Ok I found an old set of Mindblower Speakers in a box cleaning out a room. I'm pretty sure they no loner work. But it got me thinking could I resurrect these, create my own company and start manufacturing them. The company was called Tenna they were around in the late 70's and early 80's and as far as I know they no longer exist. Spent most of the day yesterday drawing it out on the computer, circuit board, components and looking up what they were called. I know nothing about electronics as I was machinist all my life with a little study in mechanical design and using CAD. They are mostly rusted and the parts have no clear markings on them! If they (Tenna) are no longer in operation can I re-do them and sell them without like copy right infringement, name infringement...etc? I would be making upgrades to the old design as they were notorious for failing after about a year with the PCB board being the worse about burning out the embedded wiring between components. But I have a few question I don't know how to get the answers too.

Without the Markings (numbers and ID's) how do you tell what they were?
And if I need to put a meter on them is there a chart that can tell me input, output voltage, ohms or whatever it's call to identify what they are.
I not trying to get you guys to do my work for me just point me in the right direction.
The unit consists of only a few parts;
1. (1) PCB board
2. (1) Transformer
3. (2) Diodes
4. (2) Capacitors, One being a ZSF the other same kind only larger
5. (2) Transistors
6. (1) Coil, I know it's function was to change it from a three wire output to a two wire output cos the first ones hooked up to special speaker with a double coil. Later models used this because the three wire speaker became hard to find or became too expensive and the coil was cheaper and you could now use any speaker on the market.
Any help or feed back would be appreciated!

 

Attempting to recreate a retro design will almost always cost you more than what you can design afresh with newest components as far as the electronics industry goes.

You can buy on eBay a 20W dual channel class-D amplifier for under US$5.
Can you beat that?

 

Why would anybody want your copy of an ordinary (but very odd) 6" x 9" car speaker that was made 40 years ago?
It was odd because it had a little power amplifier with an output transformer in it. Speakers today do not use custom-made expensive output transformers that cut low and high audio frequencies. The Mindblower control unit had a switch labelled "boost" that cut off the tweeter making the bass sound louder. The little 6"x9" woofer cannot produce deep bass sounds anyway, just boom-boom sounds.

Car radios for many years have used a "bridged" amplifier that produces 3.5 times the power per channel of an old car radio. Your copies of the Mindblower speaker will blow up if connected to a modern car radio.

 

Attempting to recreate a retro design will almost always cost you more than what you can design afresh with newest components as far as the electronics industry goes.

Yes I know but, as you said I can upgrade the design to modern components and seen where people were still looking for wiring diagrams pics of the internal components and places where to buy them. The main production facility was located in Montgomery Ala. right across the bridge from my town. iIt would be kinda retro!

You can buy on eBay a 20W dual channel class-D amplifier for under US$5.
Can you beat that?

Yes but the Mindblower came with a speaker already in the box and it was rated at 50 watts per channel but actually would output about 75 watts per channel. With those now you have to purchase a set of speakers which adds to the cost. And as mention the Nostalgia of it would be amazing.

Why would anybody want your copy of an ordinary (but very odd) 6" x 9" car speaker that was made 40 years ago?
It was odd because it had a little power amplifier with an output transformer in it. Speakers today do not use custom-made expensive output transformers that cut low and high audio frequencies. The Mindblower control unit had a switch labelled "boost" that cut off the tweeter making the bass sound louder. The little 6"x9" woofer cannot produce deep bass sounds anyway, just boom-boom sounds.

They later upgraded it to as stated to take any speaker. With the upgraded new components I could probably remove the transformer, Still looking into that! I'm sure there are work arounds on the cutting out of the low and high frequencies, Plus they sounded pretty darn good to me back then.

Car radios for many years have used a "bridged" amplifier that produces 3.5 times the power per channel of an old car radio. Your copies of the Mindblower speaker will blow up if connected to a modern car radio.

Again I'm sure there cheap work arounds for this. It was a poor mans way of not having to pay out the nose for amps like pioneer and other expensive amps. like a simple added part for making it not accept more input than needed. Them bridged amps to get a good one is what about $300 to $500 dollars. Plus most radio's come with low level outputs nowadays. And you knowing that they came with the boost control box either show's you owned a set or knew someone that did. Still looking for a pic or diagram online for that wth no luck so far.
Edit: looking into pricing the components are only cents for each of them. The manufacturing of the PCB I think would be my highest cost just guessing.

