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Speaker Selection Advice

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  • Speaker Selection Advice

    I want to turn my Philco 42-PT-7 into a bluetooth speaker with decent sound. What do you all think if I use the parts (amp and drivers) in this project, maybe without battery power?* I may not have room for stereo, so I'm ok with mono.

    I bought the radio to recap it and get it working again. It came with no tubes and is in terrible shape. And Philco doesn't leave much room to work in the underside to recap and such. It feels like more work than I want to do for poor sounding mono speaker. I have other tube radios I've rebuilt and added bluetooth to. So, I'm ok adding new tech to this one and get a casual bluetooth speaker, but I want decent sound. Ideally I'd leave the chasis, AM tuner, etc in the wooden case, but I also understand that's a lot of space to take up. i guess I'd like to allow someone in the future to bring this back to a tube AM radio without too much destruction on my part. But in the end, if I only have the wooden case with new parts inside, I'm ok with that.

    Also I've never built my own speaker. So I'm reading lots, but have lots to learn. Advice here is most appreciated to nudge me in the right direction.*

  • #2
    If your willing to part* ways with the AM tuner and be BT only, there are lots of solutions.* Let us know.


    • #3
      That woofer seems ok in that box (0.10cf w/'a 1"id x 5" long port - EA. side).
      The XO is prob. not doing that project any favors, and those tweeters may not be either.


      • #4
        One issue is you may need two drivers to get the entire stereo signal from a BT source.* Any time you use only one channel, you may lose significant content that the other channel is providing. This will occur if you use an integrated BT receiver amp module. If you use a BT receiver and a separate amp, you can "sum" the stereo signal into one amp channel using a simple two-resistor network.

        Some BT sources may have a mono setting but I think that's getting rare and would be limiting.

        You'll also need to shore up the Philco's box as most all of the TT small speaker designs require an airtight box for both sealed or ported designs.*

        Some gents here may have driver* suggestions that will work in the Philco's box without sealing it (not my expertise).


        • #6
          Originally posted by drumminhands View Post
          Good call on separating Bluetooth out of the amp and sum stereo to mono. Ive done that before no problem. How about this amp?*

          And if that tweeter isnt the best, what about this?*
          I wouldn't worry about the electronics at this point. I can point you to an integrated BT amp that will have more power than you need in half the size of a cigarette box. As an example:

          Click image for larger version  Name:	BT TPA3116.png Views:	2 Size:	565.8 KB ID:	1377895

          These older radios had open (e.g. non-sealed) enclosures and their speakers (drivers) were designed to be used that way. The current drivers (designs such as you reference in your initial post) most all require a sealed box - with or without a port. And the size of the box dictates which drivers will perform well in it. As I look at the bare enclosure the thoughts that come to mind are:

          (1) Total internal volume to work with (half of that for each side of a stereo implementation).
          (2) How to seal up the back to create an air tight box - likely ported.
          (3) Ideally, the box separated into two sealed sides separating the L and R stereo channels (ideally, not a hard requirement here)
          (4) Removing the original speaker mount behind the grill and creating a new one for the selected drivers (while maintaining the box's airtight seal).

          I really have no feel for the size of this unit. But two (L & R stereo) full range drivers might make the most sense here given you likely want to keep the front's original look by mounting them behind the grill. Frankly, I wouldn't go this route. I'd restore it as original. The front layout is very limiting for a stereo design with hi fidelity.

          Click image for larger version  Name:	Philco.png Views:	2 Size:	570.9 KB ID:	1377894
          Attached Files


          • #7
            OK. I'll rig something to close the box air tight. And I'll go mono.

            But what do you think about these parts?

            Dayton Audio DC28F-8 1-1/8" Silk Dome Tweeter
            Part # 275-070

            Dayton Audio DS115-8 4" Designer Series Woofer Speaker
            Part # 295-424

            Dayton Audio XO2W-2K 2-Way Speaker Crossover 2,000 Hz
            Part # 260-140

            Sure Electronics AA-AB32178 2x50W 4 Ohm Class D Audio Amplifier Board - TPA3116
            Part # 320-3342

            15 VDC 4A AC Adapter Power Supply with 2.1 x 5.5mm Plug Center Positive (+)
            Part # 120-057


            • #8
              Buying a small speaker kit such as the Overnite Sensation would give you better sound than the components you listed. Or, a Dayton ND90 all by itself.


              • #9
                You'll also find that this is the Project Gallery, meant and geared toward finished projects. If you have questions, you'll fare better over in the TechTalk section of the forum.
                "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
                "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
                "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
                "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

                *InDIYana event website*

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                • #10
                  Originally posted by djg View Post
                  Buying a small speaker kit such as the Overnite Sensation would give you better sound than the components you listed. Or, a Dayton ND90 all by itself.
                  +1. There are many, well regarded small speaker designs will sound much better than a pre-built XO (we can help you through building an XO from parts if that's an issue).

                  How big is the box? The first step to a good sounding low end is to determine the volume you have to work with.

                  The "Heliums" and the "Lithiums" come to mind.