Im now vertically passive bi-amping, using 2 power amps. From everything Ive read it seems this will only give me a small benefit while Im still using passive crossovers, and that I should go to an active crossover. This apparently has to do with the full signal bandwidth being sent to each speaker and being divided up on site by the crossover. If using an active crossover, then the power amp is only amplifying what it needs to rather than the entire signal.

Thats cool, I will save up and buy a <strike>Behringer</strike> DEQX one day.

BUT! What about making some passive crossovers and placing these between the pre and power amps (and of course removing the crossovers from within the speakers). Thus the power amps will only amplify what is necessary for the drivers they feed rather than the whole bandwidth.

In my mind this will have the same result as an active crossover, its just that you wont have any immediate control over the crossover points/order etc.

I suggested this to a mate and he said he thought there might be some issue with capacitance.

Any ideas?

Im now vertically passive bi-amping, using 2 power amps. From everything Ive read it seems this will only give me a small benefit while Im still using passive crossovers, and that I should go to an active crossover. This apparently has to do with the full signal bandwidth being sent to each speaker and being divided up on site by the crossover. If using an active crossover, then the power amp is only amplifying what it needs to rather than the entire signal.

Thats cool, I will save up and buy a Behringer one day.

BUT! What about making some passive crossovers and placing these between the pre and power amps (and of course removing the crossovers from within the speakers). Thus the power amps will only amplify what is necessary for the drivers they feed rather than the whole bandwidth.

In my mind this will have the same result as an active crossover, its just that you wont have any immediate control over the crossover points/order etc.

I suggested this to a mate and he said he thought there might be some issue with capacitance.

Any ideas? [/b]

Well, that's OK, however I was delighted to find that passive bi-amping made a world of difference to my system. And, mind you, this was against all my expectations and indeed was something that I tried with very little enthusiasm, particularly after doing the same sort of research that you have done.

Has your current set-up benefited from the passive bi-amp arrangement?

I should say that in my case I am using valve monoblocks for the main speakers and a separate solid state pre and power amp arrangement for the bass. Works a treat. So, I think that in marginal cases a passive bi-amp may be quite sufficient.

You would get even more benefit than that, Jake. With the kind of arrangement you are proposing, you would have the following advantages:

- Less work for each amplifier - the mid/high power amp will not have to deal with bass frequencies

- No insertion loss from the passive crossover = more available amplifier power

- No crossover network in the way = better control of back-EMF

HOWEVER, there are a few negatives:

- your preamp selection becomes critical - inserting a passive xover network between preamp and power amp increases the impedance and provides more issues with impedance mismatch,

- depending on the slopes you wish to achieve you may have issues with phase

... this is why an active crossover like the DEQX is so attractive, however this depends whether you believe that the DEQX (which redigitizes your signal and then reconverts it to analog) is acoustically transparent or not. Probably an even better solution would be to run digital into the DEQX, and then from DEQX to power amps.

Probably an even better solution would be to run digital into the DEQX, and then from DEQX to power amps.[/b]

Run digital into the DEQX? I presume you mean a digital cable (optical/coax) from source (OK from Denon). How do I achieve this from a TT? Or does the DEQX have an ADC as well (too lazy to check specs after vino)? I cant really believe this can enhance my experience...(wanna-b-purist here )

The DEQX will digitize the signal from your turntable and then reconvert it to analog for output to the power amps.

The DEQX will digitize the signal from your turntable and then reconvert it to analog for output to the power amps.[/b]

Keith, thanks for the info. I have to say that after being so skeptical of the DEQX and its derivatives I am starting to come right around. Having read glowing reviews just about everywhere I look on the net makes it sound like we should all have one in our system.

Has your current set-up benefited from the passive bi-amp arrangement?[/b]

Good question mustud. Adding the second amp for me basically enlarged the soundstage, and seemed to give me better definition between voices. I wouldnt say it was a quantum leap, but it was definitely an improvement. Mind you I got that kind of a result just from hicapping my first amp before the 2nd arrived.

