Subwoofer connection method and amp advice

[OverDrive]

Hi guys,

Hoping for some information.

From what I can see, for most 2.1 setups, a powered sub is hooked up to the amp via either the preamp out or speaker level outputs (if the sub supports it).

With both of the above connection methods I can understand that you would then use the sub's low pass filter to set a frequency to match the -6dB low freq. cut-off freq. of the speakers to allow harmonious roll off (this is the recommended method stated in my sub's manual anyway).

However, in the case of the following 2.1 receiver (Yamaha R-N803D) - which does not have preamp out - you could use the dedicated subwoofer RCA type output.

https://uk.yamaha.com/en/products/audio_visual/hifi_components/r-n803d/index.html

My question is - what frequencies are sent to the sub using this dedicated sub connection method and would you still need to use the sub's low pass filter?

A couple of things that I've read online state that these dedicated sub outputs are more the domain of the home theatre system rather than hi-fi, and as such are inferior to preamp or speaker level sub connections. Is this true?

I ask as I really do like the receiver I've linked to above and I now have a new B&W ASW608 - currently hooked up to my amp via the preamp out and working harmoniously - as if it were not even there.

Thanks.

 

[hornetstinger]

Typically AV amps sub out are filtered signal so you don't use the crossover in the sub, you bypass or set it to max.

With stereo amps a full range signal is sent.to the sub so you use the subs own crossover to around the speakers bass low end but your room boosts bass so don't go by spec alone.

You need to work out if the signal is full range of filtered.

As for high and low level being better or worse or you will notice the difference. Nah.

 

[OverDrive]

You need to work out if the signal is full range of filtered.

Thanks, how would I go about that? I could not find anything out on the website or PDF manual.

 

[lucid]

The Yamaha subwoofer set-up is covered from page 42 onwards in the download version of the user manual. It's not difficult to find.

The R-N803

However, in the case of the following 2.1 receiver (Yamaha R-N803D) - which does not have preamp out - you could use the dedicated subwoofer RCA type output.

That's exactly as you would do it if you want to run the R-N803D's automated speaker set-up wizard called YPAO. The amp uses a supplied mic and emits test tones which it then measures. It then sets its internal pre-amp circuitry to blend the sub and the front speakers.

With both of the above connection methods I can understand that you would then use the sub's low pass filter to set a frequency to match the -6dB low freq. cut-off freq. of the speakers to allow harmonious roll off (this is the recommended method stated in my sub's manual anyway).

Fiddling around with the sub's crossover and volume controls is only required if you're either setting up with the speaker level connection, or you're using the 803D's subwoofer out but not using YPAO.

My question is - what frequencies are sent to the sub using this dedicated sub connection method and would you still need to use the sub's low pass filter?

Follow the instructions for speaker set-up from page 42 onwards. No need to set specific frequencies. Subwoofer crossover to max. Subwoofer volume to 50%

A couple of things that I've read online state that these dedicated sub outputs are more the domain of the home theatre system rather than hi-fi, and as such are inferior to preamp or speaker level sub connections. Is this true?

It's six of one and half a dozen of another.

Using the amp's subwoofer out allows software to take care of the phase, crossover frequency and volume to blend the sub with the mains and, to a degree, take the effects of the room in to consideration. Some feel that where there's one sub being blended with a pair of speakers that the relative positions of all three speakers create phase problems that can only be overcome using electronic processing.

Some would argue that having all this electronic processing adds its own sonic fingerprint on to the sound. Whether or not you'll hear that depends a lot on the room and the level of gear being used.

That's the catch, really. It's a juggling act. Those using the sorts of systems with the level of resolution to be able to pinpoint and fix these phase errors and correct for in-room response will have spent high-hundreds to several thousands of Pounds (£s) just on the gear to do that job. The tech could be standalone, or it could be integrated in to a pre-amp. But whichever it is, it won't be a '£50' solution.

This brings us back to what people can achieve with more accessible gear and how much hassle they're willing to go through.

As consumers, we've got used to the idea of having AV gear do a sort of speaker auto-calibration. It is a bit of a double-edged sword. Often a manual set-up of channel levels, crossover points and subwoofer phase can yield better results so long as the user knows what they're doing. However, many buyers simply want a quick fix, and the auto-set-up routine provides that. What Yamaha are doing with their auto-set-up system is something along the same lines. It'll get a better result than the vast majority of users could achieve for themselves, and that's enough for many.

