Hi,
Adding series resistors does not drop the Fs in the same way
as adding cone mass, which does and reduces efficiency.
Series resistors effectively make the magnet less powerful
and raise Qes, resistor losses reduce efficiency. You cannot
say cone control and impulse response is not affected, it is.
There s not much going for series resistors as a valid option
for box loudspeakers. A suitable driver of suitable mass and
low Fs suited to the box, driven direct is a far better option.
rgds, sreten.
You cannot tune an ABR with a series resistor, you can
by adding mass. Again the resistor affects Qes, allowing
it to modify the raw Qms, and how they both interact
with the Q of the active driver, changing the Q of the
overall bass alignment. Don't know an easy way
of modelling the arrangement.
Adding series resistors does not drop the Fs in the same way
as adding cone mass, which does and reduces efficiency.
Series resistors effectively make the magnet less powerful
and raise Qes, resistor losses reduce efficiency. You cannot
say cone control and impulse response is not affected, it is.
There s not much going for series resistors as a valid option
for box loudspeakers. A suitable driver of suitable mass and
low Fs suited to the box, driven direct is a far better option.
rgds, sreten.
You cannot tune an ABR with a series resistor, you can
by adding mass. Again the resistor affects Qes, allowing
it to modify the raw Qms, and how they both interact
with the Q of the active driver, changing the Q of the
overall bass alignment. Don't know an easy way
of modelling the arrangement.
Your opinion is noted. I don't know if it's based on any actual testing or you're just guessing the outcome. Please keep in mind that I have merely posted it so that people don't overlook the possibility of using this idea to whatever extent they desire. The results of doing this to a moderate degree, especially on open baffle speakers has never failed to impress but your opinion may vary.
On the passive radiator, you are absolutely wrong though.
Series capacitor
Just to put some oil on the fire of this discussion
I remember owning some Wharfedale Diamond bookshelf speakers in the 70's .They had a big bipolar electrolitic capacitor in series before the filter and it worked pretty good . They sounded awesome for the small size and had a very low f3 and high efficiency for such a small speaker .
Never figured out how that worked , but there must be someone out there who can simulate it .
Cheers ,
Rens
Just to put some oil on the fire of this discussion
I remember owning some Wharfedale Diamond bookshelf speakers in the 70's .They had a big bipolar electrolitic capacitor in series before the filter and it worked pretty good . They sounded awesome for the small size and had a very low f3 and high efficiency for such a small speaker .
Never figured out how that worked , but there must be someone out there who can simulate it .
Cheers ,
Rens
Releasing the woofer from the task of producing low frequency it is not capable of, will improve something. But I think it will ruin something else. Strange how designers came up with such ideas.
I like new ideas, doing it myself. When it didn't work, I know something. When it worked, wow. I'm in this thread because I believe there are possibilities for great new ideas regarding bass enhancement techniques.
Old techniques work pretty good
Read this thread , pretty old technique , but works great for me !
http://www.diyaudio.com/forums/subw...arameters-electrical-means-5.html#post3518110
Cheers ,
Rens
Read this thread , pretty old technique , but works great for me !
http://www.diyaudio.com/forums/subw...arameters-electrical-means-5.html#post3518110
Cheers ,
Rens
Attachments
Just to put some oil on the fire of this discussion
I remember owning some Wharfedale Diamond bookshelf speakers in the 70's .They had a big bipolar electrolitic capacitor in series before the filter and it worked pretty good . They sounded awesome for the small size and had a very low f3 and high efficiency for such a small speaker .
Never figured out how that worked , but there must be someone out there who can simulate it .
Cheers ,
Rens
It's a relatively complex effect as it involves the voice coil resistance, the voice coil reactance, and the capacitors reactance to form an induced voltage on the voice coil.
If anyone knows of any formulas, I'd be happy to have them. However, the effect is quite easy to observe when you can measure both impedance and phase.
Simply put it gives an increased roll-off at frequencies lower than Fs, from Fs to Fsc it gives an increasing output (up to +6dB), from Fsc to Fs*2 it falls back to no gain, From Fs*2 to Fsc*Pi there a decreasing output (down to -3dB) which from Fsc*Pi to 2*Fsc*Pi normalizes back to 0dB again.
The larger the capacitor is compared to the Fs of the driver, the softer the effect is. Please note that since it's a capacitor in series with the driver there will be impulse response effects and these will be increasing the smaller the capacitor is. The use of bypass capacitors is strongly advised.
This is my description of the observed effect of a series capacitor. Again, if anyone have any definitive formulas for the effect, or can give more accurate observations, I would be happy to see them.
PS: The observed effect is in closed cabinet. I have not tried it with reflex or passive radiator cabinet yet.
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A little about some of the methods of using a resistor, capacitor or a vented cabinet to extend low frequencies.
https://www.lautsprechershop.de/ind...ww.lautsprechershop.de/hifi/aka_tief_c_en.htm
Simple Network Lowers f3
https://www.lautsprechershop.de/ind...ww.lautsprechershop.de/hifi/aka_tief_c_en.htm
Speaker Builder magazine 1989 "A Passively Assisted Woofer System"
There is probably more about this online also.
https://www.lautsprechershop.de/ind...ww.lautsprechershop.de/hifi/aka_tief_c_en.htm
Simple Network Lowers f3
https://www.lautsprechershop.de/ind...ww.lautsprechershop.de/hifi/aka_tief_c_en.htm
Speaker Builder magazine 1989 "A Passively Assisted Woofer System"
There is probably more about this online also.
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Thanks. Looks like it matches my own findings and with a little more information.
Very interesting to read , but what about damping factor in the lower frequencies .Out of experience I can hear that my amps with the highest damping factor gives the "tightest" bass . ( That's what interested me the most when I read adding serial resistance to lower F3 AND how I think this affects the electrical brakes on the cone when the signal has gone !)
So you get more bass , but less precise ?
Cheers ,
Rens
Dampening factor is the difference between source impedance and load impedance. In my experience smaller resistances, ie. cable resistance and parasitic resistance of inductors, tend to be part of source impedance and lowers dampening factor, and larger reistances, ie. from series resistors or putting drivers in series, tend to be part of load impedance and increases dampening factor (in the sense that it increases the overall dampening factor but the distributed dampening factor to the driver(s) remain the same). Why and how that is, and even if the observation is accurate I don't know. I can guess that it has something to do with impedance bridging where an impedance factor between source and load of 10 times or more makes an effective isolation of the two complex impedances.
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Well , time for a couple of hours of sleep ( for you or for me
)I would not be happy with a factor of 10 !!!
Have a good one !
Rens
Most tube amps or car audio sub systems are around that. But I said that a factor of 10 or more creates a so-called impedance bridge, and that might explain my observation.
From the same source I posted earlier.
https://www.lautsprechershop.de/ind...ww.lautsprechershop.de/hifi/aka_tief_c_en.htm
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