the arc audio is so expensive 700 dlls less is alot... :S and I dondt know is its really gonna work with this mental vice of audio !! tnx


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## RNBRAD (Oct 30, 2012)

I do recommend a processor depending on your system needs, however I also recommend as little of processing as possible. I think an install that negates the need for much processing is key. Get your system balanced and tuned without processing, then use it last for fine tuning.


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## file audio (Mar 12, 2013)

RNBRAD said:


> I do recommend a processor depending on your system needs, however I also recommend as little of processing as possible. I think an install that negates the need for much processing is key. Get your system balanced and tuned without processing, then use it last for fine tuning.


thats the things is getting hard to do ,, first get that balance then a final tune with the eq. thats the reason i sold my 880prs every day was tweaked then I find that phrase "the less you tweak the best it will sound" right now...im finding my system too harshy sounding, the sony xav601bt is not top notch is doing the job , it has time aligment and 7 eq bands but maybe a dsp is needed ,, with the eqs and eqx I have total control of each channel of the stage in my truck but maybe to be changing so many parameters is my problem 
YouTube


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## file audio (Mar 12, 2013)

i purchased the helix p dsp and Im not able to find that sound I want of course Ifound a difference with the dsp but ,,i think I can get better im not wise tunning and tweaking,,, even having a good musician ear, i have the vice of pick press buttons maybe thats my problem,,, and I feel that mp3 songs are on different balance between styles,,,,, thinink on sell the mcintosh but I know that with other amp its going to be the same "


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## file audio (Mar 12, 2013)

and its wad the same


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## wewewe321 (Sep 15, 2014)

I installed MC420 car amp a few days back. Everything worked fine. Then someone turned up the volume for about 2min and the amp tripped and didn't produce any sound. I turned everything off and back on again but Powerguard light stays ON.
I waited for everything to cool and still the PG light is always ON and the amp won't give any sound. I grounded the PG wire it doesn't work. I disconected the speakers and the inputs and still the PG light doesn't go off. 
Someone please help.


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## ATOMICTECH62 (Jan 24, 2009)

Sounds like bad output transistors.
Was it bridged?
What ohm load was it driving?


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## wewewe321 (Sep 15, 2014)

ATOMICTECH62 said:


> Sounds like bad output transistors.
> Was it bridged?
> What ohm load was it driving?


It was bridged and driving on 4 ohm (Canton 3.28 Speakers)
I got an email reply from McIntosh, they say the amp is in 'protect' mode and needs service. 
One more thing, does the fan in the amp always rotate or only works when it's needed?
Don't know how to fix it. *Can someone please help?*


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## Ianc2 (Feb 16, 2019)

RNBRAD said:


> I'm sure there are several great amps out there that can match the level of transparent sound of the McIntosh. Longevity and quality is the question? This winter I will start on my 19th year with McIntosh amps, one having run 1 ohm load the entire time. How many amps can match that? The McIntosh rep at a show told me to send them in at 30yrs old and have them benched, said they are guarantee'd for 30yrs to match it's original performance specifications. If they don't they will be fixed till they do. Who else does this? Who's going to be around in 30yrs, lol. I bet McIntosh will. I wouldn't say these are the best sounding amps in the world, but I would say there are non better. When you factor in all of the other aspects of design, features, quality of components, that's when you can say you have the best amplifier money can buy. As a whole, I'd be hard pressed to find a better car amplifier anywhere at any price.


This is good info .
I’m just unboxing old stuff to put in a car I’m currently building and I’m sending the headunit to Jeff on here to look at .
The amps for this system are an mc420m for front pair , and mc443m for sub .
How would I know how old they are ?
I don’t have boxes or certs anymore .


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## jcesl2 (Nov 14, 2018)

McIntosh Car Audio

Neither one of yours has an end date listed, but I think they stopped making car amplifiers in 2000.


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## Ianc2 (Feb 16, 2019)

Thanks , I remember that website from many years ago !!
Even if my amps where the first built , it seems I have a while before they refuse to look at them ...
I’ll try to get them out of shipping totes this weekend to note serial numbers etc and Maclabs a call next week about it .

I have a couple more questions , but don’t want to hijack this tread so will start another .

Thanks
Ian


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## LBaudio (Jan 9, 2009)

Great sounding amps, true classic


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## jcesl2 (Nov 14, 2018)

Ianc2 said:


> Thanks , I remember that website from many years ago !!
> Even if my amps where the first built , it seems I have a while before they refuse to look at them ...
> I’ll try to get them out of shipping totes this weekend to note serial numbers etc and Maclabs a call next week about it .
> 
> ...


No problem. They may redirect you to George Meyer. https://www.georgemeyer-av.com/

Apparently they bought all the car audio spare parts that McIntosh had and are the "official" repair center now.


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## ErinH (Feb 14, 2007)

jcesl2 said:


> No problem. They may redirect you to George Meyer. https://www.georgemeyer-av.com/
> 
> Apparently they bought all the car audio spare parts that McIntosh had and are the "official" repair center now.


Indeed, they will. George Meyer is the only authorized Mcintosh car audio repair service in the US. And it isn't cheap.


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## RNBRAD (Oct 30, 2012)

The 443 last year was like 97, I purchased mine in 95. Still wirks perfect.


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