DIY audio: what are you building?

[Misternavi]

Trying out a light attenuator with my Pass B1 Buffer. Been using a el cheapo resistor based attenuator that is scratchy so i thought i would give this a go.

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[mwhouston]

Well its a start.

[betocool]

That's one of the Jaycar enclosures, isn't it?

[mwhouston]

That's one of the Jaycar enclosures, isn't it?

That's right. I partially assemble them, mark out the back and front plate, drill, assemble the backplate then finish enclosure assembly. After doing a dozen or so of these I have come up with ways to make it easier and faster. Hoping today to mark and drill the back plate.

[betocool]

That's right. I partially assemble them, mark out the back and front plate, drill, assemble the backplate then finish enclosure assembly. After doing a dozen or so of these I have come up with ways to make it easier and faster. Hoping today to mark and drill the back plate.

 

Gotta give one of those a go I reckon...

[Nada]

Trying out a light attenuator with my Pass B1 .....

 

Smart idea. So how does it sound?

[mwhouston]

Gotta give one of those a go I reckon...

Not cheap but nice finish. Also you get two different face plates and they are made of steel not Al. Well some parts are Al.

[Misternavi]

Smart idea. So how does it sound?

work in progress, takes about 3 weeks to do a simple installation (in between work, kids, cleaning the house)

let you know in a week or 2

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[shaky]

Interested to hear your thoughts on the LDR pre once it's going Ivan. Have the same one (stereocoffee?) but with three inputs and haven't been able to fault its performance. Chris is a great bloke to deal with too, upgraded my boards to current model spec earlier in the year for the cost of postage.

[Owen Y]

Interested to hear your thoughts on the LDR pre once it's going Ivan. Have the same one (stereocoffee?) but with three inputs and haven't been able to fault its performance. Chris is a great bloke to deal with too, upgraded my boards to current model spec earlier in the year for the cost of postage.

 

Hi shaky - interested in your sonic results, comments.

And what previous vol control/s did you have?

 

Maybe post some construction pix/notes/useful info?

 

Cheers, Owen

Dark Lantern blog - http://darklanternforowen.wordpress.com/

[betocool]

Going on with the ADC -> microcontroller -> DAC thingy (best definition I found).

 

 

ADC is ready. Bloody hell! Took me a while! It's a balanced input ADC, PCM1804 from BB (Texas Instruments), and the circuitry before, as much as it's not complicated, it's a freaking ratsnest below the board. Since I'm testing, I'm not ready to commit to PCB at the moment. Plus I had the unfortunate experience with two tantalum caps, they didn't block the DC properly. Anyone ever experience something like that before? Weird. Took the tantalum cap away and chucked in an electrolytic, and all levels are level.

 

Going to start the DAC board tomorrow-ish.... PCM1793. And then we'll see further.

[selectedgrub]

...as much as it's not complicated, .....

 

 

I feel dumb.

 

But I got my fins sorted.

They need shaping and detail.

 

 

I start mounting speakers and the inside proofing.

 

 

Thanks for blowing my mind.

[mwhouston]

Nearly finished my latest Tripath T4 with the new amp modules.

 

Here some updates. Based on an article I read recently about the current demands on amps with SS rectification the 10A bridge is soldered directly onto the first filter cap bypassed by a 0.1uf poly to remove the HF spikes generated by diodes in general. Also heavy duty wiring back to the trannie (500VA) from the bridge. The second cap with have a 10uf poly bypassed by 0.01uf poly to reduce noise in the caps getting to the amp module. This also provides a cleaner audio path to the PS.

[mwhouston]

Good preparation before the amp module goes in can make for an all over easier and neater build.

Only the amp modules install now.

[mwhouston]

Complete

[mwhouston]

Finally got my digital CRO working and measured the noise in my 6V6 tube amp, Black Lace. This one has split HT rails and through my high efficiency speakers would produce a low hum. Adding another filter stage and big 470uf caps to each individual rail made the amp dead quiet.

If you measure 2.5mV of noise, that's quiet. This amp measured 955uV of noise, less than 1mV. That is extremely quiet. Interesting when I turned on the LED lighting above the RFI induction rose to 5mV. Good reason no to have LED lighting near hifi gear.

[mwhouston]

I discover the new T4 180W Tripath amp modules have the phase of one of the speakers marked the wrong way. If you wire the amp module as per the markings one speaker will be out of phase, no centre image. Very simple to fix just swap the wires around on one speaker.

I have informed hifimediy. They didn't know but have come back and told me I am right and thanked me. They will correct the screen printing on future boards. I emailed them back and said it wasn't good enough, not everyone will know the speakers are out of phase. The amp will sound bad and there will be no centre image. They must include errata notes and hand mark the brds. Dick heads.

[Stevesie]

Believe it or not, this pile o' junk actually works. And despite the somewhat sub-optimal layout, there's no hiss or hum. 

 

 

[betocool]

Believe it or not, this pile o' junk actually works. And despite the somewhat sub-optimal layout, there's no hiss or hum. 

 

And it's good for.... ? All's fair in the DIY game!

[Stevesie]

And it's good for.... ? All's fair in the DIY game!

 

Heh - it's an amplifier! Isn't it obvious?!!  

 

(Baby Hypex Class D stereo module, as used in the Nad D 3020, input buffer circuit as the module doesn't have one on board like the normal UcD modules, and a Connexelectronic SMPS. Don't worry, I will put it in a case for actual use)

[betocool]

Of course it is!

 

I was errr... asking about the... the... the... brand! Yes! The brand of the power supply of course!

 

Seriuosly though, what's the function of the middle bread board. I really (really!) can't read the description on the chip.

[Stevesie]

Of course it is!

 

I was errr... asking about the... the... the... brand! Yes! The brand of the power supply of course!

 

Seriuosly though, what's the function of the middle bread board. I really (really!) can't read the description on the chip.

The input buffer op amp is a TL072, and just a temporary +- 15v power supply to the right. Need to order some regs next week for the actual circuit.

[baMarek]

This mess is ES9018 DAC in 8 channel configuration which I'm currently testing. It's going to become the center of a software based crossover for any of my future speakers. I initially wanted to have a tube output stage but the amount of work and cost for 8 channels would be too big. Thinking of I/V now though the sound directly from the DAC chip is surprisingly good. If you guys know of any good preamp boards that can be adopted I will appreciate suggestions. Ideally I'm looking for a moderately priced low noise pcb with balanced input, with a very good power suppply that comes with a cheap opamp that I will upgrade to something classy.

Edited August 28, 2016 by baMarek

[Stevesie]

This mess is my ES9018 DAC in 8 channel configuration which I'm currently testing. It's going to become the center of a software based crossover for any of my future speakers. I initially wanted to have a tube output stage but the amount of work and cost for 8 channels would be too big. Thinking of I/V now though the sound directly from the DAC chip is surprisingly good. If you guys know of any good preamp boards that can be adopted I will appreciate suggestions. Ideally I'm looking for a moderately priced low noise pcb with balanced input, with a very good power suppply that comes with a cheap opamp that I will upgrade to something classy.

 

Your mess is quite a bit neater than my mess! Looks great!

[selectedgrub]

I got 1 coat rubber on.