Somewhere in between the people who just want to press the 'auto set-up' button and the real tweakers with their sophisticated room EQ gear are folk who take a different view. For lack of a better description, they're more your straight line purists. For them, the idea of putting the music signal through an EQ circuit doesn't fit with their ethos. They feel it robs the music of some of the essence of what they're pursuing with their "simple is best" approach.

Some subwoofer manufacturers follow the same principles.

Their subs provide the basic low-level line input connection, but also have high-level speaker signal inputs for direct integration with the main speakers. In the case of your B&W AS608, you can connect at speaker level (high-level) in parallel to the the main speaker connections if you wish. The sub's speaker input has very high resistance, so the amp doesn't see this as an additional load. The sub gets a full range music signal: 20Hz to 20kHz. The sub has a natural frequency response of 23Hz to 140Hz (-6dB). Below and above those frequencies it won't respond much, so there's a natural filtering. Within those bounds, the sub has its crossover control which means that the blend point can be adjusted down.

If you were running an AV pre-amp or an AV amp/receiver for a mixed music and movie system, then with the B&W you'd have to choose one connection or the other. You'd go for the subwoofer line out connection because this would give you the sub integrated on the main speakers and also the LFE channel which goes lower than 20Hz.

Owners of some BK subs, and some of the MJ Acoustics subs have the ability to connect both high-level and low-level connections at the same time. (There may be other subs that allow this too.) The subs have two independent crossovers, and can blend the signals from both simultaneously. In this way, the front speakers can run full range being supplemented by the sub, while the LFE signal is still supported via its dedicated channel.

 

[OverDrive]

Lucid, thank you for the very informative reply - it was a pleasure to read.

Thank you also for explaining how the YPAO digital processing works. I've done a little more reading about this Yamaha receiver. People seem to be saying generally good things about it, although there have been some reports of difficulty applying a firmware update. It also looks like quite a bit of functionality works via a mobile app. e.g. the ability to fine tune the YPAO configuration etc. This is all well and good, however who knows if it will still be supported in 10yrs time? Whatever I get next I would like to keep for at least 10yrs.

I was wondering if I should go for a dedicated integrated amplifier instead (up to around £500) - something with a DAC, dual optical inputs and preamp out for my sub and then connect a dedicated media streamer via one optical input and my computer via the other? That way in the future I could just update the streamer if needed/as tech changes and keep the amp going.

I was looking at this Yamaha unit: MusicCast NP-S303
https://uk.yamaha.com/en/products/audio_visual/hifi_components/np-s303/index.html

Would this be a better approach?

Thanks.

 

[hornetstinger]

Not sure if auto eq sets crossover on mains and sub correctly typically I found it got it wrong so set speaker crossover manually. Also I personally don't like having sub crossover to 120hz (some units allow separate speaker and sub crossovers)

Not sure if this low bass is directed or thrown away is speakers set to 60hz, sub set to 60hz.

Lfe goes upto 120hz. Lexicon MC-8

 

[lucid]

Not sure if auto eq sets crossover on mains and sub correctly typically I found it got it wrong so set speaker crossover manually. Also I personally don't like having sub crossover to 120hz (some units allow separate speaker and sub crossovers)

Not sure if this low bass is directed or thrown away is speakers set to 60hz, sub set to 60hz.

Lfe goes upto 120hz. Lexicon MC-8

Like I said in the previous reply, I too get better results setting the speakers up manually rather that relying on auto-set-up wizards. But this isn't for everyone. The wizards get more people to an acceptable basic level than would be the case with manual setup.

If we are talking about the low level input for the sub, and discussing amps with the sort of speaker set-up features commonly found in AV receivers, then I don't see a problem running the sub's crossover frequency to max.

What we want is the sub's own controls out of the way', so to speak. The amp's processing will take care of filtering bass and sub bass to the subwoofer. All the sub need do is replay the signal it receives without interfering with it. Having the sub's crossover at max in this context is part of what achieves that goal.

