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Use subwoofer crossover to high-pass to power amp: do or don't?

Smidge

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Hi all,

After reading a lot of interesting content here on ASR for the past few days, I felt it was about time to sign up. And as a means of introduction and at the same time making use of your experience, I have the following situation I'd like to hear your take on.

Images tell more than words, so let me start by sharing a basic visualisation of my current audio setup:

Audio setup_1.png


In general I'm quite happy with the audio experience. However, I'm always looking for things to improve. After doing some basic improvements with regards to listening position, speaker placement, and room acoustics, I'm not completely happy with the low frequencies produced by the speakers. Somewhere between 40 and 80 Hz (estimation) they get boomy. Of course this could be caused by many factors including room acoustics, but my hypothesis is that this is at least partly caused by the limitations of this speaker in the low end. And that's why I am considering to run an experiment to validate this:

I want to connect the DAC output to an additional pre amplifier, and connect the rca outs to the SVS sub. The sub has a build in 80Hz fixed high pass filter on its line outputs that I want to send to the Roksan bypass input (going straight into the power amp bypassing the pre-amp). That way the speakers will only handle 80Hz and above. And I will adjust the SVS's low pass filter to 80Hz so that the sub handles all audio from 80Hz and below.

Based on my understanding I can only test this with an additional pre amp because with the Roksan I cannot achieve this configuration - it's either integrated or power amp only.

Based on this I have a couple of questions I am hoping you could help me with:

• Do you think this experiment is worthwhile trying? And why?
• Using the subs high-pass filter does means the audio source travels to additional components and cables. How much of a concern is this?
• How important is my choice for a specific pre amp, in terms of impact on sound? Would a simple volume control option on a DAC suffice (for example the Topping d30 Pro)?
• Do you think this can potentially improve the issue I described above?
• What other things would you consider if you were in this situation?

Looking forward to your guidance.
 

NTK

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• Do you think this experiment is worthwhile trying? And why?

Certainly. You want to relieve your main speakers of the low bass duty and let your subwoofer take over. Producing high volume of low bass requires high excursions from the woofer. High excursions usually means higher distortions. If the woofer is also playing the higher frequencies (e.g. mid bass and up), they are often be negatively affected. Offload the low bass duties to the sub will generally let your mains play cleaner and louder mid-bass and up.

Note: If you have not, you may want to try connecting a RCA cable from the preout to the bypass input of your K3, set the selector switch to bypass, and see if your K3 functions normally (i.e. volume control works). But be sure to try it with a very low input signal first. Otherwise, if for some reason the volume is set to full, you will not damage your speakers. If this works, then you shouldn't need a separate pre-amp.

• Using the subs high-pass filter does means the audio source travels to additional components and cables. How much of a concern is this?

Not a lot IMHO. The benefits outweigh the cost of potential signal degradation.

• How important is my choice for a specific pre amp, in terms of impact on sound? Would a simple volume control option on a DAC suffice (for example the Topping d30 Pro)?

My impression is that, the pre-amp, if one is needed, is only for volume control. The Topping D30Pro should work just fine. And so should your Arcam DAC as you can control its output volume using the remote. The electrical side of audio (electrical signal amplification and manipulation) is a solved problem. If the only source is the computer or streamer, many people will find a DAC with volume control is all they need.

• Do you think this can potentially improve the issue I described above?
• What other things would you consider if you were in this situation?

Sure. Get yourself a measurement mic, such as the miniDSP UMIK-1, learn how to measure your room with REW (Room Eq Wizard). You can then perform room EQ through your Mac. The process isn't simple, but the reward is well worth it. Very rarely can any system reach its full potential without room Eq.
 
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Smidge

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Thanks NTK for your extensive reply. It helps a lot.

...so should your Arcam DAC as you can control its output volume using the remote.

unfortunately the Arcam irDAC doesn’t have a build in volume control.


Note: If you have not, you may want to try connecting a RCA cable from the preout to the bypass input of your K3, set the selector switch to bypass, and see if your K3 functions normally (i.e. volume control works). But be sure to try it with a very low input signal first

I believe the bypass completely disables the pre-amp. Although I could try what you describe I am still scared to accidentally damage my speakers...
 

Head_Unit

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That way the speakers will only handle 80Hz and above. And I will adjust the SVS's low pass filter to 80Hz so that the sub handles all audio from 80Hz and below.
It's not that simple. 80 Hz lowpass + 80 Hz highpass works in electrical filter theory, but with real speakers in real rooms sometimes the optimal crossovers will be quite different. In a different context, autosound systems often need different lowpass, front highpass, and rear* highpass settings to avoid a boomy mess, due to cabin gain.
*actually rear speakers are stupid since they just mirror the stereo. But that's a rant for a different thread I guess.
 
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