[DIY] Two way mono speaker

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Bambinz

Member
Joined 2017
#1
Hi all!

I would like to built a two way mono speaker for my daughter, to use during the birthday party or others events.

My idea is to build a single, relative small high power two way speaker with an integrated amplifier.

For the moment I have build only full-range speakers (One DCAAV and one TABAQ), therefore I have no idea how to build a multi-way speaker.

There are some guides? I have many questions:
- How choose the drivers?
- How set the distance between the driver? How to choose the drivers positions on the baffle?
- The tweeter need a separate chamber or not?
- How to dimension the cross-over frequency and how to equilize the "gain"?

For the woofer I have find the FaitalPRO 8FE200 4Ω, seems that works good in a 20L bass-reflex box and then can handle 130W RMS with an high efficiency (95dB).

The amplifier that I have found is the following:
ICEpower 200ASC Class D Audio Amplifier with Power Supply Module 1 x 200W

Thank you very much in advance for your time and help.

Excuse my English but isn't my native language.
 
#2
Bambinz said:
- How choose the drivers?
Click to expand...
Start by writing down your goals. Maximum dimensions, desired low frequency cut-off, overwhelming bass, max sound pressure level ('party with 20 men' is clear enough), required dispersion angles, max costs etc.
Then you could look for a woofer that matches the low frequency goals. The power handling ,of this woofer points to what amplifier power is required. Then find something to fill in the mid and high frequencies. If it does not have to play really loud, a cone midrange driver and a dome tweeter will do. If it has to play loud, a compression driver + horn is a better choice.



Bambinz said:
- How set the distance between the driver?
Click to expand...
As close as possible for the midrange (or woofer) and tweeter (or compression driver).


Bambinz said:
How to choose the drivers positions on the baffle?
Click to expand...
The midrange and tweeter should be above each other.


Bambinz said:
- The tweeter need a separate chamber or not?
Click to expand...
Usually it has a sealed back, so the answer is 'no'.


Bambinz said:
- 1. How to dimension the cross-over frequency and 2. how to equilize the "gain"?
Click to expand...
Designing the crossover is the tricky part.
 
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#3
Hi TBTL,
Thank you very much for your answers and informations!

Requirments:
- Max dimensions somethings arround:
- Height: 40-45cm
- Width: 25-30cm
- Deepth: 20cm
- Volume: 25-27L
- Cost:
- I think 150$ max 180$ for the two drivers only (wood and amplifier not in this
budget)
- Sound pressure:
- To do a party with 10-15 kids (9-10years old) in a place of 100-150m2.
(karaoke, dancing, ...)
- Bass and frequency:
- Of course best as possible, but i think that the limit is due to the cabinet Size.

is it enough?


I see the driver Dayton Audio RSS210HO-4, in a 20L bass reflex has a cut-off frequency of about 30Hz.

Thank you again !
 
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#6
Hi fabricadetabaco!
Thank you very much!
Probably the 10" is incompatible with my case dimensions.
What is the disadvantage of the coaxial system?

I have do some simulation with the eminence, but seems that work better the FaitalPRO 8FE200.

I think that the 8FE200 can sound quite loud with his 95db and 130W rms.

Therefore I am thinking to use:
- Woofer Faitalpro 8FE200 4 ohm
- Tweeter: FaitalPRO HF100 1" or Dayton Audio RST28A-4 1-1/8".

But I am oriented on the RST28A. With the HF100 should I buy also a Horn?

I think that with the 8FE200 a good cross-over frequency it is around 1KHz. No?
 
#7
The disadvantages of a coax is neglectible in your application, a mono party box, what you need is power handling and sensitivity and not worry about some bumpy midrange response. My niece just blew up her karaoke machine, these little monsters have no limits and no respect for things. I have the 10” myself in a 30l front ported and I’m very happy, I use them as PC monitors and have no problem with coax, in fact I prefer it and they can really take a beating too. Inner size 30x50x25. Since there is no cost impact going up to 10” and the size won’t be that much more then why not. Of course a separate horn is fine too, I hear good things about faital but have no personal experience with them.
 
#8
Thank you very much!
I think that i will try with two separated driver.

There are the first problem: Tweeter has a sensitiviti less than the woofer (92.5 tweeter and 95db woofer) therefore I think that is not good, correct?

Therefore, I should buy a high efficiency tweeter like the HF100 to equilize better the system, is it correct?

How handle the power differences?

To put some numbers:

- HF100 30W, 108dB.
- 8FE200 130W, 95dB

The ratio of power is 4.33 times -> 6.37dB.
Therefore I should attenuate the tweeter of a factor (108db-95db) = 13db.

13dB > 6.37dB.
Therefore I can work at full woofer power without overpower the tweeter. Is it correct?

In addition, which horn i should buy for the HF100?
 
#9
So a few things to think about here:

The Dayton dome, and domes in general, will have "lower" sensitivity compared to a PA bass/mid and you are right in general not suitable for your application (party speaker). On the other hand in a hifi situation you would probably have some baffle step correction on the LPF making the overall sensitivity -3dB compared to the spec of the driver so they could match theoretically, but yes for this application I see no use of a dome, you need as high sensitivity system as possible for preventing these kids turning the volume up to 11.

