TOS Build Diary

[SLW]

Well here goes.  Feel free to comment on what you see here.  I enjoy learning from others. 

The Beginning

I have never done anything like this before and wasn't sure where to start.  I decided to start at the beginning.  Props to Tubenit and Geezer for the circuit and all the work they put into the design.  I based this heavily on their design.  I wanted a tube based effects loop and VVR so I added them to the circuit.  Here are the schematic and layout that I am working from.  I used inkscape to draw everything to scale when I developed the layout.  I spent many weeks working on the layout before I ordered a single part.  I want to do everything that gives me the best chance of success on any project.  I guess I am a bit of a perfectionist.  I tried to figure out every part and its position in the amp before I ordered a single part or drilled a single hole.  Even then, I did make a few generalizations in the layout like the channel changing and 5VDC board. 

[SLW]

Boards

Here are the boards.  The big one is the main circuit for the amp.  The two smaller boards are for filter caps used in the power supply portion of the amp.  The boards are made from the turrets and board material that Doug sells here.  I cut the boards to size.  I covered the board with painters tape and laid out the positions of everything using my layout.  Drilled the holes and installed everything.  Pretty simple. 

The PCB is for the channel switching portion of the amp.   I laid out the PCB and had it made with a batch of prototypes for pedals.

[Deric]

Looking good!!  Thanks for sharing.   

[tubenit]

Very nicely done!

With respect, Tubenit

[kagliostro]

NICE !

Many thanks for sharing

Kagliostro

[stingray_65]

VERY neat workmanship!

Having built Tubenits and Geezers TOS myself I do know that lead dress will be critical.

Well worth the effort for sure, It is one of the most versatile amps I've ever heard and without a doubt my proudest build.

Ray

[SLW]

Chassis

I bought a 17.5 X 8 chassis for Watts Tube Audio.  Just like the boards, covered the chassis in painters tape.  Using my layout I marked up the cutouts and the centers for all of the holes.  I used a step drill for the larger holes.  I used a jig saw to cut the rectangles and finished them up with a file.

[Willabe]

Looks real good.

What are the little holes above the vol. and tone pots for? LED's or switches?


                  Thanks,      Brad     

[John]

Nicely done! I'm taking notes. 

[SLW]

What are the little holes above the vol. and tone pots for? LED's or switches?

They are for LED's.  I am using 3mm LED's with a bezel.  They just barely fit.  There is just enough room for the nut to turn and not hit the top of the chassis.

[SLW]

Time to start the putting it all together.   I wasn't sure where to start so I decided to start with things that were on the bottom first.  I mounted the transformers first.  Next came all of the LED bezels.  I mounted the relay board, main switch and the VVR parts.  I then started wiring things up.  The VVR, LEDs and relay board worked out fine.

Then the first two snags showed up. 

First snag.
The small board for the rectifiers, first PS filter stage and the heater connections mounted just fine in the space allowed but there is not enough room to get my iron in there.  See the photo.

Second snag.
There is a conflict of space between the second small filter board and the switch in the chassis.  When the board is mounted on the stand offs one of the caps hits the lugs on the switch.  See the photo.

I am not sure what to do.  I have thought about moving the rectifier board back but there is not enough room.  I have thought about standing the filter board up on brackets.  I have four 5 lug terminal strips that I could use somehow but I have not put any effort into figuring it out.  Any good ideas out there?

For the next amp I build I will get a chassis that has more room.

[TIMBO]

Hi SLW, Looking Good   The rectifier board,could it be mounted with some aluminium angle so that it sets above the power socket and the same with the other board so that it is mounted between the VVR and switch???

I just looked again and thinking you won't want bolt heads on the front panel.So reusing the bolt holes already there, bolt it upright with the aluminium angle.

[HotBluePlates]

First snag.
The small board for the rectifiers, first PS filter stage and the heater connections mounted just fine in the space allowed but there is not enough room to get my iron in there.  See the photo.

Twist, then attach the leads from the transformer prior to bolting the board down. you might wind up with wires a shade longer than your "ideal" but still neat and workable.

Second snag.
There is a conflict of space between the second small filter board and the switch in the chassis.  When the board is mounted on the stand offs one of the caps hits the lugs on the switch.  See the photo.

It's hard to see in the photo's perspective... can you rotate this board 180 degree to place the resistor under the switch and gain your clearance?

If that doesn't work, 2 L-brackets can hold the board up on edge. Ideal brackets may have a continuous channel running down the middle, so you don't have to line up board holes to bracket holes.

