• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Good Idea, Bad Idea?

Chrispy

Master Contributor
Forum Donor
Joined
Feb 7, 2020
Messages
8,029
Likes
6,165
Location
PNW
BLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLABLA

Sorry about that. This has been something I've been working on for a minute so a few people here already know a little bit about it. So the driver in question is the SP1632 from KEF. It's typically found in the R series, and I got a good deal on a set so i figured pull the trigger on a project. It's a coaxial driver so the mid and tweeter are together. Pretty much trying to get really big sound in a tiny package, so about bookshelf size speakers (although if I go with the two subs it will be taller). The subs are Dayton Audio E150HE-44 5 1/2". As far as enclosure design, I honestly don't know yet. I just got the "two sub" idea today. That and lately I've just been working on circuitry so haven't really touched on that yet.
Hard to call those Dayton drivers "subs" (even tho they use that description). What software are you using to design the box?
 

Salt

Addicted to Fun and Learning
Forum Donor
Joined
Aug 7, 2023
Messages
656
Likes
365
Location
DE
pull the trigger on a project
So exactly what?
- enclosure
- xover passive or plate amp or similar active with DSP
- sub passive or active with DSP
or all directed via main DSP
?
Concept?
 
OP
B

BKr0n

Active Member
Joined
Sep 6, 2023
Messages
206
Likes
64
Hard to call those Dayton drivers "subs" (even tho they use that description). What software are you using to design the box?
Well like I said, I wanted to cut down on size, and for what they are, they're actually kind of impressive. Only other thing I can think that's somewhat similar is the tang band W3-1876S and that can't even touch these.

As far as software goes I was originally just going to stick to vituix cad, but now I have no idea. It seems to be the tool of the trade, but I'm not sure if it would be good for this. Then again I haven't played enough with the software to have mastery over it so who's to say (and I'll admit the enclosure tool is a little unwieldy). If you have any recommendations I would gladly hear them :)
So exactly what?
- enclosure
- xover passive or plate amp or similar active with DSP
- sub passive or active with DSP
or all directed via main DSP
?
Low is 300, band is 300 to 3000, and high is 3000. I've kind of been going back and forth on whether I want to do dsp. I wouldn't mind going completely analog, but I would really first need to nail down the enclosure design before I do that.
 
OP
B

BKr0n

Active Member
Joined
Sep 6, 2023
Messages
206
Likes
64
OP
B

BKr0n

Active Member
Joined
Sep 6, 2023
Messages
206
Likes
64
Ya know... I don't think I would be able to do optical MFB. If i was it would be a laser diode and I would just track the change in pulse length. However, as the speakers would make sound, the enclosure would vibrate, thus shaking the laser and throwing off the laser. Only possible way I can think around that is a gyro IC and even I think that's a little overboard. Oh well. I am sure it will still turn out great :)
 

MAB

Major Contributor
Joined
Nov 15, 2021
Messages
2,163
Likes
4,890
Location
Portland, OR, USA
What kinds of issues?
You need minimum two of equal size to the active driver due to the excursion (the PR is acting like the mass of air in a port). Single radiators rock a cabinet. Dual radiators on the same side even worse, so mount them opposed. On top of the excursion, radiators are typically much higher mms than the active, this is solved by multiple radiators but you will find multiple radiators have interesting tuning requirements for mas and box.

Note that all of the box simulations are for small signal, PR's have very interesting behavior when pushed past linear. And these mass-loaded radiators can do absolutely crazy things when they go non-linear, some of them very physically hard on the active driver.

PRs are tunable by changing the mass fixed to the back of the drone cone. I machined some brass weights for mine, I would show you a picture since they look nice and I like to brag, but taking a speaker apart to change the mass is a PITA! The fact that SB sells the weights for their drones for 5 bucks each says something... I wonder what Seas, ScanSpeak, etc. would charge...:facepalm: Most of the DIY PRs I see are either not correctly mass-loaded, or use a collection washers and scraps metal to get the right mass. My friend operated his for most of his adult life with the weights fallen off and rattling around in the bottom of his cabinets.

Also, PR they are a very costly solution compared to just buying two active subs.
For instance this passive radiator:
is more than half the cost of the matching active driver:
I cynically note - some manufactures have avoided this this by increasing the price of the active driver (Seas L26 got massive price increases while the drone price has barely changed).

Given all of this, I am pretty sure that the small reduction in distortion and increase in useable bass output with a passive is insignificant to just getting two active drivers. Even sealed with DSP transform for the bass isn't likely giving-up a single iota of useful bass output. And, you can put them in individual boxes and place them around your room to solve real problems (room modes are a real problem, differences in these mechanical alignments not so much I think...). I got lots of PR subs, they are good and I like them so I am not bagging on PR, but I am not sure if they are a worthwhile undertaking.
 
