Q17 - an audiophile approach to perfect sound

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#1,903
After careful consideration and reading all the stuff about the different versions, I'm decided to go with Tim's version, mainly because of some parts being more difficult to get and I'm thinking on the long run, because I'll be staying in South America for a while, and imports from the US are very expensive, so I'll be stuck to local stores and I'll probably take some time to get all of the components, so this will be a project that will take me at least 6 months to finish just the amplifier module...

In the meantime, I'll be waiting for the boards to get here. I'll be ordering 10 pieces, because they only print in multiples of 5, and having one spare stereo and one mono, doesn't seem to be very wise, compared to have 4 spares of stereo.

So, if anyone's interested in having one of the spare stereo boards, just send me a message.

Thank you everyone, you guys are truly amazing

I guess I'm staying for a while on this forum and I'm sure I'll be posting more questions about the amp, and showing off my work in progress

Grüß Gott​

(Tim should know)
 
#1,905
Hello folks,

The Q17-Turbo PCB 1.0.2 is out. This is just a maintenance release with the replacement of the BD139G on Q12 with KSC1845 and updated footprint. I also added parts equivalences in schematic.

I'm now boxing the two Q17-Turbo boards I built to compare in stereo with the Q17-Mini. Even if the measurements are a little worse with the Turbo than the Mini, in mono, I didn't hear any noticeable difference. The real test will still be on my Dynaudio Contour and in stereo.

Regards,

Stef.



https://github.com/stefaweb/Q17-a-QUAD405-audiophile-approach/tree/main/Q17-TURBO 1.0.2
 

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#1,906
Tim1999de said:
Hi,

Stef really wants to hold on to the dual power transistor concept, as do some others. So I'm looking for solutions how this can look like - but can't find one that behaves as universal at small signals, as well as at large signals, as the single pair does.
Here I noticed a detail that I overlooked in the previously published variant. That is the matching of R12 to the higher internal resistance of Q6. This is a very small adjustment, but while we're on the subject of perfecting it....
R12=52 ohms. That's it.

Regards Tim
Click to expand...
Tim, I read that with your tests you recommend for 1 pair 1,5uH coil. I think a ready-made coil from WURTH would fit nicely there, there is enough space for a pcb.
 
#1,907
If I install a core coil with ferrite material, then the distortions increase, because the material creates distortions through hysteresis. This makes such a core even at low currents, you can try very nice in crossover tuning in speakers and listen to the differences.
Your gold-plated coil is more suitable for this.
An air coil that works doesn't have to be as accurate as Stef wound it, that can look less beautiful and work much better. Enamelled copper wire in 1 or 1.2 mm thickness is really not expensive and a thick pencil as a winding aid also has almost everyone at home.
 
#1,912
stef1777 said:
If you plan to put "6 months" to supply the components, wait until the last minute to have the PCBs manufactured because in 6 months there may be new versions of the PCBs.

Stef.
Click to expand...
Yes,
I think I'm going to take your advice... As today I took some time to search for components in South America, and I couldn't find a single online store based in Argentina, Brazil, Paraguay or Uruguay, that would have components other than Resistors and capacitors. A single OPA1611AIDR was nowhere to find, unless from Mouser, Farnell or Digikey, and at high costs (Shipping, Taxes, Customs), and no south american country can compete with the US economy, unless Ecuador as their own money is US Dollars

The only alternative is China, with something like aliexpress and alike, but that place gives me the creepiest feeling, just to think about buying something that probably is fake.

The only less costly option that I have left, is JLCPCB, I have seen that they sell that particular OPAMP with a price like 2USD, the price on TI.COM was like 7USD... I could buy from them boards already assembled, but that simply would spoil me the smell of burning solder.

Do they have the option of assembling only certain components? Like assembling everything except Resistors and Capacitors? Because that's the only thing I'm able to buy locally.

Unless that, I think I just have hit a brick wall.
 
#1,916

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#1,917
stef1777 said:
Hello folks,

The Q17-Turbo PCB 1.0.2 is out. This is just a maintenance release with the replacement of the BD139G on Q12 with KSC1845 and updated footprint. I also added parts equivalences in schematic.

I'm now boxing the two Q17-Turbo boards I built to compare in stereo with the Q17-Mini. Even if the measurements are a little worse with the Turbo than the Mini, in mono, I didn't hear any noticeable difference. The real test will still be on my Dynaudio Contour and in stereo.

Regards,

Stef.



https://github.com/stefaweb/Q17-a-QUAD405-audiophile-approach/tree/main/Q17-TURBO 1.0.2
Click to expand...
Hello Stef,

which amplifier do your Dynaudio Contour prefer?

Have you already started the big comparison test?

Regards Tim
 
#1,920
The Q17 is not in the contest because at the moment I only have a Q17-Mini with a 35v 160VA transformer for two boards. This is very insufficient to have enough current to power the Contour. I could only compare when I have a completed and working Q17-Tubro.

I'm currently stuck because I burned my power supply (the one in the photo). As soon as I pull the power supply with a large load, I have a crackling sound on the power supply board. It did before I put on the new bridge. I think I have one of the big capacitor that is dead but I haven't really found the fault yet. And I have no more spare capacitors.

Stef.
 
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