New Project: Supro Thunderbolt

[TubeGeek]

This month's project is a Supro Thunderbolt.  

I have been building lots of kits lately and this time I wanted to build one from scratch.  I didn't want to clone the original either.  I came close to having a cabinet made like the original but in the end decided to go my own route instead.

Back in Xmas 2013 my girlfriend gifted to me a set of ClassicTone Supro transformers so that kind of sparked this project.  I was already booked up in January and February with projects so March was the month of Supro!

The build went pretty smooth.  There aren't any verified layouts of this circuit out there that I could find so I made my own layout from the schematic.

After taking the time to draw it up I found that I was going to have to invert the layout because of the way I had the tube sockets laid out on the chassis.  No big deal, I had to do this years ago when I built my Hoffman AC30 project.  I simply took a pic of my layout (which was drawn up on a whiteboard) and loaded it to my photo software and then flipped the direction, printed it out and poof…had a layout to follow in front of me!

Pretty simple circuit, not much to it.  After getting it fired up and testing it all I found useful was to add the second (originally unused) V1b triode in parallel with V1a.  I just couldn't leave a triode unused.  It thickened up the signal and increased harmonic content. Very pleased with this.

I have a cabinet ready to be tolexed as soon as the tolex arrives.  It'll be covered in white sparkle tolex.  The speakers I have to choose from are a Warehouse G15C, Weber 15f150B and an Eminence Legend 15.  Currently I am trying the Warehouse and I like it so far.  The Weber will arrive this week sometime.  The 15" speaker sure sounds BIG.

Anyhow, I added a little bling to the amp for fun.  I added a DC voltmeter to the cage that is tied to the + of the power tubes cathode resistor.  It fluctuates a little bit when playing.  Lastly I added an LED strip inside the cage for lighting effect.  Nothing more than eye candy.  I almost added a magic eye tube but then thought it'd be too much, I'll save that for my next project.

Thanks for looking!

TG


http://youtu.be/6S2xAJpUjQs

[Ed_Chambley]

Hey, way cool.  It looks like you used the rectifier version.  I too have the iron for one of these things, but wasn't sure if I was going to use the circuit.  Sounds good and vintage.  May have to go that way.

do you have a layout you can share?  I know you said it was backwards, but I would like to see it.  The gut shot looks great.  So does everything else.  Great build and how cool is the meter, right?

[SILVERGUN]

Back in Xmas 2013 my girlfriend gifted to me a set of ClassicTone Supro transformers so that kind of sparked this project.  I was already booked up in January and February with projects so March was the month of Supro!

Marry that girl!!

After getting it fired up and testing it all I found useful was to add the second (originally unused) V1b triode in parallel with V1a.  I just couldn't leave a triode unused.  It thickened up the signal and increased harmonic content. Very pleased with this.

Good stuff.....glad to see you steering away from the kits on this one...
Great vintage'y sound!!...and the eye candy looks cool with the perforated cover!

Keep up the good work and keep posting!...I always enjoy seeing what you're up to 

[TubeGeek]

Hey, way cool.  It looks like you used the rectifier version.  I too have the iron for one of these things, but wasn't sure if I was going to use the circuit.  Sounds good and vintage.  May have to go that way.

do you have a layout you can share?  I know you said it was backwards, but I would like to see it.  The gut shot looks great.  So does everything else.  Great build and how cool is the meter, right?

I can share a pic of my whiteboard drawing if that'll help.  I could send it you via email if you PM your address.  The drawing needs a few little corrections though, while building the actual amp I changed a few things along the way.  You sure you don't want to make your own layout?    Mine is not perfect.

The sound of this amp/circuit is unreal.  I am really enjoying the bite and mean growl it has, especially after I paralleled v1a with the unused v1b.  It's unlike any of the other amps I have.

[TubeGeek]

Back in Xmas 2013 my girlfriend gifted to me a set of ClassicTone Supro transformers so that kind of sparked this project.  I was already booked up in January and February with projects so March was the month of Supro!

Marry that girl!!

After getting it fired up and testing it all I found useful was to add the second (originally unused) V1b triode in parallel with V1a.  I just couldn't leave a triode unused.  It thickened up the signal and increased harmonic content. Very pleased with this.

