death of zen

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janey

Disabled Account
2001-01-06 1:32 pm
Hello.
First i must say that my english is poor.
now i have some question?
did enybody bild this amplifier? (Elliott DoZ)
is this a good amplifier?
I need plans for loudspeakers with high efective drivers.
wich diy speakers are good for DoZ.

Thanks. Janey
 

janey

Disabled Account
2001-01-06 1:32 pm
Hello
i would like to bild zen or SOZ but i need the amplifier
wich could drive a 4 ohm speakers. (JM lab Point Source)
for this speakers 10w is not enought.
The Doz have bouth (4 ohm, 20w)
i build one chanel (DoZ) and sound is prety good only bass
at higher level is not so definite. i think this is hapening
beacouse speaker is not efective. (91.5 dB)
please send me some good speaker project wich are high
efective.
Janey
 
I have built a DoZ but I would prefer the Zen

I made a cheap DoZ because I had some spare transistors around and i can say it is a cheap project to make.
The sound is very good but not so good that I would prefer it more then the Zen amp. I have made other Zen projects and they sound excelent. I prefer the Zen amp better and it has a unique feature for anyone who needs to drive low ohm speakers :simply make one more amp and paralel input and output to get double current.
 
ZEN

I built my ZEN last year and I admire the work of NP for years.
Well, it made a lot of fun to build an amp for my own, but it was very difficult to find a manufacturer who was able to constuct a housing for it.
My opinion is that the ZEN is by far the most musical amp I've ever heard - and I heard a lot of ampssince I was in business for 25 years and have a full collection of AudioResearch at home.
I never will understand, why NP did never decide to make them factory-built.
By the way...
I do not intend to have my neighbors entertained by listening to music. So far, a loudspeaker with an efficiency of about 90 to 92 dB will do good jobs in a conventional environment. The only thing is they have to be as good as the ZEN and the music-sources.
 

vdi_nenna

Member
Paid Member
2000-10-10 7:27 pm
PA, USA
Long Live ZEN and Pass Labs!!

Sorry to add to the overwhelming preference to the Pass Zen amp, but I can't help myself! I built the Zen amp pretty much as the original article stated, because later came the upgrade article. My version sounds great as it stands, with room to improve upon it.

I have read in more than one place the benefits of MOSFETS over bi-polar transistors. When used correctly, MOSFETS allow for simpler circuits. Take the Citation 12 amp for example, there are less amplification stages in the mosfet design than there are for the original bi-polar design.

You have to do what's best for you at this time, though. A majority of the people's on this site seem to believe that simpler sounds better, but no simpler than need be. It may be cheaper to build a DOZ, but is it worth it in the long run?

I should have just gotten to the point. Strongly consider building the Zen amp over DOZ.

In addition, there is a ZEN amp being built commercially by Volkamp. I asked about it several months back. It's going to sell for about $1800 USD. I ordered the ZEN board from Old Colony Sound Labs for $12 and rolled (built) my own for about $175 without Chassis. I bet once people hear it, they would still pay $1800 for it. It's worth it!!

Good Luck!

Vince

[Edited by vdi_nenna on 02-14-2001 at 05:24 PM]
 

paulb

Member
2001-06-01 4:53 pm
Calgary
I'm considering building the DoZ and have acquired the PCBs from Rod. I noticed that, of these posts, only two have actually built the amp, and only one has compared it to the Zen ("sound is very good but not so good that I would prefer it more then the Zen amp"). The others just talk about the "excitement" of the Zen design, or words to that effect. I think there is serious subjectivism tied in with the Zen among DIYers (although that's part of the fun).

Has anyone found anything seriously wrong with the DoZ?

Please don't reply that it's "not as good as X" unless you've actually compared them or have found a flaw in the circuit somewhere. It's not an old design; Rod started with the Zen concept (a single transistor) and refined it, according to his criteria, to a topology that looks remarkably like the JLH Class A amp of 20-odd years ago. So it's a new design that kind of confirms Hood's design, which is still very popular among DIYers. I chose DoZ mainly because the PCBs were available and much cheaper than the JLH ones. I chose a Class A design because of the fun of telling people who know a little bit about amplifier design that I'm building a Class A amplifier, and because I happen to have a transformer that suits the amp.
My eventual plan is to biamp my system, with the Class A driving the midrange & tweeters, and a Class AB driving the woofers.
 

