Another Supro s6424 build

[CraigB]

After checking out sluckey's new Supro project, I've decided it's time to build one of these for myself using his layout (thanks Steve!).  Having restored a Gretsch 6161 several years ago and being happily surprised at how great it sounded, it's been on the bucket list of amp builds.  The circuits are virtually identical, but the 6161 doesn't have a depth control.  So S-6424 it is!


I had some fiber board left over from a Super Champ restore and decided to use that up.





Got the board all loaded up.  Hopefully I can get a little bench time today and get going on drilling the chassis.

[sluckey]

Looking good!

[CraigB]

Looking good!

Thanks Steve!  Finally got some time to lay out chassis for punching/drilling/painting/labeling.  Painted with Duplicolor "White Pearl".  Assembly was going great until momentary loss of situational awareness and dropped it off the bench.  Had to do a few touchups to the paintjob. Always wind up with a battle scar of some sort no matter how careful I am!








Didn't mount the channel switch.  Want to be real careful soldering on it.  Should be easier to wire the jumpers and shielded wire outside the chassis and make the tip and ground connections after it's mounted.  Spent a little time this morning numbering the terminals so the position of the toggle matches the front panel labeling.  These little switches are pretty fragile, so don't want to touch the soldering iron to the terminals any more than absolutely necessary. 

[sluckey]

Haha. I wired my switch backwards! Easy to do. I just swapped my cheap Dymo labels. 

If I had to do it again I wouldn't even use a switch. I'll always play this amp in the "Both" position.

[John]

Nice looking chassis! What sort of decals do you use for your lettering?

[tubenit]

Very nice!  Looks great.  I have always used spray cans of automotive paint on my amp chassis and then cover them with a clear coat.  They have held up amazingly well.  Something I'll continue to do.

Looking forward to hearing your review of the amp when completed.

With respect, Tubenit

[bnwitt]

Looking very profesional there CraigB
Barry

[CraigB]

Nice looking chassis! What sort of decals do you use for your lettering?

Thanks John!  They're laser printer waterslide decals from MicroMark under a few coats of acrylic lacquer

Very nice!  Looks great.  I have always used spray cans of automotive paint on my amp chassis and then cover them with a clear coat.  They have held up amazingly well.  Something I'll continue to do.

Looking forward to hearing your review of the amp when completed.

With respect, Tubenit

Thanks Jeff!  Looking forward to posting some clips and do some recording with it

Looking very profesional there CraigB
Barry

Thanks Barry!

[Meteorman]

Looking good, CraigB - you have motivated me to start studying & collecting parts for this build.

If I had to do it again I wouldn't even use a switch. I'll always play this amp in the "Both" position.

Steve - if the selector switch is omitted, does the jack tip still go to both grid pins on V1 ?

Also, have been studying your S-6424 schematic, layout, and build pics to assemble my parts list.
Very helpful , thank you for posting all that!
Got confused about capacitor between V3 anode pin 6 and footswitch - you indicate a 0.047uf ;   older (Valco?) schematic indicates 0.005uf.
Is this a typo, or did you make a conscious cap change there ?
Thank you sir for any assistance.

/mike

[sluckey]

if the selector switch is omitted, does the jack tip still go to both grid pins on V1 ?

yes. Or you could use 4 input jacks like the original.

you indicate a 0.047uf ;   older (Valco?) schematic indicates 0.005uf.

I debated that for a few minutes. The 1624 schematic shows a .05 cap and the 6424 schematic shows a .005 cap. Both trem circuits are identical, so which is right?    I decided to go with the .05 because it just made more sense to me to use a larger coupling cap for this ultra low frequency circuit. I had intended to try the .005 after I finished the amp but just forgot. It's still on the bench so I may just go try the .005 today. If I do I'll report my findings.

[jojokeo]

Sweet Craig! Can't wait to hear your sound "samples" also! ;-) (still enjoying that last one!)

