3D printed classic 3-way budget speaker project using SB and Dayton drivers

[ppataki]

I actually found a 8" model that would not need a very big cabinet.....

8″ SB23NRXS45-4 / Norex - Sbacoustics

Vented cast aluminum chassis for optimum strength and low compression, shallow design Non-conducting fiber glass voice coil former for minimum damping.

sbacoustics.com

I could keep the length of the cylinder (350mm); I would just need to increase its diameter to fit the driver & I would gain +3dB with the same wattage
And cost wise it is not a huge increase either

I think I just got sold

 

[kemmler3D]

I actually found a 8" model that would not need a very big cabinet.....

8″ SB23NRXS45-4 / Norex - Sbacoustics

Vented cast aluminum chassis for optimum strength and low compression, shallow design Non-conducting fiber glass voice coil former for minimum damping.

sbacoustics.com

I could keep the length of the cylinder (350mm); I would just need to increase its diameter to fit the driver & I would gain +3dB with the same wattage
And cost wise it is not a huge increase either

I think I just got sold

Very nice!

Also, too early for this, but what are you thinking in terms of finish on this one?

Since I don't have to do it myself, why not an electroplated mirror finish? Would really ramp up the space age look.

 

[ppataki]

electroplated mirror finish

Well, to be honest, I was just thinking about matte white (I know, boring) but I will give it some thoughts
For some reason there is this concept in my head that a 'loudspeaker shall be white', like some people have similar concepts of what color a car shall have

 

[ppataki]

In the meantime I have finished printing the cabinet for the tweeter

This is with the rear hemisphere not yet done:

And with the rear hemisphere:

I am extremely happy with the looks! To be honest I might as well leave it like this......

Next steps as usual: finish the internals of the cabinet (vibrodamping sheets + felt only in the hemisphere end), glue it together, etc. and then I will perform some measurements

 

[Audionaut]

That looks very good
Well done

 

[ppataki]

And the holder
The midrange will be there below the tweeter but now the whole thing serves as the holder for the tweeter

The tweeter-midrange center-to-center distance with a crossover at 2200 Hz is 15.6cm - as far as I can tell I will be just within this distance, which is great news
Measurements to follow tomorrow or on Saturday

 

[ppataki]

I have finished the cabinet completely and tested it, see a short video here:

New video · Friday, Oct 3

Tap to view!

photos.app.goo.gl

I have also performed measurements at 1 meter (in-room):

Frequency response with phase, 1/12 smoothing

Apparently the response will need some correction - with only 1 low shelf filter (LS Q Fc 4500.00 Hz Gain -7.5 dB Q 1.00) I could fix it pretty nicely:

Phase looks good to me but happy to hear any comments

Distortion-wise it seems that I might need to increase the planned crossover frequency from 2200Hz to 2500Hz

IR of the corrected response:

To me it looks fine

For 40 EUR / Pair I think this is phenomenal......

 

[ppataki]

Forgot some pictures

 

[ppataki]

I promise this is the last post about the tweeter component

I am sure everybody here is aware of the below but nevertheless I wanted to post this too, in case anybody is interested

First, to demonstrate the huge audible difference between crossover (the high-pass part in this case) slope settings
First you hear 12dB/octave, then 24dB and then 48dB (all Linkwitz-Riley at 2500Hz)

New video · Saturday, Oct 4

Tap to view!

photos.app.goo.gl

Second, to 'demonstrate' dispersion control of the waveguide, I am playing a 10kHz sine wave and moving the mic to up to 90° off-axis
The sound stays the same but gets quieter only

New video · Saturday, Oct 4

Tap to view!

photos.app.goo.gl

 

[DanielT]

I have finished the cabinet completely and tested it, see a short video here:

New video · Friday, Oct 3

Tap to view!

photos.app.goo.gl

I have also performed measurements at 1 meter (in-room):

Frequency response with phase, 1/12 smoothing

View attachment 480356

Apparently the response will need some correction - with only 1 low shelf filter (LS Q Fc 4500.00 Hz Gain -7.5 dB Q 1.00) I could fix it pretty nicely:

View attachment 480357

Phase looks good to me but happy to hear any comments

Distortion-wise it seems that I might need to increase the planned crossover frequency from 2200Hz to 2500Hz

View attachment 480358

IR of the corrected response:

View attachment 480359

To me it looks fine

For 40 EUR / Pair I think this is phenomenal......

Thanks for the test! Interesting. It looks like a good affordable tweeter. The best thing you can do is to create a custom shelf filter like you did. But for those who can't or don't want to do that, it looks like a classic treble tone control could do a similar job. Or a roughly similar job.

