Info for Supro Build

[TIMBO]

Hi guys, I have some parts gathered for a simple Supro Thunderbolt build.

I'm looking for some info before I start drilling the chassis.
It states that there is a spare triode at V1, SO............
Looking for ideas for this triode, but I'm not wanting to change V1a as to keep the Thunderbolt magic.
So I guess a parallel input could be out of the question.
Maybe a second channel with volume/tone but not identical to channel 1 and mix resistors prior to v2a???
One tube reverb after mix resistors

I have a 15" alnico speaker that I'm keen to use, but....
The OT I have is 5k:15ohm (only one tap) and the speaker is 4ohm.
I'm thinking of having a 8"/8ohm dummy speaker mounted inside the cab (combo)to make up the extra load.

Is there a better way???

[tubenit]

You might want to look at the Gretsch 6159 for some ideas?

https://el34world.com/charts/Schematics/files/Gretsch/Supro_gretch6159.gif

I've attached a schematic and a layout of the Gretsch that I drew some years ago.

With respect, Tubenit

[sluckey]

The Supro S-6424 has a one triode preamp that's different from the Thunderbolt. May be a consideration. Take a look. Schematic at the bottom of the page...

     http://sluckeyamps.com/supro/supro.htm

[jjasilli]

I don't know what you mean by a dummy speaker.  If the 2nd speaker is connected it will operate as a speaker, not a dummy.  You might just as well use a series resistor to get up to near 15 Ohm's, but this is not advisable.  The resistor will seriously attenuate the amp's output. 


I think you need the right impedance speaker; or a speaker combination to get you to 8 - 16 Ohms; or another OT.  Or an impedance matching OT.  Weber sells them; or use a line matching OT.  Or you cam calculate or measure the "line out" voltage @ max clean wattage output.  But why?  I think it's better to go with matching components in the first place.

[shooter]

it will operate as a speaker

If it can't move air it just acts like the inductor it is

[MFowler]

Funny I can't figure out to build a stock T-Bolt or add reverb etc.  Got the combo cab with 15" Weber but............


Good luck with your build and have loads of fun building it.


Mark

[TIMBO]

Thanks Mark.
I think this will work well.

Ooops, Might need a 330k mix resistor off the reverb pot.

[tubenit]

Just a thought to consider and it doesn't mean that you "should" do this …………………

I'd be tempted to run the signal from V1a to V1b to V2a and get another gain stage going like in the Gretsch 6159.  I read somewhere on the internet that the Gretsch 6159 has some similarities to the Supro 1688TN. 

The YouTube videos by Leon C.  (a forum member) of his 1688TN amps have remained my favorite "amp tone" YouTube of any I've watched including the Dumbles etc etc...     AND I have been under impressed with the YouTubes of the Supro Thunderbolts.  Just a personal taste thing & it doesn't mean that the 1688TN would necessarily be "better" then the Thunderbolt for you.

I would anticipate the one tube reverb working as you have it drawn into your schematic.   

With respect, Tubenit

[TIMBO]

Thanks T, This is the problem, they all sound great.

[TIMBO]

A bit of progress....

[TIMBO]

Hi guys, Board completed.............

I've done a VINTAGE mix with the components, just to capture some yesteryear MOJO.........

[shooter]

just to capture some yesteryear MOJO

you need some Ausie dust baked on the board to take the new board shine out 

[TIMBO]

Thanks shooter, We are just coming out of a very dry spell and there was a lot of dust around. That is now MUD, it's been raining pretty hard for the last two days.https://www.sbs.com.au/news/qld-storm-damage-bill-still-not-finalised
 All wired up and ready to rock :metalhead

[tubenit]

IF there is any way possible, I'd love to hear a sound clip or YouTube of this amp!

With respect, Tubenit

[TIMBO]

Can do.

[tubenit]

Can do.

Thanks!  I will look forward to it.  I always appreciate what you share on the forum.  You have some GREAT amp designs and some really innovative stuff that you work on. 

With respect, Tubenit

[TIMBO]

Guys, The THUNDERBOLT BOOOOOMs.
Fired up well with no problems.
I'm keen to get it into it's cab to get a better idea of sound.

[PRR]

The 150mA from the 6L6 cathodes may be used to DC-heat V1 V2.