Asen

Member
2001-01-14 1:19 am
Sofia
DoZ, JLH, Andreas Follower

I had the same problem like you with the heavy load of my speakers. I wanted to build the Zen amp, but Nelson's report about it's behaviour with heavy loads made me draw back of this idea. So I went for the Linsley Hood's old SE amp. It is something quite similar to the DoZ. I chose the JLH because it is an old, tested amp. When the DoZ appeared for the first time in the Net it was only a simulation. No listening tests had been made.
If you want 20W in 3-4 Ohms loads, why don't you take a look at the Andrea's Follower 99. It's a SE MOSFET design, no NFB. I don't expect to perform worse then the Zen. Andrea himself says that heavy loads are not a problem. In this case you should think about a good preamp too.

Regards
 
I've only just discovered this site and this is an old thread so I doubt if anyone's reading this, you're all off listening to your Zens and having a good time. I built a DoZ a couple of months ago. No attention to parts, matching, or proper heatsinking (I had to add Rods Fans). The entire thing was made from surplus stuff for probably less than $100. And it sounds great, even though it does look like some kind of motor control system. Since then I've bought two sets of boards from Rod. I've just finished a DoZ Headphone amp with everything matched and it is staggering! Based on these experiences I'll be starting on a final (houseworthy) DoZ shortly. I've got everything I need except the @#$% heatsinks. (If anyone can offer some tips on where to get big enough, pretty enough and cheap enough heatsinks I'd be most grateful). I can't comment on a Zen or variant thereof as I've never heard one, but I will say that as far as I'm concerned, Rod Elliott's the man!!
 
I'm gonna have to agree whith paulb ...

People are always likely to love their onw build amps... and ZEN amps have been buid alot... but this does not mean that it is a better design

As for the ZEN .. sorry ...
It is not suitable for difficult loads, distortion is high, efficientcy low, bandwidth little low..
I don't understand why it is so popular... well .. it is very simple.. :)

The articles of both R. Elliot and N. Pass make excelent reading.. read them both and this discussing will bennifit..

Also look for the MJ-amp (excelent simulations) on this forum and the HIRAGA's amps and so on.. there's also a excelent french site...

http://perso.wanadoo.fr/jm.plantefeve

http://www.geocities.com/ResearchTriangle/8231/my/index.html

http://www.homestead.com/whaan/files/index.html


well .. you'll find it all here..

goodluck

Thijs
 
This is my first post in this forum, what a happy day!

In the last two years I have build:

SOZ at 5W, ordinary components.
SOZ at 8W , Audio Note tantalum resistors, siliver, gold and all that.
DOZ at 10W, ordinary components.
Andrea Ciuffoli Powerfollower99 at 10w, ordinary components.
Andrea Ciuffoli Powerfollower99 at 1-2w (headphoneamp.), Audio Note tantalum, Blackgate electrolytics an so on.
Balanced Zen Linestage, high quality components.

When I heard the sound of my first SOZ, I realised that this vas something I rearley liked a lot. It was this easy comming and focused soundstage. I desided to bild the absolute version of SOZ in 8w, It did sound better than the first, but tey are in the same family, no doubt.

Then I came over Elliots homepage and his project on the Death of Zen. I decided to build one of pure curiosity. The result was indeed a very good amp, but obvios, it belongs to a quite different family of amps. In my ears it dos not have this easy and direct sound as the Zen´s and it suffers from a littel lack of deep bass.
But I am shure that there will be different opinnions on this since we are dealing with subjetive values. But calling this construction DOZ is way out of line.

Andra Ciuffolis Powerfollower has a very similar sound to SOZ, and I am very pleased with it as a headphone amplifire.

Until this point, my favorit is the SOZ combined with the Balanced Zen Linestage.
 
