BI-AMPING

[mas]

Its the updated version! We don't use 'none of that old stuff 'round here'! [] [:$][:S]

And for the record, I am thoroughly intimidated by your response. And as a result, I don't think that I can recommend this site to any of my friends!

[pauln]

Paul----Every active crossover I've seen has adequate controls for adjusting levels. From your description I'm not sure you understand what bi-amping is.

Well, that's entirely possible. I don't bi-amp. Are you positing that real bi-amping means that the crossover function occurs before the power amps so that the signals are frequency range specific to the drivers? Since the signals are going to drivers with crossovers already in place within the speakers, is it necesseary/beneficial to limit the signal before it gets there? Won't the crossovers local to the drivers handle the full signal frequency range properly?

Or are you saying that in a true bi-amping scenario there is no crossover funtion at the drivers - that the signals already banded from the crossover before the amps goes from the amps directly to the drivers? If this is so, are there names for the various degrees of bi-amping?

[ben.]

mas, I'm holding out for the 2012 version as I hate to have an obsolete version. I may even pay a little extra for it if I can find it in the fall of 2011. Forward thinking... that's me!

Paul - didja really read all the posts in this thread?

[TBrennan]

"Are you positing that real bi-amping means that the crossover function occurs before the power amps so that the signals are frequency range specific to the drivers?"

Yes.

"are you saying that in a true bi-amping scenario there is no crossover funtion at the drivers - that the signals already banded from the crossover before the amps goes from the amps directly to the drivers?"

Yes, exactly, from the amplifier directly to the driver terminals. No speaker level passive crossover.

"If this is so, are there names for the various degrees of bi-amping?"

1 Active bi-amping----use of an active crossover between preamp amd power amps

2 Passive bi-amping----use of passive filters between preamp and power amps

3 Fool's bi-amping----sending 2 fullrange signals to the high-pass and low-pass legs of a speaker level passive crossover

[TBrennan]

Passive bi-amping

[TBrennan]

Fool's bi-amping

[ben.]

Kudos, TB. I appreciate that you took the care to make the Altec and JBL compression drivers look right!

I shipped some of those big JBL lenses for my then-employer to Asia, and had to completely disassemble them so they would ship flat ala Ikea.

[pauln]

Thanks TB, now I feel educated, and I'm sure I'm not the only one here that enjoyed studying your artwork. Pauln

[FatElvis]

On "Fools Bi-Amping"....

If the speaker isn't asking for the full freqency, isn't the load on the amp reduced? E.G., filtering the full range at the passive crossover of the speaker reduces stress on the amp. Law of conservation applied... the "energy saved" has to go somewhere, and I assume that's back to the amp, allowing it greater power for low or high frequencies as needed The amplified signal doesn't simply "disappear" at the crossover.

"Fools Bi-Amping" should, theoretically, result in an easier load for the amplifier... as resistence at the the speaker is greatly reduced. No?

[Guest " "]

There's a reason why it's called "fools bi-amping"

Take a look at the last paragraph of the technical brief which explains how this can damage tubes.

Some Klipsch staff initally endorsed this practice, but after a few exchanges, retracted their position and defered to the recomendations of the manufacture of your amplifier.

In the case of solid state equipment, if you review schematics's, in most cases you will find only a 5 watt resistor from the emitter of the output transsitors to ground. This serves as a pathway in the event the amps are run with out a proper load. In the case of "fool's bi-amping", the blocked signals result in infinite resistance, the only place the power has to travel is back into the amp. It's called a reflective load.

McIntosh%20MC-275%20Bi-Amp%20Mode%20Technical%20Brief.pdf

[DrWho]

The amplified signal doesn't simply "disappear" at the crossover.

Correct, it's turned into heat.

[Guest " "]

The amplified signal doesn't simply "disappear" at the crossover.

Correct, it's turned into heat.

Correct, heat in the amp.

[cjgeraci]

There's a reason why it's called "fools bi-amping"

Take a look at the last paragraph of the technical brief which explains how this can damage tubes.

Some Klipsch staff initally endorsed this practice, but after a few exchanges, retracted their position and defered to the recomendations of the manufacture of your amplifier.

In the case of solid state equipment, if you review schematics's, in most cases you will find only a 5 watt resistor from the emitter of the output transsitors to ground. This serves as a pathway in the event the amps are run with out a proper load. In the case of "fool's bi-amping", the blocked signals result in infinite resistance, the only place the power has to travel is back into the amp. It's called a reflective load.

Good reference to the Mac caution, Fritz. However, If someone wanted to help minimize the potential strain and extra heat on the particular amp being used in "fool's biamping" (and increase the sound quality in doing so), couldn't you use a passive line filter between the preamp and amp to cut down most of the frequencies before they reach the individual amp? And then on to the applicable portion of the speaker's crossover?

For example, a passive high pass line filter at 200-300 hz for the upper end (usually where you would put the tubes)..........

Carl.

[Guest " "]

There's a reason why it's called "fools bi-amping"

Take a look at the last paragraph of the technical brief which explains how this can damage tubes.

Some Klipsch staff initally endorsed this practice, but after a few exchanges, retracted their position and defered to the recomendations of the manufacture of your amplifier.

In the case of solid state equipment, if you review schematics's, in most cases you will find only a 5 watt resistor from the emitter of the output transsitors to ground. This serves as a pathway in the event the amps are run with out a proper load. In the case of "fool's bi-amping", the blocked signals result in infinite resistance, the only place the power has to travel is back into the amp. It's called a reflective load.

