Desire to build Tweed Overdrive Special

[daveyajd]

Hello all,
I have gone back and forth about where to start with my first build. Part of me thinks it's best to start with a simple circuit like a Champ or something. But the other part thinks that if I am going to build my own then I want something different and new to me. So I want to build a TOS. I have poured over the forum for posts with gut shots, layouts, and schematics and pretty well understand most of it. Right now I am struggling with the physical layout. I am looking at a Hammond chassis sized 17"x8"x3". Is this big enough? I have seen discussions about space issues. Also, in some pictures I see 2 additional boards in the chassis. One looks like a PS cap board but what is the other one? Seems to be represented by the rectangle with 6 circles inside on the schematic. I'm sure more questions will come but this is all I can manage right now. Thanks.

Aaron

[kagliostro]

with 6 circles inside on the schematic

6 radial (electrolytic) cap instead of axial cap ?

Kagliostro

[tubenit]

I would want an 18.5" minimum width or a 20".       20 x 2.5 x 8

You can find some blank chassis on ebay under "tube amp chassis"

with respect, Tubenit

[John]

Seems to be represented by the rectangle with 6 circles inside on the schematic.

I believe that is a DPDT switch/relay.

[stingray_65]

Having built the TOS, and now working on a variation very close to that design I can share a few thoughts.

18" chassis is TIGHT. plus it is a high gain amp and lead dress is crucial, so shoe-horning it into a small chassis is a disaster waiting to happen.

The Champ is a perfect first amp build. Well the Princeton 5F2A is IMHO (tone knob). Coupled to an efficient speaker like an Eminence wizard or a Red Fang it surprisingly loud too.

You won't break the bank with a Champ or Princeton either.

The TOS is VERY rewarding. IF you follow Tubenitts layout to the T you can do it. lots of good support here too for that particular amp. I was at my wits end more than once during that build, but some great guys on this forum encouraged me and saw me through it nicely.(TY Jeff)

The Champ lets you do LOTS of mods, it can be very much yours alone when your done tweeking and playing around. I learned LOTS just from modding a Champ.

I built my TOS on 3 boards. Power supply, main board and a relay circuit. Doug sells the board, so the layout is already thought out for you and is a proven design.

What I suggest is evaluating your construction skills. How good are your soldering skills? what about fabrication? you can buy a Champ chassis pre drilled. what about troubleshooting? will you be patient enough to wait for replies to issues that crop up? how about soldering and un soldering components?

The Champ may be too simple for you and the TOS too challenging, there are other options, 5E3, 18W and its variations. They too can be modded and made your own.

It comes down to what your comfortable tackling. Tube amps aren't just thrown together. Let me rephrase that, GREAT tube amps aren't just thrown together.

Just a few thoughts and experiences.

Ray

[daveyajd]

Thank you all for your input. Like I said I am torn between a simpler build and the TOS. I consider myself handy with an iron and I have some tools so I feel comfortable with drilling the chassis. Of course I will use the board available here so that makes things a lot easier.  I am just worried about getting everything physically laid out the best way. I will plan on getting a larger chassis. Is it the chassis length that is critical or could I make something like 17 x 10 x 2 work? I can pick up a Hammond at the local electronics store here if I can make one work. Does anyone have any gut-shots they would be willing to share?

[tubenit]

could I make something like 17 x 10 x 2 work?

I would NOT attempt that with this amp. You need a longer chassis as has been recommended.  Maybe a 18.5" but preferably 20".

With respect, Tubenit

[Willabe]

Tubenit's been around the block a few times on this, I'd take his advice.     

[daveyajd]

Ok I will get myself a longer chassis. Do most/any of you put the Fatness and OD Trim pots on the front face plate?

[tubenit]

Do most/any of you put the Fatness and OD Trim pots on the front face plate? 

I think that is a good idea. Remember that you can use the smaller mini-pots in some of these situations to save space if needed.  I think they're 16mm & don't take up much more internal chassis space than a DPDT does.

I originally had the fatness pot on the back, I think (?); but it's worth having on front.

with respect, Tubenit

[daveyajd]

I am talking to a local sheet metal place to fabricate an aluminum chassis. I'm thinking 12 ga. What gauge do you all recommend? If the price is right I will go ahead and get 20" x 8" x 2.5". I'm sure I will love the additional space.

[stingray_65]

14ga (.063") is usually sufficient. 12ga is great.

will you be building a head or combo?

[daveyajd]

Maybe I will get an estimate for both. I'm thinking a combo right now. More of a grab and go amp.

