I would like to have something that can increase (I already know how to decrease) the damping factor without adjusting the amplifier feedback, such as filtering, preamp, DSP algorithm, or similar... I have seen a DSP algorithm that can increase DP but don't have access to it. I would be grateful if someone could provide even a little information
Do you want to do this for one speaker, or does it have to work for any speaker you connect to the amp?
I don't think possible. DF is the ratio of speaker impedance to amplifier output impedance. DSP, filter, preamp is not going to affect DF. Feedback or architecture change to amp output is I believe the only option.
One of the advantages of bi/tri amping is directly coupling the amp output to the speaker gets rid of the impedance of the crossover.
One of the advantages of bi/tri amping is directly coupling the amp output to the speaker gets rid of the impedance of the crossover.
This changes the response from the wanted filtered response, so you go and put it back on prior to the amp.. so there are a number of ways to effectively increase damping factor for a specific speaker.
You would have to alter the topology of the amp I think. CFP has lower output impedance than EF as an example. Lower values on EF emitter resistors should do some. If it has a bootstrapped VAS moving the bootstrap from output side of EF emitter resistor to the emitter will also lower it a bit.
Decide what the response will be under the different damping factor, and use EQ or crossover to achieve it.
1. Add multiple parallel devices to the outputs
2. Reduce or remove emitter resistors.
3. Raise bias
4. Remove output inductor.
Obviously all of these have consequences, or should i say "side effects"
If you think of yet another method, that is not pure fantasy like DSP, please share.
Agree with analog_sa. Basically DF represents how well the amplifier "fights" with the back EMF of the speaker. Any resistance in between also reduces DF.
Most amplifiers with negative feedback have huge damping factors, only removing the output inductor is going to do anything meaningful (and only at high frequency). Once the damping factor is 100:1 the resistance of the speaker leads may well dominate the actual damping ratio, not the amp.
A dampling factor of 10:1 means the EMF of the speaker sees 8.8 ohms rather than 8, not a great difference, and 100:1 means 8.08 v. 8, an even smaller difference that is only going to shift the resonance of the driver a miniscule amount. So trying to go from 100:1 to 1000:1 is doing nothing useful for instance.
Unless you have a superconducting voice-coil its diminishing returns at high damping ratios because the resistance of the voice coil is dominating the electrical damping term of the driver.
I suspect a more illuminating piece of data is a graph of damping factor against frequency. (Or equivalently output impedance against frequency).
A dampling factor of 10:1 means the EMF of the speaker sees 8.8 ohms rather than 8, not a great difference, and 100:1 means 8.08 v. 8, an even smaller difference that is only going to shift the resonance of the driver a miniscule amount. So trying to go from 100:1 to 1000:1 is doing nothing useful for instance.
Unless you have a superconducting voice-coil its diminishing returns at high damping ratios because the resistance of the voice coil is dominating the electrical damping term of the driver.
I suspect a more illuminating piece of data is a graph of damping factor against frequency. (Or equivalently output impedance against frequency).
mikeAtx made the best suggestion. You have to go active crossover, but this is far superior than any passive type crossover system. It lowers the impedance as seen by the driver and allows full damping on the driver even in crossover regions. A passive crossover insets impedance in series with the amplifier. That is never good assuming a properly designed speaker system.
Assuming the amplifier design is good, increasing feedback will improve performance. If you can increase overall gain and properly apply negative feedback you will have a better amplifier. Diminishing returns and the overall design must be good. That includes PCB layout.
Assuming the amplifier design is good, increasing feedback will improve performance. If you can increase overall gain and properly apply negative feedback you will have a better amplifier. Diminishing returns and the overall design must be good. That includes PCB layout.
Notwithstanding the 6.3 ohms of voice coil resistance.. So, does anything happen when there's series resistance which you'd say is bad?
What is your goal in seeking to avoid adjusting the amplifier feedback? By which, I presume that you refer to the feedback loop-gain, is that correct?
Shift your point of view to the drivers terminals as the generator. The impedance between it and the amplifier interferes with dynamic braking. So in other words, when the amplifier says "STOP", the cone is more effectively braked by using a lower resistance across the coil. Subway cars and trains use this principle to brake.
The fundamental resonance is dependent on the cone moving more than the signal applied to it through the mechanical resonance. If it were damped out, there wouldn't be enough bass.
Not true. If the amplifier is commanding cone motion, higher damping factor will allow the cone to follow the signal more accurately. When the amp tells the cone to stop, it stops more quickly. Conditions are different under active drive.
The "Q" of the box determines the response. A crossover can shift resonance when you design a box. Not a lot, but it can. What you are referring to is "overdamped" and that isn't what is happening at all.
The "Q" of the box determines the response. A crossover can shift resonance when you design a box. Not a lot, but it can. What you are referring to is "overdamped" and that isn't what is happening at all.
I've noticed if you thump the woofer with your hand gently you get a different sound and feel if the amp is on versus off. The amp is "shorting" the output of the voltage created by the speaker when it tries to move from the hand thump.