gedlee said:
Ok. No HP for the mains (the Summas represent a ~80Hz, 2nd order HP, right?).
This raises the next question: If the mains are 'full-range' (e.g. down to 40Hz), will the four free parameters for each sub (placement, level, LP cut-off frequency and phase) be enough to "blend" the subs into the existing sound field or will a parametric EQ be needed (for the subs and/or the mains)?
Thomas
There are three Summas and each has a different HP point. The Nathans, the smallest, are about 80 Hz.
I have found just level and phase to be pretty effective (location is fixed by practicalities), but a paramteric band of EQ or two has also been very handy. If you find you need more than two bands then the setup is probably not right as I have never needed more than two.
I have found just level and phase to be pretty effective (location is fixed by practicalities), but a paramteric band of EQ or two has also been very handy. If you find you need more than two bands then the setup is probably not right as I have never needed more than two.
markus76 said:
Sorry, I am not able. It seems that you are not willing to accept my statement "If you place a subwoofer at the node for a mode and have it play the frequency for that mode, you will hear that frequency, but the mode will not be activated. The relative level will be low because it's not reinforced by standing waves, but you will still hear it."
If that is the case, please look at Toole's book, page 224, figure 13.13a. The dotted line shows the corner subwoofer. The solid line shows the subwoofer positioned midway across the front wall, which is the node for the first-order width mode, which as you can see is no longer activated. Output at this frequency is not zero (which is what I assume you meant when you wrote "When you place a sub at a null, that particular mode is "cancelled". But that means that we will hear nothing at all"), but it is indeed much less than at the frequencies reinforced by modes. This level is what I think of as the baseline output level, although I am sure I am mangling the terminology, so please just bear with me. Adding the second subwoofer in 13.13b boosts the baseline output level, maybe around +6dB? Adding two more still in 13.13.c boosts the baseline output level further still, maybe another +6dB? Figure 13.13d shows the quarter-room placement addressing the even-order modes by placing the subwoofers in the nodes for these. Again, there is still output, but it's much less than at the height mode frequency.
If the problem is instead a conceptual one, I believe that basically all you have to do is think of a 2-dimensional wave superposition model of a source transmitting energy at a non-modal frequency. If I understand correctly, energy falls off as a function of distance but increases as one approaches a boundary.
Earl,
ok, seems I confused the names.
Are you talking about one or two EQ bands per subwoofer or two EQ bands applied to the LF channel (same EQ for all subs)?
And (sorry ...) another question:
If the mains were 'full-range' but I wanted to gain some max. SPL below 100Hz, I'd have to use a HP filter. Am I correct to assume that you would suggest to use a 'gentle' HP filter like 80-100Hz/2nd order or even 1st order? I am thinking about a multi-sub arrangement for Klein+Hummel O300 speakers. While they go down to 40Hz, their max. SPL at 40Hz (one 8" woofer in a small closed box, according to K+H 85dB SPL @ 40Hz, 1m, 3%THD, free field) is of course limited ...
Thanks
Thomas
gedlee said:
ok, seems I confused the names.
gedlee said:
Are you talking about one or two EQ bands per subwoofer or two EQ bands applied to the LF channel (same EQ for all subs)?
And (sorry ...) another question:
If the mains were 'full-range' but I wanted to gain some max. SPL below 100Hz, I'd have to use a HP filter. Am I correct to assume that you would suggest to use a 'gentle' HP filter like 80-100Hz/2nd order or even 1st order? I am thinking about a multi-sub arrangement for Klein+Hummel O300 speakers. While they go down to 40Hz, their max. SPL at 40Hz (one 8" woofer in a small closed box, according to K+H 85dB SPL @ 40Hz, 1m, 3%THD, free field) is of course limited ...
Thanks
Thomas
I was thinking of the same arrangement. I will shortly be taking delivery of a K+H 0300/0800 system and, though I was tempted to take a chance with multiple subs, I decided to start with the stock arrangement since it is reputed to blend so well.
