Hello,

When you can read german, than this booklet about circuits with audio IC's might interest you:
https://www.box73.de/product_info.php?products_id=480

Bertus

 

And (A) fan is better than (NO) fan. Why do you think they put an a fan in a computer enclosure "because the parts get hot".

I think AG's point was about enclosed spaces, not about fan quality.

If the speaker, amp, heatsink assembly is mounted in a tight, confined space (like one of those little carpeted speaker boxes,) then a heatsink will rapidly heat all the air in the enclosure with or without a fan on it. Once the air in the enclosure is hot, the heat sink is ineffective.

So, he's right that in a small enough space, the fan gets you nowhere.

 

Hello,

When you can read german, than this booklet about circuits with audio IC's might interest you:

Don't care to read in german bertus.
your signature says:
You don't have to know everything, if you know where to find it.
When you do ask questions, you may look stupid.
When you do NOT ask questions, you will STAY stupid.
I believe in this whole heartedly.
Being an administrator you should know sometimes when people come here they are looking for answers to questions they don't have the answers too.
I was born in Alabama, I speak English. Southern slang English to be exact. "like "yont-to"

 

I think AG's point was about enclosed spaces, not about fan quality.

If the speaker, amp, heatsink assembly is mounted in a tight, confined space (like one of those little carpeted speaker boxes,) then a heatsink will rapidly heat all the air in the enclosure with or without a fan on it. Once the air in the enclosure is hot, the heat sink is ineffective.

So, he's right that in a small enough space, the fan gets you nowhere.

Sorry - forgot to bring that full circle. Computer fans work by drawing in cool air from outside and expelling hot air. If you put a computer in a tiny box, the heat will build up in the box and the computer will get hotter and hotter.

 

I think AG's point was about enclosed spaces, not about fan quality.
If the speaker, amp, heatsink assembly is mounted in a tight, confined space (like one of those little carpeted speaker boxes,) then a heatsink will rapidly heat all the air in the enclosure with or without a fan on it. Once the air in the enclosure is hot, the heat sink is ineffective.
So, he's right that in a small enough space, the fan gets you nowhere.

I get that ebeowulf. If their in a trunk there is still air in that trunk and I will not enclose them totally. Even with a cover on the bottom it will have gaps all around it to pull or push the air around them. If their behind the seat there is still air back there. You can put a warning on the box "do not enclose" can't you(?) If their in the door there is still air in between the panels just like outside, might not be as much but that's what the fan is for.

 

140C is 284 degrees, do you realize how hot that is? I said in an earlier post that the Mindblower got (So) hot you couldn't touch it.
As long as I can keep it at around 110C, 120C Won't it be OK?

 

Tenna applied for the patent for the MindBlower amplified speaker in 1976. Car radios 42 years ago used 8 ohm speakers and the amplifiers were not bridged. Then the output just before clipping when the battery is charging at 14.4V was about 2W for each stereo speaker. The patent says that the MindBlower increases the output power 16 times in theory or actually 11 times. So 22W.

Most modern car radios use 4 ohm speakers (some use 2 ohm speakers) and the amplifiers are bridged for an output of about 15W per channel. The TDA7396 amplifier is bridged and also produces 15W into 4 ohms when the car battery is charging or 25W when a voltage booster boosts the supply voltage to 16V. But 15W, 22W and 25W all sound almost the same because our hearing's sensitivity to loudness is logarithmic. Ten times the power sounds twice as loud. Twice the power produces only a small increase in loudness.

42 years ago cars had only two speakers for stereo. Modern cars use 4 or more speakers so the sound level is even louder than before that used only 2 MindBlower speakers.

 

How, when using that IC/amplifier, will you get 'line out" level signals from the radio? Speaker level voltage is higher than most amps can use as inputs.

 

Three resistors mix the stereo signals into mono and attenuate the speaker levels from the radio to line level for the input to this IC amplifier.
If the radio is mono then only two resistors attenuate the speaker level to line level.
But of course this new amplifier is amplifying distortion and noise from the radio's amplifier.

 

How, when using that IC/amplifier, will you get 'line out" level signals from the radio? Speaker level voltage is higher than most amps can use as inputs.

Still working on some stuff about it shortbus. I also thought most radio's came with low level outputs. Apparently that's not the case (?)
The one I bought only has 4 outputs and there 30W per channel "just quoting what's on the box AG".

Three resistors mix the stereo signals into mono and attenuate the speaker levels from the radio to line level for the input to this IC amplifier. If the radio is mono then only two resistors attenuate the speaker level to line level.

