High Voltage Hijinks

Looking sexy @Asdrael :)

Standby .. do you actually use it? Did you implement it Valve Wizard style?

I left it off the Model T, but I thought about implementing it as a mute for a minute. I personally don't like standbys on my amps, mostly because I can forget an amp is on standby and it sits there for hours. I'd rather forget an amp just on rather than in standby because of cathode poisoning.

Yesterday as I swaging turret after turret I was thinking I should benchmark build timings.

Photo Oct 05 2025, 8 48 40 AM.jpg

I am going to bring up fun type 2 again though. I think amp building has a lot of fun type 2 activities. Fun type 2 being something that is really not fun in the moment but is ultimately rewarding. I'd bet @vigilante398 has a lower tolerance for fun type 2.
 
Hal Harvey said:
Looking sexy @Asdrael :)

Standby .. do you actually use it? Did you implement it Valve Wizard style?

I left it off the Model T, but I thought about implementing it as a mute for a minute. I personally don't like standbys on my amps, mostly because I can forget an amp is on standby and it sits there for hours. I'd rather forget an amp just on rather than in standby because of cathode poisoning.
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I use it out of habit, although I know it’s not useful or can even be detrimental. I would implement a mute switch but currently I like having a standby solely for the first startup in case I have a short… I easier to locate where when you can isolate the HT line. I implement it on both legs of the transformer before the rectifier with a fuse on a single leg. Easy enough and robust.

And I relate on the fun type two thing. I loved on it for a long time, but having less and less free time I also need some instant gratification now and then. Pedals come in handy for that, or simply plugging the rig with my seven string and riffing till the walls shake!
 
Working my way through the Model T turret board and the chassis layout...

Photo Oct 13 2025, 9 38 52 PM.jpg

I have rectifier board, bias board, heater humdinger and elevation board left to go.

Considering where to put the bias test points and bias adjust pots. I had thought on top, but I have all that space on the back panel...
 
I was going to throw this on the workbench thread, then I realized I've never actually posted anything here. This is a big dumb bass preamp I've wanted to trace for years and finally got around to it a few months ago. Then after sitting on the unverified scheme for a few months I spun a prototype (then debugged the prototype) and finally have something working. Now I just need to decide what to do with it. I mean 4x CV4010? In this economy???

IMG_20251013_223350.jpg
 
vigilante398 said:
I was going to throw this on the workbench thread, then I realized I've never actually posted anything here. This is a big dumb bass preamp I've wanted to trace for years and finally got around to it a few months ago. Then after sitting on the unverified scheme for a few months I spun a prototype (then debugged the prototype) and finally have something working. Now I just need to decide what to do with it. I mean 4x CV4010? In this economy???

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If I weren't so happy with my Nobelium, I'd be begging for it to become a c2ce project. That been said, I doubt that diy is your plan but I'd surely build one of you did. You called it a big dumb bass pre so naturally I'm 1000% super interested now.
 
vigilante398 said:
I was going to throw this on the workbench thread, then I realized I've never actually posted anything here. This is a big dumb bass preamp I've wanted to trace for years and finally got around to it a few months ago. Then after sitting on the unverified scheme for a few months I spun a prototype (then debugged the prototype) and finally have something working. Now I just need to decide what to do with it. I mean 4x CV4010? In this economy???
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Does it need the special tubes, have you tried 6AK5s in it? I think I saw some of those at the local surplus store even.

I don't like paying more than $20 for preamp tubes, NOS or no.

Speaking of the surplus store I saw this there:
Photo Oct 05 2025, 12 47 45 PM.jpg

I googled and found some rehab threads on it. No fucking way. If it was cheaper and I was sure untouched on the inside I'd buy it for the knobs and some of the other cool parts.
 
Mentaltossflycoon said:
If I weren't so happy with my Nobelium, I'd be begging for it to become a c2ce project. That been said, I doubt that diy is your plan but I'd surely build one of you did. You called it a big dumb bass pre so naturally I'm 1000% super interested now.
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I'm actually leaning toward DIY with it as it's based on something that's currently commercially available, so Sushi Box won't be touching it. My next experiment with it though is to see how much differently it behaves with 2x dual triodes instead of 4x single pentodes. I've done that before with guitar preamps and it went surprisingly well, so I may lean that way for the DIY project as it will make the assembly and the sourcing of parts much easier. Or maybe I'll do a version of each for the weirdos that like that sort of thing? I don't know. I'll think about it.

Hal Harvey said:
Does it need the special tubes, have you tried 6AK5s in it? I think I saw some of those at the local surplus store even.

