H2 V2 BUILD

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cubicincher

Member
Joined 2016
I wanted to thank Nelson Pass for the H2-generator! It is a very nice 'tool' to play around
with 2nd-harmonic-distortion. A single Jfet and its influence to the overall sound of your system.

Although I showed the pics in the 'pictures of your DIY pass amp-thread'...
I put the trimpots on the pcb to the front panel. I didn't get noise. On the backpanel are labsockets (2mm)
which make it easy to measure with the DMM.
I can switch between battery-drive and an external linear regulated PSU.
Cheers
Dirk :)
 

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cubicincher

Member
Joined 2016
Skylar88 said:
I like your implementation, Dirk. Well done!

I also wanted to put pots on the front panel, but couldn't find pots with low enough value - not even close to 50 Ohm. What value did you use? Part number perhaps?
Click to expand...
Hello Skylar88,

those are 50 Ohm-trimpots with a 270° adjustabilty (let's call it 3/4-turn). I have to check where I have bought them. :unsure:
Cheers
Dirk
 
D

DualTriode

Member
Joined 2009
cubicincher said:
I wanted to thank Nelson Pass for the H2-generator! It is a very nice 'tool' to play around
with 2nd-harmonic-distortion. A single Jfet and its influence to the overall sound of your system.

Although I showed the pics in the 'pictures of your DIY pass amp-thread'...
I put the trimpots on the pcb to the front panel. I didn't get noise. On the backpanel are labsockets (2mm)
which make it easy to measure with the DMM.
I can switch between battery-drive and an external linear regulated PSU.
Cheers
Dirk :)
Click to expand...
The trimpots, labsockets and battery-acdc toggle are nice features.

I have been probing line level distortions for a long time. Do you have any measurements.

See the attached plot of 1/2 of a 12AU7 vacuum tube done with a AP2522 audio analyzer. The tube has a higher noise floor, lower H2 and much lower H3.

Thanks DT

this is a PDF file
 

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cubicincher

Member
Joined 2016
Hello DualTriode,

this is for me a 'typical' measurement of a tube. Dominant 2nd harmonic distortion over 3rd.
We can also try to simulate this behaviour by using a JFet and trimming it to a dominant 2nd
over 3rd. The other thing is to shift the 2nd harmonic distortion in a positive or negative direction
on the X-axis (compared to the original sinus curve).
I think you have read the following article of Mr. Pass:
https://www.firstwatt.com/pdf/art_h2.pdf
I will try to make some simple measurements the next few days. But I do not have an AP-system!
Will send a sinus-signal of 1kHz through the H2-generator and try to measure with my simple setup.
We do play with distortion here.
But will take some time. I am busy with another project.
Cheers
Dirk ;)
 
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sierra_gva

Member
Joined 2006
Greetings,

I am awaiting for my order of H2 generator boards to clear French customs. I guess the presidential elections slowed things down....

In the meantime, I'd like to order the remaining components I need for the build.

Could someone point me to a few references (Mouser - digikey) for suitable PCB terminal blocks (screw type). I haven't seen the PCB yet, so not sure of the pitch.

This should going to be a fun build. Planning to test this little devil in all sorts of configurations...

thanks for your help,
Sierra
 
S

sal_cats

Member
Joined 2022
Hi,

I just put this together as my first real electronics project. I went for unity gain using the recommended values for R1 and R2 on this thread. I adjusted the pots to the recommended voltage. I just tested it without mounting it inside an enclosure and the sound is coming through alright but I'm also getting some extra noise, I guess it's probably some sort of interference, it's not particularly high pitched. Not sure if it's the 12v wall wart I bought or if it's because it's not inside an enclosure.

I was wondering if anyone could make some suggestinos as to what this might be? I plan on putting it in an enclosure anyway so maybe that will solve my issues? WIll a wooden enclosure do?

Cheers,

Sal
 
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DualTriode

Member
Joined 2009
Hello,

I just soldered in the 50R trim pots.

This PCB is clamped in my PanaVice on my bench there is no shielding. Using 1 8ah lead acid battery the FFT is quiet. There is a little spike at 60hZ and some very low level noise, but nothing to hear.
At 0.5 Volts output; Gain = 10.5, Distortion is 1.64%.

It is not just H2 distortion. This thing is a distortion Factory. I will listen to it and see my impression of how it sounds.

Next I will try out the triad switching wall wart.

see the attached FFT plot.

Thanks DT

H2 V2 13 Volt Battery 4-28-22 into 10k Ohms FFT Spectrum.png
 
D

DualTriode

Member
Joined 2009
sal_cats said:
Hi,

I just put this together as my first real electronics project. I went for unity gain using the recommended values for R1 and R2 on this thread. I adjusted the pots to the recommended voltage. I just tested it without mounting it inside an enclosure and the sound is coming through alright but I'm also getting some extra noise, I guess it's probably some sort of interference, it's not particularly high pitched. Not sure if it's the 12v wall wart I bought or if it's because it's not inside an enclosure.

I was wondering if anyone could make some suggestinos as to what this might be? I plan on putting it in an enclosure anyway so maybe that will solve my issues? WIll a wooden enclosure do?

Cheers,

Sal
Click to expand...

Sal

I am doing this for fun.

Currently I have the H2 V2 set up with a 12 Volt gelll cell. Fully charged the 8 AmpHour battery puts out 13.22 volts. 13.22 volts will not damage anything but it is above the design voltage of 12Volts. The FFT plot is posted above. The 50R Pot is maxed out there is no more adjustment.

I thought that I had a TriAD 12 volt switching wall ward but I do not, UPS is scheduled to deliver it Monday.

The battery supplied H2 V2 is very quiet without an enclosure perhaps a metal box will help only a bit.

Perhaps today I will put another resistor in series with the H2 V2 to place the T2 voltage in the sweet spot to set the correct H2 to H3 ratio. It is really not to ban now, the H2 looks to be about 12dB ish above H3.

Thanks DT
 
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D

DualTriode

Member
Joined 2009
Hello All,

So today I received the TriAd 12 Volt switching Wall Wart.

Overall this H2 V2 PCB is educational.

The battery powered H2 V2 outputs the same H2, H3, ..... series of distortion as the switching 12 Volt Wall Wart version of the H2 V2.

The TriAd 12 Volt Wall Wart puts out another world of ugly power supply switching spikes

See the attached FFT plot of the Wall Wart powered switching power supply.

Thanks DT

H2 V2 12 Volt TriAd wall Wart 5-2-22 FFT Spectrum.png
 
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cubicincher

Member
Joined 2016
Hello DualTriode,

we know about the nasty spikes a smps can send into your amp and into your AC-lines in the room.
It has become common practice to use smps. If you measure your AC-lines in the house and what is
roaming around, then it becomes interesting. Noise on the AC-lines everywhere. Some use their
AC-lines in the house for their LAN.
Although you can filter your smps. Mark Johnson has made a filter available in the diyAudiostore.
https://diyaudiostore.com/products/smps-dc-filter-p089zb-kit?_pos=1&_sid=7573ef8ef&_ss=r
I often prefer an 'old school' linear regulated power supply. More efforts on transformer, filter,regulator
producing heat,... But that is my preference... :unsure:
Cheers
Dirk ;)
 
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