[CraigB]

Looking good, CraigB - you have motivated me to start studying & collecting parts for this build.

If I had to do it again I wouldn't even use a switch. I'll always play this amp in the "Both" position.

Steve - if the selector switch is omitted, does the jack tip still go to both grid pins on V1 ?

Also, have been studying your S-6424 schematic, layout, and build pics to assemble my parts list.
Very helpful , thank you for posting all that!
Got confused about capacitor between V3 anode pin 6 and footswitch - you indicate a 0.047uf ;   older (Valco?) schematic indicates 0.005uf.
Is this a typo, or did you make a conscious cap change there ?
Thank you sir for any assistance.

/mike

Thanks Mike!  Be looking forward to seeing your build.


As for the cap, Steve, I'd really be interested to know what if any difference you note.  I was looking at the Gretsch 6161 schemo, that one has a .01.  I think I wound up using a .0047.

[CraigB]

Sweet Craig! Can't wait to hear your sound "samples" also! ;-) (still enjoying that last one!)

Thanks man!  Getting a little closer.  Got the iron installed and wired up filaments, ready for circuit board and start wiring!

[sluckey]

I played with the .047 versus .005 coupling cap in the trem circuit. With the .047 cap the trem signal at the footswitch jack is approx. 30VAC RMS. With the .005 cap the trem signal at the footswitch jack is approx. 10VAC RMS.

With the .047 cap the trem effect is strong enough to cause a 'pumping' sound when the intensity is turned way up high. No big deal. Just turn the intensity down to a more usable level. With the .005 cap there is no 'pumping' sound and there is still more than enough intensity.

Bottom line... The .005 cap value shown on the original schematic is probably correct. I'm leaving the .005 (actually .0047) in my amp and I will make changes to my pdf file.

[CraigB]

I played with the .047 versus .005 coupling cap in the trem circuit. With the .047 cap the trem signal at the footswitch jack is approx. 30VAC RMS. With the .005 cap the trem signal at the footswitch jack is approx. 10VAC RMS.

With the .047 cap the trem effect is strong enough to cause a 'pumping' sound when the intensity is turned way up high. No big deal. Just turn the intensity down to a more usable level. With the .005 cap there is no 'pumping' sound and there is still more than enough intensity.

Bottom line... The .005 cap value shown on the original schematic is probably correct. I'm leaving the .005 (actually .0047) in my amp and I will make changes to my pdf file.

Thanks for checking back in Steve!  I'll check my board and make sure I used the smaller cap...pretty sure I did.  Lucked out today.  Up until about 10 minutes ago, it was looking like I'd be working most of the weekend, but thankfully dodged that bullet!  Looks like I'll be doing some wiring instead   

[Meteorman]

Noted, Steve, thank you kindly. 👍🏻

[CraigB]

Got it off the bench this morning, checked out my wiring up close with optivisor, a little voltage/continuity testing, fired up.  Everything works, just can't play it loud since it's too early.  Will get to play it a little later.  But here's some shots of it. 








Those trannies sure seem bigger than the ones I remember on the Gretsch amp.  Barely even gets warm at idle.

[sluckey]

That looks great! What size chassis are you using?

[CraigB]

That looks great! What size chassis are you using?

Steve, it's a 16x8x3 steel Hammond box.  I prefer the aluminum ones when the iron isn't so chunky cuz they're easier to punch and there's no need to grind the paint off for grounds. 


I've got a friend that does metal fabrication, he said if I draw what I want he'll make a custom cage.  I'm thinking something retro, like the old chassis covers with louver vents?

[bnwitt]

Very nice work CraigB!

[sluckey]

Do you think the tremolo has enough intensity with the small cap?

[CraigB]

 

Do you think the tremolo has enough intensity with the small cap?