Good stuff.....glad to see you steering away from the kits on this one...
Great vintage'y sound!!...and the eye candy looks cool with the perforated cover!

Keep up the good work and keep posting!...I always enjoy seeing what you're up to  

Thanks for having a look.

Marry that girl….

Kits are fun and a time-saver.  If I didn't build kits for people, I wouldn't have toy money to buy more gear to build. 

It is nice to build from scratch though, more satisfaction in the end.

[Ed_Chambley]

Hey, way cool.  It looks like you used the rectifier version.  I too have the iron for one of these things, but wasn't sure if I was going to use the circuit.  Sounds good and vintage.  May have to go that way.

do you have a layout you can share?  I know you said it was backwards, but I would like to see it.  The gut shot looks great.  So does everything else.  Great build and how cool is the meter, right?

I can share a pic of my whiteboard drawing if that'll help.  I could send it you via email if you PM your address.  The drawing needs a few little corrections though, while building the actual amp I changed a few things along the way.  You sure you don't want to make your own layout?    Mine is not perfect.

The sound of this amp/circuit is unreal.  I am really enjoying the bite and mean growl it has, especially after I paralleled v1a with the unused v1b.  It's unlike any of the other amps I have.

Thats cool, It sounds like you do it like I do most of the time.  Sort of get a general idea and go for it.  Unless is is a complicated build I never use a layout anyway, but I was thinking of adding a few toys to mine and maybe a CF tonestack and reverb.

[John]

Nice looking build! What is the white power supply looking thing on the left of the chassis? I ask because when I get around to building another amp I'm thinking about putting in solid state reverb.

[sluckey]

Adding to John's question, what's the black thing in this pic?

[Willabe]

I think the white box is the PSU for the LED rope lights.

Yes, what is the black box? Maybe part of the meter?


            Brad    

[John]

I think the white box is the PSU for the LED rope lights.

Of course!

[TubeGeek]

Yes, the white box on the left is for the infrared remote control for the LED strip.  There is a remote that allows me to select the color of the LED strip.

The other black box is the 12VDC power supply for the LED strip.

[SoundmasterG]

You might try some experimenting around on this amp even though it sounds great already. The originals used ceramic coupling caps in most cases....which would give a unique sound of course.

For any who might want to build a clone, here are some pics of the ones I worked on when I was helping Sean Weatherford create the schematic he did for these. One is a stock solid state rectified amp, and the other was an early tube rectified amp that had been modded. You can see the ceramic caps in the pics and the layout too. There are also some pics of the cabinet and speaker too.

Greg

[Willabe]

Yes, the white box on the left is for the infrared remote control for the LED strip.  There is a remote that allows me to select the color of the LED strip.

The other black box is the 12VDC power supply for the LED strip.

Ahh. Nice!


            Brad     

[SoundmasterG]

Finally got some pics uploaded. Seems like if you get close to the allowed size limit, the new server doesn't like it much and times out and gives an error. I had to load them one at a time and upload, then go back and do again for each file. Weird!

Here are the other two pics.

Greg

[SoundmasterG]

And the last pic....

Hope they help someone! I have more if needed but these should provide views of the cab and layout and parts used. Remember that the pics of the tube rectified one above show a slightly modded amp and not a stock one. It does not use the tube rectifier anymore, and the 2nd gain stage is cascaded instead of being unused like in a stock amp. The mods were not done by me, but were done by the owner, and done well enough so the amp works and sounds fine, but it isn't pretty.

Greg

[Willabe]

Finally got some pics uploaded. Seems like if you get close to the allowed size limit, the new server doesn't like it much and times out and gives an error. I had to load them one at a time and upload, then go back and do again for each file. Weird!

Thanks for sharing the pics of your rebuild, looks real good.

Our host Doug went to the trouble and expense to get on his own single server to avoid that kind of thing and as soon as he does they run into some kind of glitch.  

Doug's on top of it and their working on tracking it down. Should be fine very soon.




          Brad    

[HotBluePlates]

As others said, kudos on the build!

I used to own a Supro amp that I think was a Thunderbolt. Some friends that had a band in Nashville borrowed it on occasion for performance/recording.