I do intend to use this set up as a basis for comparison while I experiment at my leisure with alternates to the 0800 and also the 0300.
I was exceedingly impressed with the accuracy of the tonality of the 0300, but think that I may eventually prefer more dynamic capability. The Abbey or Nathan are likely contenders.
For my purposes, though, the combination of performance, cost and size made the K+H a very persuasive prospect, especially considering their utility as portable field monitors - 250 x 380 x 290 mm and 14 kg is small, considering it includes internal tri-amplification!
In fact I couldn't think of any alternatives, so I bought them!
I came very close to taking this approach myself, ordering some Minotaur subs from BK Electronics. However I ended up cancelling my order after suffering their completely unresponsive customer service and mythical 7-10 day lead time.
Alex
Alex
gedlee said:
I pulled the text form my web site. It is not the complete discussion. In my analysis both Kn and Psi are complex. The imaginary part of Kn defines the amplitude of the modal resonance. I also never said that the eigen functions are zero anywhere. I simply said that the position of both the listener and source are equally important. What works well for one listening position may not work well for another. And if the eigen function is zero at either point then the contribution to the SPL form that mode would be zero (at all frequencies). That does not mean the SPL will be zero at the modal frequency. The part of the text in bold should have make that clear.
I simply off the software for those who care to play around with it. There are two sections, the upper section allows the user to look at a single monopole, dipole or cardioid woofer. The lower section allows the user to look at a room with up to 4 monopole woofers. Damping can be changed as well. It’s a simply model of wall admittance and I am sure you would criticize it. But it is sufficient for the demonstrative nature of the software.
An externally hosted image should be here but it was not working when we last tested it.
It's a nice little "What if" tool that lets the user have a little fun. If you can have a little fun with this you’re taking it way too seriously.
mat02ah said:
I think that EQ for each sub would be very difficult to setup, I've never done it that way. I just do the best that I can with the levels and phase and then there is usually some peaking left which I attack with the EQ on all channels equally.
As to you K&H question, 85 dB @ 40 Hz max is not even usable. A HP filter may make this more reasonable. But the question isn't about using multiple subs, but how to correct the K&H.
gedlee said:
"Not even usable" for what purpose? Home Cinema without additional subs? Yes. Music? No.
gedlee said:
What do you want to correct? This is a small speaker built for near-field applications, and certainly not a bad one.
Thanks, but this is leading nowhere.
Regards
Thomas
markus76 said:
I was talking about max. SPL, as shown here:
An externally hosted image should be here but it was not working when we last tested it.
You guys seem to be very defensive about your "local" products.
This speaker, to me, is classic in that all efficiency seems to be sacrificed for extended LF response. Exactly what I don't do. The LF extension is very good for an 8" loudspeaker, but the MAX SPL indicates that this extension is not very useful as it comes with a lot of nonlinearity (and I'm not saying that this is audible only that the VC is obviously coming out of the gap at medium SPL levels). It would be difficult for me to use this speaker in any of my applications. As a near field monitor, which it was probably designed for, it would be OK, but not in a home situation. You would have to HP filter this speaker to get any kind of SPL level in a listening room. But then all that work to extend the LF would be wasted - you'd end up with low efficiency AND no LF extension.
I am not sure who you are trying to impress with the axial frequency response. With an active system thats a no-brainer, but also not that important. And the price! Wow!
This speaker, to me, is classic in that all efficiency seems to be sacrificed for extended LF response. Exactly what I don't do. The LF extension is very good for an 8" loudspeaker, but the MAX SPL indicates that this extension is not very useful as it comes with a lot of nonlinearity (and I'm not saying that this is audible only that the VC is obviously coming out of the gap at medium SPL levels). It would be difficult for me to use this speaker in any of my applications. As a near field monitor, which it was probably designed for, it would be OK, but not in a home situation. You would have to HP filter this speaker to get any kind of SPL level in a listening room. But then all that work to extend the LF would be wasted - you'd end up with low efficiency AND no LF extension.
