TonyD'Amore Posted January 17, 2016 Author Report Share Posted January 17, 2016 It sounds amazing! Probably spent the next month just listening to it at work all day every day. It def needs a sexier front panel though, and thicker. We went with 1/4" aluminum, CNC'd on both sides, recessed areas for the meter PCBs and glass to sit in as well as beveled meter openings and our brand name carved into it. Now I send all the CAD files to the machine shop and wait. I also designed a top cover and bottom cover to match. 1/4 aluminum While waiting I ordered up some copper mesh to put over the slots to keep large things out of the amplifier and give it a unique look. As it turns out the copper mesh somehow reduced the little distortion and noise that was left even more! Not going to argue with my test equipment, I'll take it! It still gets used daily and occasionally I'll measure the temp of it. It's always between 130F - 150F depending how long it has been on and the ambient temp of my lab. Since it is Class A, it doesn't matter if it idles or being pushed hard, the temp remains nearly the same. It actually seems to cool off a little as I beat on it! Now, it would be cool if I could get this kind of sound quality in my car...... 3 Quote Link to comment Share on other sites More sharing options...
TonyD'Amore Posted January 17, 2016 Author Report Share Posted January 17, 2016 (edited) Now that we know we have a stable amplifier design, we could change the power supply from the AC/DC supply to a DC/DC supply that can run from 12V and convert to 100-120VDC. The home amp runs at 180VDC, but it is designed to run at 8, 4 and 2 ohms. I want the mobile amp to run at 4, 2 and 1 ohm so we need less voltage to make the same power. We also need a mechanical concept. All we knew at this time is that we wanted it to be a TRUE dual mono. This means 2 amplifiers, each with their own power supplies. I'm also a fan of symmetry, I may be a bit OCD. I like to use foam core paper and foam blocks from Michael's. Hmm... I like it. But can I make a PCB that works with the design? There are many voltages on the PCB that require lots of copper to carry the current. B+, GROUND, +60V, -60V, speaker output, AC output from transformer, rectified output to the power supply secondary caps to name a few. Hmm, I'll have to give it more thought later. Let's design the new input stage and voltage amplifier. This amplifier needs a gain control which the home amp didn't have. I also wanted to be able to switch it into class A/B mode for those times when I'm not critically listening and those times when int 120 deg outside in PHX. Also want to add switchable unbalanced/balance input. After several weeks of design on the computer, I sent the files to my PCB house and we ordered up all the components. They both arrived in about a week and we started to build. Magic Juan does it again! This little board has the input section, gain section, and ALL of the voltage amplification for the amplifier output. The signal will leave this PCB already amplified to its maximum voltage. The main PCB is just power supply and current amplifier. This will ensure the signal stays reallllly clean! Let's test it! If it's as badass as I think it will be it will be able to amplify a signal as fast as 100kHz without distorting it....and it DID!! Let's see a Class D amp do that! Edited January 17, 2016 by TonyD'Amore 3 Quote Link to comment Share on other sites More sharing options...
meade916 Posted January 17, 2016 Report Share Posted January 17, 2016 loving the pics!! Keep em coming!! 2 Quote All SMD products + MORE available at my store here! https://wccaraudio.com/ Subscribe to My Youtube Channel! Over 1,000,000 subscribers strong! Turn on your notifications! http://www.youtube.com/meade916 Follow My Instagram! Daily live feeds from the shop, exclusive content way before it hits my Youtube channel...and little squares with photo's in them http://www.instagram.com/meade916 The Official SMD Facebook fan Page https://www.facebook.com/SteveMeadeDesigns/ Follow my Tweet (Twitter) http://www.Twitter.com/meade916 Link to comment Share on other sites More sharing options...
BerT6801 Posted January 17, 2016 Report Share Posted January 17, 2016 Thats the Real Deal right there, I had always wondered if you designed these things or they were outsourced. My hats off to you sir. "on another level" really doesn't even say the reach of your scope or time involved. Cudos 2 Quote Link to comment Share on other sites More sharing options...
