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Bass management and speaker level inputs?


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First post on Stereonet forums so be gentle ; )

 

I have always been admirer but finally entered into the realm of decent hi-fi. After going down a highly enjoyable rabbit hole and researching every speaker under the sun ended selecting the Wharfedale Evo 4.2s and was lucky to find a mint condition used Cambridge Audio CXA80 which pairs beautifully with them. Super happy with their sound particularly great midrange.

 

I'm looking for subwoofer to complete the setup and replacing my average 12inch pioneer. Looking at SVS, Kef and Martin Logan at this stage. The Rythmik F12 and bigger Rel are out of my budget I think.  

 

Anyway my question!

 

The idea of the sub is achieve great bass and to take the load of my speakers in the bottom end so I can achieve extra volume to let the very capable mids and treble sing without overdriving the speaker woofers on more demanding bass heavy music.

 

However I have recently realised that as far as I'm aware the CXA80 has no bass management on either the sub out or pre out therefore sending full frequency to my speakers. I came to the conclusion that the only way to address it would be to either permanently reduce the bass EQ on the amp whilst slightly adjusting gain on the sub to protect the speaker woofers. However I feel this is not ideal as it will remove natural sounding bass from more subtle tracks and at lower volume etc

 

However then I read a little about using the high level/speaker inputs of the amp for the sub. So my query is will this arrangement reduce load on the bottom end of the speaker's and if not do I have any other options?

 

Thanks in advance!!

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Hi Evo,

 

I'm not an expert, but will soon be in the same boat with you. I have a B&W ASW610 on order and will be connecting it by pre-out, so the full signal. I doubt that hooking up a sub and reducing the load on the Evo's will allow you to go louder. as this does not change the watt/sensitivity ratio which dictates volume (my understanding in very basic terms ;) ) but will make the bass integration easier.  Might reduce the chance of clipping at high volumes though, less current draw ( ?? citation needed lol) 

 

With a previous sub, I used speaker connections to the sub, then from sub to the mains, with the sub only passing on the higher frequencies to my main speakers. Worked well.

 

With my new sub I know I will need time to get the cut, volume and positioning right so it blends well with the mains, but keen to see other responses here.

 

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1 hour ago, Grainy said:

 

With a previous sub, I used speaker connections to the sub, then from sub to the mains, with the sub only passing on the higher frequencies to my main speakers. Worked well.

 

Thanks for replying Grainy!  For the above did the sub have high level outputs as well to achieve that?

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If you take the first 80 hertz from the speakers and cross it to the sub you should be able to play it louder because you will find it should distort less also the amp isn't digging as low . Ironically I just did that with my set up and it made a big difference , everything is just that bit clearer . 

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24 minutes ago, Evo4.2degrees said:

For the above did the sub have high level outputs as well to achieve that?

 yes it did, so speaker cables to the sub, then speaker cables from the sub to the 2 main speakers.

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5 hours ago, DEANO23 said:

If you take the first 80 hertz from the speakers and cross it to the sub you should be able to play it louder because you will find it should distort less also the amp isn't digging as low . Ironically I just did that with my set up and it made a big difference , everything is just that bit clearer . 

I think the issue I have is that there isn't a way on the amp to control the crossover of the main speakers.

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5 hours ago, Grainy said:

yes it did, so speaker cables to the sub, then speaker cables from the sub to the 2 main speakers.

Interesting, seems to be quite rare for a subs to have high level outputs, we'll at least on the ones I've been looking at anyway.

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On 21/10/2020 at 12:47 PM, Evo4.2degrees said:

First post on Stereonet forums so be gentle ; )

 

Be aware ... what's gentle to some ... might be thought of as rough, by others.  :)

 

On 21/10/2020 at 12:47 PM, Evo4.2degrees said:

I have always been admirer but finally entered into the realm of decent hi-fi. After going down a highly enjoyable rabbit hole and researching every speaker under the sun ended selecting the Wharfedale Evo 4.2s and was lucky to find a mint condition used Cambridge Audio CXA80 which pairs beautifully with them. Super happy with their sound particularly great midrange.

 

Excellent!  :thumb:

 

On 21/10/2020 at 12:47 PM, Evo4.2degrees said:

The idea of the sub is achieve great bass and to take the load of my speakers in the bottom end so I can achieve extra volume to let the very capable mids and treble sing without overdriving the speaker woofers on more demanding bass heavy music.

 

That's certainly what I believe.  :)  (iow - you apply a high-pass filter to your mains, to stop the woofers (and the amp driving them) from exerting themselves as much ... thus reducing distortion.)

 

But be aware there is a school of thought which holds that subs should merely extend the LF response of their mains - so they don't roll off their mains.

 

On 21/10/2020 at 12:47 PM, Evo4.2degrees said:

However I have recently realised that as far as I'm aware the CXA80 has no bass management on either the sub out or pre out therefore sending full frequency to my speakers.

 

In which case, you have to:

either buy a sub which has a built-in HP filter on the plate amp (like my Rythmik does).  In which case the signal chain is:

  • pre outs to sub low-level ins
  • sub low-level outs to the amplifier which drives the main spkrs.

   In this case, the low-end roll-off for your mains is provided by the sub's HP filter.

 

*  or you feed the pre outs into, say, a miniDSP 2x4; then:

  • the HP outs on the miniDSP go to the amp driving your mains, and
  • the LP outs go into your sub.

