is there anything passive one can do to lift that low end?
I've been looking around and some of the audio\bt boards can be customised with their EQ settings, which i didnt know was possible, but looks like the change would be applied to all channels, which isnt something i would want to do.
I've been looking around and some of the audio\bt boards can be customised with their EQ settings, which i didnt know was possible, but looks like the change would be applied to all channels, which isnt something i would want to do.
That article ends with these words:
What errors?
😕
IDK...the sound propagates from the sources at Mach1 velocity, bounces to the walls and extinguishes, arrives to the ears...the brain does some calculations
What errors? 🙄
There are passive tone controls which work by cutting rather than boosting but if you have enough gain in the amplifier amount to the same thing.
Also, this very simple circuit will give you a small apparent boost at lower frequencies Baffle Step Compensation
Rod Elliott's site is somewhere you should explore I think
Also, this very simple circuit will give you a small apparent boost at lower frequencies Baffle Step Compensation
Rod Elliott's site is somewhere you should explore I think
Cheers, I've used a.BSC a few times and it was quite good, just not sure if it will provide the little bass note in a box half the size of what I'm using currently. I will have a bit of a read through that site though
He's talking about the circuits measured response Vs the simulation. Saying there's only very little error between the two and as the majority of the error is at frequencies below which we can hear it doesn't really matter.
No doubt the deviation is caused by capacitor tolerances.
No, I think you're missing my point.
My point is this:
At low frequencies, a speaker in a room will need fairly large EQ adjustments in order to produce a flat response at the listening position.
Your method seems to be be to use a Linkwitz Transform to make the speaker flat, and then apply more EQ to sort out what the room is doing.
My method is to treat the room and speaker as one, and EQ the result.
We end up with the same thing (flat response) at the listening position, but your method means you've got an stage with 6-10dB of boost when there's a fair possibility that's going to be cut down by the next EQ in the chain.
Here are the measurements:
Simulated:
Measured at the listening position:
I'm sure you can imagine what my EQ curve looks like - no positive gain is required to get a flat response.
So, if I did happen to apply a Linkwitz Transform to get flat to 20Hz, I'd end up having to make even larger cuts at the "room EQ" stage to get back down to flat.
In conclusion, instead of saying "oh yes, it's a sealed box, it'll need a Linkwitz Transform", I'd suggest that the speaker should be measured in-room before any EQ (Linkwitz Transform or otherwise) is applied.
Chris
re: passive, "3rd order" closed boxes using a series capacitor can be useful as long as the amplifier driving impedance is low and their "boost" comes from a drop in impedance where its normally risen somewhat above Re.
And of course assisted 6th order vented boxes make good use of active EQ.
And of course assisted 6th order vented boxes make good use of active EQ.
Just buy an inexpensive 10in active sub with adjustable crossover. I got a Polk PSW10 free shipping from Amazon and it integrates easily and sounds very nice. Super low hassle if you don't want to deal with all of this. This used to be only $100, but now seems like it is $150. However, it's very well made and probably worth it. No way you are going to do it yourself an nicely finished box, panel connectors, amp, crossover, driver, port tube, rubber feet, power cord, and grill cover for anywhere close to this price. But if the goal is the learning journey - then by all means DIY.
https://www.amazon.com/Polk-Audio-PSW10-Powered-Subwoofer/dp/B0002KVQBA/
https://www.amazon.com/Polk-Audio-PSW10-Powered-Subwoofer/dp/B0002KVQBA/
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Thanks for the advice and suggestions, but my intention was to use the LT in something.around the size of 0.06cuft and use a battery to power it. My idea of DIY is to do the woodworking and solder everything together and learn some of this acoustics along the way (albeit finding it a very steep learning curve)
No, I think you're missing my point.
My point is this:
At low frequencies, a speaker in a room will need fairly large EQ adjustments in order to produce a flat response at the listening position.
Your method seems to be be to use a Linkwitz Transform to make the speaker flat, and then apply more EQ to sort out what the room is doing.
My method is to treat the room and speaker as one, and EQ the result.
We end up with the same thing (flat response) at the listening position, but your method means you've got an stage with 6-10dB of boost when there's a fair possibility that's going to be cut down by the next EQ in the chain.
Here are the measurements:
Simulated:
Measured at the listening position:
I'm sure you can imagine what my EQ curve looks like - no positive gain is required to get a flat response.
So, if I did happen to apply a Linkwitz Transform to get flat to 20Hz, I'd end up having to make even larger cuts at the "room EQ" stage to get back down to flat.
In conclusion, instead of saying "oh yes, it's a sealed box, it'll need a Linkwitz Transform", I'd suggest that the speaker should be measured in-room before any EQ (Linkwitz Transform or otherwise) is applied.
Chris
Yes but only when the design itself is taken into consideration. Also, in my experience I've never encountered a system + room combo where applying a modest amount of LT boost has impacted negatively on the bass of said system.
My point is that when you've got a speaker with good extension already, like in your case, you don't necessarily need an LT as you're already well into the room gain and modal region. But we've never been discussing a system like yours.
