5E3 point to point build.

[tele_savales]

I have mapped out my p2p project in diylc and drill drilled out an aluminum chassis. I know it's not the ideal chassis to do this in, but I'm going for it anyway, partly because I can't really build a cab to fit a hammond chassis, and partly because everyone builds them with a board and I wanted to do something different that a) required more problem solving and b) I sort of enjoy the additional hassle of laying out and prepping a chassis.

I am using an LED, diode, and resistor network off the 6.3v winding for a pilot light- I am trying to swear off the rassin frassin Fender style lamp assemblies.

I am putting a slotted 2W 100 ohm pot next to the single output jack to run as a humdinger, sending the wiper to the cathode of V3.

I am putting a mini switch between the jacks and the first pot (pre PI MV) to jump the channels without a patch cord.

My only real concern is the coupling caps from V2 crossing near the output transformer on the way to the power tubes. Is this going to be a hum inducing disaster? and should I run them up to a tag strip and then run leads down from there? The capacitor lead from V2 Pin 8 will not be long enought to make it to V4 anyway without being extended.

I did the headphone trick and found the absolute quitest position and orientation on the chassis for the output transformer- right over where the output jack would normally be anyway, 90 degrees turned from the PT.

I'll try to double check the schematic against my birds nest layout and post it this weekend- It's really just a very rough guide, as the few p2p builds I've done were cake pan style and super easy to get to everything. I'm sure there will be some interesting challenges along the way.

 

[Lowerleftcoast]

Subscribed.

Please post pictures and or layout when you can.

 

[screefer]

I'll be watching!

 

[ok_state_blues]

Subscribed.

Please post pictures and or layout when you can.

Doesn't robrob have a 5E3 p2p layout on his page?

 

[ok_state_blues]

https://robrobinette.com/images/Guitar/5E3P_Build/5e3_Deluxe_Amp_Point-to-Point_layout.png

@tele_savales I hope this helps. Not trying to rain on your show

 

[Lowerleftcoast]

Doesn't robrob have a 5E3 p2p layout on his page?

Yes he does.

The OP mentioned coupling caps near the OT so I am assuming this build will be different than Rob's. Probably in a different shaped chassis.

I generally just draw a P2P layout by hand. I am sure my design would look different than any other. There are plenty of choices to make.

 

[tele_savales]

Subscribed.

Please post pictures and or layout when you can.

Yep. Will do. Just finished drilling the chassis and peeling the masking tape off

 

[tele_savales]

Here 'tis. I've made many changes back and forth, so if I've missed a component please point it out. Again it's a very rough guide.

 

[tele_savales]

The other thing I was debating is changing all the coupling cap values to .02uf from the get-go since all of my guitars have pretty high output pickups. Short of that, any components that I may swap in the future will be installed in the easiest way possible to get at them.

 

[2L man]

My only real concern is the coupling caps from V2 crossing near the output transformer on the way to the power tubes. Is this going to be a hum inducing disaster? and should I run them up to a tag strip and then run leads down from there? The capacitor lead from V2 Pin 8 will not be long enought to make it to V4 anyway without being extended.

I did the headphone trick and found the absolute quitest position and orientation on the chassis for the output transformer- right over where the output jack would normally be anyway, 90 degrees turned from the PT.

I am curious? You have done "headphone trick" but make pre amp current return flow thru chassis which increase hum and noise! Instrument cable connect to Chassis/Safety Earth and function other half of the guitar signal!

As you have test Mains and Output Transformers interact inductively but should not effect amp DC wiring?

 

[tele_savales]

I am curious? You have done "headphone trick" but make pre amp current return flow thru chassis which increase hum and noise! Instrument cable connect to Chassis/Safety Earth and function other half of the guitar signal!

As you have test Mains and Output Transformers interact inductively but should not effect amp DC wiring?

Eh, my knowledge and understanding are minimal. Generally when problem solving I try to think of what a smarter person than me would do, and try to do that. So I'm kind of just following along with what other far, far more experienced builders here are doing.

I know you've commented on this aspect (current return thru chassis) numerous times on other member's build layouts but I have trouble wrapping my mind around it. I've tried studying Merlin's text and it evades me, to be honest.

