3 way active design sanity check

[Busdriver02]

It looks like you want to head down the active/analog crossover path, so I'll have to let AnalogSteph answer. I'm not sure if you can run an amplified signal through an active crossover, or if it needs to be line level (pre-amp).

 

[tanno1]

gotcha @Busdriver02 afaik, you want to do active crossover, then amplify the signal. That is what i am trying to do. otherwise you need special components to handle the large signals and that would be $$$$.

 

[AnalogSteph]

Drivers: Dayton Audio PA130-8 5" Full Range PA Driver, Dayton Audio ND25FW-4 1" Soft Dome Neodymium Tweeter with Waveguide 4 Ohm

Hmm. Now that it's down to a 2-way you've got a small problem: The PA130-8 is a PA-style midwoofer which is geared towards efficiency, which brings with it a rather high Fs of 83.4 Hz... no wonder the frequency response spec is 90 Hz to 15 kHz. Getting a satisfying low end out of these is going to be difficult. Sub-Fs operation is possible but not easy, though when employing DSP and an active speaker you've got a decent chance of making it work. Then you still have a rather limited Xmax of only 2 mm to contend with though, so it's not exactly a long-throw woofer. All fine as a midrange but not terribly ideal down low where excursion requirements are going up with 1/f^4.

I might have a look at some of these:
Peerless by Tymphany 830656 5-1/4" Paper Cone SDS Woofer ("It's a woofer"™)
HiVi F5 5" Bass/Midrange
HiVi M5N-B 5" Damped Aluminum/Magnesium Cone Woofer
Peerless by Tymphany 830657 6-1/2" Paper Cone SDS Woofer
HiVi M6N 6" Aluminum/Magnesium Midbass
HiVi M6N-B 6" Damped Aluminum/Magnesium Cone Woofer
HiVi F6 6-1/2" Bass/Midrange
FaitalPRO 5FE100 5" Professional Midbass Midrange Woofer 8 Ohm

Amps: Dayton Audio KAB-250v4 2 x 50W Class D Audio Amplifier Board with Bluetooth 5.0

Hmm. You sure you don't want to be going with the board with built-in DSP instead? Then you'd also have the question of crossover sorted, and the SNR spec is better as well, not to mention it's a 50W/8 ohm amp rather than 50W/4 ohm.
Dayton Audio KABD-250 2 x 50W All-in-one Amplifier Board with DSP and Bluetooth 5.0 aptX HD
Maybe even the 100W version?
Dayton Audio KABD-4100 4 x 100W All-in-one Amplifier Board with DSP and Bluetooth 5.0 aptX HD

PSU: Mean Well LRS-150-24 24V 6.5A 150W Regulated Switching Power Supply

That's a pretty standard supply for an application like that. Make sure you're providing a mains PE connection but keeping the PSU chassis isolated from secondary-side ground - the amp only seems to have unbalanced audio inputs and you don't want a ground loop immediately. I mean, you could get fancy, go all IEC Class I and add audio input transformers instead (though they'd cost a bit), or think about a balanced receiver circuit (which could in principle run off of +24 V with a single-supply design, just not sure whether there is one readily available like that).

3. I calculated 436 µVrms, and 11.97 dB SPLout, adding 20 for the "hiss list" is 31.97 dB @ 1m for the full range driver. This is pretty close to what you calculated for the first set, which had a much larger diameter for the "subwoofer". Am I making a poor decision choice somewhere, or why is this so high?

You picked a 50 W amp with a 92 dB SNR spec, that's obviously not that great. Although I got "only" 355 µV. Lower driver sensitivity may be a feature, and some passive filtering may be advised (some lowpass and/or a notch for woofer depending on its FR needs, L-pad attenuator for tweeter).

 

[tanno1]

@AnalogSteph Thanks for another great reply! I am gonna go with the Peerless by Tymphany. I like the frequency response on those and the Fs is quite a bit lower. Still higher than some of the HiVi ones, but the HiVi all have ~5 dB jumps around 1 khz and I would rather prioritize the flatness of the response. Comparing to other desktop speakers, a range of 44.75 hz to 20khz looks good to me as well for my setup.

As for the board, I really want to design the crossover by myself so I can learn some in depth electronics engineering and audio testing. That 50W/8 ohm amp would be better than the 50W/4 though. If I do decide to eventually add DSP, it would be capable of that too.

I think with that, I am pretty much ready to start working on the crossover now. Im gonna sketch up a better electronics diagram and figure out how I am going to power the crossover.

