What does the term "Bi Amp" mean?

[Ole Rumblekat]

Also "DI". I read a gear review and someone said the DI on his amp was noisy. I'm sure you guys can define these.

[Greyfin10]

Bi Amp = In the application I am familiar with, there's a crossover which divides your input at a particular frequency, and then sends the high side to one amplifier, and the low side to another. In the amplifier I had years ago (Peavey Megabass) it had two 200 watt amps and a crossover. At the time I had an 1810 cabinet which had seperate inputs for the 18" speaker and the 10" speakers. In that mode (theoretically) you get better performance from both sets of speakers, because they are only reproducing the frequency ranges they are designed for.

Check out --> http://en.wikipedia.org/wiki/Bi-amping

DI = Direct Input. In an amp, it's most often used to take the pre-amp's signal straight to the mixer at mic level.
They also come in stand alone as a D.I. box. Not sure if they are functionally the same, but the name is the same. I assume they are just impedance changers in that scenario?

Check out --> http://en.wikipedia.org/wiki/DI_unit

[BassmanPaul]

Using ten inch speakers in a bi-amp system is pointless. As the gentleman above states your signal is split by an electronic crossover into it's high and low components. These are fed into separate amplifiers one driving the woofers and the other the tweeters. Crossover points are typically around 4-5KHz. In his case a 200W amp is used for the woofers and a 200W amp is used for the tweeters. This is a complete waste of power as the tweeters only need about 50W to keep up with a 200W woofer amp. In all honesty I consider bi-amping pretty much obsolete as cabinets with good high power crossovers are readily available.

Paul

[Eric Perry]

It's an amp that's trying to double his or her chances of getting a date on Friday night.

[thudfromafar]

Originally Posted by BassmanPaul

Using ten inch speakers in a bi-amp system is pointless. As the gentleman above states your signal is split by an electronic crossover into it's high and low components. These are fed into separate amplifiers one driving the woofers and the other the tweeters. Crossover points are typically around 4-5KHz. In his case a 200W amp is used for the woofers and a 200W amp is used for the tweeters. This is a complete waste of power as the tweeters only need about 50W to keep up with a 200W woofer amp. In all honesty I consider bi-amping pretty much obsolete as cabinets with good high power crossovers are readily available.

Paul

Maybe bi-amping improperly is obselete, we can only hope right...?

See the fEarful wiki for good use of bi-amping.

[BassmanPaul]

Even with a properly designed Bi-amp rig the high range drivers should still have some kind of high pass filter in the cabinet. Just 'cos an amp is only fed with a high range signal doesn't stop it from outputting low frequency crap coming off the AC mains.

Paul

[Grooveman1961]

Originally Posted by BassmanPaul

Using ten inch speakers in a bi-amp system is pointless. As the gentleman above states your signal is split by an electronic crossover into it's high and low components. These are fed into separate amplifiers one driving the woofers and the other the tweeters. Crossover points are typically around 4-5KHz. In his case a 200W amp is used for the woofers and a 200W amp is used for the tweeters. This is a complete waste of power as the tweeters only need about 50W to keep up with a 200W woofer amp. In all honesty I consider bi-amping pretty much obsolete as cabinets with good high power crossovers are readily available.

Paul

I use my gk rb800 in biamp mode. The highs go to a bfm dr 250, which has a 10 inch in it, and the lows to a bfm tuba24 which has 10 inchers. Works extemely well.

Separating highs and lows prior to the power amps also allows effects to be used on one or the other, or even different effects from the highs compared to the lows.

GK artist amps still feature biamp capability, for this very reason. Distortion is created in the "low" signal path, but the highs are kept clean.

[Grooveman1961]

Originally Posted by Eric Perry

It's an amp that's trying to double his or her chances of getting a date on Friday night.

LOL I thought it was an amp that had both plugs and jacks

[Greyfin10]

Originally Posted by Grooveman1961

LOL I thought it was an amp that had both plugs and jacks

I think that's a hermaphroamp. The more you know...

[Passinwind]

Originally Posted by BassmanPaul

Even with a properly designed Bi-amp rig the high range drivers should still have some kind of high pass filter in the cabinet. Just 'cos an amp is only fed with a high range signal doesn't stop it from outputting low frequency crap coming off the AC mains.

Interesting observation Paul. I can't recall a single multiamped PA cab that has such a filter.

Edit: I did however find an interesting online article of relevance. But now I can't recall the last time I used a power amp without turn-on transient protection built in.

[billfitzmaurice]

Originally Posted by BassmanPaul

Using ten inch speakers in a bi-amp system is pointless.

Not at all, so long as the cabs are optimized to work within a desired passband. But no commercial electric bass cabs are.

Even with a properly designed Bi-amp rig the high range drivers should still have some kind of high pass filter in the cabinet

That applies to compression drivers, where a single series capacitor is used primarily to protect the drivers from amp turn-on transients. Not necessary with cone drivers.

[1n3]

Originally Posted by BassmanPaul

Using ten inch speakers in a bi-amp system is pointless.

In the case cited by Greyfin10, it's not pointless. You've got 200 watts per side, with an 18" Black Widow on the bottom, and 2-10" Scorpions on the top. You can split at 100-400hz, and have a good power balance. I've played through a bi-amped Peavey 1820, and it sounded pretty good, especially by the standards of the day.

... your signal is split by an electronic crossover into it's high and low components. These are fed into separate amplifiers one driving the woofers and the other the tweeters. Crossover points are typically around 4-5KHz.

Aside from some G-K heads, this is not a normal bi-amp setup for bass guitar.

In all honesty I consider bi-amping pretty much obsolete as cabinets with good high power crossovers are readily available.

