It's called back EMF and it has been investigated

By Matti Otala in the 1970s or 80s. Basically at some point the reactive components in the speaker crossover and in the drivers will also "push back" signal into the output stage of the amplifier. if there is no negative feedback, this will be dissipated in the output stage as heat. In extreme cases with transistor amps this can actually shorten the life of the output transistors. Electrostatic speakers are the worst as they will push back nearly 100% of the signal fed to them.

Tube amps without feedback are largely unaffected because they already run hot and dissipate many more watts usually than they are pushing into speakers.

Now, if an amp has negative feedback it can get interesting because a portion of that speaker generated and modulated signal will re-enter the amplification chain through the feedback loop and be re-amplified as distortion. Since it has been pretty mangled by the speaker the signal no longer resembles what went in and is not in time with the original signal...this makes it distortion. THe more feedback, the more of this distortion that is fed into the input stage of the amplifier and sent back around again.

This probably has overall negative sonic consequences for that particular amp/speaker pairing and might be the hidden hand behind so-called "synergy" between components or lack thereof.

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Follow Ups Full Thread

Topic - Return from speaker to amplifier, What actually does the amp do with it? - dcuhl 04:38:40 08/23/15 (22)

It's called back EMF and it has been investigated - morricab 12:58:05 08/27/15 (1)

RE: It's called back EMF and it has been investigated - pictureguy 23:34:05 08/29/15 (0)

RE: Return from speaker to amplifier, What actually does the amp do with it? - Inmate51 22:02:11 08/24/15 (0)

Read this - airtime 06:12:35 08/24/15 (1)

That resistor - 3db 09:53:38 08/27/15 (0)

RE: I know all that and you have'nt answered the question. - dcuhl 21:20:55 08/23/15 (12)

RE: I know all that and you have'nt answered the question. - pictureguy 22:21:33 08/24/15 (2)

RE: I know all that and you have'nt answered the question. - Inmate51 07:45:38 08/27/15 (1)

RE: I know all that and you have'nt answered the question. - pictureguy 09:14:51 08/27/15 (0)

It flows back into the secondary of the power transformer - jedrider 10:24:38 08/24/15 (4)

You're wrong too - Dave_K 17:19:52 08/24/15 (2)

RE: You're wrong too - pictureguy 01:04:29 08/27/15 (1)

RE: You're wrong too - Dave_K 04:22:58 08/27/15 (0)

RE: It flows back into the secondary of the power transformer - dcuhl 16:33:50 08/24/15 (0)

RE: I know all that and you have'nt answered the question. - Palustris 07:54:03 08/24/15 (0)

That's a non sequitor - Dave_K 06:38:49 08/24/15 (2)

Hey - you're not the Kirk - airtime 06:45:26 08/24/15 (1)

The Changeling? (nt) - Dave_K 08:13:02 08/24/15 (0)

RE: Return from speaker to amplifier, What actually does the amp do with it? - ahendler 13:51:58 08/23/15 (0)

RE: Return from speaker to amplifier, What actually does the amp do with it? - hahax@verizon.net 12:23:50 08/23/15 (0)

RE: Return from speaker to amplifier, What actually does the amp do with it? - Palustris 09:31:07 08/23/15 (0)

There is no return or supply. - Kal Rubinson 06:54:59 08/23/15 (0)

Follow Ups

It's called back EMF and it has been investigated - morricab 12:58:05 08/27/15 (1)

RE: It's called back EMF and it has been investigated - pictureguy 23:34:05 08/29/15 (0)

It's called back EMF and it has been investigated

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