Making speakers sound tonally similar with an equalizer

Let’s take the same drivers, in the same box, and change only the passive XO.

Those two speakers will sound different. But the on axis FR can likely be made to be similar with a DSP.

However they cans still sound different due to the XO freqs and slopes affecting both the radiation pattern and the phase - particularly in XO band.

I created a mechanical equalizer using Helmhotz method that bent the room to the speakers large bandwifth response of timbre voices not using any thin test frequency...

Use ears not microphone..

Your two speakers sound will blend together their particular response more easily if the room is adapted to them by your ears guiding tuning..

It is a simple psycho acoustic fact that the ears/brain adapt itself rapidly to new acoustic conditions and translate sound wave into whatever the few second response to the room will make it meaningful for them ...

Acoustic is key way more than the choice of the speakers , especially if the speakers are already good...

Electronic equalization is a tool with very specific limits..

Mechanical equalization is done with Helmholtz resonators and diffusers that become integrated parts of a room..

It takes a dedicated room for sure...

As others have said, the only parameter that you can get to match, is frequency response.

But there are so many other parameters to take into consideration.

Just one example: different drivers have differences in: resonances, transient responses, dispersion, breakup, etc.

So, even if one were able to match frequency responses very closely, one speaker would probably still be better than the other with respect to: transient response, imaging, cone breakup within audible ranges, etc, etc.

Also, cabinet construction will not change. So, a resonant, poorly damped cabinet, adding it’s own set of distortions and inaccuracies, will still be there. Matching frequency response will not improve waterfall plots.

I may really be the odd man out, but I'd think absolutely no way two different speakers will ever sound the same even if equalized properly, but for an entirely different reason.

Speakers of the same type sound very different due to design and engineering.

Forgetting types of speakers entirely (box, planar, omni, etc) if you compare two equalized conventional box speakers (eg: twtr, mid, 2 woofs) they'll sound different because of how they work mechanically and move air, even if their respective frequency responses are the same.

Wilsons don't sound like Sonus Faber or Dynaudio or Revel, and keep going. If they did we could all drop $2k on a pair of floorstanders and an equalizer and then make them sound like Rockports.   (what a great dream.....  :-)

@gosta 

@holmz 

haha. I'm with you. But why put money, time and efforts into a bad speaker?

If you're a diy'er it's another game

1. If one had an either/or choice between radiation pattern and FR, then one can fix FR with a DSP.
2. If the speaker (as a whole) sucks, but the drivers are good… Then one could redo the passive-XO as an active-XO
3. If one had a choice between a passive-XO and an active-XO on a speaker, then maybe they would choose something that could have a s/w patch applied to it?

There are probably some other corner cases.

I am using some last millennium speakers and will be trying the DSP on them.

Isn't a flat response curve what a speaker designer is striving for for most accurate reproduction?

This is correct. The problem is that for the most accurate reproduction of recorded sound you want the speaker-room combination to be flat, or tuned to the house curve of your choice. Once you place a speaker in a room the anomalies of the room give you anything but a flat curve. The amount of peaks, dips and nulls created by the room can be rather astonishing.

An e.q. is a tool that can be used to electronically address some of those anomalies, usually at a cheaper cost than room treatments, with decent results. An e.q. can’t do anything with a null but it can smooth out some of the peaks and dips which can make for a more enjoyable listening experience.

As for your original question; in theory it probably could but that is not the use an e.q. was designed for.

Evolution for one million year make us focus on specific timbre voice recognition not on flat frequency response...

Mechanical equalization of a room with our EARS is better than electronical EQ with a mic...It cost nothing...Save a dedicated room...It is more fun to tune and more powerful for improving S.Q....

It take time for sure, many weeks and many months of listening experiments to tune it....

Way more gratifying than buying a tool which will make your sweet spot not so  useful  because located in millimeter... I have 2 sweet spots a few inches large in my small square room so good it is impossible to chose only one...

@holmz 

haha. I'm with you. But why put money, time and efforts into a bad speaker?

If you're a diy'er it's another game. 

@gosta

For good results of course you should use a good speaker.

Not much point in trying to make a bad speaker sound good.

Arguably ^that^ is not 100% true.

One can use cheaper drivers and use DSP to shape the bandpass to avoid resonances and breakup modes, and also to have an active-XO that is time and phase correct a lot easier and cheaper than with a passive-XO.

It may not sound as good as a better speaker and better drivers, but it is usually a lot closer than using the same drivers without using a DSP.

You can choose not to make any adjustments above a certain freq to preserve more of the speakers original response if you prefer that. 

