To my understanding, bi-amping is an old technique that was used in the old days and maybe became popular in the 70s and 80s. The reason is that a Watt in those days was quite expensive. Nowadays, a Watt is cheaper. I'm curious whether anyone still uses the bi-amp configuration these days. And why are you still using it?
According to the user manual of my speakers, the ADS L1590, each speaker has a bi-amp switch located on the crossover network. It will bypass the low-pass filter of the woofers. In other words, the woofers will directly meet the speaker terminals when the bi-amp switch is engaged.
To date, are there any commercial speakers that have a similar function to the ADS speakers? What's the benefit of this function?
According to the user manual of my speakers, the ADS L1590, each speaker has a bi-amp switch located on the crossover network. It will bypass the low-pass filter of the woofers. In other words, the woofers will directly meet the speaker terminals when the bi-amp switch is engaged.
To date, are there any commercial speakers that have a similar function to the ADS speakers? What's the benefit of this function?
Old?
Bi-amping is using 2 amplifiers and a crossover after teh pre to divide the signal before the 2 power amplifiers.
There are 2 XO kits in the diyAudio store, PLLXOs take just a few passive parts, and DSP based XOs like miniDSP are multiplying.
dave
Bi-amping is using 2 amplifiers and a crossover after teh pre to divide the signal before the 2 power amplifiers.
There are 2 XO kits in the diyAudio store, PLLXOs take just a few passive parts, and DSP based XOs like miniDSP are multiplying.
dave
There are many active speaker systems available, with each driver having its own amplifier.
Sometimes even 3 or 4 amplifiers per enclosure.
I also have a biamplified table radio, the Proton model 300.
https://www.hifiengine.com/manual_library/proton/300.shtml
Sometimes even 3 or 4 amplifiers per enclosure.
I also have a biamplified table radio, the Proton model 300.
https://www.hifiengine.com/manual_library/proton/300.shtml
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Some people (and iirc german hifi magazines in the 80ist/90ies) defined two parallel amps driving speakers through (split-up) passive x-overs as "bi-amping".
The tweeter or mid-tweeter amp would see a high impedance in the bass region. That was said to improve sound and it actually could protect tweeters from bass clipping harmonics in case of "soft" power supply.
I suspect it may also create stability issues (capacitive load).
The tweeter or mid-tweeter amp would see a high impedance in the bass region. That was said to improve sound and it actually could protect tweeters from bass clipping harmonics in case of "soft" power supply.
I suspect it may also create stability issues (capacitive load).
IIRC, in those days it was referred to as “passive bi-amping” to differentiate from “active bi-amping”, which uses a (usually) active crossover between the pre and power amps.
Talking about unexpected bi-amping: Any Macintosh with the 6-speaker (2 midTweeters and a pair of push-push bass drivers) is bi-amped.
dave
Nothing to do with power consumption, all to do with the imperfections and inflexibility of passive crossover networks. An active crossover can be programmable and highly linear, whereas a passive crossover network has limited tunability (usually just a level pot for the tweeter).
Passive crossovers also shield the drivers from the damping factor of the amp, meaning the passive crossover interacts with driver impedance in complex ways. That's why the biamp switch on that speaker does what it does.
For high power levels passive crossovers get prohibitively large and cumbersome, so PA systems are typically active crossover with multiple amps.
I’ve not heard so many qualifications for the term Bi-amp. It means two amplifiers to operate a loudspeaker regardless of crossover type or placement in the system.
While I am a fan, my bigger systems are actually tri amped or quad amped.
And that doesn’t yet count when I go wild and start strapping them.
While I am a fan, my bigger systems are actually tri amped or quad amped.
And that doesn’t yet count when I go wild and start strapping them.
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Using a small amplifier for the tweeters that matches their modest power capability protects them from burning out. And an electronic crossover uses small high-quality capacitors and no inductors, or a DSP, that have less distortion than large capacitors and inductors used in passive crossovers. And in some cases, a direct connection between amplifier and speaker provides better damping etc.
But the main power advantage is about waveform math. A given amplifier can only produce half the total power of two tones as it can for a single tone. The total peak voltage of all frequencies is the clipping limit and if that voltage is split over n frequencies, then the max power of each frequency is 1/n squared, so if you have 10 frequencies, the max power for each is 1% of the amplifier max power.
