Amp design.

[highfihoney]

Like I said earlier in the post I think we all may be misunderstanding what it means when they say that it doesn't double down. I could be completely wrong and would like to know if I am, but here it goes. I am thinking that the Mac will do exactly as any other amp would do when the impedance drops but the thing it will not do is go above a maximum value in order to keep the heat and distortion at a lower level to help protect the equipment by not allowing you to overdrive the amp.

Hi nugglets,this sounds reasonable but it is not correct, there is a device between the speaker terminals on the amplifiers & the amp itself called an autoformer that keeps the ohmage constant no matter what the speakers impendance is(this controled ohmage is what the amplifier see's)distortion is measured & controlled by another device within the amp & the 2 functions are not related.

 

[mtrycrafts]

Like I said earlier in the post I think we all may be misunderstanding what it means when they say that it doesn't double down. I could be completely wrong and would like to know if I am, but here it goes. I am thinking that the Mac will do exactly as any other amp would do when the impedance drops but the thing it will not do is go above a maximum value in order to keep the heat and distortion at a lower level to help protect the equipment by not allowing you to overdrive the amp. For example if you have a 300W amp and you are using it well below it's maximum it will function like any other amp but as you reach 300W you may start running into the problems you describe. To avoid running into those problems you have to get an amp that matches your system and listening preferences. If you are planning on driving the amp to 300W on a regular basis and the impedance dips down while the amp won't allow it to exceed 300W you probably would get a bigger amp and the problem would be solved. Like I said I could be wrong but that's one way I can think of to logically describe the Mac design without knowing many details about it.

The point is that the Mc will not increase power out as impedance decreases, beyond the amount it will into an 8 ohm load whether you need it or not. That is not how other, well designed amps perform, amp designers equal to Mc designers. It may be their philosophy, but, it isn't good.

 

[highfihoney]

There may be another explanation, if that 900W continuous you referred to was read off the MC1201's wattmeter, then depend on the position selected, it may be reading either the instantaneous peaks when in the watts position or the peaks of a sequence of peaks if in the hold position. In either case, that meter does not seem (not 100% sure) to be for indicating rms watts.

Hi peng,i did get a bit more info on this subject,from what i learned today the meters measure voltage & current then display rms watts & peak watts not "average watts",i also learned that the method to achive the standard rms measurement uses the time average of instantanious power & is not the same method used to measure average power.

I also learned that no audio manufacturer uses the average power method to denote the output from their amplifiers they all use the rms method.

I hope everybody takes this post the right way,i am not trying to argue this subject,i want to learn more about it but it is confusing to me because the differences between average power & rms power are huge.

I went back & read that link again & it seems that the average watt method used in the paper also does not coincide with how speaker manufacturers rate their speakers

As far as the average power rating i ask this,what good is it in reality if amplifier manufacturers dont use this method to rate their output power & speaker manufacturers dont use the method to rate their input power??

 

[PENG]

Hi nugglets,this sounds reasonable but it is not correct, there is a device between the speaker terminals on the amplifiers & the amp itself called an autoformer that keeps the ohmage constant no matter what the speakers impendance is(this controled ohmage is what the amplifier see's)distortion is measured & controlled by another device within the amp & the 2 functions are not related.

hifi, take a look of the diagram in this link:
http://www.mcintoshlabs.com/autoformer.aspx

This autoformer thing looks quite like an autotransformer to me. It has taps for 2,4,8 ohms. The way it works is not really impedance matching, it simply provide a lower voltages for 2,4 ohm loads in order to keep the maximum power output the same. In fact, this link:

http://www.mcintoshlabs.com/data/brochures/MC2051.16.07.pdf

tells you the output RMS voltage is 40V across 8 ohms and 28.3 across 4 ohms. That's how you get the same power output (40^2)/8=200W, (28.3^2)/4 also=200W. Not much magic to me now!