The test schematic only uses two resistors and I've took the third into account. As I said I will build several of these and find which way is best.
It will only cost $10.00 more for 6 more PCB's, (research and development) cost. When I'm done there will only be about $10.00 in each not including the speaker. 10 bucks is nothing and look what I've learned so far? I have two 8's just sitting around the house I can use for testing.

But of course this new amplifier is amplifying distortion and noise from the radio's amplifier.

There you go again AG. The Mindblower Idea was bad, This idea is bad. Remember it's my money and if I want to throw it away it's OK.
If I ever make it big I'll send you a pair "Autographed of course" for free. If I don't I'll have a cheap pair of great Mindblower amps for myself.

 

Also been looking into this for my second project.
https://www.mouser.com/ProductDetai...MkwKcEjFF1A8DaoeWfGDfrWNhX/EsaBD7JNJ3V2fRwQ==
It's Bridgeable and will put out 100W.

 

Also been looking into this for my second project.
https://www.mouser.com/ProductDetail/Texas-Instruments/TPA3156D2DAD?qs=sGAEpiMZZMuMkwKcEjFF1A8DaoeWfGDfrWNhX/EsaBD7JNJ3V2fRwQ==
It's Bridgeable and will put out 100W.

Each of its two channels are already bridged (BTL is Bridge Tied Load) so you cannot bridge them again.
The datasheet shows 70W per channel into 4 ohms with a 24V supply at a horrible 10% distortion or 57W per channel with 1% but still audible distortion.
It uses a custom modified heatsink and a "dual layer" pcb. It is tiny so its pins are VERY close together and are difficult to solder.

 

It will only cost $10.00 more for 6 more PCB's, (research and development) cost.

So you're still looking at marketing these? Have you done any research into how many people would buy them? I know as a car guy I wouldn't but that's just me. I think I said earlier, there is a reason these were never that popular and aren't still on the market.

Doing something like this for yourself is one thing, but thinking you'll be able to even get your R&D money back buy selling them to an unknown market group......?

 

Tenna Corporation applied for a patent on the MindBlower speaker in 1976 and the patent was granted in 1978.
In 1979 Tenna could not pay over half a million dollars in income taxes so applied for bankruptcy.

 

You just gotta have faith shortbus and AG, Know a few people here and there, Get some free publicity on a local radio station for opening a new business, word spreads. I learned a long time ago with my first wife not to sink yourself in debt so far it takes you under. To this day I will not have a credit card. Took 30 years to pay it off and she left 8 years into the marriage. I don't have a half million dollars AG but I wouldn't sink that much into it if I did. I may be crazy but I'm not stupid. Don't worry shortbus I won't forget you either, A free autographed pair for you also. You can add ebeowulf in, MrChips, bertus, and anyone that helped me. You can't beat "FREE".

 

Might should have said mono mode

 

When I got my first credit card I bought a business suit with it. I never received a bill for the suit, a mistake was made in the store and maybe somebody else paid it.
I have never, ever paid a penny of interest on a credit card. Instead I get points, bonuses and "rewards".

 

When I got my first credit card I bought a business suit with it. I never received a bill for the suit, a mistake was made in the store and maybe somebody else paid it.
I have never, ever paid a penny of interest on a credit card. Instead I get points, bonuses and "rewards".

We have a saying down south:
"You can't hide money"

 

Up here, money grows on trees. You simply need to reach it and pick it. But it is invisible so you need experience to know where on which tree it is, and how to make it visible so you can spend it..

 

I think @Berzerker should start investing in the speakers instead of arguing with people whether he should / shouldn't invest. This thread has been running for more than a month and he still cannot make a decision to move forward with his great idea. There are talkers in this world and doers. Doers don't sit around reading their phones all day and responding to nay sayers.

Start getting quotes for each part.
Anything custom-made will likely have a $5000 setup charge so you can't go small or your "per-unit" costs will kill you.
Any part that needs to be injection-molded will need a mold costing 50k or more. If you only need vacuum-forming, molds will run 1k to 10k.
Stamping tools will be somewhere in between.
Most companies want 3D CAD files now days for all toooling (molds). Figure 4 hours per part so about $4k each from an engineering company. Complicated parts like the speaker frame will be expensive - there may be some long conversations on designing that frame so you might want to make an estimate then double it for consultation hours (instead of drafting/design hours).

You'll likely be ready to run your first part for under $400k.

Good luck