 

Just to get my point across:
Here is a single channel 600 watt amp. with a little knowledge and redesign this could be placed on the bottom of a speaker.
$65.00

All I need is a 100 watt single channel design so there won't be as many parts!
add these for $32.00 and now your up to only $87.00
https://express.google.com/u/0/prod...ontrol_30_45&dclid=CM665fb6xNwCFRMNgQoddGoG3w

 

All cheap factory installed car radios are inexpensive and are bridged. A bridged car amplifier produces 15W into a 4 ohm speaker with low distortion or 30W with horrible distortion. Tenna listed the power of the mindblower speakers at 60W with no mention of distortion and maybe 2 speakers at 30W each.

Half-decent car radio systems already have 6" x 9" coaxial speakers with proper crossover parts already installed on the rear shelf so the boxes are used only in pickup trucks. The front doors have 6.5" coaxial speakers installed in them. Many cars have two tweeters on the front dashboard.
12 years ago I had a Chevrolet that used 2 ohm speakers with bridged amplifiers that produced 28W at low distortion per channel or 56W per channel with horrible distortion. It had an inexpensive Pioneer 10" sub-woofer driven with its own amplifier/power supply to 100W.

You talk about car amplifiers that cost $300 to $500 . A TDA7377 (European) bridged stereo car amplifier costs only $1.55 each today at Newark in the US but they are not made anymore because Chinese ones are cheaper.

 

You show a 600W amplifier. I say it produces 600 Whats which is about 100 Watts at low distortion.
Simple arithmetic shows that a bridged amplifier that produces 100 watts with low distortion into a 4 ohm speaker needs a power supply that produces 68V, not the 14.4V in a car. But 100W into a little 6" x 9" car speaker will destroy it anyway.

 

I remember the third pair I bought from them (new design) having 100 watts on the box. Bet it output more though, they were louder than the 200 watt I got in my truck now! Now you might be right Audioguru about it being 100 watts total or 50 watts per channel. I might have stated myself wrong but that's what I meant. Just looking up trying to find a new pair still in the box I can't find them! I have the schematics already drawn up and I like the Idea and am willing to put stakes in it cos I think they would sell. Even if I went with the original design I'd be willing to bet people would jump on them just to hold a piece of history. Distortion can be fixed! the newer radio's do that. And I never even paid attention to it that much anyway. They were loud and sounded great. My main reason for joining was to get some ideas where to go to get them manufactured. Like if you were going to produce a product who would you take it too? Would it be a copy right infringement?

 

Your telling me about watts and stuff, that's not what is important to me. I already said I know nothing about electronic design. Like the comment about the transformer! I'm sure there is an updated version to this. I was wanting to find out about what I needed to find out what they were.
Your only telling me I shouldn't do it right? what would happen if came back here and posted I just made a quarter million this year would you say I was wrong then? Just need some help on what to do.

 

At Walmart today you can hear the good sounds and buy a 6" x 9" tri-axial Pioneer car speaker for only $29.50CAN. It mounts on the rear shelf of a car or you can find a box to fit it into your pickup truck. It is rated for 400W MAX (only for a moment) or 45W Nominal.

Why would anybody buy your design that is not properly designed, made or demo'd?

Do you know anything about designing, parts selection, ordering thousands of parts, manufacturing a product and selling it somewhere? To be competitive you must buy parts in high quantities (cost a fortune) so you get a competitive cost. You also must pay for ads for the product.

 

At Walmart today you can hear the good sounds and buy a 6" x 9" tri-axial Pioneer car speaker for only $29.50CAN. It mounts on the rear shelf of a car or you can find a box to fit it into your pickup truck. It is rated for 400W MAX (only for a moment) or 45W Nominal.

Those were meant as an example.

Why would anybody buy your design that is not properly designed, made or demo'd?

It's already been designed and been on the market! I'm not asking you to worry about my money and I never said I didn't have business experience, you just took that for granted! I said no electrical knowledge.

Do you know anything about designing, parts selection, ordering thousands of parts, manufacturing a product and selling it somewhere? To be competitive you must buy parts in high quantities (cost a fortune) so you get a competitive cost. You also must pay for ads for the product.

Again it's already been designed. The parts are already sitting on the amp all I have to do is buy them. And you can buy prototype parts to test your design if that's what your asking. No-one in their right mind would buy 10,000 parts and not know if something was going to work! leave the marketing and money matters to me. If you want to help answer the questions I'm asking instead of telling me why it's bad idea or where this is cheaper.
1. Where to get prototype PCB's made cheap? 50 or less
2. Is there a chart that tells me what this or that component ohms at? or where could someone take it to get someone to test them and give me a list
3.Plastic parts molded?
4. Wiring harness's made?
These are the answers I'm looking for!

