DIY ACTIVE REFLEX STEREO SUBS 40 Hz – 120 Hz ?

[RaymondFromThePyrénéés]

I am about to buy a used Lyngdorf Amp with little power.
The Lyngdorf TDAI-1120 has a power rating of
60 watts per channel into 8 ohms and
120 watts per channel into 4 ohms.
It uses efficient Class-D technology that stays cool
without needing ventilation holes.
The amplifier doubles its output when speaker impedance
drops from 8 to 4 ohms, showing it has strong current
delivery for driving demanding speakers.

My idea is to use the amp for my DIY Line Arrays that
has only mediums and tweeters and to make active subs
myself. I also intend to build i the futur a full range open
baffle which would also need these subs.

I am not looking for a 30-40HZ sub but rather something like :

DIY ACTIVE REFLEX STEREO SUBS 60 Hz – 200 Hz

The crossfilter for the subs is available internally in the Lyngdorf.

In this DIY project for a stereo installation of 2 subs, I wonder
what kind of subs I would need to buy ? and the size of the box ?

Perhaps there are some designs available online ?

I am not building sealed subs after having read the recommendations
in the book by Jim Smith : Get Better Sound where Mr. Smith explains
why he prefers subs sound with a reflex, vented hole,
saying that in a concert, the subs are full alive, vibrating fully, transmitting
strong emotions, which according to him is a dry sound not very engaging.

I suppose that alone could turn out to become a heated discussion ?

 

[Redacted]

The words "transmitting strong emotions" make me want to get to the top of a tall building....

 

[RaymondFromThePyrénéés]

That is how Jim Smith express himself when compared to as he names dry sealed subs with no emotions, saying that in a concert vibrations are not dry and sealed but vibrant

 

[RaymondFromThePyrénéés]

What about this at Audiophonics in Bordeaux :

DAYTON AUDIO DCS385-4 Haut-Parleur Subwoofer 300W 4 Ohm 92dB 19Hz - 200Hz Ø38.1cm : 169€​

DAYTON AUDIO SPA100-D Amp Class D for Sub 100W 20Hz-200Hz : 149€​

or

DAYTON AUDIO SPA300-D Amp Class D for Sub 300W 20Hz-200Hz : 240€​

 

[somebodyelse]

60-200Hz is just a woofer, not a sub, so that may affect driver choice. Are you sure you don't want to play anything lower? Since you can hear where a 200Hz source is, your subs will have to be close to your line arrays. I'm assuming the Lyngdorf will let you set the crossover frequency that high - I don't see anything specific about that in the manual.

Since the Lyngdorf will handle the crossover you don't need the filtering from a specialised subwoofer amp. Do you have a suitable spare amp you could use?

 

[Redacted]

For reference, note that on a standard electric bass , the second lowest string, A, is about 55Hz, and on a piano, the lowest note is half that.

 

[Redacted]

That is how Jim Smith express himself when compared to as he names dry sealed subs with no emotions, saying that in a concert vibrations are not dry and sealed but vibrant

Just buy a basic HiFi unit - an all-in-one or a couple of nice separates, play music and be happy.
All this book stuff is a diversion - and Jim Smith never made a decent album with his old ukulele.

 

[RaymondFromThePyrénéés]

Just buy a basic HiFi unit - an all-in-one or a couple of nice separates, play music and be happy.
All this book stuff is a diversion - and Jim Smith never made a decent album with his old ukulele.

Thank you Redacted. I admit that sometimes he is a bit extreme, at least to me. Anyway, I bought my Lyngdorf this morning for 800€ with a minor scratch on the box, cannot wait to try it out.

Thank you Somebodyelse. I suppose I shall have to measure first how low my line arrays play and also see with REW if they are worth pursuing because my ears are not as experienced as the many years of experience that most of you have here. Then I will decide in which frequency I will let the subs play, using the Lyngdorf's crossover frequency.

Thank you.

 

[RaymondFromThePyrénéés]

Just buy a basic HiFi unit - an all-in-one or a couple of nice separates, play music and be happy.
All this book stuff is a diversion - and Jim Smith never made a decent album with his old ukulele.

Thank you, that is what I did, a Lyngdorf TDAI-1120. About the PC to learn about all this, perhaps I do not even need to. It is easy to lose oneself on this digital sound journey, 40 years ago, it was all about buying a CD or Turntable, hook it up to an amp and speakers and that was it.

 

[Redacted]

40 years ago, it was all about buying a CD or Turntable, hook it up to an amp and speakers and that was it.

Good for you. And really, it is pretty much as simple as 40 years ago, so long as you don't get sidetracked into buying stuff you don't need.

My Top Tip: Don't buy things assuming it will fix problem that you don't yet even know exists.

I'm a very happy listener - I have absolutely tons of music, very modest kit and yet have no need of tone controls or EQ or room correction. The odd thing I do play that sounds bad is because it is bad - I've had all all sorts or amps, speakers and rooms over the years, and some of my poor recordings remain so and no amount of "fiddling" quite fixes that for me. Besides, I'd end up fiddling with system parameters for almost every album if I got into that. I admit I have possibly been lucky with listening rooms (and a choice of them in the same house), and furnishings (my wife's choice, luckily for the sound). I go to live concerts every few weeks and always have done, so one learns that enjoying music is not about "the beauty of our weapons" as it were.

