Zvex - Nano Head

Papa_lazerous · Post by **Papa_lazerous** » 04 Oct 2007, 19:05

Does anyone wonder if there is any mis-information thrown in here......Me thinks so

Goop_buster · Post by **Goop_buster** » 04 Oct 2007, 19:09

radred wrote:
Goop_buster wrote:
radred wrote: ...The imp amp has even number pre-tubes + push pull output but
....
Actually, in each channel there's a dual opamp (in a configuration similar to that published in it's datasheet) acting simultaneously as a non-inverting pre-amp gainstage and an inverting follower thus acting as the phase splitter for the P-P stage made up of a single 6021.

I believe the heaters are running off a fullwave recto made of a pair of diodes soldered right to the heater pins...

I'm radred and I like zachary vex.

Oh I was under the impression that imp amp was advertised as an all tube amp and had a pre-stage with another 6021. But looking at a picture I see that you are right and that there is only one tube per channel.

A fun detail is that in the first imp amp video. they by mistake showed the complete schematic to prove no caps in the signal path. It was quickly taken away after a couple of days though

radred · Post by **radred** » 04 Oct 2007, 20:22

Goop_buster wrote:A fun detail is that in the first imp amp video. they by mistake showed the complete schematic to prove no caps in the signal path. It was quickly taken away after a couple of days though

Heh - yeah. I told him about that and he yanked it within minutes.

Good thing I saved a copy.

I'm radred and I still like zach vex.

bajaman · Post by **bajaman** » 04 Oct 2007, 20:31

Hi radred - care to share for everyone to see???
cheers
bajaman

Papa_lazerous · Post by **Papa_lazerous** » 04 Oct 2007, 21:04

They still show a little of the schem in the video though.....I didnt even consider for a second if it would be of any use though, if it where me I would have posted a nonsense schem in the video just fo kicks

Goop_buster · Post by **Goop_buster** » 04 Oct 2007, 22:34

Papa_lazerous wrote: I would have posted a nonsense schem in the video just fo kicks

Well that is completely possible

radred · Post by **radred** » 05 Oct 2007, 16:24

bajaman wrote:Hi radred - care to share for everyone to see???
cheers
bajaman

heh.. It's a 9Mb quicktime movie - I don't know where/how to upload...

I can send you an expressPCB file of my interpretation of it...

I'm radred and I like zach vex but he probably doesn't like me.

bajaman · Post by **bajaman** » 08 Oct 2007, 22:02

From what I have seen - it looks like vex was influenced by an earlier LXH2 design - he used EL84 tubes though

ALSO - the power supply is very conventional - NO SWITCHING MODE used

He uses two toroids - each with two 7v AC windings - that would give him the 40v DC needed for the op amp drivers

I don't know for sure what DC volts he runs his tubes off - I will have to take a look at the 6021 data sheet.
cheers
bajaman

Post by **modman** » 09 Oct 2007, 00:22

Never mind this:
-----
Admin:[/b][/u]
Moved some banter to the Catfight Thread in the member section
Chas Johnson was banned for insults (see forum rules & guidelines) until he is ready to apologize.. Please post aftermath discussion here

Please keep the discussion here on the subject at hand,
thanks for being so patient, I was Out For The Weekend

Post by **modman** » 09 Oct 2007, 08:52

Nevermind the bullock, back to business:

http://www.jjs.at/electronic/index.html

Brought up by Bumble here

Goop_buster · Post by **Goop_buster** » 09 Oct 2007, 10:18

bajaman wrote: ALSO - the power supply is very conventional - NO SWITCHING MODE used
bajaman

There was never any doubt about that regarding the imp amp. You can even read the text on the transformers in the video

. The imp is supposed to be a lot more hi-fi and it´s two output stages require a lot more current than the nano. You probably do not want a somewhat noisy fan in a small hi-fi amp. The imp is typically run in a home environment while you may possibly want to run the nano in the street or in a truck from a car battery.

Btw, the data page for 6021 got 165 or 180V as max on the plates but they sound a lot better above 200V. Nano use 230V

modman wrote:Nevermind the bullock, back to business:

http://www.jjs.at/electronic/index.html

Brought up by Bumble here

That power supply is quite close to what I use but also what I would never publish in a stomp forum. Short of the zeners there is little or not safety measures in that supply. If I was 12 and just starting out with electronics I know I would jump on a project like this for sure

and I do not think it is safe enough in the current state.