[TubeGeek]

Received the Weber 15F150B today.

Now it's a speaker test between the Weber 15F150B and Warehouse G15C.

Thanks for sharing pics of your project Greg.  I almost went that way and truly cloned it but got lazy and just did it my way.

[eleventeen]

Oh yeah! I had one of those I got for free cleaning out somebody's attic somewhere...I definitely the remember the wooden "tone block" under the chassis! 

[TubeGeek]

Well the verdict is in…..

Weber 15F150B wins hands down for this amp.

The differences aren't subtle either.  Both speakers sound good to me but definitely different.  The warehouse G15C is brighter in the high end with a sizzle that rides on top of everything.  It has a little more bottom end.  I almost don't like hearing that sizzle because it makes me think something is wrong or that I need to compensate in the circuitry for it.  Maybe the speaker needs time to break in more

I have heard this sizzle on other speakers too.  In fact I have a Weber 12F125O in my princeton reverb amp that has this same sizzle.  I don't know, I guess it is what it is.  I will use this warehouse in my next project, a tweed pro.  This speaker does sound more suitable for a tweed circuit to me anyways.

The Weber 15F150B sounds more controlled in the high end.  It isn't bright and it's not dark, just right.  The low end is there but not boomy.  It almost seems like the amp doesn't have as much gain with this Weber but I think what it is…is the sizzle is not there.  I think with a little more break in this speaker will sound even more warm.

I should mention I have two identical 15" cabinets side by side so I can quickly switch between the cabinets and not lose memory of what I am hearing between the two speakers.

I also have a 15" eminence legend I will try out.  Maybe in a day or two.

[SoundmasterG]

Received the Weber 15F150B today.

Now it's a speaker test between the Weber 15F150B and Warehouse G15C.

Thanks for sharing pics of your project Greg.  I almost went that way and truly cloned it but got lazy and just did it my way.

It wasn't really a project...the pics are not a clone by me or anything.

I rebuilt 3 original Thunderbolts awhile back and shared the info I learned with Sean Weatherford since he was trying to put a schematic together. With info from me and others, he put together the schematic that is hosted here, and on Sean's Supro site, and that you used for your build. So the pics I shared here are of original Supro Thunderbolt amps, in case anyone needed to see reference pics so they could do a layout.

Personally I like the layout you did with a board better than the PTP setup of the originals, but either method works well. If anyone needs them, I do have more pics of the original amps, though I think what I posted should give anyone the info they need to make a clone if they want.

Greg

[Ed_Chambley]

Well the verdict is in…..

Weber 15F150B wins hands down for this amp.

The differences aren't subtle either.  Both speakers sound good to me but definitely different.  The warehouse G15C is brighter in the high end with a sizzle that rides on top of everything.  It has a little more bottom end.  I almost don't like hearing that sizzle because it makes me think something is wrong or that I need to compensate in the circuitry for it.  Maybe the speaker needs time to break in more

I have heard this sizzle on other speakers too.  In fact I have a Weber 12F125O in my princeton reverb amp that has this same sizzle.  I don't know, I guess it is what it is.  I will use this warehouse in my next project, a tweed pro.  This speaker does sound more suitable for a tweed circuit to me anyways.

The Weber 15F150B sounds more controlled in the high end.  It isn't bright and it's not dark, just right.  The low end is there but not boomy.  It almost seems like the amp doesn't have as much gain with this Weber but I think what it is…is the sizzle is not there.  I think with a little more break in this speaker will sound even more warm.

I should mention I have two identical 15" cabinets side by side so I can quickly switch between the cabinets and not lose memory of what I am hearing between the two speakers.

I also have a 15" eminence legend I will try out.  Maybe in a day or two.

The Weber ALNICo California 15 is really a nice speaker.  I bought one to replace a Utah in a BF fender Pro and A/B it with the JBL 140 and I have to say it is very close.  I have never heard anyone complain about them, that is why I tried them.  I find it to have a better bass response than a ceramic Jensen.  I am interested in WGS as a lot of good words on their 15 as well.  I believe our newest Moderator may have gotten one for Christmas.  Maybe he will give a review.

