DCAudioDIY.com

Good morning all.

Has been forever since I have done anything audio forever. Apologies for the extended absence. Life has gotten the way of any hobbies for quite a while but trying to get back into some things.

The project: Installing modern components in an old Philco Radio Chassis

I want to get decent sound, ability to listen to the radio with external antenna for better reception, bluetooth would be great but I would be fine if just a 3.5 Aux in.

The tall ask. The current radio has one knob in the middle of the front, and 3 below. I can plug those if I have to, but curious if there is any way to reuse those knobs. Would really like this to maintain its appearance.

The why: I have wanted to do this for a very long time. My father passed last week, and being the antique dealer he was for years, he found a case in great shape. Need to do this

Electronics are not my thing. I built a preamp years ago thanks to this forum, which was comandeered by a family member for his turntable setup. I can solder and follow directions. Just would not know what I was actually doing. For that reason I am hesitant to use a tube amp, as not understanding what is happening and that seemed dangerous

Pictures would be helpful.

Goals? FM radio & Bluetooth only? Any other desires?

Stuart

Apologies for not providing more details of goals etc.

The hopes would be a FM tuner with possibility of an external antenna for good reception.

Enough power to drive the sprite design by Paul Carmody which I think would work well for this. https://sites.google.com/site/undefinit ... ers/sprite

3.5 mm input

Bluetooth input

Really want something where I can resuse the knobs somehow so the outside appearance is as if nothing has been done.

I am not opposed to a tube amp, but I know even less about those than I do the inner workings of a class D plus I thought going the tube route would be very expensive.

I believe the challenge is finding a way of being able to deal with FM/AM tuning, volume control, source selection and display in the digital age. From what I see, avaialble tuner modules are almost entirely digital, controlled via toggle switches and/or buttons, or if analog, use on-board pots/variable capacitors that would not align with the knob positions on the radio case. Many tuner modules come with a remote control, but you need to have a display to see tuning info and volume, otherwise you cannot see what you are doing. You would need to modify/alter the radio case to accommodate a digital display. This may involve desoldering the display from the digital FM module, install on a new board and use a ribbon jumper cable back to the FM tuner board to the removed display connections. That would be alot of delicate soldering work. You would also need to provide an IR sensor at the front of the case for the remote control. As far as an amplifier, you can use an inexpensive Class D amp to drive the speaker you select to match the mounting interface in the radio case. This is actually the easy part, except of course for volume control if the tuner module control is inadequate.

This is quite a project that will require some research, improvisation, and technical ability. You need to solve the interface issues with the specific parts you are considering using.

David

Very much appreciate the thoughtful response. I found the label inside which states it was a Philco Model 60 chassis.

Perhaps I am thinking about this the wrong way? Would it make more sense to find a rebuilt model 60 chassis, and add a bluetooth connection to it? Know they are not cheap but assuming I can find one properly working- it of course will fit the openings etc. If needbe I could mount it in an inconspicuous place so to not mess up the original appearance?

I do not know enough about what is available concerning a restored Philco Model 60 chassis + speaker. There are several versions of the radio over the years, so it may not even fit. The speakers on old radios are often high impedance, and sometimes use a electromagnet instead of a permanent magnet, the winding of which acts as an inductor in the power supply for the radio, so you need both. So to be sure, you need to know what the Model 60 uses and you may the best bet is a complete restored radio and just move the innards over to your existing radio cabinet (if it fits, of course). Also keep in mind that none of the tubes in the 5 tube radio are in production, or even available NOS, so you have to ensure you have strong used tubes (need a tester, or have someone test them). Also, they are not up to the same safety standards (after all, we are talking radios from the 1930's), so that can be a concern. Trying to add an external source (Bluetooth audio module) means finding the place on the circuit to put in a selector switch to switch between the two sources (AM radio + Bluetooth).

If all you are doing is adding a Bluetooth audio interface feeding into an new solid state amplifier (no tuner), you control the "radio" via the smartphone (as the audio source). Forget any controls aside from a power switch (maybe a volume pot on the radio itself). Since the radio cabinet is an open baffle, you might want to a speaker install a driver designed for that purpose rather than one designed for an enclosure. The Carmody design appears to rely on an enclosure based on my quick glance. This would be the easiest path, in my mind, you can likely find an amp with Bluetooth interface pretty easily on Amazon, Parts Express, etc.

David

My suggestion, for what it's worth, is to install a speaker in the enclosure that fits. A decent wide band driver can be found at Parts Express for a very reasonable price.

