Freedom from HT amp's fixed bass management (1 Viewer)

[Arup]

While on the subject of subs, I decided to free myself from the chains of my HT amps bass management which is limited to sending out 90Hz signals to the sub out. To achieve this I connected both of my subs to the passive inputs and then attached my main speakers to the sub. My main speakers are of tower type and can go down to 35Hz but I set the subs crossovers to send them everything above 45Hz and letting the sub do the dirty work of moving air below 45Hz. This way, my main speakers mids and highs become much better as now, the woofers don't have the high cone movement necessary for frequencies below 45Hz. It also adds clarity to the whole sound spectrum. Also my main amps are now free to send signals above 45Hz to the towers.

To disable bass management on the DSP-AZ1, you just have to set the speakers at MAIN. This way all LFE signals are routed to your main speakers. Earlier I had the setting at BOTH where the sub as well as the towers got all the LFE signals. When I was using this, I had to set my subs crossovers at 55Hz but the bass was never in presence as it is now. My front subs are located in corners behind my main tower speakers. I also have a rear sub and have my rear speakers set to LARGE. My center speakers are the same as my towers with two 8" woofers so I have them set to LARGE.

After having done this, the immediate effect was clarity and fantastic bass. No more boominess and the bass can now be felt rather than heard. Music has improved significantly and so has movies. Clarity and dynamics are way more improved.

Has anyone else tried this out? What are your experiences?

 

[Brett DiMichele]

I'm just curious as to how it changes anything since you
still have crossover networks inside each speaker that are
Low and HighPassed and aren't changing no matter what signal
you send through them??

If I unplug the subs on my towers the mids and trebbel
doesn't get better there is just no bass when I do that

 

[Arup]

Brett,

Speakers will only recreate what is passed on to them so in this case all LF component below 45Hz is passed on to the sub, thereby relieving the towers to do a better job. As you may be aware that the more the woofer moves, the less clearer the sound is. In this case the woofer movement is limited and so is the dreaded cabinet and cone resonance. Your power amp is also getting a better bandwidth allocation.

Give this a try and you will see the difference.

 

[Brett DiMichele]

Arup,

"As you may be aware that the more the woofer moves, the less clearer the sound is."

This is only true if the driver (be it woofer, Midrange or
Tweeter) is operating outside it's linearity. As long as
the driver is linear there shouldn't be any distorsion issues.

Cabinent resonance is a legitimate issue but this can be
eliminated by proper cabinent bracing and sound absorbtion
materials.

My Towers contain subs, no getting around it my LF comes
from my towers. Sure I can use a completely exteneral sub
but for now I am not, and even if I were I would still let
my mains produce everything down to the tuning (32Hz).

True a speaker will only produce what you feed it.. But
Cascading Crossovers is not the ideal situation. I run my
mains large eliminating any crossover in the Reciever or if
I am listening to 2 Channel I use a seperate PreAmp specificaly
for 2 Channel only operation.

The only current XO Cascades I have would be in my LF side
of my Towers. Internaly the subs cross at 100 and my external
sub amp also has an XO (Variable) I run it at 120Hz just so
that it doesn't interfere with the internals. But when I am
done reworking my internal XO's the Sub's will no longer
connect to the internal XO boards they will be direct wired
to the external sub amp with variable cross points.

 

[Dustin B]

The results of the highpass done at speaker level on most sub amps are quite unpredictable. The sub amp designer doesn't know the impedance of your speakers and a bunch of other things that would create an optimal highpass filter for your system. So the result is sub amps have a very basic 1st order high pass that is fixed in the 120hz range on the speaker level output. And if your speakers have an impedance well under 8ohms down in the 200hz range, that fixed frequency could be up over 200hz. Line level output is a different story, although most of those on plates suck too.

In case that wasn't clear, the speaker level output from the sub plate amp is not adjustable. It is fixed at above 100hz. The low pass filter however is adjustable and usually 2nd order. So you more than likely now just have a large hole in your bass response.

This setup also doesn't relieve any strain from your amps, they are still amplifing the whole signal, just part of it never makes it to the speakers.