[Willabe]

You might be able to use radial lead electro-caps?

Look's good other wise.


            Brad       

[stingray_65]

There is a conflict of space between the second small filter board and the switch in the chassis.  When the board is mounted on the stand offs one of the caps hits the lugs on the switch.  See the photo.

Fish paper,

Bolt it under the spacers on the filter board

Then slide it between the lug and cap, be generous

been done millions of times works 100%

For the next amp I build I will get a chassis that has more room

I built my TOS in a 19" chassis and I swore when I build it again I will never use less than a 24" chassis

How Tubnit and Geezer ever crammed all that into an 18" chassis...And then modded it time an again.. Hats off to them both for such a great amp but WOW I must defer to the masters for that shoehorn!!

Ray

OH!

Super Sano build! neat and clean!

[SLW]

Thanks for the help guys.

Twist, then attach the leads from the transformer prior to bolting the board down. you might wind up with wires a shade longer than your "ideal" but still neat and workable.

That sounds like a simple solution.  I like it.

If that doesn't work, 2 L-brackets can hold the board up on edge. Ideal brackets may have a continuous channel running down the middle, so you don't have to line up board holes to bracket holes.

The board will fit vertically in the chassis.  I will explore this option.

Fish paper,

Bolt it under the spacers on the filter board

Then slide it between the lug and cap, be generous

been done millions of times works 100%

Fish paper is a new one on me.  What is fish paper?

You might be able to use radial lead electro-caps?

I like radial lead caps and use them all the time in my pedals.  I will spend a little effort in my next amp working them into the build.  There is somebody on the forum that uses radial caps on a circuit board that they make.  I like the sound of that.  I decided to build this amp in the conventional way just for the experience.  I have experience laying out PCB's, but not for high voltage applications.  That will be another good thing to learn.

[HotBluePlates]

Fishpaper is a vulcanized fiber material, which can be sometimes used for insulation. Note that not all fishpaper is rated for electrical insulation; the stuff listed here has a separate listing for the stuff you want to use.

They don't give the ratings for each thickness of electrical grade fishpaper listed on that site; I'd think that 0.030" is thick enough to offer good insulation, while still being just thin enough to easily cut and punch out screw holes.

Your choice on whether to insulate and mount as originally planned, or use an L-bracket to stand the board up.

[SLW]

I finally had a rainy Saturday and a few hours to work on my amp.  We spend as much time as possible outside before winter gets here.  My 4 children keep me pretty busy and my wife gets an hour or two a day.  All that cuts into “tinker” time. 

I decided to mount the filter board vertically.  I bought a ½ X ½ Al angle and made a little bracket.  The bracket is screwed to the chassis.  The hole in the bracket is clearance for a turret.  With that mounted I attached the all the PT wires.  I did attach wires to the rectifier board before mounting the board.  The start of the heater wires are in.  I also hooked up the primary side of the OT.   I made sure to install tubes in the sockets before soldering anything to the sockets.    I will hook up the secondary site of the OT next.   After that I will install the pots and hook them up.

[stingray_65]

 I made sure to install tubes in the sockets before soldering anything to the sockets.

WHY?
I've never done that, am I missing a trick?

I will hook up the secondary site of the OT next.   

Be sure to leave your leads long, seems when I cut them to length a howl and have to reverse them.

   After that I will install the pots and hook them up.

With so many pots in my TOS build, I mounted the pot outside and soldered up all my leads and caps and what nots leaving long flying leads to solder to the board after you un-mount the pots and put them inside.

[Willabe]

 I made sure to install tubes in the sockets before soldering anything to the sockets.

WHY?
I've never done that, am I missing a trick?

Hi Ray, take a look in here, reply # 4 ....


http://www.el34world.com/Forum/index.php?topic=12428.0


               Brad      

[Willabe]

SLW, looking good! Look's like you got it wooped now.

Hey, your gut pic's are great! I just bought a dig. camera and I'm trying to learn how to how to take pic's as good as your's.     

I started a post on this here.....     http://www.el34world.com/Forum/index.php?topic=12283.0

Would you please look at it and add to it? I'm having a problem with lighting.

How did you light those shots????       



             Thanks,      Brad       

[SLW]

How did you light those shots????   

I don’t consider myself much of a picture taker.  I have two of the fluorescent 4’ fixtures above my workbench.  Each has two bulbs, no covers or anything, just a box with two bulbs mounted to it.  Enough of the bulb is above the work surface of my bench that I don’t get any real shadows and it doesn’t matter where I stand.

