Well, I admit the text is a bit terse, but if you look at fig 2, the value of R1 is a resistor in Ian's amplifier that determines the feedback factor and thus the Rout.
No Rout is given for open loop, and for R1 = 1k and 2k the Rout is shown in parentheses. The point of fig 2 is that with lower Rout, the response gets flatter, due to better damping. Open loop, top graph, with high Rout, the response ripples are largest; with R1 = 2k, Rout = 3R, the ripples are smallest.
Ian's article is not about damping perse but he showed the effect of lowering Rout on flattening the speaker resonances.
You can also play it another way as Morgan Jones has done with his Arpeggio speaker. There he specifies an Rout of 6R (IIRC) so his speaker has the best LF response. It's all engineering ;-)
Actually, the Arpeggio articles is somewhere on diyaudio as a blog.
See the section "Effect of amplifier damping on loudspeakers frequency response" in the attached article.
Jan
No Rout is given for open loop, and for R1 = 1k and 2k the Rout is shown in parentheses. The point of fig 2 is that with lower Rout, the response gets flatter, due to better damping. Open loop, top graph, with high Rout, the response ripples are largest; with R1 = 2k, Rout = 3R, the ripples are smallest.
Ian's article is not about damping perse but he showed the effect of lowering Rout on flattening the speaker resonances.
You can also play it another way as Morgan Jones has done with his Arpeggio speaker. There he specifies an Rout of 6R (IIRC) so his speaker has the best LF response. It's all engineering ;-)
Actually, the Arpeggio articles is somewhere on diyaudio as a blog.
See the section "Effect of amplifier damping on loudspeakers frequency response" in the attached article.
Jan
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^ So, I fully and admittedly struggle with inverting figures... so please bear with me....
I think I have it correct in my mind. I did make an attempt (futile as it was for now) to delve further into the article. Thank you so much! I'll continue to work on my understanding. I much more appreciate your articles. They're easier for me to digest.
Rout is INVERSELY proportional to DF, correct? So, wouldn't the lower DF have worse suppression => less suppression
You said in your article...
"Ian Hegglun [1] did some work on the effects of amplifier output impedance (and thus DF), which shows that the lower the DF, the more the speaker resonances are suppressed (Figure 2; disregard absolute level differences)."
Am I totally misunderstanding? Again, apologies and thank you for the time!
Edited to add below... I do better with graphics. Is this correct?
I think I have it correct in my mind. I did make an attempt (futile as it was for now) to delve further into the article. Thank you so much! I'll continue to work on my understanding. I much more appreciate your articles. They're easier for me to digest.
So, I think I had it correct. Higher Rout => worse damping.
Rout is INVERSELY proportional to DF, correct? So, wouldn't the lower DF have worse suppression => less suppression
You said in your article...
"Ian Hegglun [1] did some work on the effects of amplifier output impedance (and thus DF), which shows that the lower the DF, the more the speaker resonances are suppressed (Figure 2; disregard absolute level differences)."
Am I totally misunderstanding? Again, apologies and thank you for the time!
Edited to add below... I do better with graphics. Is this correct?
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Makes me wonder why we can have cars that change their suspension character depending on how they're driven, but not amplifiers that change damping factor depending on...how hard they're being "pushed", or what's being listened to.
A bit misleading statement, it all depends on Qel and Qm of the speaker. Damping of the RLC circuit is not always highest from zero impedance, but depends on Q, on R L/C ratio. However, it is still the best way to use high DF, in case that you do not make a special, tailored design by yourself. Such statements like the one above may lead to myths in laymen audience.
Guess where a part of the typical "tube sound" is secretly hiding 😉
Ever heard a solid state amplifier with an output transformer with similar output impedance?
These amplifiers are negative-feedback solid-state amplifiers, he just uses both shunt and series feedback at the output and the ratio between them is set by the knob.
Someone will do it - have the "amplifier" look at what you want to listen to first, so it know's what's coming when. Then I can imagine it would be able to do all kinds of magic, including change operating class and output impedance in a pre-emptive way.
Of course a guitar amp never knows what's coming.
Of course a guitar amp never knows what's coming.
An idea I had 30 years ago but never worked out, is an amplifier with current output and self-adjusting equalizer. It would measure the impedance of the loudspeaker and determine the pole and zero positions. It could then automatically equalize for the impedance characteristic of the loudspeaker so that the small-signal response would be the same as under voltage drive, or even act as a self-adjusting Linkwitz transform circuit and automatically correct boomy loudspeakers, if desired.
I talked about it with the owner of a DIY loudspeaker kit shop once, and he didn't like it. According to him, loudspeakers that aren't boomy don't sell and if you are going to use fancy equalizers anyway, you can better use them for room correction, or at least also for room correction.
I talked about it with the owner of a DIY loudspeaker kit shop once, and he didn't like it. According to him, loudspeakers that aren't boomy don't sell and if you are going to use fancy equalizers anyway, you can better use them for room correction, or at least also for room correction.
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Oh yeah, especially earlier high output solid state amplifiers employed an output transformer. It was the most reliable way to get the maximum power out of the relatively low voltage 2N3055 transistors, which were pretty much the only game in town for years. I built an amplifier with input and output transformers and germanium transistors for 12 volt use and it was quite tubelike; maybe a little too tubelike (it sounded tubby but not unpleasant). Still, 12 watts into 8 ohms @12 volts (more if you raised the voltage) was pretty good (and quite useful) for early 1970s.
