Passive line filter

Hello Members,

I want to tweak my passive crossover to the room and my taste
so I found the following instructions on this forum.

The bigger the first cap the more deeper the bass.

Reduce the last two caps values to bring up the mid-bass.

Are there Oris 150 user who are using a second order crossover :no:

I have the Oris 150/AER-MD1 and the Reference bass.

Correct me if I am wrong

Let me know...

Martin.

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Hello Martin,

Best way to find out what you'll need to change is to play with the volume of the bass until the crossover range sounds okay (i.e. enough warmth and body in the sound) while doing the same with inverted phase on the bass or the Oris 150's.

When that point is set then listen to the deeper bass and you'll have a better idea what it is in the sound that is not to your liking. Then come back here and tell me what you would like to improve so that I can give some suggestions.

A picture showing your setup could help too to see your listening room so that I have an idea what can go wrong with that setup if appropiate.

The filter shown below is the correct present one for your system...

Is this the filter you are using? If so, what is the input impedance of your bass amplifier?

[img]images/uploaded/image372.jpg[/img]

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BD-Design - Only the Best!

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Here a picture of the set, taken from de listening spot [img]images/uploaded/image378.jpg[/img]
Yes, that is the filter I am using, the input impedance of the bass filter is 100Kohm.The bass amps are Gainclones with an input buffer.The only difference in my set-up is that the crossover is located between my pre-amp and bass amps, the output impedance of the pre-amp is 1Kohm. :blush:
Mattijs de Vries advised to increase the resistors 20x for a better load of the pre-amp and the caps decrease also 20x to get the same crossover point. The pre-amp has a special bass amp output with an extra gain of 20db.

I hope you can follow the set-up :grin:

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Hi Martin,

Nice setup!

Why do you use the filter between your pre-amp and the bass amp? It was not designed for that use....that filter should be connected between the output of your main amplifier and the bass amplifier....

If you have enough gain(!!) then you can use such a filter between the pre-amp and bass amp but in that case I would increase the value of the resistors and at the same time reduce the value of the capacitors.

10x resistor value means ten times less value for the capacitors for the same filter character.

If you are using a buffer for the bass amp then connect the filter after that, this will then influence the output of your pre-amplifier the least..

Bert

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Bert,

I came to this set-up because I was so stupid to buy a set of expensive
output transformers for my new tube amp with a bandwide of up 100hz :blush:
The pre-amp has an extra gain of 10 for the bass amps, gain is no problem.
Mattijs advised 20x resistor value and of course 20 times less for the capacitors.
If I put the filter between the buffer and the bass amp the output impedance of the buffer is 600 ohm, the input impedance of the bass amps are approx. 20K ohm , but there is a possibility to increase this to 50Kohm.

Martin.

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Hi Martin,

The pre-amp has an extra gain of 10 for the bass amps, gain is no problem.

If this means that your pre-amp has two seperated outputs then you can connect it in front of the buffer.

Both output impedances (pre and buffer) have the same problem (being too high compared to the input impedance of the amps...) to be able to succesfully use the line level filter. Increasing the resistor/capacitor values as suggested before will make something completely different out of the filter as the output impedance should be much less compared to the first resistor of the filter and the input impedance should be much higher compared to last resistor of the filter).

You could use the buffer to create an active filter around that though (if it is an IC).

Check out the Linkwitz pages for formula's and schematics...

Or exchange the buffer for a small amplifier (IC?) with very low output impedance (0-10 ohms) to "imitate" a real amplifier so that you can use the passive line filter as intended.

Bert

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BD-Design - Only the Best!

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Bert,

Yes the pre-amp has two separated outputs, the bass output has an extra gain of 10. Off course I contacted Mattijs de Vries (the designer of the bass pre and buffer) and he was convinced that the crossover can be used, by increasing the resistor values. Because of my minimal knowledge in this respect, I am forced to seek advise by more specialised people and Mattijs advised me to start with a second order crossover and to chop off parts from the original fourth order crossover.

After this experience I contacted Tribute Audio and let them make a couple of broadband output transformers, because I just want to listen to music :shame: ! Unfortunately the good man also came with the idea to implement a passive line filter... :blush:

I found some lines about "pllxo" filters, but that is not the solution.

Please give me some advice.

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Hi Martin,

Please give me some advice.

I did gave you the options in the previous answer. What else can I do if you do not read or ignore them?

Best option would then be to follow Matthijs' suggestion and contact him for more details as he claims that a 12dB passive line filter will work just the same in combination with your equipment.

I do not have the same situation here as you have and therefore unable to try out things to find another solution.

Another idea might be a combination of a passive filter (12dB between bass amplifier and BD15) and a 6-12dB line level filter do the trick?

Bert

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Hello Bert,

I am done with all the filter stuff, the whole set-up is back to your orginal design and finally it plays music again:wink:
No more experiments for me :blush:

What is your advice "the horns crossing in front of the listening position or after".

I wish you all Merry Christmas and a happy 2008.

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Hi Martin,

I am done with all the filter stuff, the whole set-up is back to your
orginal design and finally it plays music again

It plays music again... :good:

No more experiments for me

It is always good to experiment... :wink:

What is your advice "the horns crossing in front of the listening position
or after".

I usually prefer to have them crossed behind me but with the horns close to the side walls it migth sound better to cross them in front of you (less reflections from the side walls which is not always a bad thing though...).

I wish you all Merry Christmas and a happy 2008.

Thanks, same to you!

Bert

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Hi Bert, please allow me :

...that filter should be connected between the
output of your main amplifier and the bass amplifier....

... between the output of the main amplifier and the input of the bass amplifier.

Just before things explode. :heat:
But maybe it was already clear.

Peter

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Hallo!
I´m using the BD 15/Oris 150 combination for bass and an own horn-system above.
I ´ve placed the passive filter between preamp and bass-amp, starting with a value of 1 kOhm for the first resistor.
I know, the filter was intended, to be used after the main amp, but I simply didn´t want the "bass-performance" of a set amp putting the signature on the bass system. My preamp can drive any impedance down to 40 Ohms, so that is no problem.
The matching of the single components I did first with measurements ( electrically and acoustically especially frequency response, phase, step response , group delay, dynamics) the fine tuning was made with long listening tests. I ended with about 20 % different values for the capacitors. But that is a different system, matched to one room and one listening position.
I also tried an active x-over, but was not satisfied by the sonics.
Best regards
Stephan

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