Amp-like layout for Tube Tremolo

[Pushtone]

Here is a layout I'm working on for the Bullitt Tube Tremolo by Andrew, The Tone God.
http://www.geocities.com/thetonegod/bullitt/bullitt.html

I want to build this, verify it and post the layout in a pdf file for others.
But I would appreciate any feedback on the layout as it is now.
I'm planning on using the GGG ultra clean power supply to generate the 12VDC but power supply suggestions are welcome too.


The concept is a build on perfboard that resembles a tube amp turret board with the pots on one side and the tubes on the other.
The board is 4 and 1/8 inches wide and is a comfortable fit in a 1790N enclosure with the tubes sticking out the top.
I tried a 1590BB but with the tubes and seven pots I could not find a pleasing configuration. So the box is set, 1790N it will be.

Thanks in advance for having a look.
Stay tunned to this thread for a build report and pics.

[Pushtone]

Perhaps a link to Andrews introduction thread will generate some opinions about my layout.

Many were excited when Andrew posted the schematic, yet only Donald Stringer has built it and reported back.

New Effect - Bullitt Tube Tremolo:
http://www.diystompboxes.com/smfforum/index.php?topic=44877.0

[John Lyons]

My concern would be that the layout would have some "lead dress" issues with:
The long run from the first grid of V1 across all the other wires to the right side of the board. Shielding it would help but it's a band-aid.

You could tighten up the left side of the board a good bit but if it fits in a 1790 already then it's not a big deal.
I wouldn't use the chassis as a ground point for all those pots.

I think I would separate the tube section and components one one area of the board and then build the Op amp and oscillator on another section. Keeping ticking out of the signal will require separate ground paths and power as well.

Of the top of my head this is what I think...
I'd love to hear this in action.



John

[soulsonic]

I read through the thread and looked at the project page on ToneGod's site and I have a couple questions regarding how it works. Why are the 1M grid return resistors referenced to the output of U1A rather than ground? From what I can gather from the schematic, it appears that U1A is configured as a buffer providing a DC voltage from the voltage divider network of R1/R2. Is this a fancy way of biasing the tubes? Is this large amount of positive bias voltage intended to help overcome the limitations of operating the tubes at such a low voltage?

As far as the layout goes... I would arrange it differently. I would make a point of having the oscillator off in it's own area, and I would move the tone stack components to the area of the board where the oscillator currently resides.

[Pushtone]

My concern would be that the layout would have some "lead dress" issues with:
The long run from the first grid of V1 across all the other wires to the right side of the board. Shielding it would help but it's a band-aid.

Thanks John,

Its hard to see with the resistors stacked onto the tube socket but that long wire that crosses the others is from pin-1, the anode.
The grid has a short wire straight from the board to pin-2. In the image pin-1 looks like pin-2.

Here is a larger pic with better detail but its 270k so I didn't post it originally.

However, the wire from the treble pot to pin-7 does have a long path.  I'm not sure if there is a way to fix that but it should be a non-issue because the way I'm laying out the box, the treble pot will be right next to the tube socket. I'll shield it too.

I'll re-do the layout so the LFO has a separate ground path. I can put up with a little hum but not ticking. 
As far as I can see there is separate power paths to the LFO and the tubes. Am I missing something in the DC power?
My first attempt was to include the power supply on the board but I abandoned that idea and just went with the GGG ultra clean supply.
Mostly because I have one that I'm not using. Do you think thats a sound plan?


Thanks Soulsonic,

I'll have to leave your questions to Andrew for an answer. 
I'll try sliding the tone stack over to the other side and compare the wire runs.
I'm thinking now the board should ONLY be the LFO and I should hang the tone stack off the pot lugs.

[soulsonic]

......I should hang the tone stack off the pot lugs.

If it were in an amp, I would use a terminal strip to anchor one end of the components so they're not hanging free - that's worked well for me before. But since it's in a stompbox, that might not be totally feasible.

[Pushtone]

Here is the 1790N enclosure layout.

Something about a pedal with tubes sticking out of it just seems cool to me.
I've been wanting to do one with a roll bar like I've seen from other builders.
It's a drawer pull from the hardware store.

The gain pot to grid pin-2 and treble pot to grid pin-7 have a clear and short path.

[Pushtone]

Here is an updated layout (430k pdf file).


Really all that has changed is separating the LFO ground from the tube grounds.
And the pot grounds from the chassis as suggested.

The way it fits into the enclosure the tone stack works where it is.


I'm not sure if I understand John's comment about separating the power feeding the LFO.
I though I had done that. Is there a better way to decouple the power to the LFO?

I finished the power supply tonight and hope to start this soon.
BTW, I'm using the GGG ultra clean power supply at 12VDC for this.