I think you'd be better off setting all your speakers to small, letting your receiver do bassmanagement and working with room placement of the sub along with investing in a parametric EQ and spl meter to tame any room induced peaks in your subs response.

 

[Arup]

Brett,

Your case is unique as most speakers don't have the facility of built-in subs with the exception of few like the JBL L7. So I guess the LARGE setting is sufficient enough for you. In a way by using two similar subs I am trying to acheive the same thing like you.

Dustin,
You are correct in your point of inferior crossovers in subs. In my case though both the subs and the main speakers are made by Yamaha and use the same components so that isnt an issue here. My towers can go down to 35Hz as it has two 10" woofers so it would be a shame to cross them over at 90Hz and loose all the advantage. This is where most receivers suck big time and that includes my Yamaha DSP-AZ1. This model has everything but a kitchen sink, yet no variable LFE crossover management. When are the manufacturers going to wake up on this issue? As for amplifier power consumtion, it is bandwidth related and bass is the biggest consumer of power as the woofer needs massive amount of power to move, specially the ones with big cone and magnet. By passing over the job to the active subs amp, that power is not needed so the main amp is not called for that duty.

 

[Dan Hine]

As for amplifier power consumtion, it is bandwidth related and bass is the biggest consumer of power as the woofer needs massive amount of power to move, specially the ones with big cone and magnet. By passing over the job to the active subs amp, that power is not needed so the main amp is not called for that duty.

?? You keep making the point that the amps in the Yamaha receiver have to work less now. Seems to me that they would work less with a 90hz crossover than with being selected as full range and an external crossover around 45h-ish.

Also, the last thing I ever want to do is say something negative about someone's equipment...but...

While I have lots of respect for Yamaha amps, their speakers and subs are nothing to write home about, IMO. Same parts or not (well, from the same place, but I doubt the crossovers are the same in the speakers and sub, so they are using different parts) that does not mean they are not inferior to what is in your receiver.

And lets remember that the THX spec for sub crossover is 80hz. Some people think that is still too high but my system seems to blend alright. 90hz is not necessarily too high.

Does the manual to your speakers say what the attenuation is for your speakers at 35hz? Is it -3db or -10db....and is that -Xdb from 75db or 105db peaks? Have you tried running them as small and letting your sub handle 90hz and down WITHOUT the speakers sharing the load?

Also, don't think that setting your crossover that "high" is not taking advantage of the larger drivers. For instance, the JBL L7's you mentioned use their 12" drivers for 180hz and down. So if you crossed them over at 90hz you are using them for a full octave of sound. NOT including the roll off above and below the crossover freqs.

Obviously, whatever sounds best to you is the way to go...just my $.02 here.

 

[Dustin B]

Dan is very much correct on the reiteration of how the amp is being worked. The amp will have less of a load using the receivers bass management than the way you are doing it now.

You also have missed my point. The crossover on the sub consists of a low pass filter that feeds the sub and a high pass that feeds the speakers. The dial you are adjusting on the plate amp will vary the low pass filter. The dial on the plate amp will NOT adjust the high pass feeding the speakers, this filter is fixed at a frequency over 100hz (doubt the yamaha manual will even tell you what frequency this is at, but I am very confident it will be over 100hz, likely 125hz or 135hz).

The low pass feeding the sub can be variable because the speaker level input is converted to line level (line level signals can have adjustable crossovers) which is feed through the variable low pass filter and then reamplified by the amp in your sub. What goes to the mains is not converted and goes through a very cheap and basic high pass filter fixed at some frequency over 100hz (doesn't matter that it's all yamaha, unless all their speaker models have the exact same impedance curve what I said in the previous post still applies).

From what you have said, your sub is covering 45hz and down (45hz and up is being attenuated at 12dB/octave) and the mains are covering from ~120hz and up (~120hz and down is being attenuated at 6dB/octave). The result is you now have a hole in your frequency response.

To sum up, with your current setup you are now crossing your mains at an even higher frequency than your receiver did, leaving a big hole in your bass response and making the amp work harder.