In the half dozen amps or so that I've built I generally connect Pt center tap to reservoir cap negative to ground, the screen filter supply, cathode bypass caps and so forth go to input jack ground, and use a ground bus arrangement for any grounds for the the potentiometers. Which seems to be fairly standard practice.
I've also read numerous members here saying that they heard no appreciable difference in noise floor w single point star ground.

I built Robs version JCM 800 w the 2 point ground layout and 90 percent metal film resistors and it's the quietest amp I own. Quiet in the noise floor sense, the thing is loud as hell

If you have a truly specific layout that you believe will work better I don't mind leaning about it.

 

[bigguy12321]

Here 'tis. I've made many changes back and forth, so if I've missed a component please point it out. Again it's a very rough guide.

Hey there tele-s. I built the one pictured on rob’s site. I did it “sort of” how he had it there with minimalism in mind. It was an early build and I’m pretty sure I could minimalize it some more now.

I’m not really good at paper troubleshooting but your layout looks good to me. Knowing how I roll I’ll probably copy at least some of it…

I see the hum pot for filaments. Have you noticed a need for the pot or just prefer to use it instead of the 2 100 ohm resistors?

This could be a pretty small build and that’s always good in my book!

Please add pics as you go. At least I’ll enjoy seeing them!

Aaron

 

[tele_savales]

Hey there tele-s. I built the one pictured on rob’s site. I did it “sort of” how he had it there with minimalism in mind. It was an early build and I’m pretty sure I could minimalize it some more now.

I’m not really good at paper troubleshooting but your layout looks good to me. Knowing how I roll I’ll probably copy at least some of it…

I see the hum pot for filaments. Have you noticed a need for the pot or just prefer to use it instead of the 2 100 ohm resistors?

This could be a pretty small build and that’s always good in my book!

Please add pics as you go. At least I’ll enjoy seeing them!

Aaron

It's coming along. I added a hum pot back into a 70's Twin Reverb that I rebuilt into a single channel ab763 and it seemed a lot more effective than 2 100 ohm resistors. Since the PT I bought doesnt have a center tap for the heater winding I figured I'd try the hum pot along with w voltage elevation.
That, and I bought a bag of 100 Ohm slotted pots so I may as well use them...

 

[tele_savales]

It’s going reasonably well…

 

[bigguy12321]

Looks great. You guys and your neat layouts! I started this hobby stealing from old radios and reel to reels. If those things can be quiet and not oscillate, ANY wiring job can be quiet. At least until you start pushing a lot of gain.
Thanks for the pics. Keep up the good work.

a

 

[monkeybanana]

Looks great. You guys and your neat layouts! I started this hobby stealing from old radios and reel to reels. If those things can be quiet and not oscillate, ANY wiring job can be quiet. At least until you start pushing a lot of gain.
Thanks for the pics. Keep up the good work.

a

I recently built a 5C1 like Champ point to point and it it picks up noise like you hear when you bring your cell phone near an amp. None of my other amps Fender or F clones do that. My friend's Rickenbacker that is basically a Deluxe but ptp also pickups the same noise.

Made me appreciate Fender's layouts again.

This looks like a tidy build looking forward to more pics!

 

[tele_savales]

Pics are coming. It's getting progressively less tidy w each component. But it really does make you think a lot more about what you're doing. Pretty fun.

 

[Lowerleftcoast]

Two things I noticed on the layout.
The humdinger center terminal doesn't look like it connects to the 6V6 pin8 but I think you have it sorted.
It probably doesn't matter but I would ground the input jack switch at the input jacks rather than the pots.

 

[tele_savales]

Two things I noticed on the layout.
The humdinger center terminal doesn't look like it connects to the 6V6 pin8 but I think you have it sorted.
It probably doesn't matter but I would ground the input jack switch at the input jacks rather than the pots.

Thanks

 

[tele_savales]

Got her up and running today. Let in burn in for a good while and the power tubes started red plating after 15-20 minutes or so, so I hacked together what I had for resistors. I also wired the inputs wrong. Never did a 4 holer before.
Tomorrow I will shorten and zip tie all the leads in the power section.
To late to plug a guitar in tonight so tomorrow should be fun.