It has plenty of chop with "channel 1" (V1a), but I'd like it if it came into play earlier in the rotation of the pot, which I'm sure it did when you had the .05 cap in there.  With both channels engaged, it gets kind of lost.  I think a larger cap might be better.  .01, .02?


BTW, I really like having the channel switch.

Very nice work CraigB!

Thanks Barry!

[schutone]

Looks great!

What transformers did you use in the build?

[sluckey]

...I'd like it if it came into play earlier in the rotation of the pot

A .047 cap will definitely do that. Using a linear taper pot will also do that for you.

[CraigB]

Looks great!

What transformers did you use in the build?

They're from Watts Tube Audio, Heyboer Supro Model 24.  Very nice iron!  I ran it pretty hard for several hours yesterday and they don't get hot at all.

...I'd like it if it came into play earlier in the rotation of the pot

A .047 cap will definitely do that. Using a linear taper pot will also do that for you.

Yep, I got a linear taper pot with a switch in there.  I think I might throw a .02 in there 

[sluckey]

I have a request if you experiment with different caps. Monitor the tremolo signal at the footswitch jack with an AC RMS voltmeter. Report your voltage readings for different caps.

[CraigB]

I have a request if you experiment with different caps. Monitor the tremolo signal at the footswitch jack with an AC RMS voltmeter. Report your voltage readings for different caps.

Absolutely!  I will check it tonight with the .0047 in place, and then if I decide to change that out, I will give you readings.  You can see the way I ran my wiring that the twisted pair of grid wires fly right over the top of that cap, so will need to do a little scooting around to work in that area.

[sluckey]

Don't use a soldering iron until you are sure you want to do this. Just use a couple gator clip leads to temporarily parallel the bigger cap with the present cap.

[CraigB]

Don't use a soldering iron until you are sure you want to do this. Just use a couple gator clip leads to temporarily parallel the bigger cap with the present cap.

Steve, tacked in another .0047 parallel and no difference on my meter???     It's a cheap Velleman, so probably not very accurate.   I've been wanting to get a Fluke, just haven't gotten around to it.  Sorry, that's not very helpful.


Anyways, with the .0047 alone, the trem is audible at about 9:00 o'clock on the intensity pot and maxes out around 3:00.  So there's really only a slight margin at either end of the control that has no effect.  With both caps in and intensity dimed, there's slightly more chop on tap, no speaker pumping sounds.  So there's gotta be a difference in signal that I'm not able to measure.  I think .01 is a good value.

[CraigB]

Here's a couple sound samples, channel 1 on both, volume set at 2:00 o'clock, tone set to 3:00, with my new tele-ish guitar build using Voice Record free app on my iPhone 6s.  The second one is with the trem engaged, depth set at 12:00


https://soundcloud.com/user743789963/supro01


https://soundcloud.com/user743789963/supro02

[tubenit]

Totally cool!  Sounds outstanding!   Thanks for sharing the sound clips.

With respect, Tubenit

[sluckey]

Yes, that does sound good!

[CraigB]

Totally cool!  Sounds outstanding!   Thanks for sharing the sound clips.

With respect, Tubenit

Thanks Jeff!  That little phone app is pretty cool.  You can adjust the gain of the microphone so it doesn't clip and it's got a VU meter for reference.  It allows for stereo or mono, and you can do MP4, MP3 or .wav files.  Not bad for a free app!

Yes, that does sound good!

Thanks, Steve!  Please excuse the sloppy playing  I am looking forward to dusting off my ProTools rig and doing some recording with it.  Will post a SoundCloud link here when I do.

[SILVERGUN]

Great build, nice pics, and way to finish it off with some sound clips!

 

[mresistor]

Very nice work and a great looking/sounding amp! Did you mention the name of the phone app you used, I'm interested.

[CraigB]

Very nice work and a great looking/sounding amp! Did you mention the name of the phone app you used, I'm interested.

