H2 V2 BUILD

[Nelson Pass]

MPJA.com has a cheap but functional supply for this project:

https://www.mpja.com/12VDC-1A-Plug-Power-Supply-DVE/productinfo/37752+PS/

$3.98 and they have 4,000 of them.

 

[Tom369]

Thank you for the advice. I will look around.

 

[Tom369]

Tom the new builder here. About to get started in my first project. Can anyone give me advice on good RCA jacks that I can get on Amazon in the USA? Also, what kind if wire should I use?

 

[ItsAllInMyHead]

Congrats! What type of RCA jacks? Are you putting this in a chassis => Panel mount? Do you just want some attached to wires? Color preferences? Exotic materials?

These would likely be just fine, but there might be better options.

https://www.amazon.com/Uxcell-a1601...290290&sprefix=female+rca+jack,aps,120&sr=8-8

For in and out, I like using old Cat5 wiring. Cheap, plentiful, effective, and already twisted. You'll get a zillion opinions.

 

[twocents]

I like these for panel mount RCA:
https://www.amazon.com/Terminal-Pla...9Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

+1 for Cat 5 wire

 

[peppennino]

Hi All,
If used as preamp, does it make sense to place the volume pot AFTER the board in order too have constant H2?
Thanks for suggestions.
🍻

 

[6L6]

I’d place the pot in front of the H2, like normal, BUT it’s easy enough to to try it both ways. So try both and see what you think.

I dont think it’s going to make any change on the 2nd harmonic regardless of volume pot location.

 

[vdupham]

Hi, Can I use as preamp between DAC and Whammy Headphone amplifier ? I want to use it in headphone system.

 

[6L6]

Yes.

 

[Tom369]

Hello All. I finished populating the board on my first build and all looks good. Question about testing the voltage at T2. Do I need to have the board connected to an input and output to set this value? Or can I just connect it to the 12 volt power?

 

[elwood625]

Just connect it to the 12vdc power supply.

 

[Tom369]

Hello All, I am having trouble finding a volume pot to use when I make this a preamp. I have been told that I should use an Alps RK27 50K but I can't find an online store to purchase. Of have been to places like Mouser that have many different version. Can anyone help? Thanks.

 

[audiosteve]

Hello All, I am having trouble finding a volume pot to use when I make this a preamp. I have been told that I should use an Alps RK27 50K but I can't find an online store to purchase. Of have been to places like Mouser that have many different version. Can anyone help? Thanks.

Try Parts Express .I'm not suer about RK27 but they stock the kind many people use. I've bought a few. https://www.parts-express.com/search?order=relevance:desc&keywords=Alps pot Actually, I think these are RK27s

 

[elwood625]

Here: https://www.parts-express.com/ALPS-...-Potentiometer-Solid-Shaft-023-208?quantity=1

 

[Nelson Pass]

Pot can be any value your source is happy with.

 

[Tom369]

Thanks All. I will try that one. I was not sure it would work with the board available at the DIY Store since it did not say RK27.

Nelson, can you please explain in basics what you mean by saying the source has to be happy with the pot value?

Thanks, Tom

 

[myleftear]

The pot is the source’s input impedance. Should be many times higher than the output impedance of the source (phono/tape/cd etc) cdplayers /DACs usually are happy with lowish values (>10K or so, while older gear, tapes, etc. sometimes want to see much more (25K upwards)

If this is all nonsensical, pls correct me!

 

[ItsAllInMyHead]

The pot's full impedance is a key component to determine the source’s H2V2's input impedance. Should be many times higher than the output impedance of the source (phono/tape/cd etc) cdplayers /DACs usually are happy with lowish values (>10K or so, while older gear, tapes, etc. sometimes want to see much more (25K upwards)... You'd likely be just fine with 20k. Post if you're using some older source gear or even something more modern like a CD player with a tube output stage as an example.

If this is all nonsensical, pls correct me!

Not nonsense, just one piece backwards and a bit more detail needed, IMO.

If my corrections are nonsensical, pls correct me!

 

[vdupham]

Hi, I did my diy version based on schematic. I choose random J113. My result is very noise. Is it because non matched j113 ? I just only have voltmeter.

 

[Nelson Pass]

Maybe it's oscillating. J113 is not a very quiet fet, but mostly when used as a phono stage input,
otherwise we don't hear complaints.

Do you have a Gate resistor on the Jfet and an output Source resistor in series?