Discrete Dynamics Class A Pre-Amplifier

[manniraj]

Great Joshua

I do not see any ground wire from the PSU to the chassis where you have connected the IEC ground. Is it deliberately left out for hum issues?

 

[sachu888]

Great Joshua

I do not see any ground wire from the PSU to the chassis where you have connected the IEC ground. Is it deliberately left out for hum issues?

The preamp has on board power supply. Preamp is grounded via volume pot.
Edit : I am sorry, just noticed it's IEC earth.

Regards
Sachin

Regards
Sachin

 

[jls001]

Great Joshua

I do not see any ground wire from the PSU to the chassis where you have connected the IEC ground. Is it deliberately left out for hum issues?

Ground wire is connected to the chassis near IEC socket itself.

 

[hydrovac]

The cabinet is looking fabulous... is it all Aluminum?

...

 

[jls001]

The cabinet is looking fabulous... is it all Aluminum?

...

Yes, it's entirely aluminium. The cabinet is designed and fabricated by magma.

 

[sunand777]

Finished a build for magma:
View attachment 39691

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It's configured for three sources, selectable via a 3-way relay based source selector. R-Core transformer used is from Shilchar. It has two secondaries, namely, 18-0-18V for the Preamp circuit, and 12-0V for the source selector. Pot is 50K log, Alps Blue Velvet.

Great build and finish , but why Cyan colour RCA connector instead of Red?

 

[MaSh]

Finished a build for magma:
View attachment 39691

Wow, very neat layout.

That is a nice touch to add 2 pre-outs. I am assuming one is for a Sub? Any plans of adding a crossover between the 2 pre-outs? Does connecting them directly cause any interference or ground issues? Which cable(blue) are you using for the signal?

MaSh

 

[jls001]

Great build and finish , but why Cyan colour RCA connector instead of Red?

We'll have to ask magma as he bought the parts

Well, it's just a colour. As long as we can distinguish between the upper and lower rows of RCA sockets it should be okay.

That is a nice touch to add 2 pre-outs. I am assuming one is for a Sub? Any plans of adding a crossover between the 2 pre-outs? Does connecting them directly cause any interference or ground issues? Which cable(blue) are you using for the signal?

MaSh

I'm not sure how magma plans to use the second output but as far as I know he doesn't use a sub. The two outputs are simply shorted to each other without any crossover - they're just paralleled outputs.

At home I could only try one output at a time so couldn't test for interference or ground issue.

The blue/violet coloured cable is a Helusound AES DMX cable (I think this DMX cable is meant for wiring up AES/EBU digital audio patch panels with XLR sockets). Yes, it's a digital cable of 110 Ohms characteristic impedance, and may seem unorthodox in this application, but I have tried numerous cables (various balanced analog cables, silver-plated copper, tinned copper, multi stranded copper, solid core copper including CAT 5/6, high purity solid core silver, etc as analog internal signal cabling in line level preamps, phono preamps and power amps and this Helusound consistently sounds best to my ears.

 

[spirovious]

lf connectors are neutrik,then sometimes Red is out of stock.

 

[MaSh]

I'm not sure how magma plans to use the second output but as far as I know he doesn't use a sub. The two outputs are simply shorted to each other without any crossover - they're just paralleled outputs.

At home I could only try one output at a time so couldn't test for interference or ground issue.

The blue/violet coloured cable is a Helusound AES DMX cable (I think this DMX cable is meant for wiring up AES/EBU digital audio patch panels with XLR sockets). Yes, it's a digital cable of 110 Ohms characteristic impedance, and may seem unorthodox in this application, but I have tried numerous cables (various balanced analog cables, silver-plated copper, tinned copper, multi stranded copper, solid core copper including CAT 5/6, high purity solid core silver, etc as analog internal signal cabling in line level preamps, phono preamps and power amps and this Helusound consistently sounds best to my ears.

Great. Thank you so much for the details.

My amp which Sadik had made uses the same cable I guess. I was thinking of trying something else, although I have no issues with it. However, now will drop that plan.

MaSh

 

[rikhav]

Few more pictures of the cabinet made by magma for the pre

 

[raghupb]

Love the name "Analog Control Center"
And the dot notation for inputs
Cheers,
Raghu

 

[sachu888]

Beautiful build Joshus and very nice cab Magma. The cab looks just superb.

Regards
Sachin

 

[magma]

Love the name "Analog Control Center"
And the dot notation for inputs
Cheers,
Raghu

Thanks
Raghu

I'm not the one who came up with it though

I stole those parts from my FNL friends
So credit is there's

 

[Kannan]

After looking at all these builds I dont even want to post my iteration of the Digital Design preamp
Ofcourse it could add to some good humour

 

[jls001]

After looking at all these builds I dont even want to post my iteration of the Digital Design preamp
Ofcourse it could add to some good humour

Please feel free to post, Kannan

Even my PAM 12 pre build is fairly messy as I have re-utilised my old DCB1 cabinet.

 

[Kannan]

Please feel free to post, Kannan

Even my PAM 12 pre build is fairly messy as I have re-utilised my old DCB1 cabinet.

I hope you don't mind my adding some cosmetics, the cutie kitty is for distraction.

 

[raghupb]

So it's not a preamp, it's a purramp!!
Cheers,
Raghu

 

[MaSh]

Wow lovely builds.

MaSh

 

[Beginner_N]

I hope you don't mind my adding some cosmetics, the cutie kitty is for distraction.

View attachment 39776

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Due to cat fur it will sound warmer