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Bi-amp Crossover Question


ssh

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Well, I was wrong. I will try a variety of configurations of Tri-amping. I Hope this is more fun than frustrating. Bi-amping a 3 way system seems to have more headaches than tri-amping, if one has the amps. I do, so...I'll keep you posted. Yes, with pics.

SSH

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Erik,

Initially, I think I'll start with the Bogen 232A @ bass, The JFL 2A3 monoblocks @ mid, & the Scott 299A @ high. I have a Pioneer VSX-D1X that I may try at bass just for fun. I'm prepared for some initial dissatisfaction while working-out problems. I can always hook-up a pr of LaS to an amp for some tunes, if needed.

SSH

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Erik,

My rational, exactly. That's why I tried to bi-amp. My 2A3 amps are somewhat different from the Horus, but with splended detail. But the clencher was that the amount of info going to the tweeter is minimal, compared to the problems of trying to seperate mid/highs in a bi-amped system. There is a difference in detail between each amp, but I'll give-it-a-go & see. I may wind-up with a SS bottem end, or going back to a single amp.

SSH

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What's a Marchand XM44-2? An active crossover?

I'm planning to bi-amp my Khorns too. I have a resistor circuit in my JFL Horus' to cut out low frequencies below 400hz at a 6db per octave slope. I doubt this simple resistor will take away from the sound quality of the Horus' like the last electronic active crossover that I tried did.

Adding the active crossover into the signal path ruined the sound quality, just like an equalizer or any other op-amp-heavy piece of gear has done.

Greg

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You should always read your manual. :)

Ignore the attachment, I flipped the picture the wrong way with my image editor -- the right one is in the next post.

Biamping with the ALK

This network was not designed for bi-amp operation but can be adapted to do so.

The cable to the woofer driver may be removed from the network and connected

directly to a separate amplifier. The picture shows a scheme that can be easily

done to totally bypass the 400 Hz woofer / tweeter crossover section of the

network. To do it, simply connect the high frequency amp negative (-) cable as

you normally would. The positive cable is placed under the screw holding the

terminal where the 2.2 uF Hovland, 39 uF Fast-Cap and 1 uF Harmony bypass join

together. Note that the woofer terminals are left totally open with NOTHING

connected to them. Anything connected to the woofer output (like a load

resistor) will cause the 2.4 mHy inductor and 39 + 1 uf capacitor combination to

generate a broad notch at about 514 Hz. You don't want that! This happens because

of the connection back through the fuse. A low level electronic crossover network

should be used ahead of the two amplifiers such that all signals 400 Hz and below

are sent to the woofer amplifier and all those above 400 Hz are sent to the

amplifier driving the crossover network...

post-3205-1381925950574_thumb.jpg

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Take advantage of the strength found in the ALK -- a well developed filter for the top hat section. I don't give a crap what anyone says -- there ARE major inherent advantages in a good passive design. You are not going to be able to replicate the complexity of a well designed passive with an electronic crossover. The idea is here is to take a major load off of your 300B's and pass it on to something that will move and control the woofer. So, use the HF section of the ALKs with your JFL's, and an electronic crossover with a pro-style amp like a QSD with gain controls for the bass. Keep it simple, avoid the headaches, and enjoy the music.

download.asp?mode=download&fileID=33920&

post-3205-1381925950681_thumb.jpg

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"I have a resistor circuit in my JFL Horus' to cut out low frequencies below 400hz at a 6db per octave slope."

Please tell us about this circuit.

I've been digging around trying to learn more about the issue of how a tube amp responds to passive biamping. The only thing I could find was this: As usual, interesting, but not always completely helpful.

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1056264858&openfrom&7&4

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I am not sure how a single resistor on an amp's input will act as a filter.Is it not maybe a capacitor? If so, this is a very elegant approach.There are a few caveats though;at 6 dB oct your signal will only be 6dB down at 200Hz and 12 dB down at 100Hz.Most compression drivers won't like that.The phenolic diaphragm in the K may not mind but Al,Ti,Be diaphragms may shatter,rattle or phone their union.I doubt if the K400 horn will go that low,but you may introduce audible distortion.

The problem with bi amping the K horn and most full horn speakers is that the mids are usually more efficient(sorry -sensitive) than the tweeters i.e mid 110dB/W and tweeter 104dB /W.(The only 110dB/W tweeters I could find are from ALE and Goto.Considering that these are more expensive than a whole Klipschorn,this is clearly not an option). That would mean leaving the autoformer or padding resistors in line after the amp,thus negating most of the advantages of multi amplification(in the mids at least).If one uses SET amps this will probably make for a more difficult load.After battling this for more than 6 months ,I finally came to the same conclusion:Rather tri amp Khorns than bi amp.

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Yes,I do use triamped horns.I should probably be banned for what I have done to a legendary design,but if Klipsch won't do it and JBL abandoned full horn designs 50 yrs ago,I'll just have to pretend I'm clever- even if it's difficult.

Whole system in the profile section or pics and description at www.aca.gr/pop_dreyer.htm 15.gif

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Good point

Initially I was very reluctant to put the tweeter there because of a.possible reflections and b.what I felt could be excessive distance between the tweeter and midhorn.Initially I had the tweeter right on the front of the midhorn where it sounded the worst.It measured the best sitting on top and halfway along the depth of the mid,where it sounded worst.Karel Schees ,who started this whole mess, predicted the tweeter and mid voicecoils at the same depth would be the best and he was right.

I have tried damping the top of the midhorn but frankly could hear no difference.the fact that the tweeter only comes in at 12k may make a difference ? That it enters at 12k and fades at 19k makes the whole idea of a separate amp for less than an octave absolutely stupid-but take it away and everything ,including the bass collapses-I wish someone could explain that!Maybe I should save up for a TAD tweeter that will reach 40k.At least the amp will have little more to do and it may enrich my dog's listening experience?

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interesting, I have heard others mention "collapse" when making moves with the tweeter, it seems to affect the soundstage, imaging and the perceived response all up and down the frequency spectrum. I plan to install my 2404Hs during the christmas break, probably starting with top mounting like you. regards, tony

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Be careful

Before long you start thinking -maybe I can improve the mids a little too.Then maybe the midbass (200-400 Hz fill out the khorn there a little),maybe add a midbass horn ,a Sato horn maybe-mouth only 30"x 30".Then you start eyeing the walls of the house-maybe a straight horn in concrete built where the backyard used to be.Before long you'll have this

www.belgaudio.com/auditoen1.pdf

or this

http://perso.wanadoo.fr/francois.mastroiannidiy/M%20Rogerro.htm

2.gif

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I guess you missed my posts about building the triamped klipschorn frankenstein...altec 311 mid with 290 driver, the 2404H tweeter, my 2A3 driving the mid, my EL34 driving the bass and my tripath driving the tweeter...ideas taken from john and q-mans experiments...I am still collecting parts for the project and trying to decide on the active crossover to use...regards, tony

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