Secondly looking at the Faital drivers you've selected I see the following: The 8" driver with its 130watt and 4mm xmax will not be able to fill 100m2 with much bass. At 1m it will be able to produce theoretically a sinus of 115dB (100 watt = +20dB) at 100Hz but at 4m we are looking at 103dB (-6dB pr 2x distance) absolute max and only at that frequency, anything below 100Hz will hardly be audible and may also break the driver. The HF driver with its 30 watt is probably OK if you have 18dB filter at 2,5kHz or higher as you will attenuate -12 to -15dB or more depending on the horn you chose, this will be able to produce 120dB or even more (at 1m). Further I think the overall system realistic max SPL is much lower due to the dynamic nature of music compared to sinus test tones, plus the fact that the class D amp is probably not 200watt RMS, its probably more realistic 50watt (maybe +15dB max or 110dB at 1m and 98dB at 4m at 100Hz, for peaks that is - average perceived loudness much lower maybe 85-90 depending on the dynamic range of the program music)

In a 100m2 you need bigger speakers, thats my point with all of this. The Eminence I mentioned too will not be sufficient, in this room 8" PA drivers is considered midrange, there will be hardly bass at all. Maybe you should just get a pair of cheap Behringer 12" PAs for this case, much cheaper enought SPL and easy to fix when they break it, instead of spending time and money on a non-realistic project.

Sorry if this is not what you want to hear, also I would avoid 4 ohm drivers for a class D amp.
 
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#11
Hi, thank you very much for the information.
The class D amplifier of first post is specified for 200WRMS @ 4 Ohm with 0.1% of THD.

Yes, you have right, but take in consideration that are kids. I can't reproduce 135dB SPL... seems to be that maximum limit is about 105dB for 1 houres. Therefore the target will be this level.

From the simulation the Faital driver can generate 112dB SPL from 65Hz @ 100W. Therefore 100dB at 4m from 65Hz with a sinus test tone. Therefore yes, can be to low 🙁.

I have found the 8FE300 that give a little bit extra power, but there aren't many option for a 30L box 🙁
 
#12
That 100dB is with a test tone assuming the amp can produce clean 100 watt which it cannot. With real music ie pop music with 10dB dynamic headroom and amp distortion you will obtain max 90dB perceived loudness at 4m. These kids will turn it up to max and break it within the first year. They are soon teenagers. These demons have no respect for taking care of things. Buy something that can handle a serious beating so they can have some fun until they grow up and buy their own stuff to break. A pair of 12” compared to 1 8” will play with 8 times the low end dynamic performance with the same amp and the perceived loudness therefor much higher preventing the kids to max, I think this also better for their eardrum; nothing is worse than a pushed tiny speaker and a clipping amp.
 
#13
I have a rule of thumb.

A 100 watt system, defined by the weakest link of the amp and the speaker, will be able to fill a large living room with perceived average loudness for normal dynamic music at -10dB compared to the speaker sensitivity. If the speaker is 95dB @ 1 watt 1 meter, it will produce 85dB perceived loudness with good recorded dynamic music at 3m at 100 watt. If you want to go louder you need a much bigger amp or a much bigger (more sensitive) speaker.

Here is why I believe so. This is not proven, it’s only in my head to help me chose the right stuff.

100watt RMS = +20dB
3m = -10dB
Difference of peak and average perceived sound level in good recordings could be up to 20dB (but for more recent pop actually closer to 10dB).

So a speaker with 90dB spec with a 100 watt amp will produce 90+20-10-20 = 80dB good music from normal distance. Over-compressed pop maybe 90-95.

It’s still loud though. 85dB is considered fatiguing.
 
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#15
Putting a 12” in a small box will either reduce low end or sensitivity, this is physics. A car sub play sub bass in a small box but require tons of power and filter to do so. My point is with that class D amp you need sensitivity to get bass at all in large room. A large box is the only answer. Or accept clipping.
 
#16
Thank you very much fabricadetabaco!

If I will build a 150 liter box, my wife will kill me instantly Ehehehehe. In addition, the cost with 12 inches increases exponentially.

So, I think that for the moment the best option is the 8FE200 + HF100. That way I can get some practice with a two-way system without breaking the bank. Also I will have a compact system built in, which will sound louder than a UE BOOM 3 bluetoth speaker.: D

In the future I will develop something bigger xD I have a PA amplifier (Thomman t.amp E-800) so I should only build the speaker 🙂

So, first question. Which horn for the HF100?
 
#17
If you can go up to 40-45l you have a lot more to choose in, 10 inches especially. I would consider something like Fane 10-300. With its 5mm xmax, 97,5dB and 1200 watt peak it can probably take a serious beating from the clipping class D amp and play serious levels in a box of 5x3x3 dm3 inner volumes, maybe keep it sealed for preventing mechanical damage from clipping in today’s over compressed pop music. It will not play deep bass but these kids doesn’t need that. Price isn’t much for that one. Regarding horn for the HF I have no idea. It depends on the crossover point and the desired controlled spreading. I’d look for a short horn for your application. Cutting at 3kHz or higher will protect it from clipping.
 
#19
Be aware that the 30w CD may not keep up with the Fanes peak capabilities but by adding a 10watt 3:1 clipping / bulb fuse after the HP filter and the -10dB attenuator you can limit the performance to aprox 120dB peaks for the system. Once the fuse goes the kids will know they broke it, you can shout at them tell them to get a grip, and yet fix it for 10dollar afterwards. Make the weakest link also the cheapest and simplest to replace is a good approach for a party box. The Fane will most likely handle 120dB peaks (+23dB = 200 watt) over 100Hz, but yet I'm sure the amp clip long before making it difficult to predict what will break first. 110dB system peaks should definitely be possible. At 4m distance and normal music that would make a 80-90dB perceived loudness possible with still spare headroom and that is loud enough for these kids.
 
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