Process for Building a 10 Channel Amplifier - Assembly Details Part 3

To recap what's going on here, this amp has active crossovers that drive my 4-way active speakers. So for each speaker driver in the 4-way, there's an amp board and a crossover board. I designed the crossovers based on the setting I arrived at with my miniDSP setup - the DSP setup is what I was using before I made this new amp. DSP is digital and adjustable, while this new amp and crossovers are analog and fixed. I can only change the output level on each channel, not the crossover slopes or frequencies.
Getting all of the amp boards mounted on the heatsinks and wired to the power supplies and output banana jacks took the better part of a full day. A big part of that time was me testing each board before installing it to make sure they are working correctly.
Then more metal fab, I used some scrap aluminum extrusion to make the two decks that the crossover boards will sit on. I had a genius idea to bend tabs down to support the ends of the amp boards, but that failed when the tabs broke off. Worth a try, but I wish I'd tried on a scrap of the same aluminum before cutting the shelf. Then I had to cut the other shelf in the same way so it wouldn't look odd!
And yes, I tried annealing the aluminum with a torch to make it softer - it didn't work.
With the first crossover board hooked up I can turn it on and see how much of a turn-on thump it creates. Not too bad, but I can eliminate it altogether by muting the inputs to the amp boards until the power supply for the crossovers stabilizes. Worked great and it only added one more full day to the build time!
Thanks again to Rod Elliott's ESP website for a suitable muting circuit to use:
sound-au.com/ar...
The output of each crossover board stays disconnected from the amp boards for about two second after you switch the amp on, then the relays close and connect them. I used relays because I have a bunch of them that I got for next to nothing several years ago.
When you switch the amp off, the muting circuit detects the loss of AC voltage from the transformer and immediately turns the relays off, disconnecting them from the amps. That eliminates the sound that the crossover boards make as the power supply discharges.
With the crossover installed and the metal front panel screwed in place, I moved the amp down to my listening room to setup and use. It's not finished, but it's finished enough to use (or so I thought...) and I need to take a break from the project to do other things.
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[@IBuildIt]

To recap what's going on here, this amp has active crossovers that drive my 4-way active speakers. So for each speaker driver in the 4-way, there's an amp board and a crossover board. I designed the crossovers based on the setting I arrived at with my miniDSP setup - the DSP setup is what I was using before I made this new amp. DSP is digital and adjustable, while this new amp and crossovers are analog and fixed. I can only change the output level on each channel, not the crossover slopes or frequencies. Getting all of the amp boards mounted on the heatsinks and wired to the power supplies and output banana jacks took the better part of a full day. A big part of that time was me testing each board before installing it to make sure they are working correctly. Then more metal fab, I used some scrap aluminum extrusion to make the two decks that the crossover boards will sit on. I had a genius idea to bend tabs down to support the ends of the amp boards, but that failed when the tabs broke off. Worth a try, but I wish I'd tried on a scrap of the same aluminum before cutting the shelf. Then I had to cut the other shelf in the same way so it wouldn't look odd! And yes, I tried annealing the aluminum with a torch to make it softer - it didn't work. With the first crossover board hooked up I can turn it on and see how much of a turn-on thump it creates. Not too bad, but I can eliminate it altogether by muting the inputs to the amp boards until the power supply for the crossovers stabilizes. Worked great and it only added one more full day to the build time! Thanks again to Rod Elliott's ESP website for a suitable muting circuit to use: sound-au.com/articles/muting.html The output of each crossover board stays disconnected from the amp boards for about two second after you switch the amp on, then the relays close and connect them. I used relays because I have a bunch of them that I got for next to nothing several years ago. When you switch the amp off, the muting circuit detects the loss of AC voltage from the transformer and immediately turns the relays off, disconnecting them from the amps. That eliminates the sound that the crossover boards make as the power supply discharges. With the crossover installed and the metal front panel screwed in place, I moved the amp down to my listening room to setup and use. It's not finished, but it's finished enough to use (or so I thought...) and I need to take a break from the project to do other things.

[@GregsGarage]

I am so darn impressed with the level of detail John. This is a TOP SHELF project all the way.

[@IBuildIt]

Thanks Greg :)

[@paulhirst3548]

This is wonderful and I find it very relaxing. It is nice to see such attention to detail!

[@AquaPeet]

Aweseome work John! And I loved the drum hits on the curse word... so hilarious I had to repeat it multiple times.

