Zen v.5 - the 'complimentary amp

[andrew Ivimey]

What I have been playing with all week then is a version of Zen5.

I bought two mono amp kits from an EBay HongKong company - they were about £40 each. High quality components - how do they get them so cheap over there!? I costed out the bits and thought why not, there isn't much difference and they supply the PCBs too.

Minimal instructions that I had to ask for and they tell me very very little.

It is a Mk2 version of their Zen 'passion' amp (gedditt, oh dear!). The Mk1 was more complicated (than original Zen5). This one is simpler. The company, AnalogMetric, are in the same building as 'NXT' in Kowloon so next time I'm over there I might pop in when I visit bro-in-law.

AnalogMetric also have a website BB to discuss valve amps and their kits. Building a Mattisse Fantasy modified pre-amp looks easy if you are that way inclined.

Anyway back to Zen5. Trust me to start with this one, yes, but I am doing a heavy number on PP amps. Zen5 sounds as much like a Quad303 as ... an amplifier that sounds utterly unlike a Quad303, so I won't mention it again.

I looked at all the bits - not many - stuck them in the PCB and thought long and hard about what was to happen, where and how, added a toridd 18.0.0.18 and connected meters to output and both voltage rails to 'zero' dc offset and set the amps' static currents.

The design includes a simple split voltage PSU on the PCB - very much simplified compared to Mr Pass' original circuit.

One of the mono amps does what it should easily. The other does not. So I can have 0volts dc on the output (or a few volts neg. or positive!) but I can't set the voltage rails as I should. There shoudl be a 1volt imbalance. I haven't a clue why one amp won't do what it ought as there is so little that could go wrong and the amplifier still work.

I have one 4.4amp per winding toroid and one 3.33amp toroid. It doesn't seem to matter. The heatsinks get slightly warm after a couple of hours.

Connected up to (208sigmas with Heils on tops) speakers the sound is clear and pleasant - Why did I expect dead loud and punchy? A 2A3LW is much louder than this but... having cranked up the input to max it is quite loud enough thankyou without sharing subtle bits with the neighbours, though.

So I guess it is working nearly as it should. My T-amp is no louder and I think I prefer Zen5 ... today.

I will pursue the oddity of one channel/amp and I wonder about max. and minimum voltage and how much current the PSU could supply and how much the amp would use before melting in this winter sunshine we are enjoying.

The schematic I have is in .pdf format if anyone wants a peek.

[andrew Ivimey]

just thought ..... this should be in 'solid state'.

Nick, if you want to move it, that's fine.

[Paul Barker]

What is it's purpose in your home?

[andrew Ivimey]

1. Paul, where do you get those emoticons from - I love them!

2. a) I have never done anything with Mosfets before.
b) I am not so much looking for 'the best' so just extending the range
of 'different'. There were e.g. gainclones - not impressed. T-amps,
initially impressed.
c) I can hope to find some magic.
d) Nelson Pass has done some impressive stuff over the years.
e) Zen etc is worth looking at as a concepual thing.
f) size - WAF
g) there is no 'g'
h) (in vain) I am trying to use up stuff in the 'spares box' this is a
concept thing too but because it seems that for every one thing in
the spares box I use, I still buy at least three new things to use
with the one thing out of the box.
Definitely not Zen - who am I kidding?
i) It could be better than e.g. sex amp.
j) I like building amplifiers.

for now

[Paul Barker]

1. Paul, where do you get those emoticons from - I love them!

2. a) I have never done anything with Mosfets before.
b) I am not so much looking for 'the best' so just extending the range
of 'different'. There were e.g. gainclones - not impressed. T-amps,
initially impressed.
c) I can hope to find some magic.
d) Nelson Pass has done some impressive stuff over the years.
e) Zen etc is worth looking at as a concepual thing.
f) size - WAF
g) there is no 'g'
h) (in vain) I am trying to use up stuff in the 'spares box' this is a
concept thing too but because it seems that for every one thing in
the spares box I use, I still buy at least three new things to use
with the one thing out of the box.
Definitely not Zen - who am I kidding?
i) It could be better than e.g. sex amp.
j) I like building amplifiers.

for now

[andrew Ivimey]

re:- 2(a)

I am still waiting to use mosfets in 'Amity'. Amity has not been behaving itself. Amity MK2 goes on mdf board and is to be subject to the serious clip lead and meters, scoping and sorting out. I will get round to CCS with mosfets eventually.



Ah, I see!

[Nick]

Oh dear, they fiound the extra one I instagged

[ed]

Nick

you been dripping vodka into your keyboard again???

Andrew

Anyway back to Zen5. Trust me to start with this one, yes, but I am doing a heavy number on PP amps. Zen5 sounds as much like a Quad303 as ... an amplifier that sounds utterly unlike a Quad303, so I won't mention it again.

Half in jest, but with my pedant hat firmly on my head, The passion 150 is not a zen, 5 or otherwise.

If I built a 2 stage 300b with silver opts and called it ongaku there would be a few complaints......such is what you have there.

The passion 150 has a similar topology to a zen but it is only similar and uses different devices........

I seem to have adopted the hat of champion for the absent again.....but it would be imprudent to criticise zen if your passion fails to give the required orgasm...

[andrew Ivimey]

Ed, pedant or not - that's okay.

Zen has spawned an army of adherents and an industry of spin-offs.

(loads of friends all over the world .... none here' - anybody recognise this quote? )

Similar topology and many corners cut N.B. the PSU, so fine to what you say.

I'd dearly like to be able to pop in and give yours a dead good listen to but Hull is a long way away. I looked for sources of components and asked you for suggestions and help but ...

On my own, down here, I cut corners too - not a complete waste of time.

[ed]

Sorry Andrew, wasn't meant to be contentious at all....

if you pm me your email addy I will post you the entire zen tutorial....I would post a link but the entire passlabs site seems to be down at the moment and I don't have the precise link for the zen history.

The tutorial is an absolute must if you are in the least bit curious about mosfets....

in a nutshell zen is the undergrad course and firstwatt is the polished product

[Nick]

If I built a 2 stage 300b with silver opts and called it ongaku there would be a few complaints......such is what you have there.

Well ANote UK have built a interstage coupled 211 amp and called it Ongaku, about as different from the original as the 300b amp .[/quote]

[andrew Ivimey]

phffffffffffffffffffrrrrrrrrrrroarwhooooooooaaaaaarrrrrrrrrrrrrrrrrrrrrr!

I've added four valves to add a serious slug of voltage to the input. The amp is frighteningly loud. It sounds immensely clear and clean.

I will continue with this amp. It could be very good indeed or... it could be just another SSamp.

But I don't remember hearing any SS amp like this. But(2) I haven't ever put an SS amp through single driver horns.

[pre65]

phffffffffffffffffffrrrrrrrrrrroarwhooooooooaaaaaarrrrrrrrrrrrrrrrrrrrrr!

I've added four valves to add a serious slug of voltage to the input. The amp is frighteningly loud. It sounds immensely clear and clean.

I will continue with this amp. It could be very good indeed or... it could be just another SSamp.

But I don't remember hearing any SS amp like this. But(2) I haven't ever put an SS amp through single driver horns.

Might try my old QED A240 on the Fostex later !

As you said,never tried it before.Might even try my T amp if i remember where it is !!!

[andrew Ivimey]

nope you can keep your T-amp.

This is better than that.

Kate Bush to Metallica to Shostakovich tonight.

[pre65]

Are all T amps equal ?

I think mine is a Charlease (?)