 

On 21/10/2020 at 12:47 PM, Evo4.2degrees said:

However then I read a little about using the high level/speaker inputs of the amp for the sub. So my query is will this arrangement reduce load on the bottom end of the speakers

 

No.  :(

 

Andy

 

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Thanks Andy for your comprehensive reply and being gentle! 

 

I think I have a pretty clear picture of it all now.  I was having a play around last night and Evos put out significant volume without the woofers appearing to be close to being over driven.  I also want to enjoy their full frequency range.  At the end of the day if I'm really wanting to push the system with tracks with a more demanding bottom end I can just EQ the bass back a notch on the amp and adjust the sub accordingly.

 

I still think I prefer the idea of using the high level inputs.  I imagine it would work by using the banana plugs into the back of the amp in combination with spade connectors for the sub on the same terminals?

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Potentially looking at a used Dali SWA-15 and noticed on the back that it has a high pass filter outputs but they appear they are RCA.  They say you can connect back to the amp but how would that work exactly?  Photos attached

Screenshot_20201030-092349.png

Screenshot_20201030-092135.png

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There's a few ways you could do this but as a general rule I'd suggest high level inputs are a last resort. The main reason is that this excludes the possibility of using any kind of EQ or correction, either built in or external.

 

The simplest solution is to run a line level to the sub and plug the port on your mains. This reduces bass extension by an octave, meaning that speakers with 40 Hz extension will now roll off with a 2nd order at around 80 Hz. You then adjust the crossover on the sub to match.

 

Where a sub provides high or low level outputs, they will typically include a high pass filter. The problem here is that you have no control over the slope applied or corner frequency - these are fixed and often won't be a very good match for your speakers.

 

There are two challenges in integrating a sub. The first is that it's a crossover, just like the one between a mid and tweeter. As such, it really needs to be optimised with measurements - you won't realise the full potential in doing it by ear. The second is you have a lot of peaks and dips due to the room interaction. Both of these challenges are best optimised with measurements and DSP. Now this brings me to a more advanced solution.

 

You can run a line level to a DSP crossover like MiniDSP 2x4 and set up high pass filters on your mains and a low pass on your sub. You can adjust them precisely and apply EQ to each. These are the tools that give you the most control, but I'm not saying this is easy!

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Umik 1 + REW is one way to measure crossover, not absolutely necessary but it helps. 

I like the pre outs of amp connection, I added easy accessible volume control for 2 subs - very handy for me.

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On 30/10/2020 at 9:08 AM, Red Spade Audio said:

There's a few ways you could do this but as a general rule I'd suggest high level inputs are a last resort. The main reason is that this excludes the possibility of using any kind of EQ or correction, either built in or external.

 

I don't understand this as it seems fairly trivial to run a correction system over whatever comes out of the system with the speakers and subwoofer(s) working at the same time.

 

Don't get me wrong, I think high level should be the last resort too but I can't see that it's necessary to use line level to be able to utilise a Correction\EQ system. 

Edited by Satanica
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Thanks  for the response Red Spade.

 

This sounds interesting but confuses me a bit..

 

10 hours ago, Red Spade Audio said:

The simplest solution is to run a line level to the sub and plug the port on your mains. This reduces bass extension by an octave, meaning that speakers with 40 Hz extension will now roll off with a 2nd order at around 80 Hz. You then adjust the crossover on the sub to match.

 

 

I think you're on the money here as the crossover on the dali is at 100hz and another sub I was looking at, the golden ear forcefield has a pre-set crossover at 120hz or 150hz and I believe my speakers go to 48hz.  I'd be missing out on that lower end response and sound of my speakers.

 

10 hours ago, Red Spade Audio said:

Where a sub provides high or low level outputs, they will typically include a high pass filter. The problem here is that you have no control over the slope applied or corner frequency - these are fixed and often won't be a very good match for your speakers.

 

 

But in the case I wanted to try it out I was just wondering how a rca  high level output would actually connect to  my CXA80 as I've only seen speaker to speaker inputs for high level outputs.

 

 

 

10 hours ago, Red Spade Audio said:

You can run a line level to a DSP crossover like MiniDSP 2x4 and set up high pass filters on your mains and a low pass on your sub. You can adjust them precisely and apply EQ to each. These are the tools that give you the most control, but I'm not saying this is easy!

 

9 hours ago, Irek said:

Umik 1 + REW is one way to measure crossover, not absolutely necessary but it helps. 

I like the pre outs of amp connection, I added easy accessible volume control for 2 subs - very handy for me.

 

This sounds like a good option although perhaps a little over my head.  If it had simple knobs for high pass and low pass crossover that would be good.

 

All this aside I think the wharfe's can handle a fair bit of volume without the bass driver being overdriven but it would be nice to be able to push them without worrying when I want the volume extra loud . 

Edited by Evo4.2degrees
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Do you know what's better than a good subwoofer? 

 

2 subwoofers, 😂😂😂.

 

 

Not always but I found that funny.

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Do the speaker impedance changes with frequency affect what a high level input to a sub would see?

For example, if a speaker had a high impedance around 50Hz would this reduce the bass signal to the sub high level input accordingly as it would affect whatever is connected to it at that frequency? 

@Red Spade Audio

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