DIY Audio....or how many solder burns have you had?

[Puffin]

I am a keen DIYer and have been for many years. Over that time the resources available to the Audio Diyer have exploded. However it seems that the numbers getting their hands dirty are much less than say 30 years ago?

Mind you the main cost now in making an amplifier with a linear power supply is the transformer given the cost of copper. Most Class D amps will run perfectly well with a switch mode PS as these have come on greatly in the past few years and prices are quite keen from some sources. Even Nelson Pass advocates the use of SMPSs with some of his Class A amps.

Some may say that they want something to look like a commercial offering rather than a bag of spanners. This is achievable if you have some imagination and utilise things that aren't specifically made to house electrical components. If you have your kit in a dedicated room then this maybe not so important.

What would put you off putting an amp or other audio equipment together?

[walpurgis]

I'm always tinkering with something. Doesn't necessarily have to be Hi-Fi though, but I do have another passive pre-amp to assemble and a Class D amp and speakers, if I ever get around to any of it all .

As for solder burns, I've had a few. More likely to end up bleeding than burnt though, I get a nick or gouge a couple of times a week .

[Puffin]

I was at minor injuries about 4 weeks ago after a "stanley knife incident" I was convinced my left hand was nowhere near where I was about to cut....well in fact I was trying to get an old paint run out of some fancy architrave prior to painting. Scored down and whoomp! I thought I had taken the top off my L hand index finger. Finger immediately went numb, hurt like hell but bleeding was not what I was expecting.

Had it cleaned and steristripped and was told that any numb areas are unlikely to get any sensation back Still it is only a very small part of the top of the finger between the tip and the first joint. I had said to myself in the past after cutting myself that if I were using such a knife I would wear one of the thick leather gloves like they used to sell in Poundland. Hmmm.... its seems like I am only thick element in these accidents.

Which chips are in the Class D amps? I have 2 TPA3116 amps and 2 IRS2092s one is dual mono and the other an integrated....oh yea and recently a Sure/Wondom TPA3255 said to do 300w into 4 :Ohms yea... I didn't have to put it together. It was very expensive though...£23.00 from Aliexpress.

https://www.aliexpress.com/item/1005...40b9f19cknJ0ad

They vary in price every day.

[walpurgis]

Which chips are in the Class D amps?

It's another TPA3116. Semi integrated, V/C & rotary switched input selector, but a beefy and very quiet external SMPS in separate box.

[struth]

when i worked in the trade i got burnt often whats worse tho you oft got little...and BIG shocks too.... wish i had a quid for every one.. mains was worst but a discharge from a crt hurts too..often flung you across the room

[Macca]

last used a soldering iron in 1995. Got burnt by it a few times but that's the game isn't it? Like if you have a motorbike you're going to come off it sometimes.

Only been electrocuted once unless you count pushing each other into those electric fences you get on top of stone walls in the countryside to keep the sheeps in. And not done that since school. Mind you never built electronics only speakers. And someone more capable always made the cabs for me.

[Barry]

Built a few amplifiers in my youth, both valve and solid state, because I could not afford manufacture built ones.

Nowadays, I only make up cables and in fact made up a pair only a week ago. Had very few burns or shocks. The only 'accident' I had was in wiring an electrolytic capacitor the wrong way around by mistake - that made an impressive bang with steam shooting out from one end, leaving a big fluffy mess!

[Barry]

Recently made a pair of XLR terminated cables to connect between my TEAC DAC and the preamp:



I did this for a number of reasons:

[1] The available space behind the DAC was limited

[2] The cable length is chosen to be as short as necessary, for the sake of neat and tidy cable dressing

[3] I have complete control of the neatness and quality of the soldering and assembly. Commercial ready-made cables are often very poorly made.


If you look carefully, you will see the cable entry to the right-angle XLR connectors is at 45 degree to the orientation of the pins. This is because the space behind the DAC is extremely limited, so I needed to use connectors where the cable gland can be orientated in any one of 8 ways.

Here are the connectors fitted in situ, showing the very limited space available:

[Puffin]

Nice job.

[Puffin]

I built a dual mono IRS 2092 Class D amp a few years ago which sounded fine but as I was building quite a few Class D amps at the time it got pushed to one side. I recently plundered some of the power supply for another project. A bigger PS did not make for a better sounding amp and so I put the 2092 PS back together.

Switched the amp on and one channel was oscillating ....bum. The 2092 requires a split rail supply and I had only taken bits to make a single rail supply. As I was poking around the reference 0v lead which should have been securely soldered to the capacitor bank popped off. Soldered it back and the bad board is now fine. Quite why one board oscillated and the other didn't I have no idea, but it was good that I didn't have a duff board to replace.

The amp boards are tweakable. There is a small pot for adjustment of the PWM switching frequency which really needs a oscilloscope for accuracy. However some on DIYaudio helpfully added that the higher the switching frequency the hotter the amp will run. Experimenting can get you to the sweet spot and it there is now quite a marked improvement in SQ. The amps had been running really cool as most Class D's do, but now they are pretty warm as is suggested would happen. Some kind of Class A electrickery?