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 Forum index » DIY Hardware and Software
"Crushed Glass" - Dual TUBE Oscillators
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frequencycentral



Joined: May 25, 2008
Posts: 186
Location: UK

PostPosted: Sun Oct 05, 2008 11:08 am    Post subject: "Crushed Glass" - Dual TUBE Oscillators Reply with quote  Mark this post and the followings unread

I put this noisy little MF together a couple of weeks ago on the breadboard. It seems to be getting a bit of interest elsewhere so I thought I'd start a thread for it. It uses the application of low-frequency feedback oscillation (motorboating) to create two pulse oscillators with roughly a 25% duty cycle. The top osc is LF, the bottom one HF. Not a perfect device by any means, but fun and capable of making an unholy racket. I used two 6111 submini tubes, but it should work fine with 12AU7, possible 12AT7 and 12AX7 too - just change the pinouts and power the heaters correctly. I breadboarded it, recorded it, drew up the schemo then took it apart. I made it up again from the schemo a week later just to check it wasn't a fluke! I expect it would benefit from a buffer at the output. The pots don't work across the entire range. It would be cool to use a joystick instead of pots, and possibly feed the two osc into a ring mod. Fully open for hacking, development and general ear abuse. Oh, and if you do build it you're as crazy as me!

Soundclip: http://www.aronnelson.com/DIYFiles/up/Crushed_Glass_Sample.mp3

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jnuaury



Joined: Feb 28, 2008
Posts: 162
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PostPosted: Sun Oct 05, 2008 2:15 pm    Post subject: Reply with quote  Mark this post and the followings unread

ive been looking for some simple low voltage tube circuits....

thanks

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ENDIF



Joined: Jul 14, 2006
Posts: 138
Location: Reno, NV

PostPosted: Mon Oct 06, 2008 7:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

Sweet baby jeebus yes.
This goes on the list. =]

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oscilloclast



Joined: Sep 29, 2005
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Location: VA

PostPosted: Wed Oct 08, 2008 2:27 pm    Post subject: Reply with quote  Mark this post and the followings unread

Great! more tube noisemakers, seems to be a lot of unexplored territory here. I have a few questions for you:

1. Any guess on how much power this would take, mainly talking about the two filaments (not sure if they glow in this circuit or not). would 200 - 300 MA be good?

2. What wattage should the resistors be?

3. Should there be a resistor in series with the filaments? If so what wattage and resistance value?

4. You mentioned a buffer stage, any recommendations on how to build that?

5. You also mentioned ring moding the outputs, any recommendations on how to build that?

Thanks again,
David
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frequencycentral



Joined: May 25, 2008
Posts: 186
Location: UK

PostPosted: Wed Oct 08, 2008 3:40 pm    Post subject: Reply with quote  Mark this post and the followings unread

1. I run it from a 12 volt 500ma regulated wallwart. Yes they glow a nice orange!

2. Any resistors will do - there is no requirement for high wattage.

3. No resistor needed there.

4. Any buffer really - opamp, transistor or another tube.

5. It would be fun to run each oscillator into the x and y inputs of a ring mod. I'm working on a low voltage tube ring mod - give me some time! Until that time - any ring mod would do.

have fun!

Rick

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Mubo



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PostPosted: Mon Nov 24, 2008 3:22 pm    Post subject: tube osc question Reply with quote  Mark this post and the followings unread

please excuse my ignorance...
but can you explain the bit with the 12v+ to pins 3&6??

this this is wicked! ... i have been looking for a simple tube project to get a lil experience and this one looks and sounds PERFECT!

im totally gonna do the joystick interface...got one sittin on the bench i picked up at the flea market just last weekend!

thank for the help....

-Rik
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frequencycentral



Joined: May 25, 2008
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PostPosted: Mon Nov 24, 2008 3:39 pm    Post subject: Re: tube osc question Reply with quote  Mark this post and the followings unread

Mubo wrote:
please excuse my ignorance...
but can you explain the bit with the 12v+ to pins 3&6??
-Rik


The two tubes I used, submini 6111, have a heater voltage requirement of 6.3 volts. So I'm running the two heaters of the two tubes in series from a 12 volt supply, so each heater gets the 6 volts it requires. Well within the heater tolerance.