I love to hear about speakers, so let me know what you find.  The 2 most overlooked things in tone is speakers and how you play the strings, what pick, fingers, thumbpick and strings.  The speaker having the largest influence.

Did I mention the PRO sounds better than ever.  I would use the JBL, but it is going into another build I will finish one day.

[archaos]

This month's project is a Supro Thunderbolt.  

I have been building lots of kits lately and this time I wanted to build one from scratch.  I didn't want to clone the original either.  I came close to having a cabinet made like the original but in the end decided to go my own route instead.

Back in Xmas 2013 my girlfriend gifted to me a set of ClassicTone Supro transformers so that kind of sparked this project.  I was already booked up in January and February with projects so March was the month of Supro!

The build went pretty smooth.  There aren't any verified layouts of this circuit out there that I could find so I made my own layout from the schematic.

After taking the time to draw it up I found that I was going to have to invert the layout because of the way I had the tube sockets laid out on the chassis.  No big deal, I had to do this years ago when I built my Hoffman AC30 project.  I simply took a pic of my layout (which was drawn up on a whiteboard) and loaded it to my photo software and then flipped the direction, printed it out and poof…had a layout to follow in front of me!

Pretty simple circuit, not much to it.  After getting it fired up and testing it all I found useful was to add the second (originally unused) V1b triode in parallel with V1a.  I just couldn't leave a triode unused.  It thickened up the signal and increased harmonic content. Very pleased with this.

I have a cabinet ready to be tolexed as soon as the tolex arrives.  It'll be covered in white sparkle tolex.  The speakers I have to choose from are a Warehouse G15C, Weber 15f150B and an Eminence Legend 15.  Currently I am trying the Warehouse and I like it so far.  The Weber will arrive this week sometime.  The 15" speaker sure sounds BIG.

Anyhow, I added a little bling to the amp for fun.  I added a DC voltmeter to the cage that is tied to the + of the power tubes cathode resistor.  It fluctuates a little bit when playing.  Lastly I added an LED strip inside the cage for lighting effect.  Nothing more than eye candy.  I almost added a magic eye tube but then thought it'd be too much, I'll save that for my next project.

Thanks for looking!

TG


http://youtu.be/6S2xAJpUjQs

Congrats, very nice stuff as usual ! 

Last year I planned to build that amp, unfortunately ClassicTone still don't offer a 220VAC PT, & MM offer one which is waaay too expensive...

[topbrent]

Great job on the Supro Thunderbolt, James!

They are an interesting amp for sure.  They actually sound pretty good for bass when paired with a good cabinet.  Very vintagy sounding,  not a modern full range tinny bass sound, but more "bassy" if that makes sense.

With a guitar, they can be very vanilla, in a good way.  Turn the volume up nearly all the way and then the appropriate Zep tones start to emerge.  Add a tonebender fuzz and it becomes Communication breakdown.

I picked up a really cool Thunderbolt clone from Jon over at ampgarage.  It is built with a Fender Hot Rod Deluxe power transformer and a Heyboer JTM45 output transformer.  He built it on tag strips like the original and added 100ohm screen resistors for safety.  250ohm cathode resistor on the power tubes~90% dissipation.  Wonderful amp!

[TubeGeek]

I am considering adding some screen resistors.  Any particular reason they are 100 ohms and not 470 or 1k…? Just curious.

With 200Ω I am at 25W per tube or 100% plate dissipation.

With 250Ω I am at 22W per tube or 88% plate dissipation.

[tubeswell]

I used Rg2 = 1W 470R on mine

[SoundmasterG]

I am considering adding some screen resistors.  Any particular reason they are 100 ohms and not 470 or 1k…? Just curious.

With 200Ω I am at 25W per tube or 100% plate dissipation.

With 250Ω I am at 22W per tube or 88% plate dissipation.

As noted on Sean's schematic...the stock 200 ohm bias is kind of hot...and the tubes will wear out quicker than they might otherwise. The 240 ohms will give a cooler bias point but the amp loses some richness in the sound. Personally I like the 200 ohm bias, and I just use Sovtek 5881's in a Tbolt as those tubes like to be hit hard and biased hot and they sound great and last a long time in this circuit.

Greg

[TubeGeek]

Finished the speaker cabinet this week.  I used white sparkle tolex.