[shortfuse]

Great job and thanks for showing all steps I always like looking at others work and seeing how achieving  the same things can be done differently.  The TOS will be one of my next builds.
Very neatly done looks like a lot of pre planing went into this.  Look forward to seeing more posts.

[SLW]

Today a got a couple of hours to tinker.  I finished the OT wiring and I got the FX loop jacks and pots hooked up.  I had my little buddy “helping” me tonight.  I took this shot of him looking at the amp.  Notice he is holding a pair of needle nose in his right hand.  I know this isn’t amp building but I am a proud dad.  I have some fun discussions with him while tinkering.  He is 6.

Son – what is that thing?
Me -  It’s a capacitor.
Son – What does a cap-sister do?
Me – It stores electricity.
Son – Like a jar?
Me – Yep.
Son – what is that thing?
Me – It’s a resistor.
Son – What does a re-sister do?
Me (not sure what to say) - It slows down electricity.
Son – Like brakes on my bike?
Me  - Yep.
Son – What is that thing?
Me  - It’s a transformer.
Son – What does it do?
Me -  Here is a wire.  Will you cut it into small pieces for me?

Anybody know how to explain a transformer to a six year old?

[sluckey]

Anybody know how to explain a transformer to a six year old?

Can't do it. Especially if he's seen the movies!   

[stingray_65]

a transformer transforms the voltage to either high or low?

[John]

It makes more electricity..... now keep cutting up those little wires. 

[Willabe]

Maybe show him with/on a little wall wart from one of his games or something like that? Use a DVM. FWIW, you'r a good dad teaching your son how to use his hands and mind.     


             Brad   

[moonbird]

Wow -- nice work!!

Hey if you ever decide you want to sell some of those channel switch boards, I am your man!!! I bought a TOS board awhile ago but I am very leary of taking on the whole channel switch wirefest -- but it is the real allure of this amp so I am kinda stuck!!

Been trying to get into the short-run PCB thing - been hoping Doug would answer a question I sent him about his inkjet printer hack -- but alas -- nothing yet.

Again very cool work!!   

[SLW]

Thanks for the kind words Willabe.  This son likes to tinker.  I bought him a kids carpentry book for Christmas.  We have had a good time building different projects from the book.  We have made him a saw horse, a sign in the shape of his name, a boomerang(that only flew straight) and several boats.  Having a 6 year old tell you why the boomerang did not come back is very entertaining. 

Hey if you ever decide you want to sell some of those channel switch boards, I am your man!!! I bought a TOS board awhile ago but I am very leary of taking on the whole channel switch wirefest -- but it is the real allure of this amp so I am kinda stuck!!

The board in this amp was designed with this circuit in mind.  I  have thought abought a generic relay PCB for use in amps but have not tried to take it any further. 

SLW

[Willabe]

Thanks for the kind words Willabe.  This son likes to tinker.  I bought him a kids carpentry book for Christmas.  We have had a good time building different projects from the book.  We have made him a saw horse, a sign in the shape of his name, a boomerang(that only flew straight) and several boats.  Having a 6 year old tell you why the boomerang did not come back is very entertaining. 

Sounds like you two are having a lot of fun.     


           Brad             

[SLW]

I had a chance to work on the amp this weekend.  I put the input jack and controls into the amp this weekend.    No real issues here.  Just a lot of figuring it out as I went.   Even though I spent a lot of time working on a layout, things are working out differently than I had planned.   The ground wire for the pots is a good example.  I had planned on tucking it in close and under the pots.  It turns out that there was not really enough room with the channel switching PCB in its location.  I decided to stick it out in the air above the PCB.

I have discovered that I am short a 33k resistor and a 0.0047uF.  I usually would not care too much about missing a component since I have a nice electronics store in town.   The store was flooded when we had terrible flooding here in September.  I stopped by yesterday to check on the owners progress in rebuilding.   They have been operating out of a shipping container in the parking lot.

My little buddy has a tape measure and has been measuring EVERTHING.  The TV, the furniture, me, the door, EVERYTHING.  It is pretty fun. 

[stingray_65]

My little buddy has a tape measure and has been measuring EVERTHING.  The TV, the furniture, me, the door, EVERYTHING.  It is pretty fun. 

Best way to learn fractions!

Decimals are for people who don't want to think!

