PRR

Re: DIY amplifier
« Reply #20 on: January 01, 2019, 04:22:17 PM »
> why I'm skeptical.

You are missing the obvious. If heat is about 1/3rd, it is rational for size to be 1/3rd.


Re: DIY amplifier
« Reply #21 on: January 01, 2019, 04:40:00 PM »
Anyway, here's another build pic after drilling a few holes etc.



EDIT : sorry for the blurry pic.. you can see bits of the system in the background. So far apart from the drivers and the amp power supply it's all custom made. I'm mildly excited to hear what the complete system will sound like, if I ever get it done that is.. I need to do some testing, preferrably A/B to decide whether the amps are worth building and tidy up/rework the build, then finish the case with controls, LEDs and coating etc.. no way in hell I'm lugging around a wooden office desk drawer.

EDIT 2 : added a power LED.. it's starting to look like an amplifier
« Last Edit: January 01, 2019, 07:17:35 PM by efinque »

Re: DIY amplifier
« Reply #22 on: January 01, 2019, 10:49:32 PM »
Coated the case with an oil-based primer.. I'll upload a pic later.

Re: DIY amplifier
« Reply #23 on: January 02, 2019, 01:49:27 PM »
Here's a pic of the case with 2 layers of coating applied..


iampoor1

Re: DIY amplifier
« Reply #24 on: January 02, 2019, 02:19:33 PM »
I would just buy some off the shelf amp modules and call it a day, heck, you could probably buy some good class d power amps new for even less.

Power amps can be quite sensitive to layout and construction techniques, and often fail catastrophically.  ;D

Re: DIY amplifier
« Reply #25 on: January 02, 2019, 02:56:47 PM »
I would just buy some off the shelf amp modules and call it a day, heck, you could probably buy some good class d power amps new for even less.

Yes, I was thinking about that.

But at least I know how to service it if it fails.

EDIT : of course, the PSU is tricky because like I said it's from an old cassette deck.. but I was thinking something like a 100-200VA 2x24V transformer into a full-wave rectifier. I saw Epcos caps rated at 10000uF for sale in an electronics store; the things were proper, about the size of a soda can. Probably good as a reservoir capacitor (although even now it takes like 3 seconds for the LED to turn off after turning off the device)
« Last Edit: January 02, 2019, 03:53:15 PM by efinque »

JohnRoberts

Re: DIY amplifier
« Reply #26 on: January 02, 2019, 03:05:58 PM »
Or even better, buy the amps themselves.. less trouble that way.

But at least I know how to service it if it fails.
My Hypex (classD) amp modules are on order, so I'll share how that turns out ... Even with today's cheap amp prices I can not imagine

4x70W for  65 Euro, and 2x30W for 50 Euros. Of course + shipping etc...

If you google "bang for the buck", a picture of these amps come up.  8)

JR
Visit https://circularscience.com to hear what properly "cleared" drums sound like.

Re: DIY amplifier
« Reply #27 on: January 03, 2019, 12:05:43 PM »
How about a speaker protection relay in the output? Or is it better to be done in the speaker itself?

EDIT : or a thermal fuse/relay for the transistor circuit..
« Last Edit: January 04, 2019, 11:25:06 AM by efinque »

JohnRoberts

Re: DIY amplifier
« Reply #28 on: January 03, 2019, 01:12:32 PM »
How about a speaker protection relay in the output? Or is it better to be done in the speaker itself?
Both options are available.

What Peavey did that was cost effective was a thyristor crowbar clamp on the output.

JR
Quote
EDIT : or a thermal fuse/relay for the transistor circuit..
Visit https://circularscience.com to hear what properly "cleared" drums sound like.

Re: DIY amplifier
« Reply #29 on: January 05, 2019, 04:19:09 PM »
Oh, I have a broken 250W Martin T-Rex scanner light that has a huge toroid in it (I always wondered why they weight so much).. the front motor is busted as well as the mirror and I'm too lazy to fix it. Overall it has some traces of wear and tear so I was thinking of using it in an amplifier build.

Is this generally speaking something that should be avoided as I remember reading that LED drivers and such should be avoided in audio?
« Last Edit: January 05, 2019, 04:26:18 PM by efinque »


JohnRoberts

Re: DIY amplifier
« Reply #30 on: May 16, 2019, 11:29:20 AM »
It has been a while since I started this DIY surround sound project... I purchased a broken a/v receiver mainly for the speaker jacks. The 4x60W hypex and 2x30W (for surround channels) hypex modules look lonely inside the gutted spacious chassis.

I found a cheap digital 5.1 decoder ($27) with master volume control for front end.

I was very deliberate and slow (measure twice cut once) and guessed correctly about the few things that weren't clearly called out. This has worked perfectly since I first powered it up and is a noticeable sound improvement.

Perhaps expectation bias but if anything it sounds cleaner than my old stereo AB amps.

JR
Visit https://circularscience.com to hear what properly "cleared" drums sound like.

Rob Flinn

Re: DIY amplifier
« Reply #31 on: May 16, 2019, 05:06:26 PM »
Glad you like them John.  The hypex amps are great.
regards Rob


 

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