I am not sure who you are trying to impress with the axial frequency response. With an active system thats a no-brainer, but also not that important. And the price! Wow!
Thomas, I wasn't aware of the very low max. SPL at low frequencies. You have to take the frequency response into account as Earl already pointed out. That's why I posted the diagram. The O300 is one of the best nearfield monitors on the market. But it's exactly that - a nearfield studio monitor. Most people think that nearfield is 2 m or more. That's incorrect. In a studio a nearfield monitor is placed much nearer. And that's what the O300 is designed for. Hope you don't use it otherwise.
Best, Markus
Best, Markus
I am not defending anything or anyone.gedlee said:
So we agree on that. Fine. "Any kind of level" of course depends on the room, your preferences, the neighbours ...gedlee said:
I am also not trying to impress anyone. K+H presents lots of other data, much more data than you present.
They are selling complete, active loudspeakers that work out of the box. Not a kit.
To summarize: The "Geddes approach to multi-sub placement" is not very suitable for small speakers with some LF-extension. You'd have to HP filter them and "waste" their LF-extension. You need "big" mains with some LF extension and high SPL capability for this approach. That's pretty much the answer I expected.
Regards
Thomas
Thomas, you sound rude. The "Geddes approach to multi-sub placement" works even with your speakers, but it can't compensate for the limited level capabilities of the O300 at low frequencies. They will produce a lot of distortion at low frequencies with or without multiple subs.
If you look at Klein + Hummels subs then you'll find that they use a high pass exactly as Earl suggested.
Best, Markus
If you look at Klein + Hummels subs then you'll find that they use a high pass exactly as Earl suggested.
Best, Markus
I was. What kind of miracle do you expect from a 8" woofer in a closed box?markus76 said:
Quote from the K+H O300(d) manual:markus76 said:
Most Common Application: Near-field monitoring
Minimum Distance: 0.75 m (2.5’)
Recommended Distance:1.0 – 2.5 m (3’ - 8’)
Maximum Distance: 6 m (18’)
Regards,
Thomas
What are you trying to prove? It depends on your level requirements (and in a nearfield situation on the dispersion). You can even place them at 10 m distance if you don't want to play them loud. You have to decide for yourself how much distortion you allow for.
I'll repeat: If you look at Klein + Hummels own subs then you'll find that they use a high pass exactly as Earl suggested.
I'll repeat: If you look at Klein + Hummels own subs then you'll find that they use a high pass exactly as Earl suggested.
mat02ah said:
I would say it this way:
"The Geddes approach requires a total system design which encompasses the room, multiple subs and mains wherein each subsystem is optimized to work as a whole."
What you are asking is how to "modify" a subsystem that was not designed to work with multiple subs. As Markus points out you can do that, but it will be less effective than if you had taken a full systems approach which would have not have sacrificed efficiency to extend the LF response.
The Abbeys, assembled, sell for far less than the K&H system. Performance of the Abbeys is hands down better than what you have shown.
markus76 said:
You "repeat"? Funny ... We started this discussion in a german forum (casakustik.de) where you repeatedly stated that HP filters are not needed, because you didn't think of limited SPL. Now we seem to agree that some filtering is needed. Were's the problem?
Thomas
gedlee said:
That's what I thought, too. Markus presents this method on his website as being more universal.
I am not thinking about modifying a subsytem, I am thinking about adding subs to existing O300 speakers.gedlee said:
gedlee said:
Abbeys, assembled, per speaker, without power amps: $1600+shipping+~5%duty+19 % tax=$2046=EUR1530
O300 with power amps and two years warranty:
~EUR1850, shipping and taxes included.
That's not really "far less".
It was not my intention to discuss all this. I simply wanted to find out how to make a 'Geddes multiple sub setup' with small speakers. So the answer is:
(i) You don't need HP filters to make the principle work but
(ii) if you want more SPL you will need HP filters.
I was sure about (ii) but not sure about (i).
Thomas