[HotBluePlates]

I am considering adding some screen resistors.  Any particular reason they are 100 ohms and not 470 or 1k…? Just curious.

You should size the screen resistors according to your amp's needs.


In a perfect world, no screen resistance is used. That's because if screen voltage drops, so does plate current (as you found out with swapping resistors). Screen current can rise somewhat when you're pushing towards max power output, and so a large R would cause a large voltage drop and constrict output power.


But some tubes draw more screen current than others, and screen V * screen I equals too much dissipation for the screen's rating. So larger-valued resistors are fitted to potect the screen under conditions of heavy screen current draw.


A long while back, I suggested to Tubenit that one could "abuse" this fact by making the screen resistors much larger than typical, to cause compression earlier in an amp. It works only when you're cranked, and it does reduce the max power output and take away some punchiness, but does so in the same way playing with a 5Y3 rectifier is not as punchy as a solid-state rectifier. But if you want that sound, it delivers very well.


Except for EL34 amps, you generally see tube amps (across the board, not just guitar amps) with small-value or no screen resistors. Mullard had 1kΩ on many conditions in their data sheet (though some show as low as 470Ω), and I bet many builders just copied what Mullard printed. I do also see where some of the data sheet conditions have screen current rise from 4-5mA at idle to 20-22mA at full output. 20mA @ 400v is 8w and right at the EL34's screen dissipation rating. So to keep the screens from melting when you're pummeling them in a Marshall, it's easiest to just give them a bigvalue screen resistor to drop screen volts.

[SILVERGUN]

A long while back, I suggested to Tubenit that one could "abuse" this fact by making the screen resistors much larger than typical, to cause compression earlier in an amp. It works only when you're cranked, and it does reduce the max power output and take away some punchiness, but does so in the same way playing with a 5Y3 rectifier is not as punchy as a solid-state rectifier. But if you want that sound, it delivers very well.

I had read this, and was all over it recently...
There is a big difference in punchiness just dropping from 1.5K down to 470R (on an EL34 Marshall'ish design),,,and with different amps the effect is more or less desirable...
I went as high as 10K just to hear how bad it would sound, and the most recent amp got extremely compressed and it really "flattened" the response and feel, and mushed out....the lower the value, the more immediate the response feels, and the amp sounds more "in your face"

It has become one of the last tweaks that I will try before the amp is complete.

[macula56]

great looking amp TG. what schematic did you go by for this? i there a Thunderbolt schematic floating around? Thanks, JMac

[lego4040]

Love everything about that amp man. Those turret boards are cool, I seen them at turretboard and thought about grabbing a few just so I have them.

[SILVERGUN]

Love everything about that amp man. Those turret boards are cool, I seen them at turretboard and thought about grabbing a few just so I have them.

Just for the record lego,,,stay away from the black, pre-punched boards from AES ...I found one to be conductive recently and it ruined my month, AND one of the most beautiful boards I had ever wired up.... 
Some theories exist that there is a conductive component in the black coloring.

I've never had a worse reversal of feelings as when I finished the build and then found voltage existing on a turret that wasn't connected to anything....I don't wish that misfortune on my worst enemy....

Just a head's up 

[TubeGeek]

great looking amp TG. what schematic did you go by for this? i there a Thunderbolt schematic floating around? Thanks, JMac

Thanks!


Here is the schematic I followed:


http://el34world.com/charts/Schematics/files/supro/Supro%206420TR_Tbolt.pdf

[TubeGeek]

Love everything about that amp man. Those turret boards are cool, I seen them at turretboard and thought about grabbing a few just so I have them.

I like them a lot too.  Best part about them is that you don't need to drill your own holes.  I bought a bunch of the colors they offer. 


I am gonna check the black ones for conductivity, thanks silvergun!

[SILVERGUN]

I am gonna check the black ones for conductivity, thanks silvergun!

It is my very humble and uneducated opinion that something changed in the black board after I soldered to the turrets.....black board + heat = nightmare

The fresh boards tested fine but the one I soldered on was conducting at multiple locations up and down the board length...
First I had unexplainable DC on 2 of my preamp tube grids, and then I disconnected some things and found 100 DCV on a turret that was only connected to the board 

I couldn't believe my eyes, and had to bring one of the techs here over to confirm I wasn't nuts.
AES took the boards back and gave me a refund,,,but couldn't refund all the time it took to wire up the board and then troubleshoot it....