[TIMBO]

Hey Dave, I don't think you can go wrong with this build,its a must have amp. I built the original TOS that had the "FAT" control and it is a useful thing and i had the pot on the front panel. My chassis was 20"x 8"x 2.5" and all fitted in neatly.

Then when Tubenit announced that he had upgraded the TOS to the TOS CF2 i jumped at the chance to build a new amp and i'm glad i did. This is an amazing amp that has many voices and tone to boot.

I think that starting with this type build could be a bit too much for a first build but any scratch builds are tricky but there is plenty help here. Good luck

[daveyajd]

Wow TIMBO! Those are nice looking amps. Very well put together. It looks like you did it with two boards. The main board and 1 additional board for the PS caps. Thanks for the pics I will keep this updated as it starts to come together.

[daveyajd]

Alright, I am getting my chassis made. 20" x 8" x 2.5". I made it out of .063" and it should be ready in about a week. I want to get my iron ordered and the BOM shows Super Reverb sized iron but are there benefits/risks to getting larger ones like a Twin Reverb or something? I have a chassis layout that I have been working on for all of my holes. I will post it later if I get a chance so everyone here can get eyes on it and keep me from missing something. I'm using Inkscape and if get all the layout measurements correct the place making the chassis can load the .dxf file and do all of my cuts for me.

Regards,

Aaron

[tubenit]

I don't think there are any real benefits using Twin vs. Super Reverb iron?  Just different. Maybe a Twin OT would have a little more bass response when the amp is cranked (if one would want that)?  However, I don't really know for sure? I don't see any real downside using TR iron though.

Yes, if you can share your layout design that would be great. Thanks!

With respect, Tubenit

[daveyajd]

Thank you. That was what I was thinking. I used Twin Reverb OT on my Bantam Bass (same PT as SR, smaller stock OT) and I expected more frequency response but didn't notice a drastic difference. Although I could see an argument for using a Bassman OT. Same wattage, almost the same C.T. and the secondary taps are 4,8,16 instead of 2,4,8.

[daveyajd]

Ok, so a few more layout questions. Has anyone located their PS board underneath the chassis in a "doghouse" similar to older Fenders? Also I have seen reference to some folks using a separate board for the relay circuit. I am confused on what would be on this board. What makes up the relay circuit? It's just used for switching between clean and OD right? Has anyone built this without the PPIMV or VVR? Sorry for the newb-type questions but I am still just trying to get this figured out.

Thanks,

Aaron

[tubenit]

I think you could use the doghouse approach if you wanted. Just be careful with the wiring. 

IF I had to do it over again, I would like relay switching for clean/OD (1st) and then also the mid-boost which is useful for lead.   

I think if you are using 6L6's that you're going to appreciate either the VVR or PPIMV.  Remember with the added OD gain stages that the amp can get pretty LOUD.   Maybe you could get by without those if using 6V6's?

With respect, Tubenit

[Tone Junkie]

Tubnit which switch is the midboost Im getting ready to do one to.
 Is that the other one by the pab switch.
Thanks Bill

[TIMBO]

Hi Dave,I guess if you don't have the room inside the chassis for the PS board to put it in the "doghouse" would be ok but as i have not done it that way i don't know if there is any drawbacks  
As for the relay, it is a good idea to mount the electronics on a separate board and relay close to the area that is to be switched (to keep the amp circuit wires short). Doug has lots of great info in his library,as well as the net and i think a lot of info can be easily found, so do what i do and look for stuff that others do. There is a lot of kit amps out there that are willing to offer up info that is very useful, One being CERIATONE as they have put a lot effort into designing their amps, you should be able to find what you need there.

Yes, the relay is to switch between clean and OD.
The PPIMV and VVR are very useful, They give you the ability to turn down the amp without loosing the dynamics of the amp ( allows the same sound at full tilt at bedroom level). To me the PPIMV is possibly the better way and is cheaper than the VVR.I don't think that there is any problem with deleting either but it may limit some volume control.    

[daveyajd]

Thank you TIMBO. Your statement puts a finer point on my question: What are the electronics I should locate on a separate board? When looking at the schematic,layout,and BOM it appears that the switching is done by a DPDT. I don't see anything special called out on any of the info sheets. And I don't see power of any sort running to the switch. Things may become more clear as I start acquiring parts and laying things out but this is a very confusing part for me right now.

Thanks,

Aaron

[tubenit]

That DPDT for clean/OD is a relay board with a DPDT that is switched by a relay. 

I left you a PM with some more info.

With respect, Tubenit

[TIMBO]

Tone, Yes 

[stingray_65]

OK,

The board Doug sells, which was developed by Tubenitt and Geezer does not have the PS or switching on it. So all the TOS builds have a separate PS board, and if you choose the relay switching (pedal) then you'll have that a separate board too.