One last question though, is there any downside to using an amp board with two outputs. Should I be Bi-Amping? I have read about bi-amping and it seems like if I can afford to fit another board in there, then I can reduce the power load on a single board, by splitting it into two separate boards. With the 50W/4 Ohm 2 output board though, I can't see power being an issue. Am I overlooking something?

I will post an update soon with electronics updates.

 

[tanno1]

Hey @AnalogSteph @Busdriver02, I took a break on this project as school started, but I am getting back on it.

I have compiled a list of my components and want to get a quick feedback check to see if there is anything that will not work between them in regards to electronic design. Once I get them all, I am gonna set them up, test the db/frequency response, and then start figuring out the crossover design.

Component list:
Drivers

Name	Price	Frequency Range (Hz)	Power (Ohm)	Wattage RMS	BL Product (Force Factor)	Cms (Mech compliacnce of suspension)	Le (Voice Coil Inductance)	Mms (Diaphragm mass w/ air load)	Re (DC Resistance)	Rms (Mech resistance/lossiness)	Sd (Surface Area of conne)	Sensitivity	Nominal Diameter	Link
GRS 10SW-4 10" Poly Cone Subwoofer 4 Ohm	$29.98	34-800	4	120	7.1 Tm	0.24 mm/N	1.0 mH	58.1 g	3.7 Ohms	3.27 Kg/s (calculated)	344.4 cm^2	90dB 2.83V/1m	10”	https://www.parts-express.com/GRS-10SW-4-10-Poly-Cone-Subwoofer-4-Ohm-292-482?quantity=1
Dayton Audio DC130BS-4 5-1/4" Classic Shielded Woofer 4 Ohm	$29.98	55-4000	4	30	4.8 Tm	1.08 mm/N	0.6 mH	8.8 g	3.55 Ohms	1.539 Kg/s (calculated)	93.3 cm^2	91.6dB 2.83V/1m	5-1/4”	https://www.parts-express.com/Dayto...ssic-Shielded-Woofer-4-Ohm-295-302?quantity=1
Dayton Audio ND25FW-4 1" Soft Dome Neodymium Tweeter with Waveguide 4 Ohm	$12.98	2500 - 20000	4	20	N/A	N/A	0.04 mH	N/A	3.2 Ohms	N/A	N/A	91 dB 2.83V/1m	1”	https://www.parts-express.com/Dayto...-Neodymium-Tweeter-with-Wa-275-051?quantity=1

Amps

Name	Price	Output W	Power	Output A	Size	Link
TDA7498E Class D 150W Power Amplifier Mono Bass Subwoofer HIFI Audio Board (subwoofer amp)	$27.31	1 x 150	32V DC	6A	92 x 83 mm	https://www.amazon.com/TDA7498-Class-subwoofer-Amplifier-Digital/dp/B07HQ2C21L
Dayton Audio KABM-30M 1 x 30W Bluetooth 5.0 Amp Board with EQ Programing Port	$14.99 (sale) x 2	1 x 30	12-16V DC, 4A		3.75" L x 1.25" W x 0.5" H	Dayton Audio KABM-30M 1 x 30W Bluetooth 5.0 Amp Board with EQ Programing Port (parts-express.com)

Power Supply

Name	Price	Vout	Amp	Power	Size	Link
Mean Well RSP-150-15	$44.39	15 Vdc	10 A	150 W	199 x 99 x 30 mm	[Mean Well RSP-150-15
ICEPower 300AS1 Class D Amplifier Module with Built-In Power Supply 1 x 300W	$149.98	50 V	20 A	1 x 300 W	107 x 150 x 40.58 mm	ICEPower 300AS1 Class D Amplifier Module with Built-In Power Supply 1 x 300W (parts-express.com)

Design Diagram: attached

 

[Busdriver02]

I'm confused. Your parts list doesn't seem to match your sketch. Am I correct to assume you're now looking at a subwoofer under the desk and two satellites, or are you still planning to put a 10" on your desk?

 

[tanno1]

I'm confused. Your parts list doesn't seem to match your sketch. Am I correct to assume you're now looking at a subwoofer under the desk and two satellites, or are you still planning to put a 10" on your desk?

wow something got messed up in my notion table, give me a moment this is completely incorrect and I need to fix it now.

 

[tanno1]

@Busdriver02 Here is the correct one, No idea why my sheet reverted to an old copy, that was incredibly strange. Oh well.