TonyD'Amore Posted January 17, 2016 Author Report Share Posted January 17, 2016 (edited) The machine shop usually takes about a month after I give them my CAD files so I better get to designing the heatsinks and baseplate because I'm not going to be able to test the amp with foam heatsinks! Two months and revisions later we have some aluminum! 17 pounds of it for 1 amplifier! Ok back to the power supply and current amplifier PCB design. As it turned out, I needed to use a 4 layer PCB. Like 4 circuit boards in 1, literally in layers sandwiched together. Typical PCBs in electronics have a copper thickness called 1/2 ounce. This means that for a square foot of PCB there is 1/2 ounce of copper in it to carry the current. In our design we are going to need a LOT more than that. 4x that actually so we went with 2 ounce copper, 4 layers of it. Each color you see here is copper on a different layer of the PCB. Many, many late nights later I am ready to send the files off to the PCB house and order all the components to build one. Now that this PCB is done, I get to do it all over again for the right hand PCB. No there is no magic button I can press to tell my software to do the opposite of the whole board for the other side. If you try that it will reverse all of the "footprints" for the components and when you build it every part will be in backwards and some of them can't go on the board any other way. Ask me how I know this.... $600 down the drain. Eventually I had to make the right hand board from scratch like the left hand one. Edited January 17, 2016 by TonyD'Amore 5 Quote Link to comment Share on other sites More sharing options...
TonyD'Amore Posted January 17, 2016 Author Report Share Posted January 17, 2016 Sir your on another level than us. You may be from another planet is what I am think. Tony You are the MAN. Yeah I'm a fan in a half of you. Thanks man, some people on here are on another level to me in their craft too. This is just what I do. 1 Quote Link to comment Share on other sites More sharing options...
TonyD'Amore Posted January 17, 2016 Author Report Share Posted January 17, 2016 (edited) The PCBs have arrived, I hope they fit the mechanicals! There is a little more gap between the PCB and heatsink than I wanted. This will work for testing though! Handed over to Magic Juan to do his thing. He built them up, tested, found a few problems and fixed them. Gave me a laundry list of changes for the next revision. That's how the ball bounces, the first revision is never perfect. There are just too many things to consider. That being said, you know Juan made it work! She's ALIVE! ALIVVVVEE! The original heatsinks were two pieces bolted together as you can see here. This was because we weren't sure what the top was going to need to be, but we had the big mass of aluminum on the bottom defined. Once we figured out what we needed we made it one piece. Edited January 17, 2016 by TonyD'Amore 2 Quote Link to comment Share on other sites More sharing options...
TonyD'Amore Posted January 17, 2016 Author Report Share Posted January 17, 2016 (edited) Now that we know the electricals are mostly sorted, lets check this heatsink design and see if we have enough dissipation capability. A fairly common industry test is full power sine wave into 2 ohms, and 40% power sine wave into 2 ohms. The first case stressing the power supply, the second case stressing the output section. Time to put that foam core board lid back on. I don't have photos to show, but we blew it up several times. The problem was we couldn't get the heat from the power devices (power supply MOSFETs and output section BJTs) into the heatsink fast enough. Between the power devices and the heatsink you need an electrical isolator because the mounting surface of the MOSFET or BJT is connected to the center leg of the device, which has various voltages on it that you wouldn't want on the heatsink. This would cause the amplifier to not work at all. The most basic of amplifier designs use kapton tape, it is a great electrical isolator, but a terrible conductor of heat. We didn't even try kapton because I wanted this thing to perform! The next level is various thin composite materials. One of these materials turned out to be good enough for the home amplifier and if you look at some of those pics you will see a thin grey pad under the devices. We wanted better than that because at low impedance we want to be reliable. If this topic interests you check out http://www.fujipoly.com/usa/ After weeks of testing different materials we settled on some stuff from this place that is tan in color and has a high thermal conductivity. http://www.aavid.com/products You can see it in the next series of photos. Edited January 17, 2016 by TonyD'Amore 5 Quote Link to comment Share on other sites More sharing options...
Mtnbikecrazy55 Posted January 17, 2016 Report Share Posted January 17, 2016 This is awesome, really appreciate the time you're spending to tell us the story, really really cool 1 Quote I hate long signatures.... ...what the fuck is wrong wiht you you fucking fuckity fuck fuck head... Mtnbikecrazy55 Feedback Link to comment Share on other sites More sharing options...
TonyD'Amore Posted January 17, 2016 Author Report Share Posted January 17, 2016 (edited) So it looks like the heatsink design is more than enough (even though we are not satisfied with the temperature delta between the power devices and the heatsinks yet). So at this point we called in a good friend who is a mechanical engineer to design the sheet metal top, front cover, top meter cover, and associated parts. I gave him the drawings that I had and in no time at all he sent this rendering and asked "like this?" He is the man, thanks Tom Sollars. We loved it and asked him to continue and order up some of these parts when done. A few weeks later we had these Edited January 17, 2016 by TonyD'Amore 4 Quote Link to comment Share on other sites More sharing options...
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