I'm having issues posting pics of how I did my channel switching and PS board.

I'll try again in a new post

[stingray_65]

here they are

note that I made my TOS fixed bias. I added the bias circuit to my PS board. The cathode bias components were mounted to the original TOS board, so this not being used, I modified it to mount a regulated 5V supply for the relay. This is completely unnecessary.

Here is also the schematic I went off of, it varies little from tubenitts original TOS

Also note that I did not include a shunt diode across the coil of the relay. I highly recommend doing so.

[stingray_65]

in progress, this is a 19" chassis, you can see how wide it is to fit the controls, 8 pots, input, pilot lamp, 2 mini switches, off-stdby-on switch.

I used the full width too for components, It would be less wide without the added bias circuit for fixed bias, but I shoe horned it in.

[stingray_65]

and the stealth tilt back legs

[tubenit]

Stingray 65,

NICE JOB!!!!! 

Thanks for sharing the pictures!  I like how you did yours. Very nice.

With respect, Tubenit

[daveyajd]

Thank for all of those great pics! Tubenit, thank you for finally clearing up the relay board confusion. I have a few more things that I need to add to my layout now. I will take the weekend to try to soak all this information in.

[Tone Junkie]

Nice looking amp stingray 65

[Willabe]

Ray that is beautiful, all the way around!     

                             
                                     

[daveyajd]

So I took the travel time yesterday to put together a face plate for the TOS. Drawing largely from Stingray's design here is what I have so far.



I do have a couple questions. It appears that Stingray has a Depth knob as well as a switch. Is there a benefit to the switch or is it effectively out of the circuit when the knob is turned to 0? Also it looks like an LED for the OD/clean switch. Is this powered off of the 6.3V just like the on/off LED? What type of switch did you use for the off-stndby-on switch? That is all for now thanks Stingray those pictures are very inspiring. 

[stingray_65]

I do have a couple questions. It appears that Stingray has a Depth knob as well as a switch. Is there a benefit to the switch or is it effectively out of the circuit when the knob is turned to 0? Also it looks like an LED for the OD/clean switch. Is this powered off of the 6.3V just like the on/off LED? What type of switch did you use for the off-stndby-on switch? That is all for now thanks Stingray those pictures are very inspiring.  

I renamed the fat knob to depth. the switch lifts the ground on the fat pot, giving it just a bit more. and yes it is out of the circuit when turned to 0.

It really isn't worth the time or space IMHO.

If you look at my schem for the relay, it shows the LED, it's powered off the relay supply.

Carling makes the off-stby-on switch. http://www.tubesandmore.com/ P-H520

Nice looking faceplate  

Just a few tip on making faceplates.

draw them in Corell or Ink Scape (free online), you have to have a vectorized format if you are going to send your plate out to a laser engraver.

Use cross hairs instead of circles for your mounting holes. You'll mount your engraved faceplate with some double stick tape, center punch on your crosshair, drill a 1/8" pilot hole through both the face plate and chassis then enlarge the holes.

This allows for some error in the engraving and some leeway if you are not exactly on center.

To manufacture them separately requires quite a bit of precision.

[daveyajd]

Well I picked my chassis up this week and it looks good.





I have my transformers on the way and will be placing an order with Doug very soon.

I reworked my faceplate a little just to see how it might look:



And here is the chassis layout with face and back plates attached:



Everything is drawn to scale and seems to fit but I'm not sure how big my PS board will end up needing to be. May need to rework it once I get the physical parts. Thanks all.

Aaron

[stingray_65]

You're on your way Aaron!

That chassis is as nice as any I've seen and your faceplate looks pleasing and intuitive to use.

Ray

[daveyajd]

Thanks Ray. Just a quick note to marvel at the service I get when ordering from Doug. His response and delivery is outstanding. I placed an order Sat. morning at about 9:15. Within 30 min. I had a confirmation of processing and shipment and received my parts in the mail today. Thank you Doug. Also, just to let anyone know who may be interested in building this amp I am doing all of my layouts to scale in Inkscape and it is working very well. I am always willing to share the files to help someone out. I will be posting some of them as the build goes on but if anyone wants more detail let me know.

Aaron

[daveyajd]

Here is my layout so far. I am waiting on my xformers so I will verify sizes and screw hole dimensions when they come in. I also don't have my holes for grommets yet. How does the spacing between components look? I placed my transformers using the only rule I know: place PT and OT running opposite directions. Any recommendations welcome. Thanks in advance.




Aaron