Normally the bass takes more than it's share and when the amp clips, it generates high frequency harmonics that can damage the tweeter/horn driver. In a bi-amp system, the bass can clip, and the woofer do not produce the clipping harmonics, so no one notices. Bi-amping and tri-amp, 4 way etc is mostly used in professional sound systems where systems are large anyway, so it is the best way to spend that money. A sub-woofer is probably the most practical use of the idea in a residential setting.
But the main power advantage is about waveform math. A given amplifier can only produce half the total power of two tones as it can for a single tone. The total peak voltage of all frequencies is the clipping limit and if that voltage is split over n frequencies, then the max power of each frequency is 1/n squared, so if you have 10 frequencies, the max power for each is 1% of the amplifier max power.
Normally the bass takes more than it's share and when the amp clips, it generates high frequency harmonics that can damage the tweeter/horn driver. In a bi-amp system, the bass can clip, and the woofer do not produce the clipping harmonics, so no one notices. Bi-amping and tri-amp, 4 way etc is mostly used in professional sound systems where systems are large anyway, so it is the best way to spend that money. A sub-woofer is probably the most practical use of the idea in a residential setting.
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The situation as I remember it from western Europe around 1985-1990. Bi-amping was a commercial initiative in reaction to some successful DIY-designs using active filtering. Technically bi-amping was easy to implement, just cut the passive LS filter in halves, a high pass part and a low pass part, add a extra power amplifier and it's done. Retailers made good profit selling these setups to customers willing to believe it was qualitatively comparable to active filtering.
I am biamping some Joseph Audio RM30si speakers which have a built in 200hz biamp crossovers.
I also built a 200hz Linkwitz-Riley 24dB/Octave HPF so that the treble amp doesn't have to amplifier lower frequencies.
I have 3 different amplifiers for the treble including a 5 w/ch ACA Mini built with premium parts.
Sounds great! It's a hobby so what we do doesn't have to make sense to everyone else.
I also built a 200hz Linkwitz-Riley 24dB/Octave HPF so that the treble amp doesn't have to amplifier lower frequencies.
I have 3 different amplifiers for the treble including a 5 w/ch ACA Mini built with premium parts.
Sounds great! It's a hobby so what we do doesn't have to make sense to everyone else.
i am not singling you out steveu, but this arguement has been presented many times, and this time i have decided to post.
if we have a 200w amp with a 3 way passive, then 200W is avaliable to the tweeter.
why if we then active setup, we now worry about the tweeter amp and specify smaller wattage???
200W available to the tweeter is an accident waiting to happen (the first time someone pulls an RCA plug with the system on, or a microphone goes into feedback,) which a smaller tweeter amp avoids. Fortunately, passive crossovers almost always have a tweeter attenuator so not all that 200W is available to the tweeter.
You don‘t actually use THAT small a tweeter amp when you bi amp. Yes, the average power in the tweeter is much lower, but the peaks only come down a handful of dB. At high frequency you tend to need very short bursts of moderately high power. The reason the amp size comes down so much in PA systems is the sensitivity differences. Tweeter as much as 110dB/2.83V, woofers/midbass typically 96. Even the highest sensitivity horn bass cabs only reach about 105 dB/2.83V, and that’s at midband. And with those, you typically use the biggest, highest output HF drivers to go with them.
In a home stereo system the sensitivity difference between mid/bass and tweeter may only be 2-5 dB. If you use a 100 watt woofer amp you end up using 50 on the tweeter, not 10.
In a home stereo system the sensitivity difference between mid/bass and tweeter may only be 2-5 dB. If you use a 100 watt woofer amp you end up using 50 on the tweeter, not 10.
Im building a pair of speakers right now and I am Tri-amping them.
I'm designing a BMR three-way center channel speaker for the home theater. It's actually easier for me to tri-amp with active crossovers than to design a good passive crossover. And cheaper too I think (if quality passive x-over parts are used).
With a little help from ChatGPT I found some interesting answers regarding the energy distribution in a multi way system.
Calculate the highest amplitude value of a 2.82 Vpp 100 HZ sinus wave modulated with a 2.82 Vpp 1000 Hz sinus wave.
ChatGPT
To calculate the highest amplitude value of the modulated waveform, we need to find the peak-to-peak amplitude of the resulting waveform. When two sinusoidal waves are modulated together, their amplitudes add together at each point in time.