The sound of typical guitar amps of the era depended on highish amplifier output impedance and peaky guitar speakers. Guitar speakers would have rising impedance with increasing frequency and pronounced midrange impedance spikes. This added a midrange "bite" or peaky emphasis that was favored by blues and rock musicians. In fact, there are reproductions of popular guitar speakers from that era available today.
Typical 1960's transistor radios had transformer phase splitters as well as output transformers - very tiny transformers.
I bought some 'era receiver from the thrift store. Its amplifiers look like giant versions of the 60's transistor radio and tape recorder amps. Except the output transistors are mounted to the chassis.
Much appreciated! That part seems logical. However, my core concern is that I may have this totally backwards from what I'm interpreting from the chart vs. the statement. What you're describing seems important, but more subtle.
Let me try one more time... since don't think it's a subtlety. Either Jan or I (more likely the latter, I think) have something reversed.
Perhaps I am not asking relevant questions and/or my questions are ridiculous. I am not sure.
Step by step...
We are discussing this graph from the article.
Jan says this about the graph above quoted from the article.
Ian Hegglun [1] did some work on the effects of amplifier output impedance (and thus DF), which shows that the lower the DF, the more the speaker resonances are suppressed
I had asked if my interpretation of speaker resonances being suppressed was correct. It seems to be. The "flatter" the response, the more resonances are suppressed. If I have this wrong, please let me know.
I had asked if my interpretation of the relation of DF to Rout was correct. It seems to be. The higher the DF, the lower the Rout. They have a direct inverse relationship. If I have this wrong, please let me know.
For now, what I really want to know is how can the statement be true from the graph depicted above and the article.
Ian Hegglun [1] did some work on the effects of amplifier output impedance (and thus DF), which shows that the lower the DF, the more the speaker resonances are suppressed
To me, the HIGHER the DF (lower Rout) results in more speaker resonances being suppressed.
However... I fully concede once again, that I am learning. I would simply like to know what I have wrong in my interpretation. I want to cross the main chunk of learning off the list before I try to dig deeper. If I have this backwards (and it seems I do)... I don't need to progress to 201. I'm stuck in remedial.
So... if anyone could simply let me know where I went wrong and/or if there is a typo related to that one sentence describing that one graph, I'd be very, very grateful.
Maybe it would help to look at: https://en.wikipedia.org/wiki/RLC_circuit
Then look for "critically damped response"
Basically, you have something more or less like that with a speaker, and there is value of damping resistance that dampens stored energy most quickly.
Then look for "critically damped response"
Basically, you have something more or less like that with a speaker, and there is value of damping resistance that dampens stored energy most quickly.
It's not even "more or less", but pretty much the same and it's called (lumped) mechanical-electrical analogies;
https://en.wikipedia.org/wiki/Mechanical–electrical_analogies
https://lpsa.swarthmore.edu/Analogs/ElectricalMechanicalAnalogs.html
^ I admit to frustration at this point.
Let's ignore how it all works. That can come later. I simply want to know how I've gotten just the simple interpretation of a graph and a statement backassward.
I'll fund a reasonable beverage of choice (up to $20USD) for anyone that will please, pretty please:
Annotate the graph from the article that I have been referencing to show clearly for each of the three lines -
Highest Middle and Lowest DF
Highest Middle and Lowest Rout
Highest Middle and Lowest level that represents "speaker resonances being suppressed"
I made an attempt. No one has yet simply answered whether I've done it properly.
I don't give one rat's patootey (yet) as to how this all works; just how I've so completely misinterpreted a chart / graph and an accomanying statement. Until I get that right, there's no point moving further.
<Dons Dunce Cap and sits in corner>
With my thanks and apologies for polluting the thread with what is likely so trivial for the vast majority of you. The kindness and patience is truly appreciated.
Let's ignore how it all works. That can come later. I simply want to know how I've gotten just the simple interpretation of a graph and a statement backassward.
I'll fund a reasonable beverage of choice (up to $20USD) for anyone that will please, pretty please:
Annotate the graph from the article that I have been referencing to show clearly for each of the three lines -
Highest Middle and Lowest DF
Highest Middle and Lowest Rout
Highest Middle and Lowest level that represents "speaker resonances being suppressed"
I made an attempt. No one has yet simply answered whether I've done it properly.
I don't give one rat's patootey (yet) as to how this all works; just how I've so completely misinterpreted a chart / graph and an accomanying statement. Until I get that right, there's no point moving further.
<Dons Dunce Cap and sits in corner>
With my thanks and apologies for polluting the thread with what is likely so trivial for the vast majority of you. The kindness and patience is truly appreciated.
So far as I can tell, its something like this: The graph shows the effects of some selected amplifier output impedance values in relation to the time domain damping response of some "JV60 loudspeaker [9]" for which there is seemingly no footnote [9]. Anyway, R1 is the feedback resistor; the more feedback the lower the output impedance of the amplifier. So if you analyze the speaker time-domain response with what amounts to a resistor (the amplifier output impedance) in series with a more or less ideal amplifier, we can see that added series resistance changes the damping characteristics of the network that is comprised of the amplifier output impedance and the speaker, including any crossover network and the speaker driver characteristics as represented in terms of equivalent lumped impedances.
That's kind of a rough way of putting it; maybe someone else can help further clarify.
That's kind of a rough way of putting it; maybe someone else can help further clarify.
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