Which active crossover ?

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Hello,

I am wondering about an active bi-amp with analogue active two ways filter.
I've My-ref A and in the next future I will build also a My-ref FE. My CD player is Cairn FOG 2 and i like it :)
About the speakers, I've build à two way bass reflex with passive crossover. Since my speakers are on stand, I plan to build in the future two sub-woofers that will take the place of the stands. The crossover frequency will be between 80 hz and 120 hz.

So... my question is about active XO. In these days I am reading many discussions in this Forum about active XO, ESP, op-amp and so on. About Elliott Sound Project XO some people say that is "nice", other that it is a "first step". And everybody say that op-amp have their own sound. I am newbie and I am not able to design myself an active XO. I've red also the very interesting discussion about B1 Active Crossover but there is not PCB for now... An another interesting product is SKA ActiveXO.

Which is the best solution in your opinion and experience? ... ESP with very good op-amp, SKA, B1 active XO, Marchand Electronics XM44EMB ?

My objective is to not "worsen" or changing to much the sound of my CD player by introducing a stage.

thanks :)

Marco
 
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...no reply, so there isn't answer to my question :-(
To be very synthetic, I like the SKA ActiveXO because it works in class A and it doesn't use op-amp.
Has anybody listen to this XO? In terms of design do you think it's better than ESP ?

Is it right to consider ESP and Marchand Electronic quite similar designs?
On the other side we have SKA and B1 ActiveXO. Or not?


Bye!
 
Hi KMossman,

the SKA activeXO is a "24 dB/octave line level crossover using low noise discrete compound emitter follower gain blocks. They can be NPN/PNP BJT (standard) or N-FET/BJT or mixed stages according to personal preference.The design features a discrete input buffer then 2 cascaded discrete 12 dB/octave stages for each of the High pass and Low Pass outputs".

It seems to be similar to your configuration, isn't it?

Cheers,

marco
 
If you're referring to the original post, now over 18months old, it's clearly stated

I am wondering about an active bi-amp with analogue active two ways filter.
Which in all iterations that I've seen our undertaken means filter network ahead of (or built into) amplifiers, and generally at least part of that hardware separate from the speaker enclosure. While there have been commercial products for years like Meridian and numerous powered studio monitors which incorporate much or all of the signal processing and amplification internally, that's something that I've never been comfortable with.
That's probably the result of seeing a graveyard of mainstream residential powered subwoofers at a local hi-fi shop, - some of which are less than 5yrs old- all with dead amps for which the several manufacturers no longer provides any service support.

The argument could be made all day as to merits of analog vs digital processing in filter networks themselves - as more folks are moving to all digital signal stream, there's certainly much logic to doing it there.
 
Hi,

yes, as Chrisb said I would like an active analogue XO. It's like "mission impossible" because I would like to avoid opamp and AD/DA conversion. So no Marchand, no ESP and no DEQX.
I have a CD player that I like, in the future I can built a preamplifier if I need some gain for the XO.
For the moment, I’m trying to find an active two ways XO that I will put in a separate box from amplifiers. I have two My-ref amplifiers and I could use them to bi-amp my speakers. I have done the passive filter of these speakers (6” woofer + tw).
The first step, in order to do some practice and listening, would be to replace the passive filter with an active XO, tying to filter 6” woofer and tweeter at about 2khz, also using some baffle step correction. Then, if the XO sound good, I could add 10” woofers to my speakers, using active XO for the 10” woofers and reintroducing the passive XO, as it is, between 6” woofer and tweeter.


I have read these threads, but it’s quite difficult to built one XO for me…
http://www.diyaudio.com/forums/analog-line-level/169005-jfet-active-crossover-11.html
http://www.diyaudio.com/forums/pass-labs/156094-b1-active-crossover.html
What do you think of Harolda XO ?
Could I use it with unbalanced CD ?

Otherwise, there is SKA active XO, as I said before: “using low noise discrete compound emitter follower gain blocks. They can be NPN/PNP BJT (standard) or N-FET/BJT or mixed stages according to personal preference. The design features a discrete input buffer then 2 cascaded discrete 12 dB/octave stages for each of the High pass and Low Pass outputs.”
 

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Thank you Troystg :)

... but I'm a quite obstinate newbie DIYer :D
If no PCB existe with JFET, I will try to read and read again the two threads linked above (B1 active XO and JFET active XO).

Which one of this two circuits would you suggest me to try to make?
... maybe in the Wrenchon threads there are more informations... and that's the one AndrewT has done...
 
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I did the jFET on plugboard first to see what it was capable of.
I then transferred that to Veroboard.
One channel of Low Pass filter with input Buffer, Butterworth 2pole and a second Butterworth 2pole for an LR4 running off 24Vdc (single polarity) on ~1.1sq in (36mm by 20mm). (effectively 3 pass B1 in series).
 
Thank you Troystg :)

... but I'm a quite obstinate newbie DIYer :D
If no PCB existe with JFET, I will try to read and read again the two threads linked above (B1 active XO and JFET active XO).

Which one of this two circuits would you suggest me to try to make?
... maybe in the Wrenchon threads there are more informations... and that's the one AndrewT has done...

If I were a beginner I would go the Pass-labs B1 route since there is lots of support from an awesome group of people.

As Mr. Nelson always says -> :cool:
 
Thank you :cool:

I’ve seen Andrew’s schematic in Wrenchone threads.
I’m going on reading, the difficult is that often there are many version of the "same" circuit, with some differences about the order of the filter, different kinds of transistor, baffle step compensation, volume position, gain preamp... and also PSU.
It's not easy to find all the schematics needed and "thinking" all the chain, the problem is also to choose “intelligently“ every part of the design: PSU-potentiometer - gain stage or separate preamp (?) - baffle step compensation – XO calculation– attenuation for speakers matching…
For instance, does it make sense to choose the same PSU for XO and gain stage ?

One preamp that I am looking at is alpha20 from AMB with sigma22 PSU. That is "easy" to build, a lot of available explication.

I found also the Xenover schematic… I will read it in the next day. It seems a complete article with calculation methods for the XO and some explication.
Any advise on this design for IV LR ?
 
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