If you're talking about a split at 4-5kHz, I might agree. But when you split below 1kHz, the components get heavier and more expensive. And you can't match the steep slopes of modern active crossovers, particularly those using DSP. For a woofer/mid split, bi-amping is not obsolete.

[MNAirHead]

Originally Posted by BassmanPaul

Using ten inch speakers in a bi-amp system is pointless. As the gentleman above states your signal is split by an electronic crossover into it's high and low components. These are fed into separate amplifiers one driving the woofers and the other the tweeters. Crossover points are typically around 4-5KHz. In his case a 200W amp is used for the woofers and a 200W amp is used for the tweeters. This is a complete waste of power as the tweeters only need about 50W to keep up with a 200W woofer amp. In all honesty I consider bi-amping pretty much obsolete as cabinets with good high power crossovers are readily available.

Paul

Paul,

This is not correct.

IN the Megabass 1820 configuration, the lows are sent to the `18.. the 10s receive mids/uppers.

IN this situation, the chorus is only sent to the high cabinet eliminating muddiness of full spectrum effects.

One of my rigs is biamp.. is stellar for the right situations and combinations... Bill noted that it took a ton of effort and engineering to mate 2 cabinets with the crosover point and PA to produce a killer output.

The reality is many curent speakers can do more than what we had before.

As always, I suggest to only accept opinions from qualfied people.. many times this should include folks who have gig tested the gear ai a band spectrum.

Tim

[wideload]

My bi-amped rig crossed over at 250-300hz (my choice with a variable crossover) to an 18 on the bottom and 2-10 on top. I use 2 sides of a stereo amp and mix accordingly. The 2-10 is definitely not suitable for a full range signal, but the combo works great together!

[mid_life_crisis]

When you are crossing over at a low frequency, that coil is wasting what could be considered a fair amount of power that could make the difference if the amp is marginal in power output.

[PilbaraBass]

Originally Posted by BassmanPaul

Using ten inch speakers in a bi-amp system is pointless. As the gentleman above states your signal is split by an electronic crossover into it's high and low components. These are fed into separate amplifiers one driving the woofers and the other the tweeters. Crossover points are typically around 4-5KHz. In his case a 200W amp is used for the woofers and a 200W amp is used for the tweeters. This is a complete waste of power as the tweeters only need about 50W to keep up with a 200W woofer amp. In all honesty I consider bi-amping pretty much obsolete as cabinets with good high power crossovers are readily available.

Paul

Not entirely pointless, actually…

The crossover range on my Carvin R600 amp is 200Hz – 2kHz.

If I drive a subwoofer on the low end, I can reserve a lot of the power of the high-end amp for reproducing everything else in a 2x10, for instance. A crossover point of 200 – 250Hz for this application is quite useful.

Conversely, I can use the 2x10 to drive the low end, and use the upper amp to drive a more mid/upper cab, such as one designed for a guitar. Here, the 1500 – 2000 Hz range is useful.

By utilising this, an extended range bass like a 6 string, or a baritone guitar, or a keyboard, or even electronic drums or acoustic guitar can be amplified much more effectively.

Crossover frequencies that you talk about (4kHz – 5kHz) are for driving dedicated tweeters and only really useful if you’re tri-amping in the first place.

And the main advantage of bi and tri amping is NOT to gain more power…as one poster said, the gain is actually quite minimal.

The advantage is in phase distortion. Trying to reproduce wide ranges of frequencies through a “one size fits all” cabinet with a single frequency range amp is not always easy (the cabs can get expensive).

By bi-amping and using 2 sets of dedicated cabs (or tri-amping and using 3 sets), you can produce a much cleaner, more accurate and harmonically-rich result.

[PilbaraBass]

Originally Posted by BassmanPaul

Even with a properly designed Bi-amp rig the high range drivers should still have some kind of high pass filter in the cabinet. Just 'cos an amp is only fed with a high range signal doesn't stop it from outputting low frequency crap coming off the AC mains.

Paul

Actually, the only reason you’d put a high-pass in the upper side cab of a biamp system is to prevent you from making a mistake, hooking it up to the wrong amp, and blowing the voice coil out of your speaker that was NOT designed to handle the low frequencies.

This is because of the differences in the Xmech between a woofer and that of a mid-range driver.

[MIJ-VI]

"What does the term "Bi Amp" mean?"

Bi-amp: a euphemism for 'experiment a little in college'.

[Zooberwerx]

I don't bi-amp my bass rig but I do bi-amp our PA. I've read a couple of posts where folks are setting their xovers @ 200-300 hz and sending the high-end to 2 x 10 bass cabs which, more than likely, are quite capable of handling a near-full range signal (~50 hz > whatever). I'm not sure I understand the rationale so I'll pose this question: Is this actually the most efficient method of coaxing the "most" out of a 2 X 10 enclosure in a dual cabinet (mains / subs) configuration?

Riis

[MNAirHead]

Zoober.

I own about 10 bass amps + about 10 cabinets.... this ranges from everything from small 5 watts to fork lift sizes.

My opinion....

When I'm playing a 7 string, I like to add slight chorus and presence to the upper end. If I do this through amps without a crossover/biamp, it seems to lack clarity.

Using a Biamp setup, the chorus can be split to only the upper end.;.. in essence the 7 string becomes 2 separate basses.. a low one.. and the lower end of a guitars.

When playing a 5 string, I can dial in the lows to have a bit more compression distortion and leave mids/highs with clarity.

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The above being said.. I do not use production cabinets for a biamp and my setup was reversed engineered from a typical PA spectrum.

I know some of the folks will chuckle...

It's within the realm of possiblity that the biggest benefit of this is moving my 2x10 cabinet closer to my ears.

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My sad realization was that after spending the $$$$$$$ and time with cabinets etc, I quickly migrated toward IEM and DI... this moved the cabinets to my skull and then quickly became a triamp (with less gear).