Mind Blower Speakers
Where can I find instructions for making a Minder Speaker? 3
Minder speakers were introduced in the 1970's and each has an amplifier built into the back of the magnet. I am in the process of restoring an old tr t-rod and would like to keep it in great detail available in the 70's, any help would be very helpful.
The Tenna Minders pair I have has standard 8-ohm 6X9 speakers with nothing special. I disconnected the one-line output transformer and found a double winding with each wire and then wound 72 turns. At the end of the coil a wire is attached to the other end of the wire on the elbow of the coil, the center end of which is connected to the negative.
The two independent ends are connected to the ammeter of one of the two output transistors, respectively. At this connection point, the free end of the output transformer is connected to the emitter of the transistor, to which two lines of the speaker coil are connected.
In the output voltage tests I performed on the lines with the speaker and measured the actual flux with RMS DVM, I measured the AC voltage up to 25 volts or 78,125 watts RMS at the output. With a rated output of 30 watts RMS, actually per channel, Tenna is within its rated output range.
I noticed that the control box that Tenna uses removes the top when it goes into boost mode. I have this Pioneer KP500 Turn Table with separate controls for Treble B. I noticed that there is a high end when I'm not in boost mode, but as soon as I put it in boost mode, the high end disappears.
I noticed that removing the Minder control box did not cause much loss of capacity for any output and so I had the full range. They improved it by removing the top edge. When it was removed from the circuit, I did not leave any.
The Minders I have are not Darlington pairs as I have downloaded. Each output transistor has a separate small signal transistor emitter attached to its base so that it can act as a control transistor.
You can find it under the US Patent Number. 4,130,725.
I have said many times that I want to copy the design of this amplifier and use 14 gauge wire to make it 3-4 times longer than before. Then optionally use MOSFET for the output driver. To handle the extra amperage you will need to run several in parallel and adjust the voltage high enough to accommodate the voltage surge. It would be great if this amplifier design could handle 4, 2, or 1 ohm impedance loads.
Unlike silicon polar transistors, which are current controlled devices and require input voltage, MOSFETs are tube type voltage control devices. You can copy any tube circuit with MOSFET, unless you need filament voltage or high plate voltage. You can parallel the MOSFET directly to the circuit while considering the input voltage on each transistor pole, thus amplifying the whole signal at the final output; Otherwise, the first 7/10 volts in the signal will not be amplified and will be lost.
It answers all your questions and explains all the secrets of Tina Minder system circuit design.
Mind Blower Speakers
Mind Blower Speakers
They use special speakers with center tape coils that are not currently available (unless you want to pay for the pair).
