6V6 Plexi with Crossover Distortion [Problem Solved]

[dbharris]

Somebody on the Trinity forum asked for a clip. I still feel like I have some tweaking to do for this amp. Going to add GNFB in January and then go from there.

Please excuse the sloppy playing...

https://youtu.be/h20X0cRYa1w

The Ocean is Neck/Bridge (LP), Middle (Strat)

Sunshine of your Love is Neck (LP) with volume rolled down to 8 for main riffs and and 10 for solo with tone on 0 for solo only, Neck (Strat) and same vol/tone changes on guitar

Pawn Shop is Bridge (LP) Bridge (Strat)

Then I play some open chords and roll the volume back on the guitar to clean up the tone

Last, is playing each channel separately and then jumpered together.

-Dan

[crgfrench]

That amp sounds pretty sweet to me, nice job!

[dbharris]

Thanks! I'm still getting used to the Marshall thing coming from fender style amps. It's a lot of fun getting to know this amp.

[ViperDoc]

More of a question than a recommendation: is it not advisable to separate the preamp and power amp grounds? They appear to be all soldered together.

[crgfrench]

More of a question than a recommendation: is it not advisable to separate the preamp and power amp grounds? They appear to be all soldered together.

In the image download/file.php?id=12858&mode=view they look separate. There is a physical overlap of the sections but they don't seem connected. Power ground appears to go to the left star and pre goes way over to the right.

[dbharris]

More of a question than a recommendation: is it not advisable to separate the preamp and power amp grounds? They appear to be all soldered together.

In the image download/file.php?id=12858&mode=view they look separate. There is a physical overlap of the sections but they don't seem connected. Power ground appears to go to the left star and pre goes way over to the right.

Yes, originally going by the Trinity layout they were all mixed together. I did separate them out with jumpers (green wires along the ground bus) where appropriate.

However, I did not perceive any difference in sound, hum, or noise floor following that change.

[dbharris]

Quick update, I spent some time working on the amp today and I am very satisfied with the results. I know the guts are a bit sloppy since I have chopsticked around so much and done many rounds of mods, but all of the connections are solid and sound is great.

I started out chopsticking. Was able to determine all of the instability in the amp was due to a micorphonic tube in V1. It seemed good back when I was rolling tubes, so I guess it must have been a little microphonic and got worse as I played the amp and it got rattled around. It was a new Mullard long plate. Now I have an EHX 7025 there. All good and not running off into feedback at the drop of a hat.

I alligator clipped in a couple small snubber caps across the plate resistor for the second gain stage. Settled on 470p and soldered it in. This really helped calm the ice pick harmonics of this amp.

Then, I made all of the several changes necessary to add Global Negative Feedback on a switch...PI plates, feedback resistor, changes to long tail pair part of PI, moving where the channels meet the PI and adding mixing resistors. I fired up the amp and it wasn't howling but was definitely out of phase and unstable. Switched the OT leads and all good.

This sounds like a big box Marshall to me! Nice and tight even with lots of gain. Now that I have the fat boost and GNFB switches there is a lot of variation that can be dialed in with those and different amounts of gain. Still cleans up incredibly well with the volume knob on a guitar. I am calling this one complete. If there is anything I might have done different, it would be going with a 220p or 330p snubber since the GNFB kills some high end too. But the difference is not worth opening her back up for that one cap.

-Dan

[ViperDoc]

Quick update, I spent some time working on the amp today and I am very satisfied with the results. I know the guts are a bit sloppy since I have chopsticked around so much and done many rounds of mods, but all of the connections are solid and sound is great.

I started out chopsticking. Was able to determine all of the instability in the amp was due to a micorphonic tube in V1. It seemed good back when I was rolling tubes, so I guess it must have been a little microphonic and got worse as I played the amp and it got rattled around. It was a new Mullard long plate. Now I have an EHX 7025 there. All good and not running off into feedback at the drop of a hat.

I alligator clipped in a couple small snubber caps across the plate resistor for the second gain stage. Settled on 470p and soldered it in. This really helped calm the ice pick harmonics of this amp.

Then, I made all of the several changes necessary to add Global Negative Feedback on a switch...PI plates, feedback resistor, changes to long tail pair part of PI, moving where the channels meet the PI and adding mixing resistors. I fired up the amp and it wasn't howling but was definitely out of phase and unstable. Switched the OT leads and all good.

This sounds like a big box Marshall to me! Nice and tight even with lots of gain. Now that I have the fat boost and GNFB switches there is a lot of variation that can be dialed in with those and different amounts of gain. Still cleans up incredibly well with the volume knob on a guitar. I am calling this one complete. If there is anything I might have done different, it would be going with a 220p or 330p snubber since the GNFB kills some high end too. But the difference is not worth opening her back up for that one cap.

-Dan

Congrats on a successful build. Any sound bytes?

And this may be rhetorical, but how are your tube sockets being secured to the chassis? I only see locknuts on the tubes that have accessory solder tabs.

[dbharris]

Hey ViperDoc,

I haven't recorded any clips yet after these mods. I need to get Reaper set up on my new laptop and then I'll do some proper recording and post here. Might be a few weeks though.