Goop_buster · Post by **Goop_buster** » 09 Oct 2007, 18:26

To papa

Have a look at this supply for general ideas. This is the design that I based my supply on.

http://www.ledsales.com.au/kits/nixie_supply.pdf

It is a bit strange that it is so similar to jjs design but obviously pure coincidence.

Adding heat monitoring/thermal shut down for safety should be a minimum though.

Papa_lazerous · Post by **Papa_lazerous** » 09 Oct 2007, 19:46

Goop_buster wrote:To papa

Have a look at this supply for general ideas. This is the design that I based my supply on.

http://www.ledsales.com.au/kits/nixie_supply.pdf

It is a bit strange that it is so similar to jjs design but obviously pure coincidence.

Adding heat monitoring/thermal shut down for safety should be a minimum though.

Thanks for the link Goop I saw the link in the othe forum, the power supply is already sorted for me, I am not relying on zeners for safety. I have a time delay of about 30-40 seconds so that the heaters can get all warm before HT is produced which is a nice feature and a thermal fuse to sto run away of HT if a tube goes bad. A slight variation on what I have seen elsewhere. And I thought of the nixie power supply idea a while back as I have done nixie projects

I spoke to jjs earlier he is a member here already but a lurker as yet. he has said he will post his amp in the Tube amp section. It will be cool to have such a cool member posting here

Papa_lazerous · Post by **Papa_lazerous** » 11 Oct 2007, 18:44

Output transformer turned up today at long last

Still waiting on a fwe other bits before I can build it. Problem being we had 2 48 hour postal strikes abck to back so everything is back logged

I got a question though.... When I build my switch mode power supply, does ti have to have a load across it even when testing? I am thinking it does.

Goop_buster · Post by **Goop_buster** » 11 Oct 2007, 18:48

Papa_lazerous wrote:Output transformer turned up today at long last Still waiting on a fwe other bits before I can build it. Problem being we had 2 48 hour postal strikes abck to back so everything is back logged

I got a question though.... When I build my switch mode power supply, does ti have to have a load across it even when testing? I am thinking it does.

Yes use a load resistor (calculate for about right amount of current) when testing and then remove it later.

Do not connect such a supply to any tubes before you know it is functioning properly

.

Papa_lazerous · Post by **Papa_lazerous** » 11 Oct 2007, 19:06

I figured I might have to do this, will have to do a little maths and see what this baby is gona draw current wise and have a little test. Dont worry I am not going to just breadboard it and slap the HT across the tubes. I will be having a little test of things to see everything is in order first

Goop_buster · Post by **Goop_buster** » 11 Oct 2007, 19:20

Papa_lazerous wrote:I figured I might have to do this, will have to do a little maths and see what this baby is gona draw current wise and have a little test. Dont worry I am not going to just breadboard it and slap the HT across the tubes. I will be having a little test of things to see everything is in order first

I think I used 15k which while testing which gives way to little current compared to the amp but enough to put some load there to recognize if there is some problems.

Papa_lazerous · Post by **Papa_lazerous** » 11 Oct 2007, 19:38

I was thinking and correct me if I am wrong that I will need to put at least the load of the amp on it to know that its going to behave..... I can do some testing before actually producing HT. like I can leave the switching transistor disconnected and check that I am getting oscillation at the desired frequency first then hook it up. It may pay to test at a lower level like you stated first to check there is no smoke but I think I need to prove it a little. I would like to be able to check the ripple with my scope but it only goes to 20Volts. was thinking of making a voltage devider up so I could do it though

Goop_buster · Post by **Goop_buster** » 11 Oct 2007, 20:27

Papa_lazerous wrote:I was thinking and correct me if I am wrong that I will need to put at least the load of the amp on it to know that its going to behave..... I can do some testing before actually producing HT. like I can leave the switching transistor disconnected and check that I am getting oscillation at the desired frequency first then hook it up. It may pay to test at a lower level like you stated first to check there is no smoke but I think I need to prove it a little. I would like to be able to check the ripple with my scope but it only goes to 20Volts. was thinking of making a voltage devider up so I could do it though

The total current consumption will depend on component values (cathode resistors etc).
If you are into spice I suggest searching for the 6021 model (there is one out there which is ok) instead of doing a lot of calculations

Papa_lazerous · Post by **Papa_lazerous** » 11 Oct 2007, 20:29

I really need to get into SPICE

I had a look at it a while ago and couldnt get into it, I dont know what the best version to try is.... I should definately give ti a try though.

I was the same with Eagle I didnt like th elook of it and went away and now I am into it and love it

Any spice advice apreciated certainly makes things safer and cheaper to try