Spannko wrote: ↑2023-09-10 16:30
I agree Rutger, there’s practically nothing written about how to build a musical loudspeaker. I was asked to recommend a book, and in all honesty, I couldn’t recommend one. They’re all just a collection of loudspeaker research, none of which focuses on a loudspeaker’s ability to play something as simple as rhythms and tunes. Similarly, all of the diy loudspeaker forums focus on a loudspeaker’s technical measurements. As tuneistas, we have to do our own research.
Unfortunately, it gets worse! Drive unit manufacturers don’t appear to design for musicality, and despite what their marketing departments claim, crossover component manufacturers don’t either. Every single drive unit, capacitor, inductor and resistor has its own level of musicality, and from what I’ve heard, nearly all of them are pretty poor. It’s no wonder that practically all loudspeakers on the market fail to reproduce music in a wholly convincing manner.
From a source first perspective, the crossover could possibly be the most important element, yet there’s practically nothing written about crossover design. The general approach to designing a loudspeaker is to pick drive units with good looking specs (whatever they may be!), use a computer program to design the “optimal” enclosure (whatever that is!) and then use a crossover simulator to find a combination of components which will somehow compensate for drive unit and enclosure errors and miscalculations. From a source first perspective, this appears to be total madness. If the crossover was designed first, it appears to me that there would be only one topology which would let the signal through without destroying its harmonic integrity: a series connected, first order dual filter network, consisting only of one capacitor and one inductor. I appreciate that this is a bold statement and that it places considerable demands on the drive units and may produce the type of sound people are unaccustomed to, but it seems to me that conventional loudspeaker design methodology only works very occasionally, and only then by accident. Even the more knowledgeable manufacturers struggle to consistently produce musical loudspeakers. Time will tell if I’m on the right track, but the initial results have been pretty encouraging!
Yes, its almost that the most musical speaker should be a speaker without any crossover .
One more thing I want to contribute to this thread and its something I have recently discovered.
I have always wondered why the bass quality of the Linn Keltik was so good , and why some of the successors sounded less good at some points. In my opinion, its a very bad idea to have a subwooferdriver placed very near the floor, because you excite the whole room more than having it higher up from the floor. Some might say floor level placement of the driver could be a good thing, but if a clear pitch is the goal, it probably isnt.
So, using two very expensive active loudspeaker with subwoofer, I raised up the subwoofer so it was placed about 50 cm above the floor and the soundquality regarding a clear pitch became much better.
This is a rather good video:
https://youtu.be/S_GwaGeWQOg?si=iQa9Lwc5QR1IOrJN
( he explains why its a problem with floorstanding subwoofers, but he knows nothing about the tunemethod , so he makes some wrong solutions )
Later on, with two stereo DIY subwoofers, I recognized that two subwoofers sounds the best at the exact spot as the main speakers are placed, If using tunemethod in installation. And the subwoofers sounds even better 50 cm above the floor . - exactly the way Keltik or Isobarik was made.
Conlusion : A subwoofer should be inbuilt in the main speaker cabinet and not placed at floor level.
Drawing the conclusion of some of this , my last DIY speakers was a very simple construction that had the basstube on the backside of the cabinett, about 50 cm above the floor. The sound didnt need any roomcorrection at all and this became my best construction yet.
It might be a very good idea also ( in a bass reflex speaker ) to tune the speaker below the musical tones area, ie below lowest E from a bassguitar, 41 Hz . You easily mess up the tune If its right were the musical content is. In this case, its probably better if the tuning is somewhere between 34-36 Hz.
To complicate things, the box volume must follow the chosen tuning frequency, a lower frequency usually needs a bigger a box. And different drivers needs different box volume.
Another thing happened some time ago, were my friend who has a very expensive system ( Linn exakt with klimax source ) had done a tunemethod installation off his speakers and the inside of the speakers front baffle was placed 43,5 cm from the frontwall. This was very strange because I had done the same installation at my place the week before with different speakers and source, and they also happend to be placed 43,5 cm from baffle to the backwall. Coincidence ?
If there is something in this findings, technicaly you do change the SBIR frequency when one moves speakers from the frontwall and 43.5 cm baffle-frontwall might be the optimal frequency to make the stereo system faults as ”good” as it can be and the sound most tuneful , thus making the illusion better ? This might be the wrong conclusion and maybe this is just a coincident.
Conventional wisdom also tells us that we can only hear 20-20000 Hz .
I think this is wrong - we hear from 1 Hz to 20000 Hz , but the lowest frequencies are ”heard” by the body , feeling the rythm of the beat.
A guitar cord thats been struck has a very short beginning of very low frequencies right before the string starts to resonate at a higher frequency. This is probably why one can hear that a HP filtering beginning at 20 Hz in an amplifier is bad for the sound, and why one can experience that a HP filtering of 3 Hz sounds better with less blurring of the guitar pitch. I know this is my opinion and I have heard some loudspeakers (Linn ) that sounded better with a HP crossover right below the tuning point , but If one use driveunits that can take the punishment without sounding bad below the drivers fs, the sound might get better If the amplifier is close to DC in response.
As you already know, a passive loudspeaker, unconnected and placed in the listening room will colour the pitch of the tones in the music because of sympathetic resonanses. So when doing fine tuning of damping material in a DIY speaker, its important to put away all other passive speakers in the room.
https://en.wikipedia.org/wiki/Undertone_series
More:
https://en.wikipedia.org/wiki/Sympathetic_resonance