It should be possible to get the same action out of 12au7 tubes if you can't get hold of 6111, just power the heaters at 12 volts each. 6111 are easy to find on ebay though.

I should stress that this circuit is not a precision device - but a lot of fun. I have no doubt that it could be improved. Maybe worth breadboarding and experimenting with a little!

Have fun......Rick

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Mubo



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PostPosted: Tue Nov 25, 2008 8:40 am    Post subject: Reply with quote  Mark this post and the followings unread

thanks rick!

hey... do i need sockets for those things?...or is that more of an ease of use thing?

how sure are ya that the 12au7 tubes will work?

i might build with both just to listen for a difference.... but the 12au7 tubes are like $10 for 4 on ebay....so that might be a good place for me to start.

when you commented about this not being a precision piece... did you mean the tuning of the osc. ? or am i risking explosion! Wink

anyway.. thanks for helping a toob out HAHAHHAHA noob at tubes.... hahahhah -- OK not that funny!

=Rik
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frequencycentral



Joined: May 25, 2008
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PostPosted: Tue Nov 25, 2008 10:11 am    Post subject: Reply with quote  Mark this post and the followings unread

You can buy sockets for submini tubes, but they have long flexible legs and are easy to solder.

I cannot guarantee it will work with 12au7 - but I'm pretty sure that it should. You would need to look at the data sheet and change the pinouts.

As for the precision thing - this is a raw noisemaker rather than a refined modular circuit. Dont expect stability. It wont explode though!

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Mubo



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PostPosted: Tue Nov 25, 2008 10:17 am    Post subject: Reply with quote  Mark this post and the followings unread

cool ... 'll go for the mini's then seeing as it's my 1st tube project

thanks again man!

i checked out your myspace pages... good stuff!

gotta admit, little jealous of your electro know how!

thanks for sharing
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frequencycentral



Joined: May 25, 2008
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PostPosted: Tue Nov 25, 2008 11:26 am    Post subject: Reply with quote  Mark this post and the followings unread

Mubo wrote:
i checked out your myspace pages... good stuff!


Cool - thanks!

Mubo wrote:
gotta admit, little jealous of your electro know how!


You would be amazed at how little I think I know! I'm just learning. And breadboarding. And learning. And breadboarding. And learning. And breadboarding.....................................

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Mubo



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PostPosted: Wed Nov 26, 2008 2:18 pm    Post subject: Reply with quote  Mark this post and the followings unread

ordered my tubes and waiting not so paitently!

you mentioned a possible benefit from a buffer... what exactly would that do for the circuit?... like how would it benefit from it?

thanks

-Rik
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frequencycentral



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PostPosted: Wed Nov 26, 2008 2:52 pm    Post subject: Reply with quote  Mark this post and the followings unread

Mubo wrote:
ordered my tubes and waiting not so paitently!

you mentioned a possible benefit from a buffer... what exactly would that do for the circuit?... like how would it benefit from it?

thanks

-Rik


Hey Rik - nice haircut by the way - nice Juno too. I've ALWAYS had a Juno since they first came out. I've had most incarnations - the 60 being my fave.

I tested the circuit through both a guitar amp and a studio setup. Different sounds happened with the guitar amp which I couldn't get when plugged into my studio. You could try a single opamp unity gain buffer at the output of each oscillator, then mix the two into a summing opamp. Experiments needed! Then again, maybe its the unbuffered intermodulation which makes it interesting!

