m-45 rocks

[mojoe]

I just got a M-45 amp and I must say I am really impressed with it. I don't have a matching preamp so I'm using the preout from a Marantz 2240B. My speakers are ADS L620.

This amp packs so much power that I don't need the Marantz loudness switch at low volume. Tone controls set to flat. So far I've listened to Simon & Garfunkel, Little River Band and now Metallica as I type this. My speakers have never sounded this good.

I used to have a M-4/C-6 combo but sold it. That combo sounded beautiful but did not seem to pack the punch of this M-45/2240B combo. I know the M-4 is built better but the M-45 just sounds stronger to me. Perhaps the M-4power meters just scared me cause they so easily went into the red clipping zone and I was too conservative to really drive the amp. Or maybe my M-4 needed a recap. Guess I'll never know for sure.

These ADS speakers are 6ohm and rated for up to 75w nominal power. The M-45 power meter is gauged for 8ohm speakers. I wonder at what meter reading I should stop increasing power. Or is the amp signal so clean that I only need to hold back if I sense distortion?

Another question(s)...When should I use the automatic Class A? Is this best for low level listening? Should I hear a difference?

Bottom line...Merry Christmas to me!

 

[avionic]

)...When should I use the automatic Class A? Is this best for low level listening? Should I hear a difference?

Yes at low level..Hear the difference..Maybe..Depends on the source and speakers. Should definitely notice the increased amount of heat.

 

[mojoe]

Guess I don't need to worry about the speakers. M-45 goes into protection at about 100 amps. Come right back out after "reboot". Still sounds great to my ears. Just finished some Billy Joel. Now listening to Love Jones. Not that anyone cares what I'm listening to...I'm just involved in an audio moment here and sharing the joy on Christmas Eve.

I'll try some experimentation with the class A at low volume and see if my old ears can still hear. Certainly, the source and speakers aren't up to parr with the amp but it is what it is.

 

[tubed]

If cds are your source, try using the M-45 without the "preamp".

 

[ic-racer]

Nice amplifier. I have had mine since the early 1990s. Check for capacitor goop.
http://www.audiokarma.org/forums/showthread.php?t=424327

 

[avionic]

M-45 goes into protection at about 100 amps

100 amps..I don't think so... 100 watts maybe..At 100 watts your probably clipping like hell and yes it will go into protect.
The fix... turn down the flippin volume control...:thmbsp:

 

[mojoe]

haha...yes...watts...not amps

this thing is rated at 150w rms into 6ohms...is it normal to be clipping at 100w? Is this a sign of needed preventative maintenance?

and yes I should definitely turn down the volume...generally do...but dang it...sometimes I just like to open it up for a song or two and when I do so it is jarring to suddenly shut down. It's not like I'm up all the way either...maybe it's the 6ohm speakers...but I was factoring something for that in my meter reading...actual meter readout was closer to 75w so I was compensating for the 6ohm speakers in reading it as 100w

what specifically triggers a protection shutdown? temperature? distortion?

I appreciate the input I'm receiving from everyone...it will help me to take good care of my equipment...electronic and biological

 

[avionic]

what specifically triggers a protection shutdown? temperature? distortion?

Detected DC at the amplifiers output. A clipped signal resembles DC to the DC detection circuit.
If your red eyecandy meters were registering around 100 watts. I can guarantee the low frequencys were probably trying to hit well above 150 WPC and ran out of transformer and rail voltage. The red led meter is calibrated with a 1 khz signal..So it will only be half assed accurate around 1 khz.. 300 hertz or lower who knows...Same goes for anything above 1 khz.

 

[mojoe]

It's illuminating to learn meters are not accurate across the complete frequency range. I always just assumed they were the PEAK wattage being pushed. Guess if I want to shake the house, I need more horses. However, I am completely satisfied in the sound quality of this amp.