5F10 FUN

[screefer]

The bias cap is grounded twice? And there is a jumper going from the resistor hanging off the 6v6 sockets to ground? Both of those resistors are grounded, so that jumper seems redundant.

The solder lug that the 1 ohm resistors are soldered to are isolated from the chassis denoted by 'iso'. The ground jumper from the isolated resistor
is intended to pick up the bias cap on it's way to the B+2 ground node.

Does that make sense, or am I missing your point?

What I am aiming for here is a ground scheme that has only one ground to the chassis through isolating all other points.
Probably not necessary, evinced by numerous other builds, but this is a learning exercise as much as "I'd love to build a Harvard'.

 

[screefer]

Here is my latest revision. I have re-drawn the inputs. is this right considering the Isolated jacks?

 

[King Fan]

@screefer, you are going great guns. And getting great input. If it were me, I'd keep revising and revisiting the paper build for a little while longer.

Now that you've figured out how to use flexible hookup wire instead of the straight 'jumper' tool in DIYLC, you'd do yourself a favor to make those black ground wires flexible. @Lowerleftcoast will likely know better than me, but I like to dump the input jack grounds close to the chassis ground anchor -- and close to the jacks themselves; they don't 'belong' to that filter, they're just grounding out noise from shield of the guitar cable. As for the ground from the volume knob, I like his point that it 'belongs' to the last filter node -- but I've just run it straight down to the bus, since in actual space that barely adds any length and makes for easy elegant construction.

Not to say do it my way, but for reference, here's my 6G2 with isolated inputs. (You can see the shoulder washers.) And heh, that's parallax: the bus does not in fact get anywhere near the pot or the tip prong of the jack.

Also, what exactly will you use for a bus wire? I can no longer find that nice square tinned bar, but a heavy-gauge pre-tinned wire (I've seen it down to 16ga) will be prettier and less prone to corrosion and easier to solder to than say 14ga untinned copper -- though I've used that too and it will work. For comparison, here's my first-ever 5F2a, also with isolated jacks -- the one thing I still like here is the anchor bolt:

 

[screefer]

@screefer, you are going great guns. And getting great input. If it were me, I'd keep revising and revisiting the paper build for a little while longer.

Fantastic input! Slow is the word.

Now that you've figured out how to use flexible hookup wire instead of the straight 'jumper' tool in DIYLC, you'd do yourself a favor to make those black ground wires flexible. @Lowerleftcoast will likely know better than me, but I like to dump the input jack grounds close to the chassis ground anchor -- and close to the jacks themselves; they don't 'belong' to that filter, they're just grounding out noise from shield of the guitar cable. As for the ground from the volume knob, I like his point that it 'belongs' to the last filter node -- but I've just run it straight down to the bus, since in actual space that barely adds any length and makes for easy elegant construction.

Roger

Not to say do it my way, but for reference, here's my 6G2 with isolated inputs. (You can see the shoulder washers.) And heh, that's parallax: the bus does not in fact get anywhere near the pot or the tip prong of the jack.

Keep that in mind when viewing my pix.

Also, what exactly will you use for a bus wire? I can no longer find that nice square tinned bar, but a heavy-gauge pre-tinned wire (I've seen it down to 16ga) will be prettier and less prone to corrosion and easier to solder to than say 14ga untinned copper -- though I've used that too and it will work. For comparison, here's my first-ever 5F2a, also with isolated jacks -- the one thing I still like here is the anchor bolt:

#14 solid house wire.
You inspired me to open up my 5F2a which was built in May 2020.

Here's Merlin...

"Do not be tempted to wrap component leads around the bus bar multiple times
before soldering, however, as this will make later modifications extremely difficult!"

...and I had so much fun wrapping those leads to death!!

Soldering to the untinned bar was doable and there is no visible corrosion afterr two years. I live 40 feet from the saltchuck at high tide.
I tried tinning a piece of #14 but made a pig's ear out of it.

I also should have used a kep nut, on the other side of the chassis for the bus anchor instead of the nyloc. I did use star washers though...

"I haven't been using any nuts on sockets for several years now. But if I had to, I'd use keps just because I have a good supply in sizes 4, 6, 8, and 10. If I had nylocks on hand rather than keps, I'd use them on sockets. But I would not use a nylock on a ground lug, even if I didn't have keps. I'd use a star washer. I just like the way keps or external tooth stars bite into the chassis, making a very good electrical connection. Nylocks will not do that unless you put a star washer under them."
Sluckey

My future builds will also have insulation on those naked leads

I also took the prompt from LLC to color the under-board leads.
Here's the latest with your suggestions.

 

[mrfitz98]

The solder lug that the 1 ohm resistors are soldered to are isolated from the chassis denoted by 'iso'. The ground jumper from the isolated resistor
is intended to pick up the bias cap on it's way to the B+2 ground node.

Does that make sense, or am I missing your point?

