My Tenna Mind Blowers had only standard 8 Ohm non-center tapped single voice coil speakers

I owned a pair of Tenna Mind Blowers. I dissected one of my Tenna Mind Blower amplifiers to find out why I was measuring 25 Volts RMS across the speaker terminals with a Fluke 8060A True RMS DMM from a 12 Volt DC source. That calculated out to about 78 Watts RMS at 8 ohms with them cranked way up. They had a standard 8 ohm single voice coil speaker. The speaker leads were connected at points 45c and 46c in the posted schematic drawing. The center tapped winding that you see in the output section of the drawing is the output transformer and not the speaker VC as some have concluded here. They do not show the speaker being connected to it in the schematic.

The way this transformer was wound is that they wound two wires (14a & 14b) parallel (side by side next to each other)72 turns. They connected the inner winding end of one wire to the outer winding end of the other wire for the center tap (CL3) The two remaining free ends were each connected to an emitter of the two output transistors as you see in the schematic drawing at connection points 45c and 46c at which connection points each of the speaker leads were also connected to.

Instead of the Darlington transistors shown in the schematic posted here, mine had two small signal transistors that fed each of the 220 case output transistors.

If you would like to experiment with this type of amplifier design, instead of winding it at 72 turns with 18 AWG magnet wire, you could double or triple the number of turns for higher voltage output and wind it with 14 AWG magnet wire or larger for higher current output. You will need to increase the current capabilities and numbers of the output transistors used for the lower impedance loads of today's car audio speakers.

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Follow Ups Full Thread

Topic - Why don`t we see more widespread use of PUSH PULL Double VC speakers? - nicolas 13:17:14 01/17/12 (14)

RE: Why don`t we see more widespread use of PUSH PULL Double VC speakers? - Head_Unit 23:08:02 01/20/12 (1)

My Tenna Mind Blowers had only standard 8 Ohm non-center tapped single voice coil speakers - HTA-Woofers 15:56:41 03/15/15 (0)

The Nagle speaker - Iron Knee 15:59:14 01/18/12 (2)

RE: The Nagle speaker - djk 18:19:14 01/18/12 (1)

RE: The Nagle speaker - Iron Knee 10:41:21 01/19/12 (0)

RE: Why don`t we see more widespread use of PUSH PULL Double VC speakers? - David Yost 14:09:35 01/18/12 (0)

RE: doubling acceleration, quadrupling power output all without requiring more power input. - badman 12:50:41 01/18/12 (0)

RE: Why don`t we see more widespread use of PUSH PULL Double VC speakers? - David Yost 23:17:12 01/17/12 (6)

RE: Why don`t we see more widespread use of PUSH PULL Double VC speakers? - rafaroxlm@yahoo.com 10:24:09 01/18/12 (3)

RE: Why don`t we see more widespread use of PUSH PULL Double VC speakers? - rafaroxlm@yahoo.com 10:28:45 01/18/12 (2)

apples and oranges - nicolas 14:37:56 01/21/12 (0)

Have a look at this: - b.l.zeebub 10:59:32 01/18/12 (0)

RE: Why don`t we see more widespread use of PUSH PULL Double VC speakers? - Bill Fitzmaurice 05:39:03 01/18/12 (1)

RE: Why don`t we see more widespread use of PUSH PULL Double VC speakers? - b.l.zeebub 06:36:24 01/18/12 (0)

Follow Ups

My Tenna Mind Blowers had only standard 8 Ohm non-center tapped single voice coil speakers - HTA-Woofers 15:56:41 03/15/15 (0)

My Tenna Mind Blowers had only standard 8 Ohm non-center tapped single voice coil speakers

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