|   Is lack of 'autoformer' on McIntosh MC162 amp bad? | Rush Power Windows
Dec 25, 2001 8:01 AM | | I noticed that many of McIntosh's amplifiers have 'autoformer' technology, but my 162 apparently does not. What does an autoformer do, and why does the 162 not have it? Should I be concerned? |
| some info >> re: Is lack of 'autoformer' on McIntosh MC162 bad? | ruffscruff
Dec 25, 2001 9:41 AM | | Hi - As always, I must say I'm not and expert but will pass on what I know about the autoformer. I also can't get into how it might affect sound (if it does) or any electrical formulas that go along with it. I don't think we need to make things that complicated.
As far as I know - the autoformer is used in certain models of Mc amps to put out the same wattage regardless of speaker load. Some models have speaker connections for 2, 4, 8, and 16 ohms and the autoformer makes them put out the same power at all points. Without the autoformer, the amp typically puts out more wattage at lower ohms and less wattage at higher ohms. Without - it might be 200 watts at 4 ohms, 150 at 8 and 100 at 16. One with the autoformer will put out the same at 4, 8 or 16. So - I guess if having the same wattage at all ohm loads is important to you, then lack of the autoformer might not be good. If you have plenty of power for your speakers at 4 or 8 ohms, then it's not important to have one. |
| close but not quite there yet..... | Mr.Crud
Dec 26, 2001 10:32 AM | | Yes an auto former regulates the output power, but you didnt go far enough into this to really know why they invented such a thing. The impedence of a speaker is a reactive load. This means that it changes with frequency. When one says a speaker is hard to drive, that means that the impedence is all over the place. It is tempting to lower the impedence as power increases, but the drawback is that when you lower impedence, you increase the current. And very high current is not something most amps like. Too mught voltage doesnt really harm an amp, the current that follows does. So to answer the first question, Mc Intosh puts auto-formers to protect their amps from too much current going throught them, thus frying it. It also presents an easier load to drive, making the amps job a lot easier too.
Mr.Crud |
| Out to lunch? Where were you in circuits 101 that day? | itellitlikeitis
Dec 26, 2001 12:57 PM | | Mr.Crud, I don't know what you're talking about. The use of a transformer or auto transformer in an audio amplifier is to match the output impedence of the amplifier to the load. This phenomenon is know to electrical engineers as "the maximium power transfer theorum." In the days of vacuum tubes, amplifiers typically had an output impedence of about 6Kohms due to high dynamic plate resistance. The transformer was necessary to get the tubes to see a high impedence load while the speaker saw a low impedence source and additionally to block dc from the speakers. When transistor amplifiers came along, the most common configuration was called "common emitter output" which had inherently low output impedences so only a blocking capacitor was necessary to keep dc out of the speaker. But MacIntosh didn't follow this design philosophy-------until now. Rush Power Windows, see my other reply and if you still have any questions, call MacIntosh. They are extremely courteous and helpful and will be glad to answer your questions authoritatively. |
| re: Is lack of 'autoformer' on McIntosh MC162 amp bad? | Delmar
Dec 26, 2001 5:07 PM | | I am not qualified to comment on the theoretical aspect of this issue but I recently replaced a direct-coupled amplifier with a transformer-coupled amp of the same output and cannot tell a difference between them. I am told the transformer-coupled units are more expensive to manufacture. |
| comparing my 2105 (autoformer) and my 122 (no autoformer) | sak
Dec 30, 2001 4:04 PM | | I have the same question. I have 2 systems in different rooms, both with Mac LS-330 speakers. The pre-amps have identical specs (MAC 3 and C-36. But, one has the 2105 (105watts w/autoformers) and the other has the 122 (120 watts w/no autoformers). Insignificant difference in power. I only use about 5 watts anyway. BIG difference in sound! But I don't know why. Even Roger Russell acknowledges that with dbt there's no difference in sound between amps(whether Mac or another brand).
The new manager of the Mac store in San Francisco wants me to trade in my 122 for an autoformer amp; better sound, she says. The former manager (and owner) sold me both amps, and thought that the 122 was a great (inexpensive amp).
Anyway, I have to set up both amps in the same room (they're heavy!) and see if there's any difference. Could it be the difference in the rooms (e.g., the 2105 room is carpeted and the 122 room isn't).
Any ideas? I've asked this question before, with no response. I'm thinking of getting another 2105 and selling the 122 if there really is a difference. |
| comparing my 2105 (autoformer) and my 122 (no autoformer) | sak
Dec 30, 2001 4:07 PM | | I have the same question. I have 2 systems in different rooms, both with Mac LS-330 speakers. The pre-amps have identical specs (MAC 3 and C-36. But, one has the 2105 (105watts w/autoformers) and the other has the 122 (120 watts w/no autoformers). Insignificant difference in power. I only use about 5 watts anyway. BIG difference in sound! The 2105 (besides looking better with big blue meters) has significantly better bass. But I don't know why. Even Roger Russell acknowledges that with dbt there's no difference in sound between amps(whether Mac or another brand).
The new manager of the Mac store in San Francisco wants me to trade in my 122 for an autoformer amp; better sound, she says. The former manager (who has owned this store for probably 30 years, and seems to know his Mac stuff) sold me both amps, and thought that the 122 was a great (inexpensive amp).
Anyway, I have to set up both amps in the same room (they're heavy!) and see if there's any difference. Could it be the difference in the rooms (e.g., the 2105 room is carpeted and the 122 room isn't).
Any ideas? I've asked this question before, with no response. I'm thinking of getting another 2105 and selling the 122 if there really is a difference. |
| sorry about the double post. read the second one. (nt) | sak
Dec 30, 2001 4:09 PM | | nt |
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