Thanks for your reply.

Question 1.
You stated on Oct. 31., at 4.03., that “The 8ohm woofer is not available and Dayton says they do not know when it will be available. The newer 4ohm woofer will be available on November 24.”

After checking Parts Express site, I can confirm that the Dayton Audio TCP115-4 4” is currently out of stock and expected to be available again on the 24 Nov. On the other hand, the Dayton Audio TCP115-8 4” is now available again it would seem.

But I am slightly confused about which tweeter/woofer sets you are suggesting will be the best match? You wrote that “An 8ohm tweeter will match the woofer sensitivity and will probably be less expensive” Am I to understand that an 8ohm tweeter will better match the sensitivity of the Dayton Audio TCP115-4 4” or the Dayton Audio TCP115-8 4”? Please advise, as I am interested in components that will produce the best possible end product and as much bass as possible within the confines of the 0.03 cubic feet cabinet with as little distortion as possible.

Question 2.
As stated earlier, the acoustic quality and stability of the unit has very high priority. May I inquire as to what particular components and processes I should pay special attention to secure that result. Examples could be with regards to the amplifier and the DAC converter?

 

With all due respect, I believe Alibaba carry many great products, but is it wise to shop for original IC’s on Alibaba? If not, could you kindly suggest another venue better suited for the purchase of original components such as IC’s?

 

Peerless by Tymphany OC25SC65-04The 8 ohm woofer needs a battery with twice the number of cells to have a doubled voltage for the same power as the 4 ohm woofer.
4 fully charged lithium-ion cells cells make 16.8V. A bridged amplifier will produce about 24W into 4 ohms or about 13W into 8 ohms.
Parts Express say the 4 ohm woofer will be available 10/24/2018 which was last week.
I notice that the woofers are made in China which might be bad.

The expensive tweeter you selected has a sensitivity that is 7.9dB higher than the 8 ohm woofer but since the tweeter is 4 ohms then it uses twice as much power as an 8 ohm tweeter. Therefore its total sensitivity will be 7.9dB + 3dB= 10.9dB which needs attenuation.
If you use an 8 ohm tweeter with a 4 ohm woofer then the sensitivities match better.

The woofer is small, has a higher resonance than the 8 ohm version and your enclosure is small and sealed, not ported. Then the bass will be poor with the bottom 2.5 octaves or 3 octaves of sounds missing.
Years ago I bought a pair of Radio Shack Minimus 7 speakers on sale. They were rated at 40W. When a 4" woofer burned out I saw printed on it 5W Korea. In those days, Korea made cheap stuff like China does today.

Alibaba, AliExpress, ebay and Amazon sell cheap Chinese stuff that are fakes, are defective or are poorly made copies of Western products.
I buy electronic parts at Digikey or Newark. A local store sold Western parts but the store is gone. A store from India replaced it and sells "surplus" old parts that might be defective or be used.

 

Thank you for your insightful remarks.

Query-

The cabinet volume allows for approximately 0,85L / 0.03cubic feet, while the manufacturer of the Dayton Audio TCP115-4 4” suggest a sealed volume capacity of 1,7L /0,06 cubic feet.

How will this workout acoustically in the sealed cabinet, compared to the Dayton Audio TCP115-8 4”, where the manufacturer suggests a sealed volume of 0,85L / 0.03cubic feet?

I understand, that the unit, as per your suggestion is best suited with a pairing of the Dayton Audio TCP115-4ohm 4” and an 8ohm tweeter with a close or matching sensitivity. But what effect will the differentiated suggested capacity of woofer at 0,85L / 0.06cubic feet have within a cabinet at 0,85L / 0.03 cubic feet?

And if there are negative ones, how can I counteract them electronically or otherwise?

 

Forget about using an 8 ohm tweeter. Simply attenuate the input to the 4 ohm tweeter to match the much lower sensitivity of the 8 ohm woofer. But don't forget that the 4 ohm tweeter will be 3dB louder than an 8 ohm tweeter.

The 4 ohm woofer has a deeper bass response because its resonant frequency is lower and when its enclosure is larger than the enclosure recommended for the 8 ohm woofer. But the 4 ohm woofer in the enclosure too small for it will not produce deep bass and will have a peak in its response in the upper bass causing it to sound a little like a bongo drum.

An amplifier that can properly drive a 4 ohm speaker produces almost twice the power into 4 ohms as does in 8 ohms. Then the amplifier for an 8 ohm speaker needs more supply voltage to produce the same power as an amplifier driving a 4 ohm speaker.

 

Thank you for your reply.

And forgive my ignorance, but I am somewhat confused because yesterday, at 8:38pm., you wrote;
“If you use an 8ohm tweeter with a 4ohm woofer then the sensitivities match better”.

And today, at 4:59pm., you wrote; “Forget about using an 8ohm tweeter. Simply attenuate the input to the 4ohm tweeter to match the much lower sensitivity of the 8ohm woofer.”

So my question is as follows: If you can kindly suggest exactly which tweeter and woofer mix is the appropriate choice for this unit, which per your suggestion will incorporate 4 fully charged lithium-ion cells, that will make 16.8V and produce about 24W in a bridged amplifier configuration? Is it:

1. The Dayton Audio TCP115-4ohm 4” and a 8ohm tweeter?
2. The Dayton Audio TCP115-4ohm 4” and a 4ohm tweeter?
3. The Dayton Audio TCP115-4ohm 4” and an attenuated 8ohm tweeter?