This chassis from Trinity has threaded holes for the bottom mount tube sockets. I applied some thread lock to the screw head side as well. If they ever get loose I'll add some keps nuts too.

-Dan

[TriodeLuvr]

Is this the typical way turret boards are wired in DIY guitar amps? The component leads are soldered into the turrets from the top, rather than being wrapped around? I've made small turret boards for other projects, but not long ones like these. Even then, the turrets I used weren't hollow, so wrapping the leads was the only choice.

Jack

[JMPGuitars]

Is this the typical way turret boards are wired in DIY guitar amps? The component leads are soldered into the turrets from the top, rather than being wrapped around?

That is not ideal at all. Wrapping on the outside is much preferred. the soldering thread in my signature and watch the videos to see what the proper standards are if you're interested.

[dbharris]

Yeah, I totally agree. But, I didn't know better at the time and was following the instructions in the kit. Any mods that I did with new parts later were wrapped around the turret. For what it's worth, even the connections made through the top of the turrets have a mechanical connection. I would bend the leads such that inside the turret the lead is making physical contact with the inner wall i.e. the leads bent at a slightly acute angle, not 90.

My main issue with this more than the mechanical connection is I knew I had a good solder joint but people online would comment there was not enough solder in the turret. So, I would try to fill it up and some would just never work right. I was afraid if I kept adding solder it would start leaking out the bottom of the board. Which would be very bad. I understand now that a lot of people make their solder joint and allow it to cool, then place a little ball of solder on the very top that is purely aesthetic. But I don't think that is a great approach either.

You live and you learn. My next build is with an eyelet board.

-Dan

[JMPGuitars]

My main issue with this more than the mechanical connection is I knew I had a good solder joint but people online would comment there was not enough solder in the turret. So, I would try to fill it up and some would just never work right. I was afraid if I kept adding solder it would start leaking out the bottom of the board. Which would be very bad. I understand now that a lot of people make their solder joint and allow it to cool, then place a little ball of solder on the very top that is purely aesthetic. But I don't think that is a great approach either.

You live and you learn. My next build is with an eyelet board.

-Dan

Yikes, ignore comments unless it's somebody you know has a clue. Too many people think there's supposed to be a huge convex dome on the tops of turrets, which is not correct. A LOT of people think that.

Good luck with the eyelets, let us know how you think it works compared to turrets, especially if there's a lot of components coming to the same spot. ...and don't forget you still want concave solder joints showing the outline of the leads.

Thanks,
Josh

[TriodeLuvr]

That is not ideal at all. Wrapping on the outside is much preferred.

I'm using a turret board that came with two rows of 30 turrets pre-installed. The rows are two inches apart, so most of my resistors don't have enough lead length to wrap around. Guess I need to decide whether it's worth the time and trouble to install a bunch of new turrets and maybe also slice the board to a narrower width. Always something...

the soldering thread in my signature and watch the videos to see what the proper standards are if you're interested.

Thanks, I'll take a look!

[TriodeLuvr]

My next build is with an eyelet board.

Help me out here. I don't see a difference between soldering a lead down into the hole at the top of a turret or into the hole in an eyelet.

Jack

[geoff 1965]

Marshall put components into the top of the turret in their point to point amplifiers,I do the same and have no problems.you get a better mechanical connection wrapping around the turret but if you’re like me and constantly tweaking/experimenting it’s a lot easier to swap in and out fed into the top. “different horses for different courses”

[TriodeLuvr]

Just to be clear, I wasn't criticizing Dan's work. These components are lightweight and the turrets don't move (unlike tube pins). I'm not sure robust mechanical bonding is required. On the other hand, I appreciate it when someone like Josh promotes a professional standard of workmanship, even if (sometimes) only for its own sake. That's the sort of thinking that keeps us out of trouble. I'll decide over the next few days how to proceed with this.

Jack

[JMPGuitars]

My next build is with an eyelet board.

Help me out here. I don't see a difference between soldering a lead down into the hole at the top of a turret or into the hole in an eyelet.

Jack

Some people think eyelets are easier to work with because there's less mass to heat. You can make a mechanical connection with a better bending angle in an eyelet than you can at the top of a turret, but you're right, it's not much different.

There's nothing wrong with using the top of the turret, it's simply not the preferred way, and either way, it needs to be done with good technique.

[dbharris]

My next build is with an eyelet board.

Help me out here. I don't see a difference between soldering a lead down into the hole at the top of a turret or into the hole in an eyelet.

Jack

Some people think eyelets are easier to work with because there's less mass to heat. You can make a mechanical connection with a better bending angle in an eyelet than you can at the top of a turret, but you're right, it's not much different.

There's nothing wrong with using the top of the turret, it's simply not the preferred way, and either way, it needs to be done with good technique.

Jack, I was not offended by your comment/question in any way. Always good to hear other point of view.

Josh, that's my understanding too for using eyelets. I am using that type of board because it is a two-rock/dumble style build and that is tradition for that lineage of amps. It's going to be a 100W clean machine with 3 tube reverb (clone of John Mayer's old signature amp with only 25 made)...maybe I'll post here in the appropriate forum but not sure if there is much interest in that type of amp on this board.

-Dan