Zvex - Nano Head

Evz · Post by **Evz** » 10 Jun 2009, 19:29

Thanks for all the info, it might be a while before i start the project, but i'll be sure to keep it up to date.. will probably start a thread for it, ill start ordering components soon and ill make a layout.. hopefully for one pcb for the a class, will keep you guys posted!

Evz · Post by **Evz** » 10 Jun 2009, 19:43

sorry for double posting, while on the topic of the jjs, any ideas where to mod it? ei.. volume/gain placement... tone control variants? or should i start a new thread for it?

charlietheunicorn · Post by **charlietheunicorn** » 17 Aug 2009, 12:33

Hi,

i heard the ECC 81 tubes should fit ... is this right? I dont get 6021W tubes really easy, and for me its not so important that the tubes are sub mini type. So what you are thinking about this?

frequencycentral · Post by **frequencycentral** » 17 Aug 2009, 12:53

If you're not using submini tubes maybe you should look at Doug Hammond's Firefly design.

ECC81 is a very low mu tube, lower than 6021 and 12AU7 for example.

charlietheunicorn · Post by **charlietheunicorn** » 17 Aug 2009, 17:32

the problem is, i dont get sub mini tubes very easy, so i try the ecc 81 and post my experience with them when i finished my special nano head

charlietheunicorn · Post by **charlietheunicorn** » 10 Sep 2009, 13:21

HI,

i finished my ecc81 /12at7 nano head and it works with a huge problem. there is always a noise like in the fuzz factory, the frequency of this noise is changing with switching of the treble, bass and brightness switches or turning the gain pot. so i measured the alternate voltage first ... 80 mV on the high voltage side, i dont think this is the problem.The circuits are 100% right, the switches and the gain knob is doing the right things, except this terrible noise. I grounded everything, the tubes are shielded, but the noise isnt gone. i must say, i used the voltage supply from JJ's Class A subminiatur project, not the Nixie.
Andy ideas to solve the problem? Thats my first tube project, im happy that i have come so far.

frequencycentral · Post by **frequencycentral** » 10 Sep 2009, 16:58

Your unwanted noise, is it whining or humming? There are a few things it could be:

- The ampreage of the power supply? JJS: "The wallwart must be capable of sourcing 1 A of continuous current. Peak current may well be a lot higher."

- The amperage rating of the inductor you're using. JJS uses 0.5A

- The heat dissipation from the IRF740. Is it adequetely heatsinked with thermally conductive gel between the IRF740 and the heatsink?

Have you checked the voltage output of the SMPS? The voltage in that particular SMPS is only held in check from running away by the three zeners D4, D5 and D6. The higher the voltage output, the more ma the SMPS will need to draw, and the hotter the IRF740 will get. The other nixie SMPS JJS links to uses a BC547 and a 1K trimmer to momentarily switch off the 555 at whatever voltage you dial in on the trimmer, it's a 'governer' - a lot more flexible IMO. You might also try a snubber to filter out any high frequency content from the SMPS

charlietheunicorn · Post by **charlietheunicorn** » 10 Sep 2009, 18:02

hi, thanks for your help! the sound is more whining, but in some switch positions also humming. the frequency changes when i get contact to some capacitors, especially the capasitors on the high and low end switches, also when i have the tubes unshielded. The Nano head is built in a 8 inch speaker cabinet, i will test the Nixie or a Hammond 269EX. The inductor is a 77A High current suppression coil 3,3mH, it was the only one i got with such a high inductivity. the IRF hasnt got a heatsink, in my opinion it wasnt needed because he's getting only 30 - 40 °C. The Weekend isnt booked out, so i will go on.

ansil · Post by **ansil** » 29 Sep 2009, 21:49

frequencycentral wrote:If you're not using submini tubes maybe you should look at Doug Hammond's Firefly design.