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Mubo



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PostPosted: Wed Nov 26, 2008 2:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

was the audio clip from the studio or the guitar amp?

and yes.. i too love the junos!
both of the ones i have are original purchases from back in the good ol' days!

im looking forward to pumping this tube osc thru my ms-10...should prove interesting.

as far as experimenting... well im more of a kit builder or schematic builder than an experimenter ... but im getting there
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frequencycentral



Joined: May 25, 2008
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PostPosted: Wed Nov 26, 2008 3:03 pm    Post subject: Reply with quote  Mark this post and the followings unread

Mubo wrote:
was the audio clip from the studio or the guitar amp?

and yes.. i too love the junos!
both of the ones i have are original purchases from back in the good ol' days!

im looking forward to pumping this tube osc thru my ms-10...should prove interesting.

as far as experimenting... well im more of a kit builder or schematic builder than an experimenter ... but im getting there


The clip was Behringer Mixer > Echo Gina 24 > Wavelab.

+1 to the MS10, I've had the whole series of them too. I sold my MS20/MS50/SQ10 when I bought my Roland 100m. Made the Korg stuff seem really cheap.

Did you see the tube VCF thread? Might go nice with Crushed Glass! I've got the tubes, just thought I'd design my own multimode version - breadboarding!

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Lofi Ninja



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PostPosted: Mon Dec 01, 2008 4:45 am    Post subject: Reply with quote  Mark this post and the followings unread

I have two Ecc81 tubes that I wish to use for this awesome sounding device! I just don't know how to modify the schematic for them.. Sad I can't find the pinouts for the tubes that you used, so.... And i don't know general tube diagrams Sad Please help me out Cool

Btw, here's the datasheet for my tubes:http://www.drtube.com/datasheets/ecc81-philips1969.pdf

Ok, I've just been looking it over, and I think I may got it.. Can someone verify this. First row of numbers is the 6111... Also is there any components that need changing ?

1->1
2->2
3->4
4->3
5->8
6->5
7->7
8->6
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frequencycentral



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PostPosted: Mon Dec 01, 2008 10:08 am    Post subject: Reply with quote  Mark this post and the followings unread

ECC81 = 6111

Pin 1 Pin 1 Plate
Pin 2 Pin 2 Grid
Pin 3 Pin 4 Cathode
Pin 4 Pin 6 Heater ground
Pin 5 Pin 3 Heater +ve
Pin 6 Pin 8 Plate
Pin 7 Pin 7 Grid
Pin 8 Pin 5 Cathode
Pin 9 ----- No connection.

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Lofi Ninja



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PostPosted: Mon Dec 01, 2008 10:26 am    Post subject: Reply with quote  Mark this post and the followings unread

frequencycentral wrote:
ECC81 = 6111

Pin 1 Pin 1 Plate
Pin 2 Pin 2 Grid
Pin 3 Pin 4 Cathode
Pin 4 Pin 6 Heater ground
Pin 5 Pin 3 Heater +ve
Pin 6 Pin 8 Plate
Pin 7 Pin 7 Grid
Pin 8 Pin 5 Cathode
Pin 9 ----- No connection.


Thank you VERY much ! I know what I'll be doing today!

Aargh shit.. The pinout is it when you look at the bottom or from the top ?

Uhh, I got distracted abit, but now I got the parts gathered.. On with the build Razz

Last edited by Lofi Ninja on Mon Dec 01, 2008 3:18 pm; edited 2 times in total
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frequencycentral



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PostPosted: Mon Dec 01, 2008 10:52 am    Post subject: Reply with quote  Mark this post and the followings unread

No problem - just bear in mind that each ECC81 heater wants 12 volts across it, rather than the 6 volts that the tubes I used required.

Good luck - have fun! Please report your results!

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Lofi Ninja



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PostPosted: Tue Dec 02, 2008 9:12 am    Post subject: Reply with quote  Mark this post and the followings unread

Ok I finished it..

I have glow.
I have oscillation.

I have problems Sad

I have a serious ground humm.

Depending on which tube I put in which socket, I have good sounding, controllable (on one of them) oscillation, and if I touch the legs of the other pot I can hear both oscillators. Yes, that's right, it seems like one of my tubes are bad ? Be cause if i don't touch the legs of that pot to that tube, I can not hear it.. But if i switch the tubes around I only have very faint oscillation. Maybe it's the components ? I don't know.. I guess I need to try some different caps..

