3 prong speaker

[Bob0513]

Hello,
I am looking to use a pair of Yamaha drivers that I salvaged out of a keyboard. However, they have 3 prongs. Two of the connect to the speaker cone and one connects to the metal frame. I figure that the two pins connected to the chassis are the pins for the signal and the one connected to the frame should be grounded. Is this correct?

Thanks,
Robert S

[Bob0513]

I don't like to bump my own topic, but I need an answer to this question.

[Cal Weldon]

Hi Bob,

It sounds right but I've not seen that. Perhaps someone will help chime in this time.

[moray james]

The third connection that ties to the speaker chassis makes electrical contact to the speakers top plate. If it does I would suggest that you then solder a short jumprt between tis tab and the speaker negative tab and listen to see what you think. Regards Moray James.

[BassAwdyO]

Sounds like the third terminal is def a ground...


If that is the case the third terminal is useless... But if you're really unsure just do a test with a 1.5 volt battery... connect wires to the leads and touch them to the batter and see which two wires make the speaker go 'pop'. Just touch it and take it off... thats all you need to do(also a good way to test the polarity of the terminals)

[Bob0513]

Thanks guys. Shorting the ground connection to the negative speaker terminal worked fine. The system I am building is just a med-fi, all salvaged parts amplifier I am making to ease my way into diy-audio. Its a basic amplifier based on a TDA1517 amp I found on an old sound card, some caps I salvaged, and 3 cigar boxes I was given. Basically, its a ghetto amp that looks pretty, sounds alright, and cost next to nothing to make.

Thanks again,
Robert Schwartz

[zeropanic]

Bob,

I hate to pry and pry out in the open at that- but it seems the board has measures to keep people from being anti-socal and having to post before they can email.

Question: Did you ever finish your amplifier based on the TDA1517? I too salvaged one from an old Turtle Beach ISA sound card. I've found the datasheet on the chip but it makes no sense since I'm totally new at the homebrew thing. I'm trying to build a low level input amp for little or no cost (I think I have all the parts at home).

Many thanks.

[Bob0513]

Hey,
I did actually finish it and love it. I built it into a cigar box with two matching cigar box speakers. I built the amp more or less according to figure 6 in the datasheet, but with more smoothing capacitance, since I used a wall wart power supply. I didn't use quality components or anything, and the amp seems to be very forgiving; perfect for us newbies! What specific questions do you have about the tda1517? Probably not the best method, but it worked and I have no noticable hum, but I built the amp on one of those pre-printed circuit boards from radio shack, and just tied all of the grounds (signal and power) together onto a single bus.

[zeropanic]

Well I think I understand the jest of it- and I do apologize but I'm still at a VERY VERY basic level of understanding. I thought it might be better to illustrate my questions, so I've attached a jpeg of the application note.

The other question I had was how did you control the volume as I don't see a rheostat anywhere in the diagram?

Many thanks for your help and patience with an extreme newbie. I do intend on taking some electronics classes at the local technical school :-)

[Bob0513]

I attached an image showing the hookups to the chip and for volume control. The volume control image shows for only one channel. You will probably want to control both channels from one knob, so you would need to use a potentiometer that is "double ganged", meaning that there are two sets of variable resistors, but the wipers are controlled by only one shaft.