[SLW]

I had time to tinker this holiday between all the eating.  I finished wiring it up!  I added all of the wires that go under the main board first.  Wires that went from a tube socket to a pot are shielded.  Next I added all of the wires that are under the board that run between turrets.  With all that done I installed the board.  I then made all the connections between the board and the off-board parts.  As you are all aware it is a lot of work.  Next I will sit down with the schematic and go over everything.  I need to build a lamp limiter.  Then I will try to start it up.  Keep your fingers crossed.  

I am happy to have it finished.  There are some things I would change at this point but I am going to leave them as-is and move forward.  Things I would change are:

1. The area behind the pots is very busy and cluttered looking to me.  Heaven help me if I ever have to change a pot.  Looking at it now I should have soldered the ground buss to the back of the pots or did it like they used to in the old days.
2. I would like to have the channel switching on the main board.  
3. A larger chassis and more room would have been great(I have already whined about this).
4. I used 18gauge stranded wire for most of the connections.  I have a lot of this stuff on hand(enough for 10 amps easy) and want to use it up.  Solid wire makes for better looking connections and is easier to deal with in tight quarters.

I have learned a quite a few things and about building an amp.  

1. Orange drops are huge!
2. There is a limit to how many connections you should make on a turret.  In one place I have six.  The turret looks like a tree.  I try not to look at it but it is like looking at a train wreck.  
3. Only two leads fit into the top of a turret.
4. I can’t see small things as well as I used to.  The magnifying glass is handy.
5. I need to have a set of design rules in place before I layout an amp.

It has taken nearly a year to get this far and it has been a lot of fun.  

SLW

[tubenit]

Wow!!!  That looks fantastic!  Great job. 
 

Thanks for sharing the photos!  Can't wait to hear how you like it.

With respect, Tubenit

[stingray_65]

Don't be so critical!

It really looks great! Tear apart an old AA5 radio and you'll know what a real mess is! and landing 6 leads on 1 turret is a trick in itself! damn the aesthetics!

That flying ground bus WORKS! I used it in my TOS build.

Soldering a ground bus to the back of pots REALLY makes a job out of replacing pots.

There are pro's and cons of stranded vs solid wire, the trick is using them in their best situation.

The TOS is a high gain amp and susceptible to crosstalk in many areas, what looks neatest may very well not be what will sound/perform best.

I think it looks like a really clean, well thought out build. It is NOT an easy build at all.

Kudos to you!

[HotBluePlates]

You've done an outstanding job! Really great looking build.

I'm trying to plan more upfront to avoid the midstream modifications (a la custom motorcycle builder shows).

[SLW]

Thanks for the kind words guys.  I do apreciate it.

I'm trying to plan more upfront to avoid the midstream modifications (a la custom motorcycle builder shows).

I am convinced that a lot of effort in the planning stages pays off in the build phase.  I spent many weeks with the layout.  I drew everything to size(and color) in my layout and kept adjusting the position of it all before I drilled a single hole.  Even with that prep I had three unexpected issues to deal with during the build.

A set of design rules makes a lot of decisions before you even begin a layout.  For my next amp I will write down my design rules before I start the layout.  Design rules could be anything from colors and gauges of wires to grounding schemes to the number of leads per turret.  You could be as complicated or as simple with the rules as you like.  I believe everybody has a set of design rules.  Some folks write them down and some commit them to memory.  We could start another topic about design rules. 

[shortfuse]

Outstanding build please report back or add a sound clip when you fire it up. 
One of these days if I ever get any time again I want to build this amp also.

[SLW]

I built a lamp limiter and began to start it up.  I plugged in the limiter and turned the amp on with no tubes in it.  The lamp flashes and goes dark.  I install the first tube and switch it on and get the same response from the limiter.  I continue adding preamp(two 12AX7, 12AY7, 5751, 5879) tubes and testing with the limiter.  I am still getting a flash then a dim bulb.  I feel pretty good at this point.  I install the two 5881's and test it again.  This time the bulb stays bright.  I quickly turn it off and start to worry. I am using a 100W bulb and the current limited by the bulb should be 100/115 = 0.87A   I then realize that heater current should be about 3A with all those tubes in so the lamp should be bright at this point.  I think I feel a little better but...  I hope you more experienced builders can chime in here and tell me if my thinking is correct or flawed. 

[Willabe]

No, if it stays bright then there's something wrong.   


             Brad

[SLW]

Well OK.  I was just in denial I guess.  I have never used a lamp limiter before so I am not sure what to expect to see.  I repeated the test.  When the power tubes are in the light glows bright.  If I just put one power tube in and flip the switch the lamp takes many seconds to brighten up. 