Did you know that the Dayton tweeter is available in non-WG form at hardly any cost at all? If you want to test and compare, that is:

(Right now they didn't have any in stock so it wasn't available but they will get some in the future)
Although without WG it does pose some challenges with good tweeter-mid interaction. It might therefore be easier to EQ via a low shelf filter like you did?

Edit:
That's a good tweeter, that ND25FW. Here in a pair of TQWT/Voigt pipes boxes (that I got for free). Crappy bass driver and a lot of resonances due to little stuffing in the boxes BUT the tweeter is great. Crossover point 2.6 kHz, 24 dB filter.

(LD Systems X 223 active crossover, bass powered up by HK 670 and tweeters by HK 330C receiver. Later tested together with Wiim Mini RoomFit auto-creation. It got better with that.)

OT:
Those TQWT/Voigt pipes would probably be best with a pair of SB Acoustics SB20FRPC30-8 broadband drivers instead but I'll leave that aside. Just thought I'd mention my TQWT/Voigt pipes because I like the Dayton Audio ND25FW-4 tweeter.

 

[a4eaudio]

....Did you know that the Dayton tweeter is available in non-WG form at hardly any cost at all?

We are really spoiled in the US... That ND25FA is $11.49 (€9.79) on this side of the pond.

 

[DanielT]

We are really spoiled in the US... That ND25FA is $11.49 (€9.79) on this side of the pond.

Around 50% markup. Not too bad though since they are so cheap to begin with.

The other way around, from Europe (Italian manufacturer) to the US, it can be at similar markups:

 

[ppataki]

I have to share this here, it was kind of an eye-opener for me

I have been suspecting that distortion in high frequencies do correspond to how we hear those high frequencies (I did post about this here on ASR a while ago). I have built many (15+) DIY speakers using full range loudspeakers and the highs were never sounding just quite right, not even with robust DSP

After performing the above measurements for the Dayton Audio tweeter it occurred to me that I have previously measured some projects in the same room using full range drivers

So let's see the distortion measurements: the Dayton tweeter vs. Markaudio Pluvia 11, Markaudio CHR120 and the SB Acoustics SB20FRPC30-8 full range drivers
(same room, distance and SPL)

The difference is massive, in the range of 15-20x in terms of distortion %

I know it is not 'fair' to compare a tweeter with full range drivers but after seeing these results I am pretty positive that this is one of the main reasons why treble sounds tricky with those full range drivers (the other reason I guess is the huge directivity errors and dispersion anomalies they exhibit)

 

[a4eaudio]

Maybe...what about the fact that HD below 1% (and likely even 2%) is inaudible to almost all humans? IF true, then our ears see this...

 

[DanielT]

Maybe...what about the fact that HD below 1% (and likely even 2%) is inaudible to almost all humans? IF true, then our ears see this...

View attachment 480771

Maybe so, but here is what a technical consultant in acoustics and audio technology writes. Okay, he has had a whole professional career practicing detecting and as you know, with practice comes skill. And yes, he has participated in various blind tests over the years.

Thread title: Intermodulation distortion for better or worse.

Which raises the question of the audibility limits of different distortion types relative to frequency

As for the basic question, there are mostly older reports available in the field if you are interested in more elaborate science. In my opinion, these works suffer badly partly from the rather inadequate recording and playback systems of the time and partly from not having divided the listeners into insensitive and sensitive groups and have therefore arrived at relatively high limits of audibility.

Since the majority of listeners are quite insensitive to distortion, this is not a priority area and no one will therefore invest the resources required to dig deep. In addition, the insensitivity unfortunately increases via listening to today's torn and thus very distortion-dense productions. It's not just the lack of dynamics that makes the audiophile's ears bleed.

In general, however, it can be said that it seems that sensitive listeners under optimal conditions can approach the hearing threshold, but that you (of course) cannot fall below it (I would not attach too much importance to the subliminal speculations). In practice, however, the background level in the room in the frequency band where the distortion components appear will constitute the final limit.

Masking means that harmonic components often become completely inaudible, while intermodulation components often appear very clearly. Even perhaps less well-known issues like Doppler Distortion (FM Distortion or a form of IMD) have a greater impact on the sonic characteristics than one might think - especially with some modern drivers in a two-way configuration, where linearity is good but the radiating area is small, which leads to high diaphragm velocities already at moderate sound pressure levels. Even turbulence modulation noise from bass reflex ports can be clearly detectable as a particular kind of rawness or indistinctness in the sound.

Anyone who has embraced the use of truly low-distortion speakers knows what this means - going from around 0.3-0.5% THD in the midrange and treble to around 0.05-0.1% THD clearly reduces a grittiness that you don't always be aware of before the switch. A warning should be issued here, as there is no going back after hearing what it should sound like.

