Semi-active bi-amping

[meibdk]

Hi,

I have an integrated amp and a power amp - the amp stages are identical.

I have the opportunity to use them for bi-amping (speaker manual mentions it specifically, though nothing about active and/or passive bi-amping).
Having an integrated amp mean that I cannot fully active bi-amp, but only use an active crossover before the power amp.

My speakers are 2-way with a 2000hz crossover, 6ohm.

So in theory… What is best to use the power amp for? Low/mid (< 2000hz) or mid/high (2000 hz <)?

I think it makes best sense to use the power amp for mid/highs because it will be more likely to stay Class A - it’s an Atoll AM200 Signature, and Atoll claim it works in Class A up to about 40W under 8 Ohm (read on another forum).

Does it make sense…? Or should I sell both amps and buy a bigger one (not likely to happen though).

Edit: Just saw the “review” in the end of this section name. Please move the thread

 

[izeek]

iono what semi-active is. do you mean passive biamping where you use the speaker's crossover? active crossovers means you opened your speakers up and removed the its internal crossover. otherwise whatever it puts out will be added to the speakers crossovers.
whichever is the most powerful should run your woofers as mid/hi does not use as power.
if your integrated has a pre-out you're set.
the atoll is rated 120wpc at 8Ω.

 

[izeek]

you might read this.

Thread 'Bi-amping 101' https://audiosciencereview.com/forum/index.php?threads/bi-amping-101.22817/

 

[meibdk]

A follow up question... I'm going fully active bi-amping.

However, removing the passive crossovers... Is it really just that straight forwards?
Rip them out and solder the wires from drivers directly onto the binding posts?

Both my amps and crossover allow for gain-adjustment, I use a power sequencer to make sure amps are turned on last, powered off first and so on.

 

[sergeauckland]

A follow up question... I'm going fully active bi-amping.

However, removing the passive crossovers... Is it really just that straight forwards?
Rip them out and solder the wires from drivers directly onto the binding posts?

Both my amps and crossover allow for gain-adjustment, I use a power sequencer to make sure amps are turned on last, powered off first and so on.

Yes, going active does 'just' require unwiring the passive crossover and wiring the drivers direct to the binding posts.
However (isn't there always a however?)

1) Put a capacitor in series with the tweeter to protect the tweeter from a fault in the power amp that could put some 50v DC directly across the voice coil and burn it out. It will also protect against any (hopefully small) switch-on or switch off thump.

2) Set your electronic crossover frequency to match the passive setting, and use the steepest cut-off you have available, as that will reduce distortion and improve power handling as the drivers won't be doing anything much outside their passband.

3) Set up the crossover levels and any EQ to be flat pseudo-anechoically using a calibrated measuring microphone and free software like REW. Keep a record of the settings. You can then always adjust the sound to your preference, knowing you have the settings to go back to nominally correct settings at any time. You can also change the crossover point up or down a few hundred Hz and see what difference that makes.

I did mine around 10 years ago, and have been extremely happy with the results.

S.

 

[meibdk]

Thank you for a good useful reply

1) What would the specs of such capacitor be? XO-point for my tweeters are 2000hz and the speakers have a nominal rating of 6ohm impedance.

2) Exactly my plan - it will be a 24/dB Octave roll off. I run a sub as well, which be run through the crossover as well.

3) My preamp is a NAD C658 which features Direct Live. I'll be adjusting the crossover best way possible before doing the calibration, EQ features off. For the record I'm running some Audiophonics Purifi amps

 

[sergeauckland]

Thank you for a good useful reply

1) What would the specs of such capacitor be? XO-point for my tweeters are 2000hz and the speakers have a nominal rating of 6ohm impedance.

2) Exactly my plan - it will be a 24/dB Octave roll off. I run a sub as well, which be run through the crossover as well.

3) My preamp is a NAD C658 which features Direct Live. I'll be adjusting the crossover best way possible before doing the calibration, EQ features off. For the record I'm running some Audiophonics Purifi amps

The capacitor needs to be a non-polar electrolytic of something around 100-150uF rated at 100v. That will block anything below around 200Hz so well away from the crossover frequency. Value isn't critical as it's only there to block DC, but if too small, will start affecting the crossover point, and if too large will still allow slow variations, like a switch-on thump, to get through. If you're of that sort of mind, you can use a plastic film capacitor, but they're bulky and expensive, and as there's practically no voltage across this capacitor, there's no reason not to use a non-polar electrolytic which costs pennies.

S.

 

[meibdk]

Thanks. I'll order a pair of Mundorf Ecap Audio Raw 100uf 100v/36v DC/AC then : https://www.mundorf.com/audio/en/shop/capacitors/audio_caps_ecap/ecap_raw/ECap100/?card=2038