In fact, if you connect your 4 ohms speakers to the 8 ohms output terminals (autoformer tap), the Mc will double down the same way as a Krell will. Obviously they want you to connect them to the 4 ohms terminals to make sure nothing get overheated.

Don't take me the wrong way and I am not trying to argue neither. I think we both are curious enough to want to understand something a little better. Now, you turn.

 

[PENG]

Like I said earlier in the post I think we all may be misunderstanding what it means when they say that it doesn't double down. I could be completely wrong and would like to know if I am, but here it goes. I am thinking that the Mac will do exactly as any other amp would do when the impedance drops but the thing it will not do is go above a maximum value in order to keep the heat and distortion at a lower level to help protect the equipment by not allowing you to overdrive the amp. For example if you have a 300W amp and you are using it well below it's maximum it will function like any other amp but as you reach 300W you may start running into the problems you describe. To avoid running into those problems you have to get an amp that matches your system and listening preferences. If you are planning on driving the amp to 300W on a regular basis and the impedance dips down while the amp won't allow it to exceed 300W you probably would get a bigger amp and the problem would be solved. Like I said I could be wrong but that's one way I can think of to logically describe the Mac design without knowing many details about it.

You are not exactly right.

1) They never said they wouldn't double down if you connect a 4 ohm speaker to the 8 ohm output terminals.

2) You are right about the Mc amp will do what other amps do when the load impedance dips below the nominal impedance of say 8 ohms.

3) You are quite likely not correct in saying that it will not go beyond the maximum specified output. Take a look of the brochure for the MC205 that zumbo used as an example, the output voltage at rated output is 40V across 8 ohms and 28.3 across 4 ohms. So if the 8 ohm load dips down to 4 ohm momentarily, the output voltage stays at 40V (maximum limit) and power=40^2/4=400V. This is assuming no line voltage drop etc. but it will be closed to double down.

When they talk about the same power output regardless of impedance they meant maximum power at nominal impedance, not the actual dynamic impedance of a typical speaker. As you know, the dynamic impedance of a loudspeaker varies with the signal.

 

[Nuglets]

In fact, if you connect your 4 ohms speakers to the 8 ohms output terminals (autoformer tap), the Mc will double down the same way as a Krell will. Obviously they want you to connect them to the 4 ohms terminals to make sure nothing get overheated.

Don't take me the wrong way and I am not trying to argue neither. I think we both are curious enough to want to understand something a little better. Now, you turn.

So the amp really isn't limiting itself at all unless you connect it to the 4 ohm terminals, right?(not really limiting either just lowering the voltage as you said) Which could be viewed as a bad thing by some people, but really isn't in my opinion for the simple fact that it helps keeps the heat at more a more reasonable level to increase longevity. And considering that Mac doesn't lose it's resale value even after long periods of time would indicate to me that it works quite well to make it last for a long time.

 

[Nuglets]

You are not exactly right.

1) They never said they wouldn't double down if you connect a 4 ohm speaker to the 8 ohm output terminals.

I think that is exactly what mtry's argument is though. Maybe I misunderstood though. Regardless of that...this thread has taught me a lot and is very enjoyable.

 

[highfihoney]

hifi, take a look of the diagram in this link:
http://www.mcintoshlabs.com/autoformer.aspx

This autoformer thing looks quite like an autotransformer to me. It has taps for 2,4,8 ohms. The way it works is not really impedance matching, it simply provide a lower voltages for 2,4 ohm loads in order to keep the maximum power output the same. In fact, this link:

http://www.mcintoshlabs.com/data/brochures/MC2051.16.07.pdf

tells you the output RMS voltage is 40V across 8 ohms and 28.3 across 4 ohms. That's how you get the same power output (40^2)/8=200W, (28.3^2)/4 also=200W. Not much magic to me now!

In fact, if you connect your 4 ohms speakers to the 8 ohms output terminals (autoformer tap), the Mc will double down the same way as a Krell will. Obviously they want you to connect them to the 4 ohms terminals to make sure nothing get overheated.

