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  • smpcorp commented on Thiwe's instructable The budget suitcase boombox6 days ago
  • smpcorp commented on Thiwe's instructable The budget suitcase boombox1 week ago
    The budget suitcase boombox

    Love the concept! I did something like that many years ago by putting a factory AM/FM radio in a suitcase and used a 12V Gel-cell. The sound was very big! It was a great Ghetto Blaster in the parks.

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  • smpcorp commented on diggoryrush's instructable Retro-Mod - Bluetooth Speaker Madness1 week ago
    Retro-Mod - Bluetooth Speaker Madness

    That radio chassis was in excellent condition and totally restorable! If it was me I would have made the radio, or at least the amplifier section functional using the vacuum tubes in the audio amplifier section and simply added a bluetooth receiver to it. THAT would be cool.

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  • Make Your Own Simple & Cheap Portable Bluetooth Speaker

    One of the best bluetooth speaker designs I've seen. There are options of using higher buck boost supplies to bring the voltage higher and use a higher power stereo amplifier. The instructions are very simple and obvious for anyone with the most basic knowledge with electronics construction. The cheapest sources for parts are from Tayda.com and banggood.com.

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  • smpcorp commented on amackay's instructable Junkyard Radio to Table Radio4 weeks ago
    Junkyard Radio to Table Radio

    In response to your comment, I was never a mecp certified installer. However, I have been designing analog audio amplifier circuits since I graduated college as an analog electronics engineer, of which I am currently employed. ALL automotive factory head units have ONLY 13.8 volts as a supply voltage. There is NO switching supplies in factory systems to "UP" the voltage. Therefore designers use the lowest impedance the amplifier can handle to get the most power out of them with the given 13.8 volts. So... Yes, all factory amps are looking for a 2 ohm load to get the most out of them. They do this by pairing speakers and choosing the proper crossovers so as not to create too low an impedance wit the tweeters connected.Again, you CANNOT connect all outputs in parallel. Th...see more »In response to your comment, I was never a mecp certified installer. However, I have been designing analog audio amplifier circuits since I graduated college as an analog electronics engineer, of which I am currently employed. ALL automotive factory head units have ONLY 13.8 volts as a supply voltage. There is NO switching supplies in factory systems to "UP" the voltage. Therefore designers use the lowest impedance the amplifier can handle to get the most power out of them with the given 13.8 volts. So... Yes, all factory amps are looking for a 2 ohm load to get the most out of them. They do this by pairing speakers and choosing the proper crossovers so as not to create too low an impedance wit the tweeters connected.Again, you CANNOT connect all outputs in parallel. That is cardinal rule #1 in audio power amplifiers.

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  • smpcorp commented on amackay's instructable Junkyard Radio to Table Radio1 month ago
    Junkyard Radio to Table Radio

    I'd like to offer some constructive criticism:1. All of these car radios are stereo. Connecting just one speaker will have half of the music content missing. 2.Why does everybody need to make everything compact? Make the box bigger in width and put a speaker on each side. Bigger almost always sounds better. As well, car stereos want to see a 4 ohm load to get the maximum efficiency out of the amplifiers. Use a "pair" of 4 ohm speakers. Maybe upgrade to 5-1/4" ones! Be sure to allow enough space on each side to give enough clearance between the radio and the speaker magnets.

    The average factory car radio prior to the bluetooth days requires at least a 2A power supply. 4 amps would be better but they are pretty scarce. That .500 ma power supply is way too small to get any volume out of the radio without noticeable distortion. There are several wall warts around that will be able to provide that. A car battery charger will never work properly as they are usually only half wave rectified. There is really no filtering that you could to to completely silence the 60 Hz hum. Try to find an older wall wart that has a transformer (a heavy one) instead of a switching supply. Switching supplies usually put out a lot of interference that will greatly affect the radio sensitivity to pull in stations.

    Agreed that the world has gone to smaller and smaller with audio devices. The same occurred in the early 1960s when radios shrunk to tiny sizes compared to the1940s huge radios. They eventually grew into monstrous boom boxes in the 80s during the era where people appreciated "good" sound quality. We're back to small again.As far as joining the left and right channels to blend them into mono, the answer is no. You will get sound but it will sound pretty terrible. However, you "could" try using the + from one channel and the - of the other channel but you will have to be sure the balance control is set to center. Some amplifiers can tolerate that condition.

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  • smpcorp commented on r570sv's instructable Ammo Can BlueTooth Boom Box4 months ago
    Ammo Can BlueTooth Boom Box

    Love this project. One of the most practical ones I've seen here. The ammo box appears to be steel. Doesn't that act like a Faraday cage around the transciever and greatly reduce the range of the Bluetooth?

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  • smpcorp commented on r570sv's instructable Ammo Can BlueTooth Boom Box4 months ago
    Ammo Can BlueTooth Boom Box

    You are picking up AC line hum from the unfiltered battery charger. You can eliminate the hum by replacing the charging wall wart with a 13.5V 2A power supply. They are filtered and if you use a regulated power supply the battery will last up to 10x longer because you won't be over charging it.

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