Tedious fault finding…

I tried “re-wiring” the outputs on the FreeDSP classic board, the board that worked well but for the total silence in the left channel mids/highs (passively x-overed).

The output I thought might be bad works now, but I still don’t get sound from the B&G Neo 8 that I use for HF.

I think Maybelline the old PIO’s in the x-over has passed their prime. I have some MKP’s on a way to replace them.

On top of that the amp driving the woofers had blown its main fuse. Mains are 230VAC here and the fuse was 1.6A slow blow. Granted, I don’t have any softstart in that amp, yet. I’m not sure if I should use a higher value fuse? 300VA toroid, each channel of the amp has two tda7293’s.

Going for a walk with the fiance and my daughter now, more to come.


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Main system…

…I got the idea to get the main system up and running today, sort of a test run with the FreeDSP classic.

I hooked up the DSP with analog in and used the internal D/A-converters. To power the woofers I used the modular TDA7293 amp(2 TDA7293/channel), for the passively x-overed mids/highs I used my Arcam Alpha 8 power amp. I used my AD797 & BUF634 headamp (with XMOS USB and ES9023 DAC)as a preamp, the source was a raspberry pi 3 running OSMC.

First I was very happy that I got sound, no noise or hum, but then I noticed that the left mids/highs was quiet. After ruling out all other possibilities, I determined that it was the FreeDSP classic that was the culprit, why it doesn’t work on that output is something I’ll have to look at another day. It is not a big deal as long as I can get it to work with two ES9023 boards via IĀ²S.

I have issues letting a problem be and revisit it another day. So…I kept at it longer than I should have considering I’m still recovering from the neck surgery.

Anyway, I finally dropped it, went for a walk, and now I’m resting.


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“main stereo system” slowly getting there

I’m slowly getting to the point where I can test the main system with the FreeDSP, new DAC (s) and two new amps.

For now the BCL clone, I guess it’ll be mkIII, will be acting as a preamp. It’s got very nice parts and closely matched transistors (I believe it took me something like 200pairs BC550C/560C to get the matches I wanted. Slightly less for the BD139/140’s. I figured that if it drives my Philips Fidelio X2’s with authority, it’ll drive the FreeDSP classic with ease.

The BCL clone is the one with a wooden front, if the HP-jack isn’t clue enough šŸ˜‰

The one on it’s right is the FreeDSP classic with power supply. I will fit an audio-widget board and two es9023 DAC’s in there as well, along with a TPS7A4700 for the +5Vdc for those.

The larger enclosure is housing a 2xTDA7293/channel amp with spkr-protection and a 300VA 2*24VAC toroidal transformer and 4* 10000uF/63V capacitors.

On the floor in front is an Arcam Alpha 8P that may or may not retire as the amp driving the mids/highs of my dipole speakers.

I still have the TDA7293(one per channel) with 2SC5200/2SA1943 to complete and test. If it is as good as stated on diyaudio amongst other places, it’ll probably end up driving the Dayton 15″ IB’s in H-baffles that takes care of the LF in the dipole speakers.


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DIY USB audio cable

I decided to make my own USB audio cable. The parts I used are:

Aucharm 4 lead shielded cable

5u Gold plated connectors

Parts(minus heatshrink and sleeve

Finished cable

As I had less sleeving of the correct dimension then I thought, I had to use more heatshrink.

I think this cable will be an OK USB audio cable, to my surprise the vbus and gnd leads were shielded from the signal leads… shielded within the shielded cable you could say.


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The weather is amazing

But I did manage to do some DIY, I drilled and tapped holes for the TDA7293, 2SC5200 & 2SA1943.

So, the heatsinks are done. Waiting for another fan, fan-grilles and some mounting hardware. 

Short post today, the sun is calling šŸ™‚


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LM317 compatible TPS7A4700 regulator

I got the boards from oshpark today.

They look quite nice, I only have bad cellphone pics…but here they are.


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LM337 alternative using TPS7A3301

I threw this layout together quickly, maybe too quickly, as it needs to be mounted with the back of the PCB facing “forward” to match the pinout of the LM337.

No big deal though, not for me anyway.

GND pin is adjust pin on the LM337.

I’ve got 3 of these and 3 of the positive version on the way from Oshpark.


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