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Can someone explain crossover to me please...(RF-7ii) thanx !


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hi again everyone, in the last 6 months i've gone from a little "ghetto blaster" to now i'm ready to biamp my rf-7ii's... i think i have all the toys i need... all i have to do is set up my tube active crossover...i just have no idea what this means....(besides i have to "operate" on my speakers)

here's what i have : pair of RF-7ii's (fronts)

Audio Research VT-50 (tubes for my horns)

Yamaha M-85 (solid state for my mains)

Luxman A2003 tube active crossover (6 or 12 db slopes) this is a 2 or 3 way crossover and the crossover can be changed by changing the caps on the molex connectors

Onkyo HT-RC370 receiver (somehow i'd like to keep this in my system becuase i can go from 2 channel to 7.1 in a flick of a button)

Audio Research SP-9 tube preamp (not hooked up at this point becuase i don't know how or where it fits in the system)

Klipsch SW-115 subwoofer

pair of RF-82's for my surrounds

RC-52 center channel (way too small but for now all i can afford)

here's my question.......the crossover point on my RF-7ii's is 1200 hz... becuase it's a 2 way speaker do i set my active crossover to 1200 hz and up for my horns and 1200 hz and down for my lows ? am i way way too far in left field ? (i know i know nothing about what i'm about to do ! lol ! but i'm going to do it anyway ...

everytime i "do something different" to my gear it sounds better....biwiring, then having solid state and tube amps working together...now i want to take the plunge, go active and never ever EVEN THINK ABOUT buying more stereo equipment ! lol ! ....i can't afford it any more !...

thanx for the help everyone ! i've read and used almost everyone's advice so far and it's really helped !

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A passive crossover not only divvies up the frequencies for the appropriate drivers, but may also have baffle step compensation and/or specifically address the particular response of the drivers. I don't think your tube active crossover can adequately model what the passive RF7 crossover does. Your plan is a shot in the dark at best. I wouldn't do it.

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Thanx for the response ! (not really what i wanted to hear...lol !) I'm not afraid of going active. (at least to try it) it's a simple operation on the speakers and easily converted back if i don't like it. it seems everyone that's gone active loves it and the folks that haven't are afraid to try (therefore they don't like it) the hard part is setting up the crossover to match the speakers (and that is what i don't know about )...lol ! i'm hopeing someone could explain this to me...i did hook up the crossover for a few mins and it sounded good (the highs were too low becuase the crossover isn't yet set up properly) but i can tell that there's a definite "possibility" of it sounding great...do you (or anyone out there) know if all the highs are above 1200 hz and all the lows below ? is that what the 1200 hz crossover point means ? thanx again !

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I always caution tweakers to take a cautionary approach to active xovers. In better quality speakers the original passive design is engineered for the specific speaker system. The designer knows that “perfect world” theoretical applications of filter design go out the window using actual drivers in actual enclosures. The theoretical design may be a starting point but rarely survives in the final design.

Inserting an active filter into the system takes you back to the “perfect world” point though some features allow you some added flexibility such as adjustable slopes and gain controls to match driver sensitivity. If the drivers you use are relatively flat around the xover point you may have good success with off-the-shelf filters. This is often the case crossing a woofer to a mid where each are well behaved an octave or so around the xover point.

You may not be so lucky in the case of the RF-7. The passive design likely compensates for the diffraction loss with woofers on a narrow baffle as Ski Bum mentions. The high filter likely has some equalization built in to compensate for the horn response fall off at higher frequencies. I could go on with other examples but you get the point.

A xover point is where the frequency response is transitioning. A high pass filter set at 1200Hz means frequencies above 1200 are allowed to pass but roll off below that frequency at a graduated rate. A typical design will have the response already down 3-6 dB in magnitude at the 1200 Hz xover transition point and continue to attenuate going down in frequency so many decibels per octave depending upon the filter configuration. A low pass is the inverse.

Tweaking can be fun and I say try it but be honest with yourself in whether this change results in an improvement.

[edited for clarity]

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That means above 1200Hz the lower freqencies will be cut by 6-12db at 2400Hz? High-Pass Filter: A high-pass filter blocks (attenuates) the low
frequency signals below the cutoff frequency, but passes high frequency signals.
It is sometimes called a low-cut filter. The high pass filter in most modern
receivers have a 12 dB / octave slope, http://forum.blu-ray.com/showthread.php?t=95817.

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....i'm still stumped ! but, thanx for the reply !....i think i spent alot of money for what i've been told is a super top notch crossover (and not from the seller) but "you gotta know how to use it"....(it was actually described as a f-16 fighter jet....if you're a trained pilot you have the best...but if you're a regular guy.....it a'int flying and it's gonna run like s#@* !) i guess i'll have to figure this thing out....the luxman has molex connectors that the crossover points can be changed by swapping caps...it also can be "fine tuned" after that (dials and stuff)...i'm still convinced that it's a great unit and that i want to try going active... i just have to figure out how to set it up...i think i've started a new "obsession"....lol !...problem is i'm as dumb as a stump and...bullheaded too...no electronics experiance what so ever...no friends...lol ! well, some but they look at me like i have 3 heads when i talk about "biamping" or "tubes".....

