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I just found 4 speakers and want to make a speaker box. Can anyone help me? Answered

 I found 4 speakers (2 subs about 5 inches diameter each and 2 tweets about 2 in diameter) in a TV that was left on the side of the road.  I would like to make a speaker box for them, or a mini-amp for my electric cello.  In either case, I have very little technical knowledge in this area, and will need some very clear instructions as to what I need.
I took from the TV:
4 speakers (see above)
Each speaker has a red and a black wire coming out the back of it (power cables presumably).
The smaller speakers are connected to the larger ones by similar cables.  There are also two more cables similar to the others, but one is white and black, the other green and black.  These connected the larger subs to the main power of the TV I think.
I also took the power chord from the TV.  It has a connector that was joined to a plug inside the TV.
The speakers say on the back:
ZM   YD150-B1-20W-8*     for the larger speakers and
ZM   YDG70-A1-10W-8*    for the smaller speakers
* means the sign for ohms (my rather dusty chemistry knowledge from high school tells me this, I could be wrong, it's the omega sign from the Greek alphabet anyway)

That's all I think.  I would like to know what I will need to make these speakers work, and if it is worth my while and not too expensive, and whether or not I will kill myself in the process.  I have never done this kind of project, but have always fancied the notion.  If anyone can help out, or even start me in the right direction, I would greatly appreciate it.  Is there anything else I should take from the TV while it is there still? Like the line-in plugs etc?


From your description, you have 2 full range speakers (5") and 2 tweeters. Both sets are 8 ohm impedance. The 5" is rated for 20 watts and the 2" is rated for 10 watts. The 5" is listed as close to a 6" (150mm), most likely outside frame diameter. Likewise the 2" is listed as 2-3/4" (70mm), probably outside diameter. The red wires are the positive and the black wires are the negative. The white and green wires are the left and right positives, and the black wires that went with them are the grounds/negatives.


Since there aren't any Thiele-Small parameters available for these speakers, I cannot design a sealed or a ported box for them. I can design a transmission line box, though. A transmission line speaker is a very smooth speaker, most suitable for jazz and classical music. The construction is generally a box with a slot port at the back (on the bottom) with a folded port of the same cross-section attached to that slot. The folded port is then lined with damping material at a rate of 1/2 pound per cubic foot. This material can be very loose batting or craft stuffing, the kind you use for pillows. For a 5" speaker with a guesstimate of 40 Hz resonant frequency (Fo), the box volume should be about 1/3 of a cubic ft. (0.33 cuft.), the cross-sectional area of the line should be about 19.5 square inches with a total length of 2.5 feet (30 inches). The weight of the damping material should be about 3 ounces for the whole length of the line.


For the box initial box size (0.33 cuft.), you have 2 options, the golden rule and the acoustic ratio. I'll give you numbers for the inside and outside dimensions of both using 3/8" plywood:



INSIDE DIMENSIONS = 13.41728 H, 8.292508 W, 5.12477 D.

OUTSIDE DIMENSIONS= 14.16728 H, 9.042508 W, 5.87477 D.



INSIDE DIMENSIONS = 10.44773 H, 8.292508 W, 6.581764 D.

OUTSIDE DIMENSIONS= 11.19773 H, 9.042508 W, 7.331764 D.


Place your 5" and 2" speakers on the vertical centerline of the face and move them up and down to your liking. Draw your holes for the speakers and cut them out.


Whichever box you choose, you must then size the transmission line to the width of 8.29 inches, which works out to about 2-1/3 inches across. To measure the length, measure it along the centerline, curving through the middle of each bend. When you reach the end, start your outlet port (just stop the face and leave it open). Before you seal up the edges, place your damping material inside the line.


To make sure you don't damage your tweeter, place a 10 uF (approximately 100V rated) nonpolarized electrolytic capacitor in line with the positive wire (red). This will keep frequencies about 2000 Hz and lower out of it. You don't need to worry about the 5" speaker, it was meant to take all frequencies.


***PLEASE NOTE: This is for only 1 speaker pair (5" and 2"). You will need to build 2 to use both sets. Just do the same thing twice. Also, you may change the dimensions to something easier to actually measure. So you can change 13.41728" to 13.5" etc. It won't have that much effect on the overall sound.




You will need some sort of amplification to use these speakers. You can search this site for many different amplifiers from the Ruby amp (1/2 watt) up to Tube style amps. Look through the instructables and the questions for links. If you need more direction, I can help out there.


If you still have access to the TV, you may want to take any jacks or other mechanical parts including the transformer. It is a good way to stock up on parts and save the environment from all the e-waste out there. The pc-board will give you good practice on soldering and de-soldering.


Here is a side view of a transmission line speaker to help you put it together.



Good luck on your build. Let me know if you need any more help.




hello Quercus austrina

I just salvage the exact same speakers from an hold TV. But I also have
several other speaker (also salvaged from other stuff). Their dimensions are around
3” and they came from several surround systems. I would like to incorporate a
combinations of all of these into two floor standing speaker.

You seem
to be familiar with speaker design so can you explain the math behind the
dimensions you provided? I’m new to audio stuff so an explanation about wiring
configuration would be appreciated. I understand I may be asking too mutch so
if you know of a good tutorial on this stuff that also would be greatly appreciated.

I’m not trying
to become well versed in speaker design just looking for a nice project to do
as a gift for someone. As such I would like to do something decent.



8 years ago

Since you're new to electronics, I suggest finding an amplifier kit to build up.  They're available online from a number of places, and at retail stores in very few places.  Build up the amplifier, connect the speakers, and build a box for them.

Also do a search on Instructables.  There are plenty of speaker ans amplifier projects here to get you started.