Last edited:
OP
B

BKr0n

Active Member
Joined
Sep 6, 2023
Messages
206
Likes
64
Thank you that was very educational :) I was actually think of using three radiators per. Two on each side and one facing front. Not directly on the subs, but within the space they're radiating into. If it's just an open air chamber, I would imagine you could send the sound wherever you want given the right construction.

Incidentally, the daytons actually have an accompanying PR kit. They each come with three weights.
 

voodooless

Grand Contributor
Forum Donor
Joined
Jun 16, 2020
Messages
10,520
Likes
18,582
Location
Netherlands
Given the maxSPL curve of the Dayton driver, I would definitely suggest using it in reflex or PR:

1700479191200.png

[ green reflex 20L , blue closed 15L]

If closed, make sure you have a few extra drivers if you don't plan to use a sub below 80Hz.

Also note, as I already mentioned, that you cannot use MFB with anything other than a closed system.
 

Salt

Addicted to Fun and Learning
Forum Donor
Joined
Aug 7, 2023
Messages
656
Likes
365
Location
DE
Did a little Webcrawling and found this on yt .
Furthermore did a quick and dirty simulation for BR that resulted in an organ pipe for BR, as the driver is not dimensioned for that.
So either PR or closed with EQ.
 

DVDdoug

Major Contributor
Joined
May 27, 2021
Messages
3,079
Likes
4,055
I would skip the motion feedback, especially on a small speaker. Put your money & effort into a bigger driver, or more woofer drivers, or a bigger box*, etc. Things that will really make a difference.

If you are going to use DSP (or analog EQ), it can help but a lot but there are limits... You can't get bass you can feel in your body from a 5-inck "subwoofer".

Repeating what someone else said, minimum power requirement doesn't make any sense... A lot of manufacturers give a minimum power recommendation, but the sensitivity is what you really want to know. The sensitivity spec tells you how loud it goes with 1W at 1 Meter, and along with the maximum, that tells you how loud you can go.

And, model the design in software before deciding on what you're going to build. (I've used WinISD, but it only handles "basic" sealed & ported designs.)


* A bigger box isn't always better but up to a point it usually is. And, your speaker design software will tell you.
 
OP
B

BKr0n

Active Member
Joined
Sep 6, 2023
Messages
206
Likes
64
Did a little Webcrawling and found this on yt .
Thanks that was very informative :) one thing I'm definitely going to need to figure out is a way for the enclosure to not jump around. I'm not going for super hard bass. More articulation in the lower end is what I'm going for.
I would skip the motion feedback, especially on a small speaker. Put your money & effort into a bigger driver, or more woofer drivers, or a bigger box*, etc. Things that will really make a difference.
If you are going to use DSP (or analog EQ), it can help but a lot but there are limits... You can't get bass you can feel in your body from a 5-inck "subwoofer".
I mean... physics is till a thing so I don't expect the bass extension to go below 30Hz. The real question is whether a design using two would give the biggest net gain while remaining true to the concept.

I also realize now that isobaric is going to be difficult in a small enclosure. Definitely not a terrific idea to put them in the back. Not ruling out a second driver, but definitely needs a design change.

The SP1632 sensitivity is 93db. The sub from dayton is 83db. I was initially going to run the main driver and tweeter at 20 watts. To make up 9db, I would need to run the sub at 160 watts (not expecting it to ever run it that high). That said, the dayton caps out at 200 watts rms. To match the sensitivity any higher I would need to add another driver or risk damaging the first one.

Edit: This is also an active design... need to figure out where I'm gonna put the guts too :p
 
Last edited:

voodooless

Grand Contributor
Forum Donor
Joined
Jun 16, 2020
Messages
10,520
Likes
18,582
Location
Netherlands
To make up 9db, I would need to run the sub at 160 watts (not expecting it to ever run it that high). That said, the dayton caps out at 200 watts rms. To match the sensitivity any higher I would need to add another driver or risk damaging the first one.
You’ll need much more than that. With music most energy is in the bass. It can easily run 10 to 15 dB hotter than the rest. Also remember that your 93 dB is not at 1W, but at 2.83V.
 
OP
B

BKr0n

Active Member
Joined
Sep 6, 2023
Messages
206
Likes
64
You’ll need much more than that. With music most energy is in the bass. It can easily run 10 to 15 dB hotter than the rest. Also remember that your 93 dB is not at 1W, but at 2.83V.
I'm not sure I'm following. The sub is measured by the same metric. Or are you saying I need to add an extra 10-15db in order to push the sub? If so, with the circuit I made, I could potentially run it at 2 ohms, but then I would have to redo some of the circuit.
 

voodooless

Grand Contributor
Forum Donor
Joined
Jun 16, 2020
Messages
10,520
Likes
18,582
Location
Netherlands
I'm not sure I'm following. The sub is measured by the same metric. Or are you saying I need to add an extra 10-15db in order to push the sub? If so, with the circuit I made, I could potentially run it at 2 ohms, but then I would have to redo some of the circuit.
This is the average music spectrum:
1700546467462.png


So your 60Hz content is in average 10 dB louder than your 500 Hz content. So you need way more power in the bass region than you need for the rest if you want a balanced system. Also don’t forget the baffle step, that is another 3dB lost in the bass.

