The Zen 9

[Ian Mackenzie]

As I am building a Zen 9 amplifier I thought I would devote a few posts here.


For details of the design go here: http://www.passdiy.com/

As with all these class A amps heatsinks are first and foremost so I started off by coming up with a chassis based on some Conrad Heatsinks I had at home.

These particular extrusions are rated a 0.25 degrees C per watt and will reach an operating temperature of about 50 degress C at an ambient room temperature of 25 degrees C. They are flanged and have an inset at the ends which neatly allows a plate of 3 mm aluminium to form the front panel. The overall heatsinks dimensions are 300 x 150 x 45 mm and form the sides of the chassis as can been seen from the image below.

The overall chassis external dimensions are 480mm x 300 mm x 150 mm.

The two smaller vertical finned heatsinks at the rear are used exclusively for the Power JFets

Using short sections of L angle and some 12 mm x 12 mm square rod I made some backets and used M4 bolts to secure everthing together.

I then milled out the holes for the mains IEC socket, mains power switch and RCA inputs and Speakon output sockets and the Blue Led for the front panel.

The Zen 9 amplifier design has it origin in the single stage Zen but uses a unique LU1014D Loveltech Power J Fet as the key gain device. (see article for details).

Four installments in the article discuss in depth the circuit theory and performance benefits. The amplifier has particular potential for high efficiency driver and horn devotee's give the amplifier has very low noise and distortion in class A operation.

When I complete the main pcb's I will post another image


Ian

[northwood]

Master Ian
Very nice work.Planing to make a small power Pass power-amp for my high efficiency speakers[LE8T and D130],and wanna feel the difference between the Mosfet and Tube [just got a pair of vintage Fisher 80AZ and A pair of Leak TL12].:)
Learning from you:applaud:


-----------------------
Northwood

[Ian Mackenzie]

Hi Northwood,

Here is some discussion on the Fisher , I have not had any experience wit it. I have heard the leak TL 12 on ocassions and I don't care for it.

These valve amps are sophisticated designs compared to the single stage Zens. May I suggest that you read the earlier Zen articles regards the benefits of mosfets at the above link.

Also look at the Passlabs download owner manuals for discussion on tubes versus mostfets.

http://www.passlabs.com/downloads/old%20product/a3man.pdf


Nelson Pass is one of the most highly respected amplifier designers of our time and his experience with power mosfet's as gain devices is unique.

regards

Ian

http://www.audioasylum.com/scripts/t.pl?f=vintage&m=48899

[northwood]

Hi Northwood,

Here is some discussion on the Fisher , I have not had any experience wit it. I have heard the leak TL 12 on ocassions and I don't care for it.

These valve amps are sophisticated designs compared to the single stage Zens. May I suggest that you read the earlier Zen articles regards the benefits of mosfets at the above link.

Also look at the Passlabs download owner manuals for discussion on tubes versus mostfets.

http://www.passlabs.com/downloads/old%20product/a3man.pdf


Nelson Pass is one of the most highly respected amplifier designers of our time and his experience with power mosfet's as gain devices is unique.

regards

Ian

http://www.audioasylum.com/scripts/t.pl?f=vintage&m=48899

Thank you my friend Ian,I'm downloading the file u gave to me and I've read the discussion about fisher 80AZ,people here call it locomotive.The talk about that is very worthy to read,thank you very much.Price here is 1/3 higher:( . Leak TL12 has another verison of BBC,bigger and heavier,totally different transformer,as good as american made transformer.
I used Marantz9 and Mictosh275,they are much better,same the price^_^

The joy of us fans is the changing and changing of taste,except the faith to JBL.

_________________
northwood

[Ian Mackenzie]

Looks like a Valve tester.

Ian

[Ian Mackenzie]

This is the Green Etch stage of the Pcb fabrication for Zen 9.

[northwood]

Looks like a Valve tester.

Ian

Yeah,u r right my master Ian:)

[northwood]

This is the Green Etch stage of the Pcb fabrication for Zen 9.

:D ,I want

[Ian Mackenzie]

Give me the address of Shanghai Jail and I'll mail yu a pair

http://www.northchinamarines.com/id31.htm

Macka:D

[northwood]

Give me the address of Shanghai Jail and I'll mail yu a pair

http://www.northchinamarines.com/id31.htm

Macka:D

:biting: :banghead:

[northwood]

very interesting story,I'll be reading more:)

[Ken Pachkowsky]

Ian

Needless to say, damned fine looking work Ian.

I will be watching this with keen interest.

Wish you were not so far away.

Ken

[northwood]

How about this one,our Mosfet master??:)

[Ian Mackenzie]

Northwood,

What model is it? .....perhaps these images would be better served in an audio classics thread??

[mech986]

Hi Ian,

The Marantz preamp in Northwood's picture is the venerable Marantz 7 tube preamp. Looks in very nice condition too. It is considered one of Audio's classic designs.

In the same vein, the two small Rogers speakers are the classic BBC LS3/5a's. Northwood, from what I can see, the top speaker is Teak and the bottom is Walnut? Judging from the Rogers Badges, the top may have a serial number of SO7xxxAB to SO18xxxAB while the bottom will be from SO24xxxAB to 45xxxAB or so. Do you own these, and do you have any photos of the backs showing the serail numbers and of the fronts without the grilles? This will help me to figure out whether the bottom pair is a 15 ohm mid 80's version or the later so called 11 ohm revision form 1987 on.

I'm moderator of the Yahoo! LS3/5a group ( http://groups.yahoo.com/group/ls35a/ ) so that's why the interest. Ian, if you feel this is sort of a hijack on your Zen thread, I can move this to a new thread or PM. Thanks.

I have always admired Pass's designs and followed all his Audio Amateur/Express published papers as well as the passdiy projects. Would love to see how yours turn out.

Regards,

Bart

[Ian Mackenzie]

I think these image would better serve the forums if they were in an Audio Classics thread...no doubt other members could also contribute.

[northwood]

sorry,I'll ask the moderator here to deleat them all

[northwood]

Hi Ian,

The Marantz preamp in Northwood's picture is the venerable Marantz 7 tube preamp. Looks in very nice condition too. It is considered one of Audio's classic designs.

In the same vein, the two small Rogers speakers are the classic BBC LS3/5a's. Northwood, from what I can see, the top speaker is Teak and the bottom is Walnut? Judging from the Rogers Badges, the top may have a serial number of SO7xxxAB to SO18xxxAB while the bottom will be from SO24xxxAB to 45xxxAB or so. Do you own these, and do you have any photos of the backs showing the serail numbers and of the fronts without the grilles? This will help me to figure out whether the bottom pair is a 15 ohm mid 80's version or the later so called 11 ohm revision form 1987 on.

I'm moderator of the Yahoo! LS3/5a group ( http://groups.yahoo.com/group/ls35a/ ) so that's why the interest. Ian, if you feel this is sort of a hijack on your Zen thread, I can move this to a new thread or PM. Thanks.

I have always admired Pass's designs and followed all his Audio Amateur/Express published papers as well as the passdiy projects. Would love to see how yours turn out.

Regards,

Bart

Yeah, u r right about the speakers and Marantz Pre-amp,I'll take the photoes of them for u later.

[Ian Mackenzie]

Further details of the project rollout can be found here:



http://www.diyaudio.com/forums/showthread.php?s=&threadid=82197

[Ian Mackenzie]

Northwood,

I have updated the link with more pictures at the end of the thread. Have a look. I spent most of the day working on it .

If the diy Moderator makes the effort to clean up this thread I will post hi resolution images for you.

macka