[adamG]

Hi Tim,

You've made me interested in your build.
I must be crazy of my consideration to try again another Supro replica, because of you;). I used to build several amps in same time, but this one seems to be tempting very much!
My first question is about the reverb. How does it sound to your ears? Can you recomend it in this modified amp's circuit?
How about the gain? Previously, I followed Sluckey's 6424. That amp is rather not too much gainy. I'd like to follow your idea with more gain then 6424. I don't mean to convert vintage amp into the monster but to receive the gain as the present reissues have.
I remember the Sluckey's topic of 6424, where I asked for types of caps. Some replied with info that in Supro/Gretsch ceramic caps were provided. What do you think about it?

Thank you in advance.

Regards,

Adam

[TIMBO]

Hi Adam, I need to finish the cab to get a better idea of the sound, but I can say they do have a gainy sound.
I sure the cleans can be dialed in.
I used whatever caps I had in hand, some old some new, could be a good thing.

[adamG]

Hi Tim,

To tell the truth, Sluckey did the very good job with 6424 including layout, the whole project. But as I mentioned, that amp is rather smooth and gentle;), IMO. Very classic machine!
This time, I'd like to try Supro more gainy with the simple reverb stage, as you did.
Acc.to my brief experience, I think that the beauty of tubes' sound is within them, nevertheless the circuit of an amp. More or less of course;)
Ok, I'll be waiting for the info form you, when the cab is finished...

Thank you and kind regards,

Adam
 

[TIMBO]

Hi guys, Had a good day in the shed and knocked up the cab.

I'm doing a bit of a test run to make sure everything fits.......
As I said a trial run  :redfaced
I am really wanting to use the 15" speaker but it is only 4ohm and the OT is 15ohm.
So the DUMMY 8" speaker is to make up the extra load, even though it still is only 11ohms as per the MM.
I hope to get a stunt guitarist to give it a whirl.
If it sounds crap I have only cut the opening in the baffle to take a 12" and the ply mounting the 8" is only tacked in.

[Glenn]

Timbo, I follow your threads with great interest. I love how you make everything yourself.
I’m going to copy how you make a chassis and especially how you construct your cabinets.

I have a friend at work who was saying his father in law is wasting away alone... he’s a retired carpenter.
So I asked if the guy would build me a cab, and I sent home blueprints for a Trainwreck cabinet. I’m going to pick it up tomorrow, I don’t know what it looks like but whatever.... sorry rambling a bit.

CAn you take a pic of the front of the cabinet? While it’s still naked?
I hope it sounds great for you, mine does, it’s a Sluckey supro
Thanks....mate

[TIMBO]

Hi Glenn, Some pics... (this is another similar cab)

Front

As you can see I don't do anything special.
I simply butt the corners together, glue and nail and brace the cab square.
When the glue is dry I put in some 6mm dowels.
17mm baffle board is a neat fit at the moment but will be plained down to take in the thickness of the tolex and grill cloth.

This is just a perfect picture.

Hope this helps.

[Glenn]

Thanks a bunch Tim... it will help. I have 6 amps that have been without a home for a year or so
Most of them willl go into heads but I would like to try a combo cab for 1 of them

[DummyLoad]

very,very nice timbo. can't wait to see finished product.


--pete

[TIMBO]

Well Pete wait no more, the Supro is done.....







I changed the three .068u coupling caps to .047 as it made channel 1 quite dark and muddy.
Channel is still a bit dark but blends well with the other channel.


The P15N speaker may also be adding to the darkness.

[66Strat]

Great job! I would really like to hear some sound clips. I'm particularly interested in the sound of Channel 1 and how the sonics of that channel might compare to a 5D5 Pro.

[TIMBO]

Thanks guys, I did forget to mention there is a feedback thing happening with the reverb........

[tubeswell]

Looks real swish.

Thanks guys, I did forget to mention there is a feedback thing happening with the reverb........

Put your finger on the back of the pan when its ringing just to confirm its a microphonic pan, then put the pan into a bag, or wrap it in bubble wrap with corrugated cardboard and duct tape or something

[acheld]

When I saw that you had mounted the reverb pan to the back panel the other day, I thought it was an interesting use of the back panel. 

But, the placement on the (thin, vibrating) panel just behind the speaker may enhance the microphonics.

In addition, reverb tanks are rated for their mounting positions:

https://www.amplifiedparts.com/tech-articles/accutronics-products-and-specifications

If there is space, the easiest fix may be to mount the thing on the floor of the cab, and (acoustically) insulate it if you need to.

[TIMBO]

The reverb tank is the right type to be mounted that way, but probably not the best position for it.
I'm also not a big fan of the long tank, just had it on hand.
So I'll do some tank rolling.......