Im not sure about it being enough though. I will probably end up getting hold of a DEQX though at some stage. After hearing my mate's speakers tri-amped with actives mine has never sounded the same again...

My gear is all boxed up and moving it to my new house tomorrow, so I will have to see how it all sounds in the new joint.

On another forum Rod Crawford of Legend Acoustics and previously Linn says now that he's using the 96/24 beta update on his DEQX, he's very pleasantly surprised how good his Linn LP12 sounds through the analogue inputs on DEQX. So yes, it goes through an ADC, but it sounds good. But for a CD source you'd use the digital inputs and avoid the initial ADC.

And of course if you feel the DAC's in the DEQX really aren't up to the task, you can order your DEQX with digital outputs and use your favourite external DAC's. But if you're biamped or triamped, then that means 2 or more DAC's. That can get expensive.

I,m looking at putting the passive components in front of the amps as well need to do more research .If I could drop 4K on the DEQX I would and build 2 more dacs . Have a look at this site about passive parts http://www.audio-consulting.ch/ .

Cheers .

- your preamp selection becomes critical - inserting a passive xover network between preamp and power amp increases the impedance and provides more issues with impedance mismatch,

- depending on the slopes you wish to achieve you may have issues with phase[/b]

Keith, I believe that the impedance output of my preamp can be changed?

And as for the crossovers I was going to mirror those that Audiovector have already made (2nd order). Actually, as the speakers are already tri-wirable then cant the crossovers be simply removed from within the speakers and placed inline between pre and power amps. Then phase is sorted as it is now, and impedance remains the only issue, and surely thats just a matter of measuring it and then modding the preamp accordingly.

(sorry for all the questions!)

I,m looking at putting the passive components in front of the amps as well need to do more research.[/b]

56oval, good to see someone else is on to this!

Actually, as the speakers are already tri-wirable then cant the crossovers be simply removed from within the speakers and placed inline between pre and power amps.[/b]

Hello Jake,

The crossovers can be removed form the speakers of course, but this same crossover is of no use to you with line level signals out of the preamp into the power amp. Inside the speaker the crossover sees a nominal 4 or 8 ohm load from the driver. A crossover placed between the preamp and power amp would see the input impedance of the power amp as the load- typically 10,000 to 100,000 ohms.

You could design something to work passively between the preamp and power amp, but it obviously would need R&D/measurement to work well and protect the drivers and even then there would be compromise. I have done something like this using a simple high quality capacitor to act as a 6dB/Ocatve high pass filter to take the load of the main speakers for use with subwoofers. I wouldn't push it much more than that- an active device would be far more flexible and drive the amplifiers with greater ease.

Best

JA

Hello Jake,

The crossovers can be removed form the speakers of course, but this same crossover is of no use to you with line level signals out of the preamp into the power amp. Inside the speaker the crossover sees a nominal 4 or 8 ohm load from the driver. A crossover placed between the preamp and power amp would see the input impedance of the power amp as the load- typically 10,000 to 100,000 ohms.

You could design something to work passively between the preamp and power amp, but it obviously would need R&D/measurement to work well and protect the drivers and even then there would be compromise. I have done something like this using a simple high quality capacitor to act as a 6dB/Ocatve high pass filter to take the load of the main speakers for use with subwoofers. I wouldn't push it much more than that- an active device would be far more flexible and drive the amplifiers with greater ease.

Best

JA[/b]

Well there goes my simple solution JA! I knew there had to be a catch otherwise everyone would be doing it. Although I have made my own speakers and crossovers in the past (and quite succesfully) there is still so much I dont know. Thanks for clearing that up.

I can see that R&D would certainly be required. Just one more reason for me to head towards a proper active solution.

Just doing some good reading on the whole subject here at:

http://sound.westhost.com/bi-amp.htm#basics