Good reference to the Mac caution, Fritz. However, If someone wanted to help minimize the potential strain and extra heat on the particular amp being used in "fool's biamping" (and increase the sound quality in doing so), couldn't you use a passive line filter between the preamp and amp to cut down most of the frequencies before they reach the individual amp? And then on to the applicable portion of the speaker's crossover?

For example, a passive high pass line filter at 200-300 hz for the upper end (usually where you would put the tubes)..........

Carl.

Sure, a passive line level filter would be fine. At the line level stage, the parts costs for a passive line level filter would be very low.

[cjgeraci]

Wow, much better. I've previously tried "fool's bi-amping" with somewhat mixed results. Tonight, I inserted simple line level filters coming off of my tube preamp (and before my amps) - 200 hz high pass and 500 hz low pass respectively, 12 db slopes, and tried "fool's bi-amping" again. Just using a modded Dynaco Stereo 70 for the top end and a QSC PLX for the Khorn bass bins, I am getting a really clean [but sweet] sound. This is a keeper. I will have a nice dilemna once I get my Marantz 8B rebuilt.

Carl.

[cscmc1]

Just using a modded Dynaco Stereo 70 for the top end and a QSC PLX for the Khorn bass bins, I am getting a really clean [but sweet] sound. This is a keeper. I will have a nice dilemna once I get my Marantz 8B rebuilt.

Carl.

Nah, just TRI-amp!!!

[cjgeraci]

Just using a modded Dynaco Stereo 70 for the top end and a QSC PLX for the Khorn bass bins, I am getting a really clean [but sweet] sound. This is a keeper. I will have a nice dilemna once I get my Marantz 8B rebuilt.

Carl.

Nah, just TRI-amp!!!

Well, maybe sometime down the road. I can always move my rodded ALK srs. to my rear Belles later on.

And, for now, I have no desire (or extra funds) to shell out the $800-$1000 to get a decent active that I would want nor do I have the time or effort to tweek an active setup, including but not limited to time delay issues, etc.

So, its good enough for now..............

Carl.

[Guest " "]

Wow, much better. I've previously tried "fool's bi-amping" with somewhat mixed results. Tonight, I inserted simple line level filters coming off of my tube preamp (and before my amps) - 200 hz high pass and 500 hz low pass respectively, 12 db slopes, and tried "fool's bi-amping" again. Just using a modded Dynaco Stereo 70 for the top end and a QSC PLX for the Khorn bass bins, I am getting a really clean [but sweet] sound. This is a keeper. I will have a nice dilemna once I get my Marantz 8B rebuilt.

Carl.

Great news.

Curious the values of parts used, and the factors considered. Or did you find a nice website with a sample layout?

[cjgeraci]

Wow, much better. I've previously tried "fool's bi-amping" with somewhat mixed results. Tonight, I inserted simple line level filters coming off of my tube preamp (and before my amps) - 200 hz high pass and 500 hz low pass respectively, 12 db slopes, and tried "fool's bi-amping" again. Just using a modded Dynaco Stereo 70 for the top end and a QSC PLX for the Khorn bass bins, I am getting a really clean [but sweet] sound. This is a keeper. I will have a nice dilemna once I get my Marantz 8B rebuilt.

Carl.

Great news.

Curious the values of parts used, and the factors considered. Or did you find a nice website with a sample layout?

Actually, I cannot take credit for figuring cap values, etc. That kind of analysis usually hurts my head, and I'd rather leave those calculations to Dean. []

Instead, I referenced Al's graphs and crossover points posted on his website for the ALK, Sr. (which uses a 1st order for the bass bin and 2nd order for the squawker). Then, i purchased some of the preset F-Mods inline crossovers (brand - Harrison) that you insert directly in the chain of your RCA cables. I found that Crutchfield had a pretty nice collection of various frequencies to choose from and simply chose set frequencies close to (but above or below) where the speakers' networks would lop them off at the end - but instead I'm also cutting down the frequency signal fed the amp very dramatically early on in the chain. The F-Mods inserts are only a couple of inches long and simply plug into the feed coming from the preamp. I have not noticed any sound degradation (quite to the contrary). Two pair - to do upper and lower run about $60 or so. I could have done it cheaper, but this was the easiest way to do it. Obviously where you place the F-Mods is going to be dependent upon where the speakers' crossovers are doing their duty - and how steep the slopes are. Older Klipschorns have traditionally cut off at about 400-450 and 6000, and the AK4 I believe may do it about 450 and 4500 - with steeper slopes yet.

Carl.

[Guest " "]

I checked the Crutchfield site, those fmods look pretty good for Heritage B-amping.   I'm going to recommend this to folks who do not want to go active, and think they want to do fool's bi-amping.

 The 500hz hi-pass and 500hz lo-pass would do the trick. 

 Nice and clean little adapters. 

 Now if they had a 5000hz lo-pass and a 5000hz hi-pass, we'd be set for some tri-amp action. 

 We could in-line a 500hz hi-pass combined with a 5000 lo-pass to come up with a 500 - 5000 bandpass.

If you were not using integrated amps, you could also put in some cheap DIY passive pre-amps to adjust the levels.  I made some cheap passive pre-amps using niles type wall mount autoformers that worked amazingly well.