Don't use the black ones, my friend......they cause massive brain trauma 

[Willabe]

SG, just to be clear your talking about the old style vulcanized fiber boards and not the black fiberglass boards they now have, right?


            Brad     

[SILVERGUN]

SG, just to be clear your talking about the old style vulcanized fiber boards and not the black fiberglass boards they now have, right?

They are the ones that AES still sells....listed as "Glass Epoxy Unclad Laminate"....I told them what happened and they still sell them.
I read some older posts here and there is some thought given to the theory that there may be carbon in the black coloring....

As far as I can tell, this material is not "Garolite G10", but a cheap (probably Chinese "equivalent")

I probably should've started a thread at the time, but I was soo distraught at the time that I didn't even want to talk about it  ,,,or deal with the guys who would say "are you sure?'.....yes, I was 1 million % sure.....it happened, and I wish it didn't. That's why I disappeared from the forum for a little while there, I took a month off, and thought about whether I was mentally stable enough to deal with that type of catastrophic failure. 

I went and bought a sheet of Garolite G11 (green board in pic), for it's superior electrical properties ( only marginally better than G10),,,in hopes that it would never happen again.
Here's the before and after shots, so you can see that I actually did wind up doing a whole new board:

[Willabe]

I remember when that happened to you and was 1 of the reply posts. I seem to remember Doug replied saying he liked the fiber glass boards and didn't trust the old stuff either.

But I thought you were talking about the old style vulcanized fiber board that was in the old Fender amps and is still being sold today. I'm pretty sure we all did.

Gerald Webber was the 1st guy I saw say he thought it might be the black dye they use to color the fiber board as it contained carbon that made it go conductive over time. He ended up claiming he was using a fiber board that was basically the same except it was not died and was a light gray color. He said it was used in some type of commercial electric work as an insulator, I think in the big step down PT's on the power poll for the electric company?

I did see conductive/insolate ratings listed on the McMaster/Carr site when I was looking at Garolite and was surprised at that. I figured fiber glass was fiber glass no mater what it's color? Wasn't 1 type they sell even made to be conductive?


            Brad           

[Willabe]

BTW, that's a real nice looking build you just posted.

Yes you had to make another board but better that then have to punch a new chassis. That is what I worry about, the chassis and face plates.


          Brad     

[SILVERGUN]

I remember when that happened to you and was 1 of the reply posts. I seem to remember Doug replied saying he liked the fiber glass boards and didn't trust the old stuff either.

Wasn't me,,,but I read that thread, and that's where I gathered some of my info.

I did see conductive/insolate ratings listed on the McMaster/Carr site when I was looking at Garolite and was surprised at that. I figured fiber glass was fiber glass no mater what it's color? Wasn't 1 type they sell even made to be conductive?

Yup, there is a purposefully conductive board type available.....Electrically Conductive Garolite (Glass carbon) and it's BLACK!!! 

BTW, that's a real nice looking build you just posted.

Thank you very much ...I still owe you guys the thread for it...I need a little time to clean up the schematic and record a clip, etc.

Sorry for the Hijack TG!

[Willabe]

Yeah, here's the description from McMaster/Carr on line. It's for the black Garolite. 

The graphite-carbon portion of this glass-based material conducts electricity, removing static charges. Material is sometimes called industrial laminate or phenolic.

There's other guys selling the black colored fiber glass board. I wonder if it's all conductive? Woops. 


               Brad     

[Willabe]

Wasn't me,,,but I read that thread, and that's where I gathered some of my info.

Wait, it was a guy who had a Victory amp.

I bought a bunch of the colors they offer.

No thread hijack.
             

                Brad   

[SILVERGUN]

There is a black Garolite G10/FR4 material that is OK...it is listed as flame retardant ...also avail. in blue or tan
http://www.mcmaster.com/#garolite/=rjsp2x

Here's an old thread:
http://el34world.com/Forum/index.php?topic=10120.msg93180#msg93180