 

[RaymondFromThePyrénéés]

Thank you. Are you saying that the sound you had before the digital sound, was as good as the sound we have today with all the corrections ?

I know from reading you all here that the room and placement of speakers and listener is far more important than anything else but there is also on the same time lots of discussions about sound coming out of the hardware but perhaps this is all to early for me to appreciate now.

I suppose then that was has changed is that one can build a good system with less money than what was possible in the past ?

 

[Redacted]

Not sure what you mean by "before the digital sound" - all my music used to be on vinyl (I'm old), but I was happy sell it all and replace with digital - I actively dislike vinyl, it's just nasty to use. I did not bother with any EQ/tone corrections back in my vinyl days, and neither do I do now.

I have heard friends' systems that have correction with digital filters calibrated by microphones (Dirac was one) and was unimpressed. I don't always sit in the same place in the room, so sometimes the sound gets weirder than it naturally does if you move around. "Yes but you can it it wider or narrower or for several points in the room" I was told, but so what? My friend was always recalibrating, which is the exact thing I don't want to get into. Move a coffee table? Recalibrate. Cat keeps walking past? Recalibrate. I know most users aren't like that though!

I have got the best "mileage" from lots of time spent on positioning speakers, and blending in the subs - you may recall I said 3 straight days and endless tracks played. My kit is basically old-ish and cheap but honestly, most music make the speakers disappear now - it can feel like the band has set up in my room (without the hiss etc from live gear!).

Last point - you absolutely can put together a stunning system for far less money today, than ever before. I'd even say that within the last 4 years or so, that that is even more true. But I am a bit of cheapskate and prone to WAF considerations.

 

[RaymondFromThePyrénéés]

Thank you for sharing all this, I will take it into consideration when moving forward.
I am lucky to have a pretty big room for my music, our cat is very curious streaking along the door to this room, but it is definitely a NO

When I said before the digital, yes I meant before CD but of course, the digital sound has gotten so good today that one cannot dismiss it, although one can prefer vinyl sound even if it is a distorted sound.
I cannot wait to get going.

Will I try to measure my sound with a REW, yes, I am curious but if the sound is good, I will not spend hours and hours to try to make it a little bit better except for room acoustics and speaker and listener positions. And of course, I would also like to find the sound where the speakers disappear, I think that this is the goal for everyone here.

 

[Redacted]

Disappearing speakers is just time and effort, not money or mystical magic sauce. And possibly luck!

 

[RaymondFromThePyrénéés]

Yes, that is what Jim Smith write as well, small small movements until it happens.
Thank you.

 

[Flaesh]

speakers disappear

Any functioning speaker, when positioned normally and listening to a normal stereo recording, is always hidden from the ear. Those interested can discuss various details of sound phantoms. But the "separateness" of sounds from the speakers is simply a symptom of a functioning stereo system.

I am not building sealed subs after having read the recommendations
in the book by Jim Smith : Get Better Sound where Mr. Smith explains
why he prefers

Have you already yourself compared normal sealed subwoofers 20 Hz 0 dB with ventilated holes 60 Hz?))

 

[RaymondFromThePyrénéés]

Actually no. I just finished reading his book, Get Better Sound.
Seems as if he has lots of experience with many hundreds of system
he has set up.

Jim Smith often prefers subs with a ventilated pole piece, but when it comes to enclosure type, he actually recommends ported (vented) subs over sealed subs for several reasons:

1. Efficiency: Ported subs are generally more efficient than sealed subs, meaning they can produce more bass with the same amount of power.
2. Low-frequency extension: Ported subs can often extend lower in frequency than sealed subs, especially in the 20-30 Hz range.
3. Dynamic range: Ported subs can handle more dynamic range and produce more SPL (sound pressure level) than sealed subs.

However, sealed subs have their own advantages, such as:
- Tighter, more controlled bass: Sealed subs tend to have a more accurate, "tighter" bass response.
- Smaller size: Sealed subs are often smaller and more compact than ported subs.

Ultimately, the choice between sealed and ported subs depends on the specific application, room size, and personal preference. Jim Smith's preference for ported subs is likely due to their ability to produce more bass and dynamic range, but sealed subs can still be a great option for certain situations.

 

[Redacted]

Sub efficiency is arguably irrelevant in the days of huge and cheap class D plate amps.

 

[RaymondFromThePyrénéés]

I might have mistaken myself on the 60hz, but what I understood was
that it is more interesting for a good sound to RELIEVE the midrange
of some of the burden by increasing the range for the subs,
by having the sub avoid the very very low frequencies that might not
matter so much in lots of music we listen to.

I might be wrong.

 

[RaymondFromThePyrénéés]

Sub efficiency is arguably irrelevant in the days of huge and cheap class D plate amp

Hmmm, that is a factor that I did not think about. But what Jim Smith is refering to in his book is also that the sound of a closed sub is rather DRY, compared to a live concert with low frequencies that are far from DRY ?