Zeny based on Nelson Pass cascode design

[lineup]

Arensattic

I just discovered your thread and I am interested in building a (new) dedicated amp for my Grado headphones.
I have been a fan of the Zen creations of Nelson Pass since a long time as you can learn from my website:
http://home.hetnet.nl/~a.van.waarde/index.html
Therefore I would like to build a "mini-Zen" for headphones.
Best regards from grey and cold Holland

🙂 --- 🙂 --- 🙂
I can really recommend a visit to arensattic little website.
It is good nice and easy to build diy audio stuff.
Nice Speakers, Unusual MiniTube Amplifier and some more ....

You can find this link also in arensattic profile or click 'www' under his posts.
This is the correct working link to his website with audio:

http://home.hetnet.nl/~a.van.waarde/index.html

Zen Revisited Power amplifier.
SE power amplifier with just one active device (MOSFET) per channel

An externally hosted image should be here but it was not working when we last tested it.

Jericho Horns.
Fostex FE208 Sigma dual-cone full range loudspeaker in exponential horn

An externally hosted image should be here but it was not working when we last tested it.

 

[jh6you]

Very fresh web site .. 🙂
I am pretty sure that your 'mini-Zen' headphone amp will be successful ..

Regards
jh

 

[jacco vermeulen]

Aren has the cosiest attic i've ever seen. Lukewarm is a nice ancient word.

 

[jh6you]

Hi Arensattic

This would be to your interest..

🙂

jh

 

[arensattic]

Thanks for the information

Hallo JH6YOU,

Thanks for the information on headphone sensitivity and amplifier requirements, I have just downloaded it from the German site.

Aren

 

[jh6you]

Here is a new picture . . the first one and the second . .
Today, I changed all IRF620 with reliable parts (no copies, but the original products) . . At the same time, for the second Zeny, I reduced total number of IRF620s form seven in one box to six . . 🙂 This second version is my specialty for me to own alone . . 🙂

And, I compared Zeny's sound with my another tube headphone amp . .
Mmm . . difficult to say which one is better . .
Nevertheless, if I have to say something . . I d like to say: Zeny might be good before sex, and the toob after it . . 😀

Regards
jh

 

[jh6you]

Okay . .

Here is my Zeny of the 1st generation . .
This is the final version . .

Enjoy!

jh

 

[jh6you]

Here is her PSU . .
This is the final version . . .

I have found this PSU among others works best for Zeny . .

Enjoy!

jh

 

[jh6you]

If you want to have equal distribution of electrons between L and R channel . . try to match mosfets . .

I tested 41 and found wide variety of Vgs values . .

Enjoy!

jh

 

[adolphe]

Hey jh, nice work on this design. I'm currently looking to build my first headphone amp. I was just wondering if you've built any of the "common" DIY headphone amps out there like the Millet or M3? If so, how does the Zeny compare?

I will likely build this one at some point, just trying to decide which one to start with!

-Scott

 

[jh6you]

Honestly I do not know both of Millet and M3.

I know Lehmann, and I own one tube headphone amp.
Zeny has a good sound charactor, for me.

Regards
jh

 

[jh6you]

Why

So far, I have tried Zeny with 5 different cans:

- Audio-technica ATH-W5000 (40 ohms 102dB/mW) - mine
- Audio-technica ATH-A900LTD (40 ohms 103dB/mW) - 2nd son
- Sennheiser HD600 (300 ohms 97dB) - mine
- Sennheiser HD595 (50 ohms 112dB) - a girl
- AKG K-501 (120 ohms 94dB/mW) - her father

Yeah . . . Zeny of unity gain has well driven these, except AKG K-501, which has low SPL of 94dB.

Hhmmm . . .

I have taken some thinking and decided to develope a new Zeny having variable voltage gain up to 3 (about 9dB), as shown in the picture. Now, AKG sings like thunder . . .

 

[jh6you]

How

In development, I have applied the amp design philosophy of Nelson Pass - "simpler" - for the followings:

- total four IRF610s per amp
- simple power supply regulation
- voltage gain up to 3 (about 9dB)
- class A (single ended)
- no negative feedback
- good sound
- no technical trouble for minimum 6 years

Of course, I have stolen about 50% of Nelson Pass design.
And, I think that I have got most of these.

 

[jh6you]

Fabrication

I have never used PCB for my diy.
But, this time I have used a kind of multi-purpose PCB for testing and experiments.

Doing testing and experiments, I have focused on avoiding any hard connection (electron path) between boards and heat-sinking plate because the hard spots are often initiating short-term fatigue failure (even during fabrication) at the connections. In my opinion, while the flexible connections give me somewhat ugly looking, but will actually secure longer life of the amp.

 

[jh6you]

Next step

I will test this new headphone amp 6 months more so that I could inform you further. Meanwhile, I am going to find a good looking and strong chassis . . .

Regards

🙂

 

[Zen Mod]

 

[steenoe]

Hi JH, did you get my emails?

Steen🙂

 

[jh6you]

Email . . . ? About JFET . . . ? No.

Could you kindly re-write in the next week as I am out of office this week.

Many thanks

jh

 

[steenoe]

Email . . . ? About JFET . . . ?

Yep🙂 I sent the first mail on the 13. April. I must be getting filtered out somehow.
Could you send me an email, and I will try and reply to that.

Steen🙂

 

[jh6you]

Sure, will do 🙂