I highly recommend you read these three things:

My explanation of the basics of crossovers:
http://www.hometheaterforum.com/htfo...602#post523602

Quote from a post by Brian Florian of Secrets of Hifi:
http://www.hometheaterforum.com/htfo...537#post739537

The article on Secrets of Hifi spawned from the above quote:
http://www.hometheaterhifi.com/volum...rs-9-2002.html

The mental block you have to get past is that you are wasting tower speakers setting them to small and crossing them over at 80-90hz. This is very much not true, especially when you have a quality sub.

But, also like Dan said, if you like the sound don't worry about what I think.

 

[Arup]

Dan,

You have no idea about Yamaha in general, much less about their speakers. I guess your idea of Yamaha subs and speakers is the crap you see at Best Buy as most of the high end Yamaha speakers arent even available in the US. Have you heard of the NS-1000x? I dont think so or else you wouldnt make a blanket statement like this. These legendary speakers took the audio world by fire and are still traded for high$$$$ on the net. They were used by monitors and have been tested for the flattest response ever. Before you go making comments like this, do some studies. Yamaha makes musical intruments of high quality and it is the same department which makes their speakers and amps. Your attitude is typical and sadly there is no cure for blindness and prejudice. The crossovers in the Yamaha are one of the highest quality you can find with all Elna and Nishicon affair.

The NS-300 speakers have the truest sound and the YST-SW 800/1500 active subs blow other subs in its class to pieces but yes, they are made in the Orient so the prejudice and perception is normal and predictable. I suggest you audition Yamaha NS-200/300 speakers which the British and German magazines gave five stars and the award winning YST-SW800 sub and maybe your perspective will change. I guess Euro reviews dont matter here either. If put down or war is what you wanted with your comments on Yamaha speakers, then you got yourself in this mess. I never meant to insult anyone's equipment unless I have some knowledge and have auditioned the equipment extensively. Yet, unfortunately, you had to bring this ghost up. Well if Yamaha is sub-standard to you, then I guess my ears and my taste are sub standard too but in case you have noticed or read my profile I have a Canton Ergo 120 too and have been ex-owner of junk like Martin Logan Quest and overpriced hype like B&W 801. Magnepans though are sweetest and is going to be on line for my next speaker purchase unless Yamaha gives me something new. BTW: Zubin Mehta, Von Karajan and Kurt Masur listen to music on Yamaha speakers and I guess their taste is sub standard too.

Now for your confusion on bass management. Ask yourself, before HT days of stupid on board crossovers, what did a person with two subs do? Exactly what I am doing now unless you had a passive sub in which case one had to resort to using an outboard high quality crossover. There was no problems then with the setup or else I am to assume people were stupid in the days of non HT. I measured my system with a RTA, SPL and a Aviva test disc and there is no holes in my setup regarding bass. I guess with inferior subs most use, that must be the common case.

END OF CONFUSION.

 

[Dustin B]

This is getting frustrating. I won't comment on the quality of the Yamaha speakers you mentioned. But, back to the bass management stuff.

Can you please clear a few things up.

1) Do you have more than one sub?
2) Are they active or passive models?
3) Are you feeding them a signal with line level or speaker level inputs? If speaker level, is a wire going from the amp to your sub and then from your sub to the speaker?
4) Are you using the crossover in the sub's plate amp or are you using an external crossover?


Reading the Yamaha manual for the YST-SW1500, the line level high pass filter output is fixed. You can choose from 80hz or 100hz. Doesn't mention any filter at all on the speaker level outputs. And from the instructions on page E6 I'll assume there is no filter on the speaker level outputs from the sub and your speakers are getting a full range signal. This would explain why there is no hole in your systems response.

After looking at the manual, I lied, I will make one comment on the subs. The YST-SW1500 is seriously underported and tuned too high. There are many subs available that will easily outperform it at a lower cost (at least in North America).

Lastly, before HT days most people didn't use subs. And those that did, did what you are doing. Feed the speakers a full range signal and then feed the sub the same signal and try and low pass it such that it will blend into the system similar to what is done with the second woofer in a 2.5way speaker. But with the bassmanagement of modern receivers this method became obsolete. And now, the people who dislike receivers or pre/pro's bass managment take a line level signal from a pre/pro, run it through an active crossover with adjustible high and low pass filters, than feed the low pass to the sub and the high pass back to an amp that then feeds the speakers.