 

[hornetstinger]

Yeah I bypass crossover in sub itself.
But my mc-8 has separate lfe crossover which has a few options. Unlike other avr where you only have a single crossover for the whole lot.

 

[OverDrive]

For me the pure quality of the music is the most important thing - I feel a little uncomfortable with automatic digital processing and the risk that some lower frequencies will get thrown away. I don't mind trying different speaker/sub positions and tweaking the crossover to get the sound that I enjoy. I must admit that I am leaning more towards the integrated amplifier with separate streamer route.

My current speakers are B&W 685 S2s with an ASW608 subwoofer. I've been using a Monitor Audio A100 for the last two years now.

I quite like the Yamaha A-S801 integrated amp - available for £600
https://uk.yamaha.com/en/products/audio_visual/hifi_components/a-s801/features.html#product-tabs

It provides more power than I currently need, but as I am planning on keeping it for at least 10yrs - it's good to have the overhead in case I change speakers further down the road.

What do you guys think? Really appreciate your opinions/expertise.

Also, is the streamer I listed above okay - I would like AirPlay (I know it's crappy - but I have Apple Music) and DLNA to play FLAC files from my NAS. I would also hook up my PC to the amp directly via optical. Having internet radio on the streamer is also nice.

Thank you.

EDIT: Just noticed the A-S801 has only 1 optical input and I don't believe it has preamp out.

 

[hornetstinger]

If that Yamaha had bass management either via DSP crossover and/or analogue line level high pass like outlaw ICBM-1 the give a bit more flexibility when it comes to speaker/sub setting up. I find sub integration a lot easier on the avr compared to stereo amp.

 

[james.miller]

Using the amp's subwoofer out allows software to take care of the phase, crossover frequency and volume to blend the sub with the mains and, to a degree, take the effects of the room in to consideration. Some feel that where there's one sub being blended with a pair of speakers that the relative positions of all three speakers create phase problems that can only be overcome using electronic processing.

The problem with subs driven by a high level signal from the amp powering the front speakers is this:

You have to run the front speakers full range. Any signal you cut from the fronts, will be cut from the sub also. This is not so much an issue if you are using large fronts to begin with, however if you have smaller bookshelf or stand mounts, this is a much bigger issue because of course one of the reasons you would buy a sub to go with these speakers in the first place is to handle the low end, sparing the fronts....

Additionally, the front speaks and the sub with each have their own and very different group delay plots. Most decent subs using simple designs will push the group delay far enough down the frequency range that this isnt normally an issue, but cheaper or should i say more poorly designed subwoofers can have have a shift in their group delays high enough in the frequency spectrum that pushes them out of phase with other speakers producing the same frequencies (remember, we're having to run the fronts full-range here...) and this is a problem. Additional, some designs inherantly have poor group delays results, such as subs using a driver+passive radiator combo. All of this of course is without mentioning the obvious drawbacks when running small front speakers full-range.


My answer to all of that is simple; Don't use high level inputs unless you are prepared to modify the crossovers on the main speakers or there are absolutely no other solutions available. There's no need to introduce these issues if there is a better alternative available.

 

[lucid]

Lucid, thank you for the very informative reply - it was a pleasure to read.

Thank you also for explaining how the YPAO digital processing works. I've done a little more reading about this Yamaha receiver. People seem to be saying generally good things about it, although there have been some reports of difficulty applying a firmware update. It also looks like quite a bit of functionality works via a mobile app. e.g. the ability to fine tune the YPAO configuration etc. This is all well and good, however who knows if it will still be supported in 10yrs time? Whatever I get next I would like to keep for at least 10yrs.

I was wondering if I should go for a dedicated integrated amplifier instead (up to around £500) - something with a DAC, dual optical inputs and preamp out for my sub and then connect a dedicated media streamer via one optical input and my computer via the other? That way in the future I could just update the streamer if needed/as tech changes and keep the amp going.

I was looking at this Yamaha unit: MusicCast NP-S303
https://uk.yamaha.com/en/products/audio_visual/hifi_components/np-s303/index.html

Would this be a better approach?

Thanks.

"Better" depends on the total package of your wants and needs.

The separate streamer gives you flexibility, sure. Having the amp separate could provide you with something sonically superior. Whether you hear that difference does depend on the amp and the speaker package you run with it.