Don't take me the wrong way and I am not trying to argue neither. I think we both are curious enough to want to understand something a little better. Now, you turn.

Sorry,i assumed we all knew what would happen if the connections were inversed from 4 ohm to 8 ohm but that would be using the amplifier in direct conflict against its own design & probabally not the best move under any circumstances.

 

[Nuglets]

Sorry,i assumed we all knew what would happen if the connections were inversed from 4 ohm to 8 ohm but that would be using the amplifier in direct conflict against its own design & probabally not the best move under any circumstances.

Bad assumption(j/k ), I definitely didn't realize that until PENG and your latest posts.

 

[PENG]

So the amp really isn't limiting itself at all unless you connect it to the 4 ohm terminals, right?(not really limiting either just lowering the voltage as you said) Which could be viewed as a bad thing by some people, but really isn't in my opinion for the simple fact that it helps keeps the heat at more a more reasonable level to increase longevity. And considering that Mac doesn't lose it's resale value even after long periods of time would indicate to me that it works quite well to make it last for a long time.

No, not a bad thing at all, as you said, we should just buy the power we need. I am beginning to agree to zumbo's view. Can't believe I actually said that........and I am not ready to re-vote yet...

 

[zumbo]

Well, before everone gets too excited, let me put on the brakes. There seems to be different technology. The MC 205 doesn't seem to have seperate terminals (Output Autoformers) like some of the other Mc amps, it's different. That feature is not listed.

Unlike other high-current designs, The MC205 delivers the same 200 watts per channel into both 4-ohm and 8-ohm loudspeakers. The Dynamic Power Manager automatically controls and optimizes the power supply’s voltage and current balance delivering higher voltage that 8 ohm speakers require, and automatically adjusting for current-hungry 4 ohm speakers.

 

[mtrycrafts]

hifi, take a look of the diagram in this link:
http://www.mcintoshlabs.com/autoformer.aspx

This autoformer thing looks quite like an autotransformer to me. It has taps for 2,4,8 ohms. The way it works is not really impedance matching, it simply provide a lower voltages for 2,4 ohm loads in order to keep the maximum power output the same. In fact, this link:

http://www.mcintoshlabs.com/data/brochures/MC2051.16.07.pdf

tells you the output RMS voltage is 40V across 8 ohms and 28.3 across 4 ohms. That's how you get the same power output (40^2)/8=200W, (28.3^2)/4 also=200W. Not much magic to me now!

In fact, if you connect your 4 ohms speakers to the 8 ohms output terminals (autoformer tap), the Mc will double down the same way as a Krell will. Obviously they want you to connect them to the 4 ohms terminals to make sure nothing get overheated.

Don't take me the wrong way and I am not trying to argue neither. I think we both are curious enough to want to understand something a little better. Now, you turn.

Sure looks like the confusion is clarified

 

[Yamahaluver]

Nowhere do I see any so called bad review of the MX-D1 in Stereophille, what they have done is nitpicking and that you will find even with the best amp review, you can't just go out and say its perfect, imaging and focus problems are also due to amp/speaker interaction and not solely and amp charecteristic. They also called it accurate, now is that an attribute or a fault? The Yamaha amp has a shut down circuit, trust me when that comes on, your speakers are already dangling out of their sockets I have heard McIntosh amps, have owned several in past, they are quite good, warm, although accurate they never will be, no matter what speakers they are hooked up with. As for autotransformer, well the Yamaha delivers 500@x2RMS into 4ohms or 8ohms, same effect, just use of different technology.

 

[zumbo]

Sure looks like the confusion is clarified

Who was confused?

 

[zumbo]

Nowhere do I see any so called bad review of the MX-D1 in Stereophille, what they have done is nitpicking and that you will find even with the best amp review, you can't just go out and say its perfect, imaging and focus problems are also due to amp/speaker interaction and not solely and amp charecteristic. They also called it accurate, now is that an attribute or a fault? The Yamaha amp has a shut down circuit, trust me when that comes on, your speakers are already dangling out of their sockets I have heard McIntosh amps, have owned several in past, they are quite good, warm, although accurate they never will be, no matter what speakers they are hooked up with. As for autotransformer, well the Yamaha delivers 500@x2RMS into 4ohms or 8ohms, same effect, just use of different technology.