 

[Arup]

Yamaha makes the most musical tight sub and is not for people whose idea of bass is boominess. Very few subs in North America comes close to the accuracy of the Yamaha YST-SW800/1500. They will sound underported to ears expecting something other than real bass. Audio World in Germany, Hi-Fi in UK, Audio Enz in NZ all gave fantastic ratings to the Yamaha subs but I guess they are not American so it doesnt matter. I owned a Velodyne SPL-1200 before I switched to Yamaha and it was for the reason that this woofer sounded the most musical. As you wont comment on Yamaha speakers, I wont comment on Klipsch horn loaded PA speakers passed of as Hi-Fi either. Different taste for different folks I guess. A piece of history, Yamaha was the first to launch negative feedback, active servo design which they picked up from the Swedish company they bought over and the YST-SW 800 was the first class D amp sub. Now M&K and Velodyne is also using class D amps for their subs. I guess people in Yamaha dont know about bass and their pianos low pedals are just there for show.

I have two YST-SW800 attached to the speaker level and then going to the amp from the sub. There is a variable crossover dial in front and I have it set to 45Hz. The high pass is set to 80Hz. It is exactly attached like people did in the old days and there were a lot of people like myself using subs as I never believed that a full range speaker was ever possible. It still isnt till this day. As I said before, there are no holes in the system as per my tests and that is what matters.

 

[Michael R Price]

Arup,

I must agree with Dustin that you are not fully understanding how the high-level crossover in your sub amp works. It is simply a capacitor tossed between the speaker level input and output. The effect of this capacitor on your speaker's response is entirely dependent on the speaker's impedance, so it is most likely not near an optimum 6db/oct slope and the corner frequency could be anywhere (the 80Hz spec is only true if your speaker is a constant 8 ohm resistance). Additionally this capacitor may be hurting sound quality outside bass frequencies (at the value needed to get that cutoff frequency, it's got to be a bipolar electrolytic). Please reconsider using your processor's onboard bass management and playing with placement in order to get the best sound quality; the speaker level connection method you are using is far from ideal.

 

[Arup]

Michael,

Many thanks for your advice. I was using this method before. My contention is with the fixed LFE setting on the recievers. In my case, I would like my towers to only get signals up to 45Hz and leave the rest of the dirty work to my subs. This way, I get way more clarity for some reason.

The DSP-AZ1 has two line out for stereo subs and earlier this is how it was connected but the problem was that unlike the subs, my mains too had to do hard work at the lower frequencies and all I am trying with this method is to eliminate that chance. This method was also suggested by Audio Perfectionist magazine, specialy for those who listen to music in 2 channel mode with their HT amps.

 

[Dustin B]

They will sound underported to ears expecting something other than real bass.

What exactly do you think I mean when I say underported and tuned too high?

The dimensions show the enclosure to have roughly 45L of net internal volume. The lowest you can tune with a 3" port would be 27.5hz in that enclosure. I'd also bet they didn't make the port as long as possible and that the enclosure is tuned to 30hz or higher. So with that in mind it is a physical impossibility for the SW800 to do much below 30hz. You could tune lower with a smaller port but the smaller the port diameter the lower the output level at which port compression will set in.

If you decide to learn what a port does and what Hoffman's Iron law is this discussion will get somewhere, until then it won't. There are very very few commercially avaiable subs I don't think have major design trade offs. The trade off most often made is enclosure size (a 45L enclosure is tiny, and no 10" driver can displace enough air to produce decent levels of clean deep bass). The size trade off hurts performance the most. Which is why I built my own sub.

 

[Dustin B]

that unlike the subs, my mains too had to do hard work at the lower frequencies and all I am trying with this method is to eliminate that chance.

If this was the case you didn't have your speaker set to small. Try using the LFE outputs again, but this time set all your speakers to small so that you get a properly match high and low passing at 90hz.