ECC81 is a very low mu tube, lower than 6021 and 12AU7 for example.

sorry to bother you but an ecc81 is a 12at7 with a mu of around 60 roughly the same as the 6021 a 12ax7 of around 100 ish 12au7 around 20 based of an average datasheet spec's and no load

cheers

svz · Post by **svz** » 31 Jan 2010, 10:02

Hi guys,
I've got recently some problem with the "gain" pot in my Nano head. Unfortunely I can't find this pot's value on schematic given above here (https://www.freestompboxes.org/viewtopic ... =40#p55083).
Maybe You know what is the value of this pot (500k?), cause after screwing the body off I saw just "Alpha" written on this pot which stands for the company of it. Or I wonder, if someone of You replaced by yourself this pot?
The reason I want to do it are scratches, cracks and disfunction during its usage.
Cheers

JiM · Post by **JiM** » 31 Jan 2010, 12:16

svz wrote:I've got recently some problem with the "gain" pot in my Nano head. Unfortunely I can't find this pot's value on schematic given above here (https://www.freestompboxes.org/viewtopic ... =40#p55083).
Maybe You know what is the value of this pot (500k?)

It's written on the Bill Of Materials next to it.
https://www.freestompboxes.org/download/ ... &mode=view

svz · Post by **svz** » 01 Feb 2010, 07:40

JiM wrote: It's written on the Bill Of Materials next to it.
https://www.freestompboxes.org/download/ ... &mode=view

Thanks for info

teleted · Post by **teleted** » 08 Feb 2010, 10:19

Thank you very much for the circuit!!
I build one myself with not exact the same parts but it`s just amazing sounding little amp!
I used 6922 tubes and experimented with the powersupply wich i can easy do because i got an old Roband Electronis powersupply.
Its not completely finished but so far so good!

Grt. Teds Tube Amps.

dimi3 · Post by **dimi3** » 09 Feb 2010, 16:55

helo,

I'm new to forum and i'm interested in mini amp's, I will give a try to couple of designs, is someone build this amp succesfuly from existing schematic?

Wold be any interese here to do a proper PCB layout of the schematic? like a "group" project? I can do schematic in EAGLE, but I would need some help with the board layout or at least review.

But the first step would be to redraw schematic (if someone done it already please let me know

), existing design uses proper power supply, we could implement some proven designs SMPS as power supply, better than original, and pack it to small enclosure.

If someone is interested let me know and if you are willing to help also

regards,

rasta_maleek · Post by **rasta_maleek** » 30 May 2010, 07:54

hi all, i made some mini jj´s amp and its sound awesome, i recomend this proyect.
look at this video, epi zakk wylde-krank distortus clon-zombie chorus-delay-mini jj´s

jeaniturrizaga · Post by **jeaniturrizaga** » 02 Sep 2010, 16:56

Hi there, I think that my first post didn't go thru, I'm trying to get the resistors and caps to build this little amp. I tryed mouser and digikey but there are so many choices between tolerance, power rating(watts), volts, packing (ammo, bulk, reel etc) , size, temperature, etc is there a standard for guitar amps?, even better does any one has the codes to buy this items from the websides I mentioned or any other webside with decent prices, thanks guys..

ansil · Post by **ansil** » 03 Sep 2010, 03:03

general rule of thumb tube amps half watt for high voltage. ss 1/4watt for basic preamp stuff.

bass_ennyday · Post by **bass_ennyday** » 03 Sep 2010, 12:13

Great project again!

As far i as understad the Nano Head is an guitar amp only ... possible to modify the circuit so a bass amp turns out?

ansil · Post by **ansil** » 18 Sep 2010, 08:12

yes quite easy but it just doesn't have the output so it wouldn't be bad but its would depend on the user. its easy to build many amps take the preamp of an ampeg svt and build a small output section to tack on the end of it.

marakesh · Post by **marakesh** » 27 Sep 2010, 07:02

hi, i've got problems with power supply. does nixie power supply and hammond 269ex work fine in zvex clone with 220-230 VAC or only with 120?