Missed the "iso"

Curious to see how this turns out. Of course, unless you build one using the "traditional" layout we'll never have anything to compare it with. I guess you'll just have to build 2 of them.

 

[screefer]

Of course, unless you build one using the "traditional" layout we'll never have anything to compare it with.

I was thinking of putting the isos on a mini toggle switch to ground (edit: chassis)...just kidding?
although.....

I guess you'll just have to build 2 of them.

I'm in!

 

[King Fan]

Re your Romex core -- much neater and straighter than mine. Carry on!!

Re your DIYLC drawings: Isn't it striking how smart revisions often make neater or prettier drawings? "Elegant" is a thing. And don't worry about 'too many versions' -- I've probably done hundreds of DIYLC revisions for a handful of amps I've planned.

 

[screefer]

I've probably done hundreds of DIYLC revisions for a handful of amps I've planned.

The following is revision # 24!!
I've decided to sneak the Vol. ground back to where @Lowerleftcoast recommended. As he said, it would be consistent with Merlin and is actually shorter.
I also have moved the jacks and pots a bit to reflect the true scale of their positions. A few other minor tweaks as well...This DIYLC is 'Jake the Bear'!

Re your Romex core -- much neater and straighter than mine. Carry on!!

The photo of mine does show that is is not parallel with back of chassis. Looks like you had better success tinning your bus.

 

[screefer]

Meanwhile I thought I would determine outer foil on my coupling caps.
I used a 1/4" bare phone jack into a Blackstar fly with vol and gain dimed. Swapped the leads and the difference in noise, when squeezed, was huge.
Marked the negative end of the quietest configuration as outer foil.
Is this correct?

 

[Lowerleftcoast]

I like to dump the input jack grounds close to the chassis ground anchor -- and close to the jacks themselves; they don't 'belong' to that filter, they're just grounding out noise from shield of the guitar cable.

KF the grid leak resistor does have some DC. In the case of the 5F10 the grid leak is one or two of the 68k resistors. Like you, I tend to terminate the jacks near the chassis terminal but Blencowe clearly shows the grid leak terminating at the last filter cap.

 

[screefer]

Done.
Thanks for the reason why @Lowerleftcoast

 

[King Fan]

KF the grid leak resistor does have some DC. In the case of the 5F10 the grid leak is one or two of the 68k resistors. Like you, I tend to terminate the jacks near the chassis terminal but Blencowe clearly shows the grid leak terminating at the last filter cap.

Thanks, LLC. Makes sense.

@screefer, I admire your quest for full Merlin-ization here. I sense you're doing it as a learning exercise; in any case, *I'm* learning from it.

For new builders struggling with ground theory and hoping to follow a standard modern layout, I'll note *very* few of the builds we see here go for the whole Merlin enchilada. For one example, I appreciate the note above from LLC that even he doesn't usually isolate his speaker jacks. I think most experienced builders can agree with the several spots where Merlin admits a simple bus without perfectly ordered and grouped bus stops can be 'good enough' for our smaller, low-gain circuits. And I've often defended the simple split-bus schemes Rob has drawn and hundreds of folks have built; I've only seen one or two cases where folks found a single bus quieter, and that was usually in amps of some complexity.

But: This isn't your first build, and you're doing this by choice, happily doing a ton of reading and revision. Keep learning, keep drawing, and keep sharing what you learn.

 

[screefer]

But: This isn't your first build, and you're doing this by choice, happily doing a ton of reading and revision. Keep learning, keep drawing, and keep sharing what you learn.

It is by choice and I fully appreciate what you are saying.

Isolating everything only costs a couple of bucks in parts and any excuse to tinker is manna to me.

I really appreciate the help and comments from you and LLC.

This won't be my last build for sure.

So I'll soldier on, as the rest of the build will be traditional practices and hopefully I can improve my chops regarding those practices.
And continue to learn!

 

[screefer]

Some progress to report.

I made a new board out of this Vector material.

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Marked out the holes and staked with a punch two taps a piece.







Then I installed isolated bus and tag strip and dry fitted the board/spacer/backer.

 

[screefer]

A nice thing about the Vector board is that it transparent.



Here's the populated board.

and the back...

Now all I need is a hot iron and some courage...

Hope I've not missed anything?

 

[screefer]

More prep work.

 

[screefer]

All soldered up except the B+1 is tacked and the 56k NFB is bare.
I was able to reach the lead from the plate resistors with my small side cutters. Need to find some mini cutters?

Edit.. found these..https://www.homedepot.ca/product/klein-tools-flush-cutter-lightweight-5-inch/1001331556

 

[CascoSieg1]

I'm new at this, but is that bias supply diode oriented how you want?

 

[screefer]

I'm new at this, but is that bias supply diode oriented how you want?

It sure isn't!!
Thanks

 

[screefer]

I'm new at this

Three cheers for new members!!
Welcome!