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Bi-Amp question / thought


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So I have my SS set by N. Pass and it sounds great but as expected there is no real bass SLAM so I am considering Bi-Amping the cornscala, My question is this, Cant I simply disconnect the woofer from the Crossover, use the existing crossover for the top half with my set amp, and get an active crossover and a more powerful amp with Volume control for the bass section set the X-over at the same freq. as the original passive, and simply adjust the volume on the bass amp for integration of sound. 

 

thoughts ?

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Your crossover needs to be bi-wire-able.  You would need to get the low frequency section out of the power path because no telling what impedance the amplifier will see if you remove the woofer load (12db+ crossovers).  6db with only a coil the circuit will be open on typical crossovers.  This also depends on the the type of crossover along with the possibility of changing the frequency response some along with impacts on the actual crossover point and slope of the electronic crossover.

 

It would be much safer if your woofer and upper range were able to be isolated so you could remove the woofer section from the circuit.

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1 hour ago, pzannucci said:

 You would need to get the low frequency section out of the power path because no telling what impedance the amplifier will see if you remove the woofer load (12db+ crossovers).

I am no expert on such things but I was wondering the same thing.  The crossover was designed to produce an 8 Ohm load and if you take the woofer out (which consumes most of the power) the impedance would not be right.

 

In the four years I have been posting here I've never read about anybody running a passive HF section and an active LF.  I have to tell you it sounds like an interesting idea.  I hope you follow through with some more technical discussion to find out why this idea is, or is not feasible to produce the bass slam you want.

 

Maybe this will be your next million dollar idea!  B)

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It is most feasible if you can get the low frequency crossover out of the picture.  The key thing would be the phase / time domain and roll off since the passive high frequency and low frequency sections were designed to compensate for each other.

 

Edit: many electronic crossovers are 24db per octave.  Most default configurations are 12db on the passive.

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It shouldn't be that hard to bypass the hi-pass portion of the passive crossover and drive the mid/high drivers using the hi-pass of the active crossover.

 

If you could post a picture/schematic of the passive crossover, we could find out.

 

Mike

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I've been curious about the Xkitz products too. 

 

If you are willing to do some DIY, I'd be happy to send you a pair of Marchand XM1's with 500 hz modules, as well as the power supply for them.  They are unbalanced input/output only.  

 

Regarding Al's crossover, hopefully someone smarter than me will chime in.  It appears that the ends of the 33uf cap are soldered to copper (?) posts.  If one were to connect a 14 AWG wire with alligator clips to the two posts, would that not bypass the capacitor completely?  Now the crossover will only passively split the high pass signal from the active crossover to the mid and high drivers.

 

Mike

 

 

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If the mid/treble section isn't behind the woofer choke, you can probably just unhook one leg of the choke from the input terminal.  That will get the woofer completely out of the circuit.  If Al tied the mid/treble behind the choke for some reason, you can't do that.  I doubt it is though.

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On 5/2/2018 at 9:28 AM, wvu80 said:

In the four years I have been posting here I've never read about anybody running a passive HF section and an active LF.  I have to tell you it sounds like an interesting idea.  I hope you follow through with some more technical discussion to find out why this idea is, or is not feasible to produce the bass slam you want.

 

Since I physically time aligned the mids and tweets on my LS, it is something I am working on as well. I would use the 75wpc amp to drive the LS bottoms, and 2a3 amps (3.5 wpc) to drive the mid/tweets through the passive.

 

I am sure there are others on here who have done this. As Peter has said, the woofe portion of the crossover has to be out of the circuit. IOW, you just need a two way crossover for the mid/tweeters.

 

Bruce

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12 hours ago, Marvel said:

 

Since I physically time aligned the mids and tweets on my LS, it is something I am working on as well. I would use the 75wpc amp to drive the LS bottoms, and 2a3 amps (3.5 wpc) to drive the mid/tweets through the passive.

 

I am sure there are others on here who have done this. As Peter has said, the woof portion of the crossover has to be out of the circuit.

 

IOW, you just need a two way crossover for the mid/tweeters.

 

Your comment (bolded by me) exposes my ignorance of exactly how crossovers work.  If a 3-way has an 8 Ohm resistance, if you take the power hungry woofs out of the circuit, what would the mid and tweeter need to show?  Surely not an 8 Ohm load, but not 4 Ohm either.

 

Feel free to pose/answer a better question if mine is not the right one.

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Sure, a passive for a two way Jubilee is a nominal 8 ohms. You just have one that crosses over at 4.5k or 6k. The electronic crossover would then protect the mid by sending only 400Hz and up, or whatever the Cornscala woofer to mid gets. Exactly what The Dude states above.

 

A simple crossover is designed for the two impedances of a two way and an overall impedance.

 

Bruce

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Marvel, You are saying (I think) if I take the woofer disconnect it & bypass the cap, I would then essentially have a 2 way Passive sending only 500hz up to the mid and that crosses over again at 5800 for the tweet. and a load close to 8 ohm ?

 

I am going to try this no matter I just have to get the crossover when $$$ allows, I have a pair of Pass ACA set amps for mid highs, and a passive pre with 2 outputs so only needing a bass amp with a volume control, and the active crossover for the bass set at 500 HZ.

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13 hours ago, joessportster said:

 

I tried one of those with some La Scalas a few years ago and could hear some background hiss at low volume music listening.

 

 

 

On ‎5‎/‎2‎/‎2018 at 4:16 AM, joessportster said:

So I have my SS set by N. Pass and it sounds great but as expected there is no real bass SLAM so I am considering Bi-Amping the cornscala, My question is this, Cant I simply disconnect the woofer from the Crossover, use the existing crossover for the top half with my set amp, and get an active crossover and a more powerful amp with Volume control for the bass section set the X-over at the same freq. as the original passive, and simply adjust the volume on the bass amp for integration of sound. 

 

thoughts ?

 

Maybe your room acoustics are affecting the bass response. Does the bass sound better in a back corner of the room, or on the other side of a doorway into another room. If so, you may have standing waves causing a null at the listening position. Eliminate that possibility before spending money on more equipment.

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Not sure if this helps, but here's a Type-A-BA (bi-amp) crossover I'm working on.  SInce the active crossover replaces the 2.5 mh inductor (low pass filter) and the 13 uf capacitor (high pass filter) of the Type-A crossover, all that remains is an autoformer and 2 uf cap.  I even went so far as to reverse the function of the autoformer.  Instead of attenuating the mid by 3 db, the autoformer passes a 3 db gain to the tweeter.  

 

Since I'm using the same amp type for the low and high pass, I run the low pass amp at full volume, and the high pass amp at around 12 o'clock.

 

Mike

 

 

IMG_0275.jpg

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On 5/2/2018 at 4:16 AM, joessportster said:

So I have my SS set by N. Pass and it sounds great but as expected there is no real bass SLAM so I am considering Bi-Amping the cornscala, My question is this, Cant I simply disconnect the woofer from the Crossover, use the existing crossover for the top half with my set amp, and get an active crossover and a more powerful amp with Volume control for the bass section set the X-over at the same freq. as the original passive, and simply adjust the volume on the bass amp for integration of sound. 

 

thoughts ?

  since you're already a fan...

 

41887289662_1a035f026f_c.jpg

41213311974_2f1365701f_o.jpg

 

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