Your point about whether the features of the app will be supported in the longer term is well made. If that is a major concern then purchase a small Android tablet to use exclusively with the amp. You won't have to worry then that your newer generations of phone are leaving the amp's app behind.

Choosing a different amp - something more conventionally a 'Hi-Fi amp" - probably means doing away with the convenience of the auto-set-up features. Unless the amp has bass management features and auto-set-up, all you'll get from the pre-out socket is a line-level version of what the main speakers are receiving.

Your sub's volume will change with the main speakers, but you'll have to set up the crossover frequency and the phase and the relative volume level by ear when you first put the gear together. Is that something that you are prepared for?

 

[hornetstinger]

Bass management or some kind of high pass is useful in a hifi stereo system, you may use it or not but if it's there can experiment.

For example in my room I have dac, pre-amp, power amplifiers, subwoofer with high pass, outlaw ICBM-1. Floorstander speakers.

The high pass in the sub is 80hz fixed so bit too limited, but I can go pre amp into sub, then sub RCA into poweramps then into speaker. So poweramps get >80hz

Or doing the same iwth outlaw in between the pre and power but ICBM-1 had few more crossover settings so can tailor to speakers and room response.

 

[lucid]

The problem with subs driven by a high level signal from the amp powering the front speakers is this:

You have to run the front speakers full range. Any signal you cut from the fronts, will be cut from the sub also. This is not so much an issue if you are using large fronts to begin with, however if you have smaller bookshelf or stand mounts, this is a much bigger issue because of course one of the reasons you would buy a sub to go with these speakers in the first place is to handle the low end, sparing the fronts....

Additionally, the front speaks and the sub with each have their own and very different group delay plots. Most decent subs using simple designs will push the group delay far enough down the frequency range that this isnt normally an issue, but cheaper or should i say more poorly designed subwoofers can have have a shift in their group delays high enough in the frequency spectrum that pushes them out of phase with other speakers producing the same frequencies (remember, we're having to run the fronts full-range here...) and this is a problem. Additional, some designs inherantly have poor group delays results, such as subs using a driver+passive radiator combo. All of this of course is without mentioning the obvious drawbacks when running small front speakers full-range.


My answer to all of that is simple; Don't use high level inputs unless you are prepared to modify the crossovers on the main speakers or there are absolutely no other solutions available. There's no need to introduce these issues if there is a better alternative available.

Do you really think it's as black and white as that? Low level connection: Good. High level connection: Bad.

[For the benefit of anyone else reading this and wondering what Group Delay is; it's the physical effect of a time delay in the signal that becomes more significant as frequency reduces. This is affected by certain aspects of equipment design. When it comes to speakers, it shows up as stuff such as slower bass response the bigger the driver, or a tendency for bass reflex (ported) speakers to sound subjectively 'slower' and 'looser' in their timing than sealed (infinite baffle) speakers. It's why sealed subs are recommended more for musical precision whereas ported subs are deeper and louder for the same cabinet size (good for slam) but aren't considered as agile-sounding for music.]

Granted, if a sub sits in the middle of the ,connection between the amp and the speakers, and if it is actively filtering the audio so that the sub passes only higher frequencies to the main speakers - whatever size they happen to be - then sure, the time taken for the signal to pass through that electronics will delay it to some degree, and the effect of that delay gets progressively larger for lower frequencies.

However, there are a couple of big ifs there.

What happens if the sub isn't connected in-line? So many subs now use a parallel connection with the speakers for the high level input, and at high impedance too, so that the amp doesn't 'see' the sub as a conventional speaker load. In fact it doesn't really see it at all from a power perspective. That's how the B&W AS608 would connect at speaker level.

Connected in this way, the signal reaching the main speakers is unaltered. It hasn't passed through any circuits that could add delay; and so the inherent group delay of the main speakers is unaltered. The frequency of the signal from the amp is still 20Hz-20kHz. The main speakers have their natural roll-off; something in the low 20's for large speakers and something in the 40-60Hz range for small bookshelf speakers, and so they'll respond according to their design.