You do however need an LT when your speaker only goes down to 100Hz, or even higher. That's how the original posters system presents and also how my examples present.
Your replies just came across as overly negative in a post where the criticisms you had weren't really relevant. Ie the speakers in question were only ever going to have a small amount of boost to start with and even with the boost wouldn't get down low enough to interact much with the modal region of the room. And even if they could tickle the 40-50Hz primary modes, with speakers this small, the boost would be entirely welcome.
You must have an absolutely tiny, and very well sealed, listening room to be getting ~28dB of room gain by 10Hz. Most get more like 15dB. And also I wouldn't recommend anyone use room EQ on a stereo system, let alone a single bass source in room. Otherwise you're going to get very uneven bass as you listen anywhere other than the primary listening position.
What speaker is it you're using? You didn't answer the first time round.
Hi, I hope I can hijack this thread. What would you assess as modest amount of LT? I am tinkering with following design idea. Make two 6.5" woofers act as one 8" woofer with the help of LT. Main reason for a pair of two woofers is elegantly sleek box, approx 1m high
I am tinkering with drivers with following specifications:
Fs 51,4 Hz
Le 0,34 mH
Qe 0,64
Qm 8,86
Qt 0,59
Re 5,95 Ohm
Sd 137 cm2
Vas 22,5 l
Would it be possible for above 6.5" pair to outperform (go little deeper) single 8" inch speaker? One like this:
Fs 29Hz
Le 0.62mH
Qe 0.67
Qm 2.32
Qt 0.52
Sd 219cm²
Vas 2.47ft³ (70l)
Cms 1.07mm/N
BL 6.88T·m
Mms 27.5g
Xmax 4.25mm
Which sounds darn good btw 🙂 Of course this one employs no LT transform advantage.
I am tinkering with drivers with following specifications:
Fs 51,4 Hz
Le 0,34 mH
Qe 0,64
Qm 8,86
Qt 0,59
Re 5,95 Ohm
Sd 137 cm2
Vas 22,5 l
Would it be possible for above 6.5" pair to outperform (go little deeper) single 8" inch speaker? One like this:
Fs 29Hz
Le 0.62mH
Qe 0.67
Qm 2.32
Qt 0.52
Sd 219cm²
Vas 2.47ft³ (70l)
Cms 1.07mm/N
BL 6.88T·m
Mms 27.5g
Xmax 4.25mm
Which sounds darn good btw 🙂 Of course this one employs no LT transform advantage.
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The speakers I've simmed and measured are my main L/R speakers (no subwoofers required!). Each has 2x Seas H1252-08 - their 8" aluminium-cone midbass driver - in a shared sealed chamber of approx 30L. The room is a typical UK living room. Brick wall construction, double-glazed windows. The stairs come down into the living room, too, and the kitchen/dining room is a badly-sealed door away.
I haven't seen many nearfield vs far-field measurements of different speakers in typical rooms, so I can't comment on the 15dB vs 28dB difference. I can say, though, that the LF response is similar across the 3-seat sofa I usually use for listening/movies, so the EQ correction works for 75% of my seating. Perhaps I've got lucky.
I don't think anyone has mentioned a particular speaker, LF cutoff, or how much boost may/may not be applied.
Apologies for the negativity. It wasn't my intention to come across that way particularly - I just wanted to highlight that, IMO, below 150Hz-ish, the speakers + room should be treated as one lumped system, and EQ'd accordingly.
Chris
Hi,
I implemented Linkwitz transform circuit after active crossover circuit,
I did some new measurement, and I've realized that the step response curve is inverted, it going down first (Blue color). I did some ltspice simulation, and same result. I guess the opamp inverting it. Then I tried to flip the polarity on speaker side. Then the step response measurement looked even more strange, and the frequency response also changed a lot.
Coud somebody explain why is it happeing, and how to avoid it? Need an inverting buffer stage between the active crossover, and the Linkwitz transform circuit? Why flipping speaker cable polarity didin't work?
Frequency response:
I implemented Linkwitz transform circuit after active crossover circuit,
I did some new measurement, and I've realized that the step response curve is inverted, it going down first (Blue color). I did some ltspice simulation, and same result. I guess the opamp inverting it. Then I tried to flip the polarity on speaker side. Then the step response measurement looked even more strange, and the frequency response also changed a lot.
Coud somebody explain why is it happeing, and how to avoid it? Need an inverting buffer stage between the active crossover, and the Linkwitz transform circuit? Why flipping speaker cable polarity didin't work?
- Blue color is the active crossover with Linkwitz transform
- Red color, active crossover, Linkwitz transform reversed speaker cable polarity
- Brown, driver response without crossover, and Linkwitz transform
Frequency response:
- Blue color is the active crossover with Linkwitz transform
- Red color, active crossover, Linkwitz transform reversed speaker cable polarity
I measured only the pure driver’s Q and Fs before I started to do the crossover and the Linkwitz circuit.