Need advice.... BSC on 1.5,inch drivers? Any poin?t?

[3rutu5]

Been fiddling around with the print for the tiny ghetto blaster and was wondering if there would be any point/need etc to have a BSC or any other filter on these tiny drivers? I'm using the DMA45-08's for this project

[neildavis]

This would be a good application for one of those new 4-channel BT/DSP boards. You could add a tweeter and have a nice 2-way stereo BT setup. I've been working on the CPU code for an ESP32 micro that lets you control this amp using your cell phone. One of the menu items is BSC, which for this design would be fairly high (800Hz and up). It's also got full EQ and ADI's SuperBass algorithm. I still need to add the ADI DynamicBass algorithm, which will adjust the bass HPF based on the volume. Once I finish that, I will post a link to the code at this location: Mom’s Bluetooth Garden Table – Audiodevelopers Reborn. The link currently only has some background info, but details are coming...

I like the work you are doing with 3D printing, and I see a good match with the electronics described on my website. I'd be happy to send you a CPU or working CPU/amp, if postage isn't too nuts.

[Billet]

Think of baffle step as a tone control, add it if needed.

[DeZZar]

Baffle step happens regardless of the size of the driver. Where it occurs is a relationship between driver size and baffle size. Use the Diffraction tool in Vituix to play around with different baffle sizes, drivers sizes and driver positions to see the effects.

[DeZZar]

1.8 - 2.0mh + 8ohm.

[3rutu5]

So being only 2 1.5 drivers, this isn't going to act as a low pass but instead remove any humps around 300?

[3rutu5]

Damn was going through my left overs, had 2 DNR-4's, 2 LW18-50's, 2 2.5 iron cores and some other things.

[3rutu5]

This would be a good application for one of those new 4-channel BT/DSP boards. You could add a tweeter and have a nice 2-way stereo BT setup. I've been working on the CPU code for an ESP32 micro that lets you control this amp using your cell phone. One of the menu items is BSC, which for this design would be fairly high (800Hz and up). It's also got full EQ and ADI's SuperBass algorithm. I still need to add the ADI DynamicBass algorithm, which will adjust the bass HPF based on the volume. Once I finish that, I will post a link to the code at this location: Mom’s Bluetooth Garden Table – Audiodevelopers Reborn. The link currently only has some background info, but details are coming...

I like the work you are doing with 3D printing, and I see a good match with the electronics described on my website. I'd be happy to send you a CPU or working CPU/amp, if postage isn't too nuts.

Hey mate, I don't think I have much room internally on this one as it is a quick reduction of the bigger one I'm hoping to do. I'll have a look later tonight after work, oh and I'm an Australian so probably cost a kidney to send anything my way

[DeZZar]

So being only 2 1.5 drivers, this isn't going to act as a low pass but instead remove any humps around 300?

No its a shelf filter. It does this:



Which is the opposite of the baffle step effect which in something like this:




On its own it wont compensate for anything else going on with the driver.

[3rutu5]

Sorry if I add if on its own it won't compensate?

[DeZZar]

No it will compensate for baffle step, I meant it won't compensate for anything else. It might need a notch or something also depending on the response of these drivers.

[3rutu5]

Too easy, thanks mate. I grabbed some jantzen inductors and some 8.2ohm res from a local joint. Hopefully come by the weekend

[Chris Roemer]

The BSC filter CAN be used (externally) on any (impedance compatible - to the filter "load") speaker - between the speaker and the amp.
(Like if you had a small pr. of computer speakers (w/OUT BSC) and just wanted to temp. "try" the filter to see if you liked it.)

I know YOU won't be using it in this way, since everything'll be inside your B-Box. Just sayin'.

[fpitas]

The (tiny) elephant in the room here is your drivers will run out of Xmax even quicker.

[3rutu5]

yeah that is true and most on here know i try to break the speakers first run....its going to be interesting on what im wanting to do thats for sure

[3rutu5]

No its a shelf filter. It does this:



Which is the opposite of the baffle step effect which in something like this:




On its own it wont compensate for anything else going on with the driver.

Hey mate, me again, you mentioned series for this filter, so dumb question I assume that means soldering from the wire to the inductor, then inductor to the resistor then to the other end of the wire

--------|----R------->+

I finally got aeound to fixing my printer so reprinting the tiny Bluetooth speaker idea

[JRT]

No. The filter is comprised of inductor and resistor wired in parallel. The filter is wired in series with the speaker. The effect is that the resistor is in series with the load current and the inductor provides a bypass path for current around the resistor at lower frequencies.

[3rutu5]

Thanks just noticed it, it was the 18 Guage series not the thing in series.....what a. Doofus, put that down to being half asleep

[DeZZar]

Looks like you're all sorted. Don't worry I still end up questioning myself - is this series or parallel? But yeah as JRT pointed out, parts in parallel, filter in series with driver. The inductor controls the point where the attenuation starts and the resistor controls how much attenuation is applied.

[3rutu5]

No its a shelf filter. It does this:



Which is the opposite of the baffle step effect which in something like this:




On its own it wont compensate for anything else going on with the driver.

Hey mate, after doing a couple of these now i'm wanting to double back and try a 12v version and look at putting that bass shelf on. I've had a play in VituixCAD and looking at the filter tab can see that 0-300hz remains similar, but everyting past that drops 4-5db's. So assuming this works by lowering everytyhing else. I tried messing around with something similar on the QCC3003 chips but didnt quite understand it as it kept playing nothing if i got it above the zero telling me it was saturated.

It is interesting to see that once you plug the ZRD and FMA's in for this little driver that the majority of the DB's are below 80dbs even though it is listed online as 82dB 2.83V/1m. Which im wondering if there is an error online as the DMA45-8 is listed in that late 70's terrority.

[billfitzmaurice]

Where are you seeing 82dB? The spec sheet says 76.9dB, and only above 200Hz. In any event one cannot call this a full range driver. It's a midrange. The only way you'll get true full range performance from a 1.5 inch is if it's in headphones.

[3rutu5]

billfitzmaurice here for the DMA45-4 driver, the sensitivity shown is 82db. Am I misreading it?

[billfitzmaurice]

I went by this. If in doubt model the specs in your box program. https://www.daytonaudio.com/images/r...tion-sheet.pdf

[3rutu5]

Yeah that's the 8ohm, I thought there was a typo in the 4ohn

[davidB]

You've got the 8ohm job, Bill.
Still seems a too big difference, maybe differing measurement methods?

[3rutu5]

You've got the 8ohm job, Bill.
Still seems a too big difference, maybe differing measurement methods?

looking at the graph on the sheet most of the time it's below 80. They sound fine at the level I play it I was thinking more we the addition of the BS if it's going to affect the sound level as it is being lowered at those higher freq. but it's also going to have 12v and more watts than what I'm use to

[billfitzmaurice]

I used the 8 ohm because that's what you noted in your original post. At 2.83v the 4 ohm would be about 3dB higher in sensitivity, but that's not one watt, it's two.

[3rutu5]

I have both to be honest, got 4 8ohms sitting there and I don't know what to do with them and 4 of the 4 ohms. If I can get similar or better performance out of the 8ohm I'd consider using it on a project. It does model slightly better