It is also interesting that deliberately rather "dirty" popular music recordings also sound cleaner, or perhaps rather more distinct, even though the raw sound even increases, i.e. that the listener hears exactly the distortion that was intended. The difference can sometimes be strikingly large even here, which probably surprises many
_________
Technical consultant in acoustics and audio technology

faktiskt.io • Visa tråd - Intermodulationsdistorsion på gott o ont.

Edit:
There's no way I could detect around 0.1-0.05% in the midrange/ treble region. Maybe if I were young and had better ears and trained like hell for a long time, maybe. Or maybe it doesn't require that much training? I don't know. On the other hand. The Dayton Audio ND25FW-4 tweeter falls into the low distortion category and I can listen to that tweeter for a really long time without experiencing any fatigue, so...Now I'll stop waffle.

 

[a4eaudio]

Also, to be clear...I am not doubting that @ppataki hears a clear difference from the full-range drivers vs having a dedicated tweeter. Just questioning whether it is the Harmonic Distortion vs other things, like IM distortion, off-axis behavior and related room reflections, etc. I am also NOT saying that it is NOT HD, just asking the question.

... warning should be issued here, as there is no going back after hearing what it should sound like.

I have heard several people say this with respect to Purifi drivers, where a lot of the amazing distortion results are below would conventional wisdom says is inaudible.

 

[DanielT]

Also, to be clear...I am not doubting that @ppataki hears a clear difference from the full-range drivers vs having a dedicated tweeter. Just questioning whether it is the Harmonic Distortion vs other things, like IM distortion, off-axis behavior and related room reflections, etc. I am also NOT saying that it is NOT HD, just asking the question.


I have heard several people say this with respect to Purifi drivers, where a lot of the amazing distortion results are below would conventional wisdom says is inaudible.

It is interesting in any case. And it is in itself a reasonable starting point, if we generalize without dwelling on % levels and types of distortion that if you hear better speakers, those are the speakers you want and not go back to those with worse performance. Perhaps an obvious point to make, if you are interested in good sound/hifi, but still. Audible differences, not imaginary ones, I should add.
Then we have the really tricky part. That if you imagine hearing differences (think op amp swapping for example) or not. If it really is audible or not.

Between different speakers, however, there is probably no one who claims that you cannot hear a difference between X and Y speakers, especially if there is a big difference in dispersion, distortion and above all in FR between them.

 

[a4eaudio]

What is the reason for that? I mean I will have 2 subs helping these speakers, hence I thought a pair of 6.5" would be OK - 110dB at 1 meter at 80Hz would be more than enough for me (at 3 meters that is still 98dB). And I could keep the cabinet pretty small.

But I am way open to changing the plan still, hence I am asking for the reason...

I think you are correct. Take a look at the Barefoot03 studio monitor. The 3-1/2 inch midrange covers 350Hz to 3.9Khz, reducing intermodulation distortion. A 6-1/5 inch midwoofer can play down to 80Hz with very little excursion (and if you are crossing at 80Hz, it is already down 3dB at that point). With a 6-1/2 inch two-way, you are stuck crossing around 2.5kHz or lower.

Midrange: SB Acoustics SB12MNRX2-25-4 (90 EUR/pair from TLHP)

Planned HPF at 300Hz, planned LPF at 2200-2500Hz since that is where the off-axis curves start to fall but please correct me if I am wrong with this notion

I didn't see any comments on your statement above, but I think it is pretty normal to crossover where the midrange off-axis is already falling. For example, where the 30 or 45 degree response is down 6dB from on-axis. I think a 4" driver can easily cross in the 3kHz to 4kHz range. But I would add 2 points: (1) your actual measurements with practically no baffle are not going to look that much like the infinite baffle measurements from the data sheets; (2) If you keep an eye on your PIR, power, SPDI, etc. curves, the crossover point will reveal itself.

 

[ppataki]

I think a 4" driver can easily cross in the 3kHz to 4kHz range.

Thanks for commenting on this point, indeed nobody had commented on it yet

The tweeter distortion measurements clearly show what I kind of already suspected: I shall not cross it below 2500Hz - so the mid/tweeter crossover point will be at 2500Hz (with a 24 or 48dB/oct. slope). This also corresponds pretty much to the point where the on-axis and off-axis curves of the midrange driver start to diverge
I am happy to stand corrected though if there is a better approach

What is left to be seen is the low/mid crossover point - the rest of the drivers will hopefully arrive on Friday so I shall be able to measure the midrange driver's distortion during the weekend and that will help with the crossover decision (albeit I believe the 300Hz idea shall be OK)

 

[ppataki]

A tiny update, here is where I am at now:

Center-to-center distance (max. 13.72 cm for the 2500Hz crossover) shall be fine too so I am really happy

Next post: midrange cabinet finalization, midrange driver measurements, tweeter-midrange with crossover measurements