With 200W into the sub, you hit about 102 dB, same goes roughly for the KEF at 20W. With music, you’ll definitely be safe for the KEF unit. If 102 dB peaks is enough is for you is up to you, it means music playback at an average of about 87 dB (15dB crest factor), which is arguably loud, but not very loud. It roughly similar to what something like a Genelec 8040 will do. They definitely pack a punch, but they won’t go super loud.
 
Last edited:
OP
B

BKr0n

Active Member
Joined
Sep 6, 2023
Messages
206
Likes
64
This is the average music spectrum:
View attachment 328196

So your 60Hz content is in average 10 dB louder than your 500 Hz content. So you need way more power in the bass region than you need for the rest if you want a balanced system. Also don’t forget the baffle step, that is another 3dB lost in the bass.

With 200W into the sub, you hit about 102 dB, same goes roughly for the KEF at 20W. With music, you’ll definitely be safe for the KEF unit. If 102 dB peaks is enough is for you is up to you, it means music playback at an average of about 87 dB (15dB crest factor), which is arguably loud, but not very loud. It roughly similar to what something like a Genelec 8040 will do. They definitely pack a punch, but they won’t go super loud.
I see what you mean now. I'm just trying at this point to be able to reproduce as much as possible. That's why I went with the daytons. They have low extension for the size. This is going to be for a small room, although it would be nice to have a little headroom in case I move them. That said, my concern is 20w won't be enough for a room. Hence why I was looking into another sub to add to the circuit.
 

voodooless

Grand Contributor
Forum Donor
Joined
Jun 16, 2020
Messages
10,520
Likes
18,582
Location
Netherlands
That said, my concern is 20w won't be enough for a room. Hence why I was looking into another sub to add to the circuit.
Two drivers will definitely make a difference if you can match the power. You’ll need twice as many PRs though and more volume.
 

Salt

Addicted to Fun and Learning
Forum Donor
Joined
Aug 7, 2023
Messages
656
Likes
365
Location
DE
Walking the Dayton-way collides with bookshelf size.
You will have to put 2 Woofer opposite left/right and either two large PRs or four of those in the video alongside.
Consider changing design to floorstand, alternatively find a more fitting woofer.
 

Salt

Addicted to Fun and Learning
Forum Donor
Joined
Aug 7, 2023
Messages
656
Likes
365
Location
DE
Just presented the YT-video to my youngest, and he commented with a grin "that car hifi guys sometimes do weird things".
Ok, he's into PA where equal or less than 15" is a Mid and a Woofer goes up from 18" (the latter can be found in his 13 square meter room :mad:, roof-lifting included).
 
OP
B

BKr0n

Active Member
Joined
Sep 6, 2023
Messages
206
Likes
64
Two drivers will definitely make a difference if you can match the power. You’ll need twice as many PRs though and more volume.
Walking the Dayton-way collides with bookshelf size.
You will have to put 2 Woofer opposite left/right and either two large PRs or four of those in the video alongside.
Yeah that seems to be the challenge. I'll have to play around with the box design, but I think its doable. It's the form factor that's going to be the biggest issue.
Consider changing design to floorstand, alternatively find a more fitting woofer.
Don't really have room at the moment for floor standers. Will probably just get speaker stands for them. That will be a whole other issue.
Just presented the YT-video to my youngest, and he commented with a grin "that car hifi guys sometimes do weird things".
Ok, he's into PA where equal or less than 15" is a Mid and a Woofer goes up from 18" (the latter can be found in his 13 square meter room :mad:, roof-lifting included).
Lol it's ok. I've been getting a lot of flak throughout this whole experience just because I wasn't thinking audio first. My background is much more about "what is the thing and what do you want it to do?" Not so much on "is it car audio, PA audio, or hifi?" Apparently its sacrilege to mix car audio with hifi :eek: As long as it performs the best it can and fits the intended build concept then who cares?
 

Salt

Addicted to Fun and Learning
Forum Donor
Joined
Aug 7, 2023
Messages
656
Likes
365
Location
DE
Will probably just get speaker stands for them. That will be a whole other issue.
That was the question for 'concept'.
If there would be speaker stands, You can substitute them by woofer enclosures, and then Your Dayton-Dream may become reality.
Two woofers with PR in separate and seperated enclosure in the basement and mid/high seperated on top.

Amplification and Xover would be then the next challenge.
 
Top Bottom