[@k-sell4065]

I’m just mind blown wow😮thank you so much! Now I know what I need to do

[@sc0or]

6:36 I like that the most. this is why it's always interesting to watch your vids, sir, because (like that heat sink made of angled aluminum) there are big chances that you unveil some brilliant engineering idea.

[@atheron1776]

When looking at audio gear: it always seems the more expensive and higher-end products have fewer buttons, switches, vu-meters, etc. This is one heck of an amp, it's got exactly one switch and nothing else (because that's all it needs).

[@k-sell4065]

Awesome build 😮👊🏾

[@dimalebedev3193]

Hello, thank you for the very interesting videos and for the work that you do. Please tell me what power each amplifier is at 8 ohms. Could you please provide the schematic and PCB of your analog crossovers, is there a link where I can learn more about them? Thank you.

[@FOH3663]

Noticed the input tubing shields in a previous vid, not sure if I've ever seen that practice before. This one was particularly enjoyable to watch. Looking forward to further updates. fwiw, in scenarios where compressed air etc., is less desirable ... a tape "moat" can be quickly placed to catch debris. Even with catching the debris, compressed air is still prudent. I believe some QSC amps have internals oriented upside-down ... so as much dust/debris over time doesn't settle on the boards. Especially good for live work and liquids!

[@IBuildIt]

Thanks! This is the last build update on the amp. Eventually when I get back to it and finish it, I'll make a full build video to post on my main channel. That'll recap the stuff in these videos, plus details on the finishing touches. Oh, I like the idea of mounting it all upside down. Certainly makes it easier to blow the dust out every few years.

[@sevestan]

Sober tweakin'....love it😇

[@user-fi6wi8gl8r]

Man you got my ass jealous as fucckkk 😂. Good work!!!

[@MrYosephL]

You need to calculate your bend allowance and K factor when bending aluminum.

[@karafarinperesentati]

John, would you help me here? I have 3 ICEpower modules with integrated power supplies. Two of them are identical, the other one is pore powerful for the base. I don't know if I have to connect them in series or in parallel. Obviously I want to use them in one enclosure for 3x2 channel Amp. Your help will much appreciated ! Thank you

[@pascalhibon7928]

While you added the relays, you could have gone for DC protection on the amps instead. That would get rid of plops when the amps switches on and off. And the added benefit is DC protection for your expensive speakers. I personally wouldn't trust an amp without DC protection. There are way too many situations when amps fail with a blown power transistor. That puts DC rail on your speaker terminals. Your power supply fuses are too slow to prevent speaker damage in such case. I like your design but I suggest you rethink that bit.

[@petertimp5416]

😊👍

[@TheLukemcdaniel]

Don't try this with a sawstop...

[@JasonsLabVideos]

Why not just use a SSR on the output..

[@IBuildIt]

Using the word "just" suggests that you think it's simple. The very best way to set this up would be to have relays (mechanical, not solid state) on each of the 10 (yes, 10, not 1) outputs that would delay turning on until the amps and crossovers stabilized. They would also have short circuit and DC protection along with that delayed turn on. But, unless you can buy those boards ready made with relays that are capable of switch 30amps of DC current, it becomes a part of the project that's almost as big as the project itself. And expensive as well. And space - they will consume a lot of the space inside a chassis that is already packed full of the stuff that's actually needed. Barring accidents that no protection could possibly prevent, amps like this that are well made and not messed with can last for decades without any of the faults the output protection is made to prevent. For you that might not be an acceptable risk, so when you make your own 10 channel amp you are free to include that extra protection. For me, I'm willing to take that extra risk to save time and money. Simple as that.

[@JasonsLabVideos]

@@IBuildIt I’m assuming you don’t know what a ssr is ?

[@IBuildIt]

Enlighten me.

[@JasonsLabVideos]

SSR = Solid Stat Relay, a mosfet. I did a video of a build. kzbin.info/www/bejne/haLCemeoi9JqfKM @@IBuildIt

[@IBuildIt]

Yes, I said mechanical, not solid state for a relay in my reply. That should have been enough to show that I knew what you meant by ssr. What did you think I meant? Do the math. 10 x cost plus space they take up for a "what if" situation. And is the mosfet operating in a perfectly linear way? Mechanical relays don't add distortion, and the greatest source of distortion in a power amp is from the output stage because the devices are conducting a lot of current. Adding something like that would be okay if you are more concerned about possible faults than you are about sound quality. And you've been a bit of a broken record on this topic, and it should be clear by now that I don't have any intention of adding anything like it to the amp, so maybe you should think of something else to talk about.