I have a thing about reviews. I look at it a little differently. You never see a review that states, "this thing is a piece of junk." You have to read into them. I look for faults, and see if they matter to me. Faults are the best part of a review. The rest is usually BS.

The faults given to that model Yamaha wouldn't cut it for me. Don't get me wrong, I toot Yamaha's horn all the time. They hare my favorite receivers, and players. I can't help it they got out of the high-end game. Had nothing to do with me. I would love for them to follow Denon into seperates again. But, at the moment, that one amp doesn't do it for me.

 

[zumbo]

Funny thing about the poll.
There are 20 votes for the first choice, but only 15 members listed.(at the moment) That means someone has voted 5 extra times.

There are 5 votes for the second choice, and 5 members listed. Looks like honest people vote for honest products.

 

[mtrycrafts]

Funny thing about the poll.
There are 20 votes for the first choice, but only 15 members listed.(at the moment) That means someone has voted 5 extra times.

There are 5 votes for the second choice, and 5 members listed. Looks like honest people vote for honest products.

Or, there is a problem with the program? Once you make the mark, the ability to cast again disappears for me at least.

 

[PENG]

Well, before everone gets too excited, let me put on the brakes. There seems to be different technology. The MC 205 doesn't seem to have seperate terminals (Output Autoformers) like some of the other Mc amps, it's different. That feature is not listed.

Unlike other high-current designs, The MC205 delivers the same 200 watts per channel into both 4-ohm and 8-ohm loudspeakers. The Dynamic Power Manager automatically controls and optimizes the power supply’s voltage and current balance delivering higher voltage that 8 ohm speakers require, and automatically adjusting for current-hungry 4 ohm speakers.

I am not sure who is excited, but you may be, if you read the owner's manual of their multichannel amps such as the MC207. You will see that although they talk about the DPM feature, they do have an "impedance Switch" that allows you to choose 4 ohm or 8 ohms. They do not use autoformer in the these multichannel amps.

All of their monoblock and Stereo amps have autoformers. I wonder if it is a cost issue. For 7 channels, two complete sets of output terminals and a large autoformer would add cost.

Anyway, I bet if you leave the impedance switch in the 8 ohm position, the MC205 through MC207 will pump more power into your 4 ohm speakers. It may not double to 400W but it will be close, especially if you can hold the line voltage at 120V. It has to, because in the 8 ohm position the output voltage will be higher, 40V across 8 ohm so across 4 ohm will get you 400W!

 

[Yamahaluver]

If you pick the negative in any review, then afraid there is nothing that can remotely satisfy you. I had the Krell KSA-150, as an amp, it was formidable, excellent dynamics and control, superb low impedance power handling but guess what, it was shrill and harsh, at that price point it made my Martil Logan Quests sound like a cave full of bats, that would not take out the fact that Krell makes fantastic amps, pair them with Magnepan and they sound excellent, fact about the Stereophille report on MX-D1 was that they were impressed with its sound despite of the negative points and thats what that matters most.

 

[zumbo]

Anyway, I bet if you leave the impedance switch in the 8 ohm position, the MC205 through MC207 will pump more power into your 4 ohm speakers. It may not double to 400W but it will be close, especially if you can hold the line voltage at 120V. It has to, because in the 8 ohm position the output voltage will be higher, 40V across 8 ohm so across 4 ohm will get you 400W!

That would be correct. Mt Linear Power amps have tabs inside. You take the cover off the amp, and move from 4ohm to 2ohm when bridging. But, we all knew what would happen if you left them on the 4ohm tabs. So, we did.

I wouldn't want to do that now. My main thing is to keep distortion at it's lowest, and not put any stress on an amp. So, the key is to buy the power you need.