Run a speaker wire out of the back and connect it to a radio capable of driving it. I'm thinking a nice table radio that you can sit off to the side, even in another room.

I'd go with a Tivoli Model One BT. Check out the selection: https://tivoliaudio.com/collections/radios

Now here is the tricky part; will the radio drive your new speaker? It's doubtlessly low wattage so a high efficiency driver is needed. Look for over 90dB/W.

If the radio output is too weak, a small, very inexpensive amp can be added inside the Philco chassis. Padding the output of the Tivoli with a divider, leaving the Tivoli speaker in place will allow a low level signal for your "booster" amp.

Of course, when you open the Tivoli chassis and connect an external speaker cable, your warranty is up in smoke. Just be aware.

A couple of ideas:
Under $50 for the amp and power supply: https://www.parts-express.com/TDA7492-D ... quantity=1

If it is an 8" speaker: high efficiency for use with the Tivoli amp: https://www.parts-express.com/GRS-8FR-8 ... quantity=1

Breakup over 3kHz or so, almost 90dB/Watt. Depending on how loud you want to play (how big is the room?), this could do the trick.

For a little more money (you didn't mention budget), this Visaton driver looks great. 92dB/W and much smoother HF response. https://www.parts-express.com/Visaton-B ... quantity=1

Keep in mind, asking any 8" driver to cover the full range will result in a whole lot of beaming. That is, high frequency response will be very different off of center axis of the speaker. Unless you go coaxial, this would be my choice.

Lower efficiency for the Parts Express amp: https://www.parts-express.com/Goldwood- ... quantity=1

There is a lot of cone breakup over 2kHz, so don't expect sonic perfection.

Just a thought!

Stuart

Thanks Stuart. I had not factored much into a budget, as I foolishly was thinking I could build the sprites inside the case essentially and make some new openings in the front and use some leftover antique style speaker cloth I have from a long ago project. Figured the mini receiver essentially would not be much money. Problem for me- is while I have built 7-8 sets of speakers, I would be lying if I said I understood what I made. I know I love music and think my speakers sound amazing, but from the science aspect of it all, I am very ignorant. Listening area, this was going to sit on a table in the dining room, which is open to the kitchen. About 30x12 area or so. I wish I understood the terms you go into detail about. Break up, beaming etc I am unfamiliar with. Embarassing I know.

I remember going to CAF over a decade ago and listened to 105K dollar speakers and being in awe of how badly they sounded, whilst I listened to Salk's Magico's and was in absolute wonder how amazing they sounded. Why the differences? No idea lol. Got to meet Dennis Murphy that day though so that was pretty amazing as he was very active on TT in those days.

At the end of the day, I feel I need to be honest with myself as far as what I understand and know, and while this radio case has sentimental value, my Dad put a wireless Bose speaker in it and loved it. I think perhaps I am overcomplicated this all.


Of course as I am searching for options I found this just released by PE. Wondering if I just get this kit I can retrofit it in the existing case I have. Don't have a 3D printer anyway and would not be interested in a plastic case. https://www.parts-express.com/Antique-S ... quantity=1

Not exactly what I wanted to do, but at the end of the day the project I had in mind was substantially beyond my capabilities I think

Dave Berning may have interest in this project. Right up his alley! ( Sorry Dave)

Thanks, Jim!

Actually I was going to add my two cents. If you are going to make a package with an FM tuner that uses an antenna, you will need to be very careful with shielding and layout of any digital circuits. And I would not recommend a class D amp as it will wipe out the FM unless extraordinary measures in shielding are implemented. A simple transistor class AB or B amp would work. These can be had in IC versions or a discrete component circuit board. The Wi-Fi is tricky due to the interference problem. As a takeoff on Stuart's suggestion, you could put the amplifier and the speaker in the radio housing and have the FM tuner feed at line level.

Now here's a hoot. Obtain a restored Philco 60 chassis with speaker, which will be AM. Then get an FM tuner and feed through an FM to AM converter module. They used to sell these for AM radios in cars. Don't know if there are any new ones but probably used ones can be had on E-Bay. If you can't find a restored Philco, I might be able to help you restore it if you lived nearby. The tubes are not in production, but they can be had. In my experience the tubes it would come with are often serviceable, unless someone has stripped it. An unrestored radio like this would need to have the capacitors replaced before attempting to power it up. I don't know if the model 60 has a power transformer. Most radios this old do, but if it didn't you could still use the converter module safely. This approach would give you true vintage sound to go along with the vintage looks.