Also I'm using 2 wallwarts. One for the heaters and one for the rest.

Power is supplied in parralel for the heaters.
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frequencycentral



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PostPosted: Tue Dec 02, 2008 10:54 am    Post subject: Reply with quote  Mark this post and the followings unread

Great that you have oscillation and glow!

Shame you have hum though!

I would guess that the hum is almost certainly due to the power supply. I've built quite a few tubes effects, as have other members of Aron's DIY Stompbox forum. When anyone reports hum it's almost always due to a cheapo wallwart. Tubes like a good quality filtered/regulated supply.

What you could try is using a 7812 voltage regulator between the supplay and the circuit. And a 100uf electro cap between +ve and ground to smooth things out.

I'm not sure why you're using two wallwarts? One should do the job. It's the tube heaters that draw most of the current, the plates themselves draw relatively little. A single 12 volt 500ma wallwart should work out fine.

Hey - good that it's working though! Just a hum issue to debug. Does it sound suitably crazy?

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Lofi Ninja



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PostPosted: Tue Dec 02, 2008 11:07 am    Post subject: Reply with quote  Mark this post and the followings unread

Ok, I will try your suggestions.. Actually I don't know why I used two.. You know, thats just one of those odd things you can't explain, that happens when you build..
Also the wallwarts are variable ones, but good quality ones..

Yes it certainly sounds fking wicked when it's happy...

Btw. These tubes are ~ 60-70 years old.. I pulled them from a "Radiometer Copenhagen RV23d Vaccum Tube Voltmeter"

Update: I fixed it so it's only using one wallwart, and I put a 100 uf cap on it.. The ground humm is gone ! Nice Very Happy
But theres still the "only 1 oscillator working" problem.. It appears not to be a tube problem, although one deffenetly works better than the other. The problem is on the channel with a 10 uf cap on the output. It simply won't oscillate (atleast not in the audible range).. I've tried replacing the electrolyte with 1 uf electrolyte and .1 - .01 - .047 ceramics but no cigar..

As I did not have 100K ohm linear pot's I'm using 1M ohm linear.. I will try and change them when I get a chance, but I doubt that is the problem..

Also I'm not using shielded wires.. Should I ?

Update 2: I changed the pot on the non working "channel" and it actually made a difference, very small thou. New pot is 100K, but I'm unsure if it's lin or log.

Just for kicks I tried the other tubes I have, the markings are gone so I don't know what they are. One actually worked better than the less working ECC81 Shocked I have no clue to the pinout or type, but something must be right. It got VERY hot so I will try again tomorrow, feeding the heaters 6 instead of 12 V. Unfortunately I still can't get the distinct two osc sound.. They just kind of have the same freq. Sad

I will make some sound samples if anyone's interested ?

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Mubo



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PostPosted: Tue Dec 02, 2008 4:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

my tubes are on the way!!!
im stoked someone else jumped on board too!

i also got tubes to make the VCF... woohooo!!!!!!!

keep ya posted
-Rik
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Mubo



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PostPosted: Mon Dec 15, 2008 1:45 pm    Post subject: Reply with quote  Mark this post and the followings unread

hey rick ...
got my tubes... missing a few caps..

dont have a 120pf handy (got a 100pf)
also no 1uf in my bin ....

any suggestions on replacement values?

thanks
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frequencycentral



Joined: May 25, 2008
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PostPosted: Mon Dec 15, 2008 3:09 pm    Post subject: Reply with quote  Mark this post and the followings unread

I wouldn't worry too much about absolute values - just use the closest you have. If you can socket the caps you can play about with the values.

The 100pf will be fine.

For the 1uf you could use anything from 0.1 to 22uf really!

Like I said earlier - not a precision device!

Have fun with your build - and post someclips!

Rick

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