The sub will, of course, have its own group delay characteristics. Being predominantly a bass device, it will sound less agile than the 4" or 5" drivers commonly used as mid-bass drivers in main speakers. But then again a pair of full range speakers with 8" or 10" bass drivers will sound deeper but slower in bass response than a small pair of bookshelf speakers. In fact, wouldn't it be true to say that slow bass (larger group delay) is a problem for all speakers as driver size increases? That's why big cheap speakers with bass ports aren't such a good deal, and why it costs a lot to build big speakers where the bass sounds taut and rhythmic.

Another little wrinkle about Group Delay is that human hearing isn't so sensitive to these bass frequency delays as it is to mid or treble delays.

Where group delay is really a big big problem is in any sort of live monitoring situation. For performers on stage, having their P.A. rig sound like it's half a beat behind their performance would be really off-putting. In situations where there's nothing to compare to though, such as when playing a music file, the entire system could delay the sound by 5 seconds and no-one would be the wiser unless some other device was also playing the same source but with less delay. What it comes down to then is how 'fast' the system sounds, and I think that's as much to do with the quality of the gear as anything else.

 

[Emmitt46]

@lucid you knows these subs iside and out. Can you recommend me one?

Sorry for being off topic. I'm looking for a good sub for my truck and can't wrap my head around which would suit me best.

Do I need to spend over $1000 to get some decent sound? I've been reading the reviews all over the internet and I didn't get closer to finding a solution. Plus most reviews are hype. Blatant copy of manufacturer's features that's it. Now I've found a different site which writes more on our language. Still there are 10 subs on the page and it's hard to choose. The greatestspeakers.com site popped up when i was searching for the best car subwoofer. What I loved about the reviews were that he highlights many negatives. Best of all they are not watered down.

What are the most important things when you're looking for a sub? Any tips?

 

[hornetstinger]

@lucid you knows these subs iside and out. Can you recommend me one?

Sorry for being off topic. I'm looking for a good sub for my truck and can't wrap my head around which would suit me best.

Do I need to spend over $1000 to get some decent sound? I've been reading the reviews all over the internet and I didn't get closer to finding a solution. Plus most reviews are hype. Blatant copy of manufacturer's features that's it. Now I've found a different site which writes more on our language. Still there are 10 subs on the page and it's hard to choose. The greatestspeakers.com site popped up when i was searching for the best car subwoofer. What I loved about the reviews were that he highlights many negatives. Best of all they are not watered down.

What are the most important things when you're looking for a sub? Any tips?

This place is for in home subwoofers, for in car the design will be different.

I'd probably stick to sealed box subs for in car use though

 

[lucid]

@lucid you knows these subs iside and out. Can you recommend me one?

Sorry for being off topic. I'm looking for a good sub for my truck and can't wrap my head around which would suit me best.

Do I need to spend over $1000 to get some decent sound? I've been reading the reviews all over the internet and I didn't get closer to finding a solution. Plus most reviews are hype. Blatant copy of manufacturer's features that's it. Now I've found a different site which writes more on our language. Still there are 10 subs on the page and it's hard to choose. The greatestspeakers.com site popped up when i was searching for the best car subwoofer. What I loved about the reviews were that he highlights many negatives. Best of all they are not watered down.

What are the most important things when you're looking for a sub? Any tips?

As @hornetstinger said, we're really about home audio gear here. Car audio gear has a different set of start points. For example, the space is smaller, but background noise is worse. Any gear has to cope with a huge temperature range from frozen to near melting point. The amount of juice from the battery/alternator system is limited, where you can put gear is restricted too. It makes my job spec'ing home audio gear look simple HA-HA-HA.

The point in mentioning all that is, like any hobby, there are people who just want something decent without blowing their life savings, and there are those who spend ridiculous sums. You can never really be sure what the agenda might be of the person you're reading, so take any recommendations with a pinch of salt until you've had a chance to listen for yourself. I've experienced both ends. Some think they're doing a favour by recommending something cheaper that they're happy with personally, but I've found it didn't quite hit the mark. The flip side is the person who says I need to spend a minimum of X, but I can't tell the difference to something at say half the price.

Check out this forum: https://www.caraudio.com/forums/subwoofers.10/

I had a quick look at the sticky for "Subwoofer Recommendation Requirements" and immediately it struck me that the old hands are asking newbies for a decent level of starting info, so the recommendations are based on something more solid than what's the current flavour of the month. That's a good sign.

Best of luck with your search