 

The parts from what I see are mere cents and the transformer couldn't cost more than a few dollars.
Do I need to disassemble one to ohm the parts out?
Help me with these questions.

 

The values of the resistors, capacitors and inductors must match the specifications of the unknown raw speakers you will use.
A speaker output transformer has not been used for 40 years so a custom-made one must be designed and manufactured at a very high cost and for the lowest cost you must buy thousands of them. The one transformer designed and made for your prototype will also be very expensive.

Where will you find the specifications for the transformer? The spec's for the transformer must match the spec's for the unknown raw speakers but some of the spec's can be measured.
Nobody makes or sells a transformer with the spec's you need but a 50W output transformer for a vacuum tubes guitar amplifier is sold today on Digikey for $123.70CAN each.

 

Some one has the read deal for sale at $225 a pop.
Said they got a bunch when they shut down the company that made them.

 

The values of the resistors, capacitors and inductors must match the specifications of the unknown raw speakers you will use.
A speaker output transformer has not been used for 40 years so a custom-made one must be designed and manufactured at a very high cost and for the lowest cost you must buy thousands of them. The one transformer designed and made for your prototype will also be very expensive.

When I read this I googled speaker output transformer and found loads of them with all kinda specs. some with multiple connectors for different uses and output ranges. You can't tell me one won't be close enough to make it work. found one for less than $10.00.

Some one has the read deal for sale at $225 a pop.
Said they got a bunch when they shut down the company that made them.

Yea I searched the other day but I didn't find any now. I would be willing to pay that much just to get the numbers off of it.

 

http://www.partsclassiccar.com/car-...wer-Speakers-mindblower-6x9_111997943824.html

 

http://www.partsclassiccar.com/car-...wer-Speakers-mindblower-6x9_111997943824.html

Gives price, no date as to when it was posted or if they were sold.

These rare mind blower speakers are fresh NOS that never made it through the entire manufacturing process according to previous owner. The speakers are complete with grilles but the amplifiers were never attached to the back. They were in the factory wrap as you can see in the photo but I recently removed it for a thorough inspection. I can only assume these were some of the final speakers left over at the plant after shutdown. I can't express enough how rare these are, Mind blowers are impossib…

This says it all!!

 

If they (Tenna) are no longer in operation can I re-do them and sell them without like copy right infringement, name infringement...etc?

No. I'm sure the details have changed, but in round numbers a patent extends for 17 years. A copyright extends for 50 years *after the author's death*. Or something like that.

Car radios for many years have used a "bridged" amplifier that produces 3.5 times the power per channel of an old car radio. Your copies of the Mindblower speaker will blow up if connected to a modern car radio.

With a little thought, no they won't. Each of the two outputs that make up a single bridged output are a complete audio signal referenced to GND. Assuming the source amp is switching, you might need a simple R-C lowpass filter at the input of the new speaker amp. If the source is a linear amp, then the interface *might* be nothing more than a coupling capacitor. Ground noise might be a problem; won't know until you try.

For the 19 reasons stated above, the resulting audio will not be stellar. But there is nothing technically difficult about interfacing it to a modern car radio output.

ak

 

THANK YOU ! Analogkid
For answering a question I asked!
I'm searching patent and copy rights as I post this. No tenna or mindblower in the patent office. But you got me thinking there are several companies out there with the same name, they just do different things. And I was more looking at the mindblower part than tenna.
I was going to use my own company logo and just market it as a Retro Re-Make. Yea Audioguru has me puzzled? It's like I had a good Idea and he doesn't want me to do it because he didn't think of it or something. Must be in Audio sales or whatever. Never answered "NOT ONE" of my questions. Hate to have him for my motivational therapist.

 

When I read this I googled speaker output transformer and found loads of them with all kinda specs. some with multiple connectors for different uses and output ranges. You can't tell me one won't be close enough to make it work. found one for less than $10.00.

Many guitar amplifiers use output transformers to match the antique high voltage vacuum tubes in the amplifier to the speaker.
Close enough?? Does the amplifier on the Mindblower speaker use a high voltage and vacuum tubes??

The amplifier for store background music has an output transformer that steps up the signal voltage then each speaker has a transformer to step the signal voltage down to normal. Then the current in the high voltage wires is less so that thin and cheap wiring can be used. Just like electricity. They step up the voltage to hundreds of thousands of volts to send it across the country with fairly low current so that the wires can be thinner, less weight, less movement by the wind and cheaper.