I have checked the wiring and everything matches the schematic and layout.  I am not sure where to look next.  You guys will surely suggest something.

[stingray_65]

I then realize that heater current should be about 3A with all those tubes in so the lamp should be bright at this point. 

3A x 6.3V = 18.9W

If the light is bright, something is drawing heavy current

[Willabe]

SLW, I'm not the guy you want to help you trouble shoot this, but I wonder if it's the VVR?        Maybe you could try to bypass the VVR?

Also are you sure those OP tubes are good? The pics you've posted sure look good, looks like you've been careful wiring up things.    

The guys will help you find it.    


               Brad      

[HotBluePlates]

Do you have any good closeups of the output tube sockets and associated wiring?

Without looking back at a schematic, this amp appears to be cathode biased, judging by the big resistor on the board.

How about taking voltage readings with the tubes out. You should have only high (and essentially equal) voltage on pins 3 & 4 (plate, screen). Is that right? There's nothing boogering the wiring to pin 5 is there?

[SLW]

Here is a pic of the output  tube sockets.  The amp is cathode biased.  I took voltage readings on the output tube sockets with the tubes out.  All of the preamp tubes are still in.

Pin 3 - 410V
Pin 4 - 406V

I don't see anything wrong with pin 5 wiring.  I checked for a short to ground or another pin and such.  I did not find anything wrong. 

Can an output tube fail in a way that causes high current to move through them.  I have a pair of 6l6 and a pair of 6v6 tubes I could try.

Thanks for the help. 

SLW

[SLW]

The Story Continues.

I tried my 6L6 tubes with the same result.  After flipping the switch from stand-by to "on" I get a flash on the lamp limiter that quickly goes away.  After 10 seconds or so the lamp starts to get brighter until it is glowing well and there is hum coming from the speaker.  I interpret this to mean that as the output tubes warm up and start to conduct, the current through them is going crazy.  This happens if only one tube is in either socket.  This does not happen when the output tubes are removed. 

I decide that the problem is something that the two tubes have in common.  I start with the VVR like Willabe suggested.  I remove the VVR from the circuit and replace it with a jumper.  I power up the circuit and get the same result from the limiter. 

I double check the values of all the resistors that are part of the output tubes circuit and find no errors.  None of the caps short to ground.  At this point I am scratching my head.  The other things that the two tubes have in common are the filter caps, the cathode connections and the two transformers.   

I am not sure what to check next.  I am looking for suggestions.  Feel free to state what might be obvious to you.  There is obviously something wrong.

Thanks for the help.

SLW

[shortfuse]

Wish I could help but I am just a beginner I have very good building skills but still lacking in the practical knowledge.  I don't understand the power tube pin 1, 4 jump along with jumping pin 1 from one tube to pin 1 of the other.  I always thought pins 1 & 8 tied together for use with EL34's or 6L6's.  I also dont understand the pin 5,6 jump and never messed with a VVR.  But I will tell you I have done some pretty stupid things and thought all was installed correctly only to find later I had something backwards.  At least you used the lamp limiter unlike me on my 1st build and toasted the PT.  I did use it on other builds and it did save me like it seems to be doing for you.
Looks like you did everything methodically from the layout & schematic to the final build so I would tell you the same as I was told on a post a while back.  Divide and conquer, go back and trace it all out again but with a different mind set that something is wrong.  Look to see if something is wired reverse but in your mind it looks correct.  I would think if something was wrong in the schematic you posted one of the guru's on here would have picked it out earlier on. 
Hopefully you find that one small something and one of the senior guys on here will eventually be able to help you.
Good Luck

[TIMBO]

Hi SLW,shortfuse may have hit the jackpot!!!! I to have limited knowledge on how all this works, so i tend to try to do the things that most other builders do to try to limit problems. Pin 1,8 on these types of power tubes are for cathodes as some and aren't connected internally and you are using pin1 as a support for the screen resistor. If you can place a tag strip near pin4 and use it to support and solder wire to. In future tie pin1,8 together for interchangeable power tubes.

As for pin6 this is not used for any type of power tube so can and is often used to support the grid resistor.Hope this helps.

[tubenit]

In the picture you have posted, the pin 8 wiring on the power tube socket on the right side doesn't look very solid?
However, that might just be the picture angle?  But if it's not a solid solder, that would account for too much current, I think?

Also look at the pin 2 heater wiring on that same socket on the right. That doesn't look solid either?

I am wondering if the VVR is playing a factor in this also?  Does anything change with the light glowing if you change the VVR setting? 

With respect, Tubenit