Thanks MrR! App's called "Voice Record Pro" by Dayana Networks Ltd.  It has a VU meter and an input gain control so you can set it according to volume of the amp not to clip.  Also gives option of recording MP4, MP3, .wav, etc., and then you can send to email, text message, save to DropBox, Google Drive, OneDrive, iCloud, post to YouTube, FB, website upload and more.  Pretty cool for quick sound sample recording or songwriting

[tubenit]

So how is the amp playing and sounding?

Did you miss his sound clips in Reply #29?

With respect, Tubenit

[Crate50watt]

Looking good!

Thanks Steve!  Finally got some time to lay out chassis for punching/drilling/painting/labeling.  Painted with Duplicolor "White Pearl".  Assembly was going great until momentary loss of situational awareness and dropped it off the bench.  Had to do a few touchups to the paintjob. Always wind up with a battle scar of some sort no matter how careful I am!








Didn't mount the channel switch.  Want to be real careful soldering on it.  Should be easier to wire the jumpers and shielded wire outside the chassis and make the tip and ground connections after it's mounted.  Spent a little time this morning numbering the terminals so the position of the toggle matches the front panel labeling.  These little switches are pretty fragile, so don't want to touch the soldering iron to the terminals any more than absolutely necessary. 

How did you get that stencil lettering on the front for the controls?? I have yet to figure out a way to do that!

[bnwitt]

I know many folks are building Sluckey's Supro amp and I came across the Royer Labs "Recording Electric Guitar" videos on YouTube.  One of the amps in the series is the Supro.  Check it out:

https://www.youtube.com/user/royerlabs/search?query=Recording+Electric+Guitar

Barry

[CraigB]

Looking good!

Thanks Steve!  Finally got some time to lay out chassis for punching/drilling/painting/labeling.  Painted with Duplicolor "White Pearl".  Assembly was going great until momentary loss of situational awareness and dropped it off the bench.  Had to do a few touchups to the paintjob. Always wind up with a battle scar of some sort no matter how careful I am!








Didn't mount the channel switch.  Want to be real careful soldering on it.  Should be easier to wire the jumpers and shielded wire outside the chassis and make the tip and ground connections after it's mounted.  Spent a little time this morning numbering the terminals so the position of the toggle matches the front panel labeling.  These little switches are pretty fragile, so don't want to touch the soldering iron to the terminals any more than absolutely necessary. 

How did you get that stencil lettering on the front for the controls?? I have yet to figure out a way to do that!

Hey Crate50Watt, that is laser printer waterslide decals buried in clearcoat.  I get my decal paper from MicroMark.  Works great.  Larger decals are challenging to apply.  I typically print at least two of each decal in case I accidentally tear one, which is VERY easy to do. I also bought the their decal application kit, which comes with decal setting solution (white vinegar) and decal solvent for textured surfaces.  I do my logo on the headstocks of my guitars the same way.

[CraigB]

A little slow on getting this project completed, but finally chopped up some metal and made a chassis cage.  Hard to see in the pictures, but I made the bottom plate/feet so there's enough clearance to sit over the top of a dogbone style handle.  Thanks again to Steve (sluckey) for sharing the board layout and other info!

[sluckey]

That reminds me of the old Bogen Challenger PAs. Looks bullet proof. Much better quality than the originals. You did a great job on that project!

[tubenit]

What a superb job!    Thanks for sharing the photos and previous soundclips! 

With respect, Tubenit

[CraigB]

What a superb job!    Thanks for sharing the photos and previous soundclips! 

With respect, Tubenit
 

Thanks, Jeff!  Always appreciate the Tubenit thumbs up!

That reminds me of the old Bogen Challenger PAs. Looks bullet proof. Much better quality than the originals. You did a great job on that project!

Thank you again, Steve!  What a great little amp!

[davidwpack]

That's super--nice! That doesn't look like a home-built amp at all. I'm thinking about a Supro as my next build. I've been looking at the Dual Tone, Thunderbolt, and the Coronado but haven't decided.