[John Lyons]

That looks good Dave. The grounds and +voltages are coming straight form the power supply for the tube and Oscillatior sections.

Hanging the resistors off the tube sockets is my only other concern. For a tube amp I'd install a terminal strip and wire the free ends to it but in a pedal there isn't going to be space. Maybe shrink wrap and some hot glue to get them stuck down would be ok.

Looking good.

John

[Pushtone]

Finished the perfboard circuit build.
It turned out just as I imagined, like a tiny turret amp board. Hence the "amp-like" layout in the subject line.



The mini-turrets are the pins from a machine DIP socket.
Pots will be to the right and tubes to the left.




Found an error in the layout and made a new pdf. The link above is now dead.
Here is the new one.

[soulsonic]

That looks cool.

[cheeb]

The link doesn't work for me.

[Papa_lazerous]

doesnt work for me either   its the old 404.....

[Pushtone]

Here it is.
LINK

Needs a little tweaking for the pot lugs.
As is now the LEVEL and DEPTH pots work backwards. Same issue is shown on Andrews schematic.
The bypass switch is not included in the layout.

Also, there is strong interaction between the tone controls and the depth pot.
Changing the tone controls, particularly the bass, effects the depth.
Not a big deal since its natural to set the tone of the preamp first, before engaging the tremolo.
Why this happens I can not even begin to guess. The LFO and audio signal look to be quite separate in the schem.
Perhaps we can put our heads together on that one.

I plan on fixing this layout and writing a build report.

Now that I've built it I would have to say it's a more of a cool "tube" project for someone wanting to build something with tubes
than it is a great tremolo project. An EA Trem would be way easier and a Lune would be more flexible.
The appeal lies in the tubes, and for me, making them stick out the top.

[puretube]

_

[Pushtone]

Thanks for the link back to the PICTURES thread PT.
Since that photo I added some shielded wires and put a heat-sink on the PSU regulator.

Here are a couple more build pics

Flush tube socket








GGG Ultra Clean Power Supply with 16VAC wall wart to yield VCC at 12VDC
As you can see I hit 12.01VDC using...
r1a = 270R
r1b = 2k7
r2a = 2k7
r2b = 12k
(although I should meter the actual values because I'm using my cheapo bulk resistors here)
The regulator gets very warm so I put on a clip-on heatsink.

[Pushtone]

I'm getting to like the way the tone controls interact with the depth.
The interaction makes it a more flexible tremolo.
I can get a smooth, rounded tremolo or a choppy one through the interaction.
I'll try to get to recording some clips this weekend.



On the debugging side.
I need to re-think the way I just stuffed the PSU regulator in there.
After about 45 minutes the regulator over heats and there is a power failure.

It runs fine when the lid is open but overheats when all closed up.
All I have cooling the reg is a clip-on heatsink.
Just blowing on it will produce more regulated voltage.

I could mount the regulator directly to the case, perhaps with another heatsink in between but I would have to use jumpers from the regulator's pins to the PCB.
Or I could mount a tiny fan on the opposite side and drill some air intake holes.

Perhaps there is a better choice of power supply. I'm looing at the PSU for the Shaka Tube.

[bancika]

it reminds me of my build



I like the idea with "turrets", I'll try when making something with submini tubes. It would be cool

Cheers

[John Lyons]

Short of another PSU maybe you could take the Regulator off the board and bolt it to the chassis, lots more surface area there.
Looking forward to those clips. looks good!

John

[Pushtone]

I bolted the regulator to the box as suggested by a few folks. Thanks for the tip John and Andrew.
I had to use jumpers between the reg and the PCB.

HOWEVER, I'm concerned because mounting the reg has charged the chassis voltage positive (V+).
I had to change to plastic isolated 1/4" jacks or the PSU is shorted to ground.
Because the chassis is charged, I suppose if the roll bar comes in contact with another effect at bare metal or the screw heads, there could be some shorting and arching.


I can't believe how lucky I get sometimes. The reg chip fits perfectly off the screw for the roll bar.
Now the roll bar serves two functions, heatsink and tube protector. It gets warm to the touch.
I've had this arrangement running for several hours.

Here's a photo,
,


and another Regulator Pic 2.


And the finial working gut shot photo.



Pretty much like the first gut shot but now with the isolated jacks. You can see the RED, WHITE, BLACK jump wires to the regulator overtop the power filter caps.

I figure that the tubes are drawing 150mA each. So a 300+mA draw makes this reg very hot.
The layout I posted works OK aside from a couple reversed pots, but one may wish look at power supply alternatives or plan ahead for a heat sink.

I'm working on shrinking the layout and building a second one in a BB sized box. I'm feeling more confident when it comes to punching the holes for a tube and I'm sure I could mount two tubes in the same style into the smaller box. I think I will eliminate the tone stack for the BB version.