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In this day and age most folks that go active use a digital processor. With a DSP you not only get a variety of slopes but also any exact crossover frequency the speakers require at the touch of a button. You also get parametric EQs, delays, and limiting. The tube unit, doubtless good in it's day, is pretty much obsolete nowadays. Behringer makes a DSP for about $300 with all of the bells and whistles that many around here use with good results.

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  • 6 years later...

I God a Luxman 3 Way all tube Crossover unit The fact settings are at 500hz to 4000 hz i like to know if i can change the settings with the Frequency Shift  knob it goes up from zero to 5 steps + or -  please explain should i want to set it to around 600 hz to 5000 hz how can i shift the Frequencies.

Kind Rgds

Frank Jansz

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6 hours ago, Frank Jansz said:

I God a Luxman 3 Way all tube Crossover unit The fact settings are at 500hz to 4000 hz i like to know if i can change the settings with the Frequency Shift  knob it goes up from zero to 5 steps + or -  please explain should i want to set it to around 600 hz to 5000 hz how can i shift the Frequencies.

Kind Rgds

Frank Jansz


Oh, I wish I had a great animation, WAIT!!! Youtube is GREAT:
 


John Kuthe...

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8 hours ago, Frank Jansz said:

I God a Luxman 3 Way all tube Crossover unit The fact settings are at 500hz to 4000 hz i like to know if i can change the settings with the Frequency Shift  knob it goes up from zero to 5 steps + or -  please explain should i want to set it to around 600 hz to 5000 hz how can i shift the Frequencies.

Kind Rgds

Frank Jansz

 

Don't you have a manual?

 

What's the model number of the unit?

 

Did you google the model number to see what kind of information you could find on it?

 

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On Wednesday, July 04, 2012 at 6:37 PM, Kev the ironworker said:

....i'm still stumped ! but, thanx for the reply !....i think i spent alot of money for what i've been told is a super top notch crossover (and not from the seller) but "you gotta know how to use it"....(it was actually described as a f-16 fighter jet....if you're a trained pilot you have the best...but if you're a regular guy.....it a'int flying and it's gonna run like s#@* !) i guess i'll have to figure this thing out....the luxman has molex connectors that the crossover points can be changed by swapping caps...it also can be "fine tuned" after that (dials and stuff)...i'm still convinced that it's a great unit and that i want to try going active... i just have to figure out how to set it up...i think i've started a new "obsession"....lol !...problem is i'm as dumb as a stump and...bullheaded too...no electronics experiance what so ever...no friends...lol ! well, some but they look at me like i have 3 heads when i talk about "biamping" or "tubes".....

Dear Friend. 

I too own a 3 way All Tube active Luxman Crossover.  This unit is factory Set at 500hz to 4000 Khz. I need the Caps Values on The C 1 and C 2 So i can chsnge the Frequencies to 600 hz to 5000 Khz any ideas will help. And this model has a Frequency Shift Knobs on it i need to know what does it do can it Change the Frewuencies from what it is set at any help will be Appreciated.

Kind Rgds

Francis Jansz

My Low End Klipsh k33E specs state that it works from 50 hz to around 600 hz my 2 "Throat Midrange Horn Drivers works fown to 600 Hz and up to 12.KHz  my tweeters start from 5000khz and works up to 18.000 KHz.

Please explain .

Kind Rgds

Frank Jansz

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On Saturday, October 06, 2018 at 1:56 AM, Deang said:

I googled the Model no A 2003 3 way all Tube Luxman Crossover unit. And got no where. Please Help.

Rgds

Frank Jansz

Don't you have a manual?

 

What's the model number of the unit?

 

Did you google the model number to see what kind of information you could find on it?

 

Luxman A 2003

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1 hour ago, Frank Jansz said:

Dear Friend. 

I too own a 3 way All Tube active Luxman Crossover.  This unit is factory Set at 500hz to 4000 Khz. I need the Caps Values on The C 1 and C 2 So i can chsnge the Frequencies to 600 hz to 5000 Khz any ideas will help. And this model has a Frequency Shift Knobs on it i need to know what does it do can it Change the Frewuencies from what it is set at any help will be Appreciated.

Kind Rgds

Francis Jansz

My Low End Klipsh k33E specs state that it works from 50 hz to around 600 hz my 2 "Throat Midrange Horn Drivers works fown to 600 Hz and up to 12.KHz  my tweeters start from 5000khz and works up to 18.000 KHz.

Please explain .

Kind Rgds

Frank Jansz

My Amps are as Follows Bottom End Amp Solid State Amcron Power Line 3 about 70 watts per Channel in Class A and it work at 8 ohms at 4 Ohms and at 2Ohms

 

Midrange All Tube Cary 6 Pack mono Block class a at 8  ohms and 4 Ohms  50 watts on Class A operation

My Third Amp for my JBL 2402 Super Bullet Tweeters is . Single Ended Class A  15 watts per channel ising 1150 Volt Double C Core Transformer Gives out 15 watts on each mono block and uses 2 X  6SN7  and one  211 Output Tube.  Great  Amp  Designed by a 80 years Audio Engineer who has been working on Tube Amps for Just over 57 years .

Hope this will Help

 

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