Given:
- Amplitude of the first sinus wave (100 Hz): 2.82 Vpp (peak-to-peak)
- Amplitude of the second sinus wave (1000 Hz): 2.82 Vpp (peak-to-peak)
V(t) = A1 * sin(2π * f1 * t) + A2 * sin(2π * f2 * t)
where V(t) is the voltage at time t, A1 is the amplitude of the first sinus wave, A2 is the amplitude of the second sinus wave, f1 is the frequency of the first sinus wave, and f2 is the frequency of the second sinus wave.
In this case, f1 = 100 Hz, A1 = 2.82 Vpp, f2 = 1000 Hz, and A2 = 2.82 Vpp.
To calculate the highest amplitude value, we need to find the peak-to-peak amplitude of the resulting waveform, which is the sum of the individual peak-to-peak amplitudes:
Vpp_total = A1 + A2 Vpp_total = 2.82 Vpp + 2.82 Vpp Vpp_total = 5.64 Vpp
So, the highest amplitude value of the modulated waveform is 5.64 Vpp.
Why do higher frequencies tend to have a smaller amplitude than low frequencies?
ChatGPT
In the context of sound waves, higher frequencies tend to have a smaller amplitude than low frequencies due to various factors related to the physics of sound propagation and human perception.
- Attenuation: As sound waves travel through a medium, they experience attenuation, which means they lose energy over distance. Higher frequencies are more prone to attenuation compared to lower frequencies. This is because the medium through which sound propagates (e.g., air) has inherent resistance to rapid oscillations, leading to a gradual reduction in amplitude for higher frequency waves.
- Dispersion: Dispersion refers to the phenomenon where different frequencies of sound travel at slightly different speeds through a medium. In most cases, higher frequencies have slightly higher phase velocities, causing them to spread out or disperse over time. This can lead to a decrease in the overall energy concentration and, consequently, a smaller amplitude for higher frequencies.
- Resonance and Harmonics: Objects and surfaces have resonant frequencies at which they naturally vibrate. When sound waves encounter these resonant frequencies, they can amplify certain frequencies, creating harmonic overtones. In some cases, these resonances can favor certain low-frequency components, leading to higher amplitudes for lower frequencies.
- Human Perception: The human ear is more sensitive to mid-range frequencies (around 1-4 kHz) than to extremely high or low frequencies. Consequently, when listening to sound with a wide range of frequencies, our perception might emphasize the mid-range frequencies, making the higher frequencies seem relatively smaller in amplitude.
- Source Characteristics: The nature of the sound source can also influence the amplitude distribution of frequencies. For example, a musical instrument might be designed to produce a more pronounced sound in the mid-range frequencies, resulting in the perception of lower amplitude for higher frequencies.
why do high frequency waves have more energy?
ChatGPT
High-frequency waves do not inherently have more energy than low-frequency waves. The energy of a wave is determined by its amplitude (the magnitude of its oscillation) and not its frequency. The relationship between frequency and energy is not direct; instead, the energy of a wave is related to its amplitude.
In the case of electromagnetic waves (such as light), which is where the misconception might arise, higher frequency waves do carry more energy per photon compared to lower frequency waves. This relationship is described by Planck's equation:
E = h * f
where E is the energy of a photon, h is Planck's constant (a fundamental constant in quantum mechanics), and f is the frequency of the wave. Since the frequency is directly proportional to the energy, higher frequency photons (e.g., gamma rays, X-rays, and ultraviolet light) have more energy per photon compared to lower frequency photons (e.g., radio waves and microwaves).
However, this concept does not necessarily translate to other types of waves, like sound waves. In the case of sound waves, the energy is primarily determined by the amplitude of the wave. A high-frequency sound wave with a large amplitude can have more energy per unit of time compared to a low-frequency wave with a smaller amplitude. But, if we compare two waves of the same amplitude, their energy will be the same regardless of their frequency.
In summary, the relationship between frequency and energy depends on the type of wave (e.g., electromagnetic waves, sound waves) and the context in which it is being discussed. For electromagnetic waves, higher frequency photons do have more energy, but for other types of waves, energy is primarily determined by the amplitude of the wave rather than its frequency.
When is ChatGPT going to get an account on DIYAudio? 🙂