And the time domain and impulse response (and phase EQ) are doing additional things that are not captured in the frequency response plot.
Arguably that may be more important than, or as important as, the FR alone.

’@bjp9738

Maybe you've missed that the more professional dsp’s come with different house curves and you are also allowed to set your own curve for the frequency response.

You can choose not to make any adjustments above a certain freq to preserve more of the speakers original response if you prefer that. 

"Science" says most humans don’t prefer a fully flat freq curve. Flat curve is fine for recording.

Also you can build different curves for different types of music or rather recordings or whether you’re listening to music or watching movies. And on and on...

For good results of course you should use a good speaker.

Not much point in trying to make a bad speaker sound good.

@jaferd 

Isn't a flat response curve what a speaker designer is striving for for most accurate reproduction?  

Yeah generally they are concerned mostly with frequency response.

However there is the time domain performance. And how it performs in an impulse response.

So there are some speakers that are designed as to be time and phase correct.
There are also DSPs that make the Impulse response more correct.

Isn't a flat response curve what a speaker designer is striving for for most accurate reproduction?  

Similar? I would say sort of if the speakers are similar in design. Room EQ software like ARC Genesis, Dirac Live, Room Perfect, Audyssey, etc. all strive for a flat frequency response. So if you run every speaker through the same software, in theory, you should get similar output. Within reason, of course, and assuming all the speakers have a similar frequency range to start with. It's for this reason that I don't like to use eq calibration on my mains in my HT setup. The resulting flat response curve negates the speakers' natural response curve.  I'm waiting for the day when room eq software is intelligent enough to add the right filters so the speakers produce their natural response curve regardless of the room conditions, rather than a generic flat curve.

Ok, "issues" then...

Am a intrigued to try an omni (like MBL or GP) to find out if a such would enhance the listening experience (and yes that would be a little much to ask dirac).

But I’m unsure. A few listening test tells me omni’s could work rather nice for more quiet acoustic music, but not so much for music with a lot of energy. I felt the mids and highs just disappeared at higher volumes. What’s left was a bassy and warm sound but uninteresting.

They do seem to solve the problem with very closed mic’d singers you tend to get in your knees while placing the soundstage well behind the speakers instead of in front of them.

All reviews I read are so very positive - which make me a bit suspicious.

Sorry for these thoughts that have not so much to do with the op’s original question, but he or she seems to be sleeping anyway.

Maybe you know!

If they have the same radiation characteristics and you are using a digital equalizer then yes, you can make them sound very similar. 

Frequency response is only part of the picture: pattern of sound radiation e.g. bipoles/dipoles/omnis plus wide dispersion vs (? more typical) narrow dispersion, etc.

Ok, so I will also correct some speaker issues.

Maybe…

One usually needs to do any phase (and time) work in more of an echo free environment. Or close mic it.

It is not easy to do this stuff outside, and most people don’t.

^That stuff^ is what is used to make the speakers sound similar.

The stuff < 400 Hz is a somewhat different deal addressing the room.

Ok, so I will also correct some speaker issues.

The recommendations from the experts are to use eq to balance room effects below 300 hz. 

The last I would do is to make my speakers (Salon 2) sounds like Harbeths. :-)

But seriously, I would never listen to or try to evaluate speakers if they hadn’t been corrected for room issues below 1000Hz. That would be very unfair to the speakers. 

Looks like out of 4 responses, I am in the minority again.

However Dirac Live, and other EQ systems, sort of make the opinions that it makes bad sound seem a bit more like opinions than anything based in fact.

For example, the Lyngdorf “Room Perfect” intentionally only does room correction as the impulse response correction (like Dirac Live) would make all speakers largely sound the same. And tehir customer wanted their speakers sound character to not be altered, irregardless of whether it was right or wrong.

But that can devolves into whether “it sounds better, but is worse at matching the signal” is wrong… it is certainly not right though. And a 100 people will tell you that they trust their ears more than a microphone. 

No never dream on.

Bad idea.  You won’t get there, and inserting another piece of equipment in the signal chain is also not optimal.  Save up for the real thing rather than throwing $$$ down the drain on an equalizer.  My $0.02 FWIW. 

Issues like phase non-linearity cannot be fixed with an EQ- it usually makes it worse!   Measuring and using a parametric to compensate can help response within the room but it cannot fix room problems which are usually at the heart of most of poor performance issues.

Brad

Only to an extent.
One cannot overcome the passive crossover, so one can only work around that.

If it s was bi-amped or tri-amped, then it is easier to get to where you describe.