What’s On the Bench Tonight (OBT)

Hi again,
on the bench - my new HyperSET preamp😀
Now I have to integrate it into my system - and the listening can start.

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@Plott

Absolutely superb execution and industrial design Plott, I love it! 2 BIG thumbs UP! 👍 🤓 😍

More pics please!

Best,
Anand.
Hi Anand, man thanks! I very much stick to the industrial design for whatever reason :spin: - glad you like it :cheers:
Pics will follow next week - I have to change both switches... The output selector switch was broken after switching 5 times... I have now ordered two new switches, they will arrive next week. And I will take puctures.
 
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You can relax and listen to it now.
First impression after just a few songs: WOW!
This amp sounds gorgeous 😍 Period. It's very dynamic but at the same time very relaxed, not strained, not exaggerated.
It creates a huge soundstage with depth and width and height, the instruments are placed very well. Singing - beautiful. Chantal Chamberland stands in front of me, her voice is completely natural, the s-sounds are perfect. Goosebumps.
All these comments concern the tube output.
 
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Returned on my bench for several days, but finished this afternoon : my Audio Research SP3A1 from 1974...

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The gain difference between both channels L and R - in any input mode and at any volume level - is less than 0.1dB at 1kHz sinus, now. All the other controls are also well L-R balanced also.

What I still have to refine is the RIAA of the phono section, where I measured gaps up to 2dB at the extremes, due to unexpected R or C drift values : the parts will be ordered soon...

T
 
On the bench tonight is the rev B of the Line Noise Black Hole. I have reduced it down to two CMC’s in a 5th order Chebyshev filter the achieves a predicted -55dB at 100kHz and -47dB at 60kHz. I tested it at 60kHz and measured 2.8mV out of 508mV for -45dB, close to -47dB.

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Good for 10A of current at 110 to 230vac. Built in triple MOV/GDI lightning suppressors for protection of your equipment from HV spikes. It’s a very compact and robust package now.
 
Hi Tubelectron,
Thanks! I really use it all the time - it’s as integral as my Fluke multimeters where I use this type of instrument/meter on a daily basis. It has a built in function generator so makes for a perfect one unit testing solution.

I love your vintage preamp - that is a nice looking piece of gear. Very cool to have a bit of history when listening.
 
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In the bench tonight is the Desktop Diamond Plus (DDP) Headphone Amp designed by Jhofland. It is similar to the Desktop Diamond Buffer HPA but has a built in AC/DC PSU with a filter and low dropout voltage regulators. Plus a solid state relay headphone output protection with turn on delay to prevent turn on thunp, and instant off to prevent turn off thump. Also includes a 3 way selector for 0/6/12dB Gain.

I am using a 1kHz Akitika oscillator and Focusrite 4i4 audio interface.

Max power before clipping into 33ohms is 7.0vrms. That’s about 1.5Wrms.

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The THD is 0.011% at max power.

At a more reasonable power level of 1.00Vrms (30mW into 33ohms) the THD is 0.0013% and FFT is all second and third harmonic with dominant second:
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The noise floor measures 850nV rms. The 60Hz mains peak is at 5uV rms. This means that the amp is absolutely silent with no music playing.

But if I increase the gain in the input output of the Focusrite by about 15dB to fully utilize the dynamic range, the THD is now only 0.00064%:
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Here is the test setup:
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Amp:
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