DOZ VS, NP ZEN AMP

I DESIGNED , BUILT AND TESTED THE DOZ AND THE NP ZEN. I LIKED RODS BETTER. I DESIGNED MY VERSION OF THIS AS A EMITTER FOLLOWER AFTER TRING THIS http://www.pha.inecnet.cz/macura/audiopage.html AND THIS AMP HERE > http://www.pha.inecnet.cz/macura/follower_e.html

THIS AMP WAS THE CLEAR WINNER IN HI-FI SOUND AND SIMPLICITY. MY DESIGN IS A FOLLOWER THAT USES MULTIPLE BIPOLAR TRANSISTORS FOR THE ACTIVE STAGE AND IT'S CURRENT SINK.THIS LOWERD COST OVER THE MOSFETS ,GIVES MUCH MORE THEMAL MARGIN , HANDLES HI SPEAKER CURRENT WITH BETTER LINEAR REPRODUCTION AND THE MY AMP DESIGN IS EASY TO SCALE TO HIGHER POWER AND STIL BE CLASS A , I SCALED MY TEST VERSION TO 60 WATTS = 17.78 DBW AT 8 OHMS, THUS GOOD BASS WAS NO PROBLEM. I USE ZERO GLOBAL FEEDBACK INSURING GOOD GROUP DELAY SPECS , LOW TIM ,LOW TIM , WIDE BANDWIDTH = OVER 40 KHZ . I USE 12 VDC FANS RUN AT 7 VDC RUN IN A COOLING TUNNEL FOR THE HEAT SINKS. I WAS ABLE TO USE MOSFETS AS A SUBTITUTE WITH JUST BIAS CHANGES DIALED IN . I'D LIKE TO DRIVE IT WITH A ZERO GLOBAL FEEDBACK TRANSFORMER LESS TUBE AMP AS A PRE AMP-DRIVER AMP WHERE MY POWER STAGE ACTS LIKE THE OUTPUT TRANSFORMER DOES IN A TUBE POWER AMP , THE DIFFERACES BEING : A MORE LINEAR LOW PHAZE SHIFT IMPEDANCE TRANCEFORMER .
THIS SHOULD BE MORE TRANSPARENT AND LET ONE A HEAR THE TUBE POWER AMP SOUND AND EXTEND TUBE LIFESPAN BECAUSE THE TUBES CAN BE RUN AT LOWER POWER DUE TO LACK OF CORE POWER LOSS AS SEEN IN THE OUTPUT TRANSFORMER .
I WILL BE DESIGN A LARGE SWING , ZERO GLOBAL FEEDBACK , LOW Z OUT SOLID STATE PRE AMP - DRIVER AMP 1ST ,,UNLESS SOMEONE HAS A GREAT INTEREST IN TUBE SOUND WANTS TO PARTENER IN THIS RESEARCH, E MAIL ME HERE >>

amps0001@aol.com

HAPPY LISTENNING ,,CRAIG A. FAWCETT C.E.T.
LIFTIME FCC 1ST CLASS LICENSE PG18-15024
TELEPHONE 773 531 5580 CHICAGO 60628 USA
 

Netlist

Ex-Moderator
2003-01-18 9:50 am
Hi Graig,
Thanks for the info.

We’d be happy to see you make use of the Shift-Lock key so your post would be more effortless to read. You might not know but in general, the use of all-caps would be considered as shouting which was certainly not your intention. :)

/Hugo
 

Nelson Pass

The one and only
Paid Member
2001-03-29 12:38 am
tschrama said:
It is not suitable for difficult loads, distortion is high, efficientcy low, bandwidth little low..

Now I happen to like the JLH very much, but I don't think the
comparison of a 3 stage Bipolar design to a single stage Mosfet
is particularly apt nor is it that accurate.

Three stages allows lots of open loop gain for feedback, a
resource that the Zens use very sparingly if at all.

You might as well compare DOZ to an Adcom GFA555, (which I
designed) where it would lose handily by your criteria.

High distortion? The DOZ is quoted as .2% @ 15 watts, while
ZV4 is .3% @ 10 watts. I don't see such a difference.

Low bandwidth? Some of these circuits are easily as fast as
the alternatives. I'm listening to one right now without
feedback which measures -1 dB at 100 KHz.

Don't forget that the Zen series is an exploration into what
can be done with maximum simplicity. I think it has
accomplished that goal, and there are yet more designs
waiting to be released.
 
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