Name	Price	Frequency Range (Hz)	Sensitivity	Impedence (Ohm)	Wattage RMS	Nominal Diameter	Link
Peerless Tymphany SDS Woofer	$27.7	40 - 4,000	88.2 dB 2.83V/1m	8	60	6 1/2”	https://www.parts-express.com/Peerless-830657-6-1-2-Paper-Cone-SDS-Woofer-264-1088?quantity=1
Dayton Tweeter	$12.98	2500 - 20000	91 dB 2.83V/1m	4	20	1”	https://www.parts-express.com/Dayto...-Neodymium-Tweeter-with-Wa-275-051?quantity=1

Amps

Name	Price	Output W	Power	SNR	Size	Link
WONDOM AA-AB32189 2x100W TDA7498 Class-D Amplifier Board	$41.98	2 x 100 W @ 6 Ohm, 2x 56.25 W @ 8 Ohm	24V DC	94.96 dB	4.8 x 3.6 x 1.53 in	https://www.parts-express.com/WONDO...98-Class-D-Amplifier-Board-320-303?quantity=1
Wondom 1 x 60W Class D Amp	$20.61	1 x 60 @ 4 Ohm, 1 x 30 @ 8 Ohm	10V-24V	101 dB	3.6 x 2.7 in	https://store.sure-electronics.com/product/AA-AB31211

Power Supply

Name	Price	Vout	Amp	Power	Input power	Size	Link
Mean Well LRS-150-24 24V 6.5A 150W Regulated Switching Power Supply	$22.75	24V Dc	6.5 A	150 W	85-370 Vac	6.25” x 3.82” x 1.181” (LWH)	LRS-15-24
Mean Well RT-65B	$24.81	+/- 12V	12V/2.8A, -12V/.5A	64.6 W	88-264 Vac	129 mm x 98 mm x 38 mm (LWH)	Mean Well RT-65B

 

[Busdriver02]

I'll leave the electronics to someone else, just be careful with that woofer and your enclosure design/ amp strategy.
You don't have a lot of excursion to play with. It should be fine with a highpass filter below your port tuning frequency.

Those amp specs look better though.

 

[tanno1]

I'll leave the electronics to someone else, just be careful with that woofer and your enclosure design/ amp strategy.
You don't have a lot of excursion to play with. It should be fine with a highpass filter below your port tuning frequency.

Those amp specs look better though.

Okay. Any suggestions for the design and amp strategy? I have mainly focused on the electronics up until this point, but I got a feedback on a reddit audio forum and I am feeling confident in ordering these parts. I did swap out the amps for a stereo amp though. I wanted to have the electronics beneath the actual speaker in a separate area, with cables coming upwards through the enclosure into an area above it that would have the drivers. I will attach a photo. I think that would be an interesting design and help not have any issues between the backwards audio waves (idk if there is another name?) and the electronics. I can then focus more on the geometry of the box in the area behind the drivers. lmk if that is not clear.

 

[Busdriver02]

Okay. Any suggestions for the design and amp strategy? ...the electronics beneath the actual speaker in a separate area, ... help not have any issues between the backwards audio waves (idk if there is another name?)

-Since you're using a woofer with smaller xmax, design the enclosure to get the bass response you want (best you can) and don't rely on crossover/amp boost to get it. Build a model in VituixCAD, that will allow you to include the baffle step in the woofer model.
----Example: There is a thing called a linkwitz transform. It allows you to take a woofer in a sealed enclosure and make it have the response of a different alignment. So you could put a driver in a "too small" enclosure, and then get the response of a larger cabinet, or vice versa. Moving between the curves below. Don't do that with your woofer. You need a bunch more xmax to pull this off. The linkwitz transform only works on a sealed enclosure anyway.

-Don't forget amplifiers get hot. Even class D amps. Most active speakers have a metal plate on the back, which doubles as a heat sink in addition to being where all the electronics are mounted. If you moved the electronics section to the back wall you can keep the acoustics isolated and still provide for a heatsink and easy access for future repair needs. Check out the link below, this is from Hypex's website for commercial amp applications. It has some info on class D amps and thermal requirements.

----https://www.hypex.nl/media/b8/33/ac/1686146768/AN_Thermal_design.pdf

-The separate chamber is likely overkill though. If you mount the electronics to the bottom of the cabinet, that back wall is still available for damping material. A bass reflex cabinet will have some air movement naturally, and it looks like most of your electronics come with fans.

-How much space is all that electronics going to take up? Make sure you can fit it all in. You'll end up with dead space in the passive speaker, which you'll need to take up so you have the same enclosure response.

 

[tanno1]

@AnalogSteph @Busdriver02 Hey! I just posted an update on my crossover design. If any of you are interested, could you check it out and give me some feedback?