 

[Arup]

Yamaha uses active servo technology and the Hemholtz tuning to acheive a degree of success with Hoffman's Iron law. Yamaha is multi million dollar Sumitomo group employing talented bunch of technicians and musicians and to say that a home made DIY can even come close to it is a bit too ambitious. If that was the case, Chevrolet, MB, Yamaha, REL, Canton wouldnt exsist. All of us would be on DIY stuff built in our nice friendly home enviroment. Hoffman's iron law is circumvented by Yamaha using highly efficient negative impedance digital amp and Hemholtz tuning. Read the manual for full explanantion. Get a RTA and do a analysis and you will see the YST-SW800, M&K, both small subs easily go down to 19Hz. The YST-SW1500 goes down to 16Hz. No law is iron in this case.

Setting my speakers to small defeats the purpose of using big bass capable towers. For me the ideal point would be in the range of 55-45 Hz which in this case is not possible.

 

[Dustin B]

Hoffman's iron law is circumvented by Yamaha using highly efficient negative impedance digital amp and Hemholtz tuning

Thanks Arup, that gave me a good laugh.

Must leave this thread alone, but, but just can't.


By the way what is Hoffman's Iron law anyways and which part of it has Yamaha figured out how to circumvent? Also why is Yamaha's Hemholtz tuning better than the bass reflex designs used by others?

 

[Arup]

Gotta thank you for entertaining me with some great assumptions. A DIY sub taking on a 100 year old company dedicated to music. What next, a Grand Piano with more bass maybe?

Hoffman's Law described by Henry Kloss and later mathematicaly derived by Theile describes the relationship between volume of the sub and the woofer's efficiency.

In case of Yamaha, woofer dispersion and proper tuning along with negative impedance amp enables them to effectively generate good bass from a small enclosure, a sort of turbocharging situation in automobile. I am too tired to describe Yamaha's Hemholtz tuning but since you claim to have the YST-SW 1500 manual, read it. BTW: Have you really auditioned the sub or have just downloaded the PDF manual to make your DIY sub look superior to the Yamaha. Since my chat with Pete from Yamaha USA, very few, if any shops in the US are stocking the YST-SW1500. So either you work for Yamaha or you have a very good source. May I ask where you auditioned this sub as many of my friends in the US are interested in buying this as they arent that brilliant to go DIY or have the space to buy a sub following Hoffman's Iron rule. BTW: Didnt Henry Kloss also make the best bargain, crappy sounding, giant killer CSW sub-sat speakers. Seems like they had the same line as yours. Will beat any high priced sub with their $399 speaker system. If you look at the CSW subs, you will notice that Kloss himself was breaking his own Iron rule. You also criticized Yamaha speakers and I really doubt if you have ever heard the $4500 NS-1000x or $5500 NS-2000. I even doubt if you heard the NS-300 or the NS-8HX which was recently awarded the coveted Grand Prix 2003 award in Japan for best speakers. This was from selection of speakers by B&W, Wharfdale, Paradigm etc. The $16000 SONY SS-M9ED came in second. No DIYers here but I guess the Japanese too dont have any ears like me as they must be stone deaf cause Yamaha speakers and subs are sub par and any DIY man from the US can kick butt of anything from the Orient. Are you aware that Yamaha makes an awesome class A amp which was rated better than a Nelson Pass amp or that Yamaha's DPX projector and DVD player was rewarded with the top performance award last year.

I know, the guy who builds his own hot rods always thinks he can take on the F-1 cars and this is typical with most DIYers and it seems you are no exception.

You dont have to leave this thread alone, my whole source of this week's entertainment will cease.

Just because you build a sub can make you challenge others and ask them questions like describing Hoffman's Iron Law. How about the Trapezoidal rule and its interpertation in Lazy Lambda Calculus? It has to do with audio in case you are wondering. No law is rigid, there are infinite variables to any law and mathematicaly it can always be proven.

 

[Jason Brent]

How about using the Outlaw ICBM?? Would that work with his receiver? This would be a real good option if it can work with his Yammy.

 

[Arup]

Thanks Jason, the Outlaw unit does look promising but I am interested in putting minimal amount of proccesing and keep my signal path pure and simple. Adding this to the signal path might alter the sonic signature of Yamaha which I prefer although I do wish Yamaha had incorporated something similar in this amp.