4. The Dayton Audio TCP115-8ohm 4”and an attenuated 4ohm tweeter?
5. The Dayton Audio TCP115-8ohm 4” and a 4ohm tweeter?
6. The Dayton Audio TCP115-8ohm 4” and a 8ohm tweeter?

7. The Dayton Audio TCP115-4ohm 4” and a calibrated 4ohm tweeter?
8. The Dayton Audio TCP115-8ohm 4” and a calibrated 8ohm tweeter?

A simple and concise choice involving only one of the above will be most appreciated.

Again, thank you.

 

Here we repeat the basics of speakers and electronics again.
1) A tweeter is more sensitive than a little woofer.
2) Using only one amplifier for both a woofer and a tweeter then Ohm's Law says that the 4 ohm (tweeter) uses double the power of the 8 ohm (woofer) then the tweeter will again be more sensitive.
So if the tweeter is 8 ohms and the woofer is 4 ohms then their sensitivities almost match. But it doesn't matter because an attenuator will match their sensitivities.
3) Using 4 lithium cells the battery is fully charged at 4.2V x 4= 16.8V. The bridged class-AB TDA7396 amplifier datasheet has a graph that shows its distortion is 1% at 25W into 4 ohms when it has a 16V supply then with a 16.8V supply its output will have less distortion at 25W.
Its low distortion maximum output into an 8 ohm speaker will be almost half the 25W due to half the current. Then the supply voltage needs to be higher (5.5 cells making 23.1V) for 25W into 8 ohms but the TDA7396 amplifier maximum allowed supply is only 18V so it cannot do it.

Your choice is to use a 5.5 cells battery with the 8 ohm woofer or make a larger enclosure and use the 4 ohms woofer with a 4 cells battery.
Wait a minute. Why does this little speaker system need to blast 24W? 24W or 48W in stereo will fill a huge room with sound. 12W will sound only a little less loud since our hearing's sensitivity to loudness is logarithmic.
Editted.

 

I think there has been a misunderstanding. I have no need for the speaker to blast at 24W, nor do I want to lose any more space to an extra fifth battery cell. 12W or slightly more will do just fine.

I am merely pleading for you to kindly suggest a pair of tweeter(ohms) / woofer(ohms) and amp to function with the above mentioned wireless connectivity systems, in a configuration that will work seamlessly with a 4 cell supply voltage.

As I mentioned earlier, I am a novice within this realm and in need of guidance. However, I beg that said guidance be as simple and concise as possible.
So to summarize, all I am asking is if you will kindly suggest a tweeter and a woofer configuration that will function well in the given cabinet volume and system configuration. And to that end, I presented the above list from 1 – 8, asking that you suggest one of them as a viable pair. That is all.

Thank you.

 

A few hours ago you said you said you want 24W but now you say that 12W is fine.
You have a cabinet for the 8 ohm woofer, then a TDA7396 bridged class-AB amplifier will drive it to about 12W when it is fed a fully charged 4 cells battery. When its voltage drops and it is playing loudly then you will hear distortion until you turn down the level.

You can use any tweeter you want with an attenuator to match the sensitivities.

Do you know how to design a crossover network for the two-way speaker?
Do you know how to design a battery voltage detection and cutoff circuit when the battery voltage is low to avoid destroying the battery?

 

I merely mentioned 24W in context to you saying earlier, that; ”4 fully charged lithium-ion cells make 16.8V. A bridged amplifier will produce about 24W into 4 ohms or about 13W into 8 ohms”. on Friday at 8:38.
The suggestion of 24W was therefore in that context, and I ask it be forgotten, so that we may proceed forward. I am only relieved and glad that we are back on track.

To put the matter into perspective, it is my design intent, that the unit can play well and loud for about 8 hours in an average room of 30m².

You asked whether I know how to design a crossover network for a two-way speaker, and a battery voltage detection and cutoff circuit. The answer to both questions is no.

I am first and foremost a designer with a passion for music., albeit a designer with a willingness to learn and expand my sphere of knowledge on the subject of electronics. I must however concede, that I do need heavy guidance on some points of the journey of speaker building, especially with regards to electronics.

However, on Wednesday at 4:03pm., you mentioned that you designed and made amplifiers. This revelation promptly made me inquire whether you were willing to design a schematic covering the connection/operational schematics of all the involved systems above, regarding: drivers, amplifier, crossover, power supply, batteries, protection circuitry and wireless connectivity systems? In other words, how will the respective modules be connected schematically if we were looking at a completed unit.

You did not however respond to that particular inquiry, but only offered a schematic for the amplifier.

So to summarize, if you are offering to assist me in either the design of the crossover and/or the design of the battery voltage detection and cutoff circuit, then I accept your offer in either, or both cases. If it involves a fee, I will also accept, countering a potential negotiation, if deemed necessary.

In either case, please know that I am grateful for the assistance and time you have granted my project.


Thank you.

 

I like chatting about complex electronic circuits with my peers who know all about electronics. Sorry, I am not a teacher of the basics.
But on this forum there are some teachers who might design the circuit and maybe even build it for you.

 

I completely respect and understand where you are coming from on the matter. And as I mentioned earlier, I deeply appreciate your efforts.

P.S. Are there any of your peers, in particular you had in mind, that might deem my plight and project interesting enough to help me with the schematics?

In any case, I bid you well and thank you very much.