I don't like paying more than $20 for preamp tubes, NOS or no.
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It can absolutely run 6AK5, and that's what I had been planning to use but apparently I forgot to order them, so I pulled these CV4010 out of the original unit I traced just for testing. I'm more than happy to flip something with NOS Mullard CV4010s in it, but I'm with you there, anything past $20 is too much. Especially when there's four.
 
Merlin’s new book is ass. Going through it has made me come to conclusion that I’ve made and my amp makers have done stupid choices. Now I’m fixing these thing one by one and I really want to get rid of this original PCB and rework whole circuit to turret board. It’s sp hard to add extra components on this build as you can see below…

IMG_7331.jpeg
Bias supply ”fixed”, but not secured. :D Maybe a dab of silicone there could fix my nerves until I get motivation to build this amp all over again?
 
JohnnyCreepy said:
Merlin’s new book is ass. Going through it has made me come to conclusion that I’ve made and my amp makers have done stupid choices. Now I’m fixing these thing one by one and I really want to get rid of this original PCB and rework whole circuit to turret board. It’s sp hard to add extra components on this build as you can see below…

Bias supply ”fixed”, but not secured. :D Maybe a dab of silicone there could fix my nerves until I get motivation to build this amp all over again?
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I'm half way through the new book :)

I wouldn't sweat it too too much, it's a snapshot of your skill at that time. You have to break some eggs to make an omelet. Psionic Audio... I watched one video where he talks about Merlin's writing on grounding and then on another video he uses the chassis as a ground bus on a new amp design...

I'd put a dab of silicone in there!

I loooooooove turret boards. There's nothing that compares for rework. I forgot a cathode resistor and bypass cap on one build and found it as I was attaching wires to the board. 5 mins later I had drilled and installed a turret for it. I mean you can't do that easily at the end but still. Better than discovering an error after your PCB arrives on the long boat from China. I won't go much further against PCBs, especially given what the main purpose of this forum is haha.
 
How do you guys even plan a turret board? Is there some alien technique, workflow or software? I am already brainstorming for a much further build that would require a lot of trial and error so I am figuring turret is the way to go.
 
Hal Harvey said:
I'm half way through the new book :)

I wouldn't sweat it too too much, it's a snapshot of your skill at that time.
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Sometimes I get cutoff when hitting preamp with some high gain input signal so revisiting bias and around PI is must for me.

Off went PI anode balancing pF cap. Reduced bias circuit uFs drastically and divided it across wipers with separate caps. Added 3x4007 series diodes across anode and gnd node on pwr stage. Gonna tweak input circuitry as now it has too much dB gain and I really cannot rise tone stack volume past 2/10.

This book is golden for learning while hands dirty as described phenomenons are easily witnessed in use.
 
Asdrael said:
How do you guys even plan a turret board? Is there some alien technique, workflow or software? I am already brainstorming for a much further build that would require a lot of trial and error so I am figuring turret is the way to go.
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Have you ever seen a thing called a schematic? :ROFLMAO: When you finally find one, open DIYLC and start planning. I found it time consuming and unmotivating, but in the end it rewards. Guess good planning makes job half done. Also remember Rob and Doug have collection of turret layouts to modify for your needs. No need to figure out everything from the start!
 
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Asdrael said:
How do you guys even plan a turret board? Is there some alien technique, workflow or software? I am already brainstorming for a much further build that would require a lot of trial and error so I am figuring turret is the way to go.
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Some use https://diy-fever.com/software/diylc/ that @JohnnyCreepy mentioned.

I've used Visio too. It's O K.

But lately I just use Affinity Designer for EVERYTHING. I have it set for 1/4" grid. I can go from front panel graphics to chassis layout to turret boards and it's all in the same program which is handy AF. For turret boards I just have the few generic pieces as groups. Like a resistor. You can select it and drag while the alt key is down and it makes a copy. Double click the text on the label to edit it. Done. Odd dimension components that comes in Satan's system of measurement - you can just type in 25mm or whatever and it converts it to the measurement system of the document. I started getting fancy and I have octal socket graphics that are properly dimensioned etc.
 
This is a snippet from Affinity Designer of one of the preamp boards. I print out the boards at 1:1 for drilling, and then shrink the whole thing as a reference during construction. When I am doing chassis layout I can use the same board without reference for placement. I can see proximity to pots, tube sockets, whatever.

Screenshot 2025-10-15 161221.png
 
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JohnnyCreepy said:
Have you ever seen a thing called a schematic? :ROFLMAO:
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🖕 :ROFLMAO:

When you finally find one, open DIYLC and start planning. I found it time consuming and unmotivating, but in the end it rewards. Guess good planning makes job half done. Also remember Rob and Doug have collection of turret layouts to modify for your needs. No need to figure out everything from the start!
Click to expand...
Yeah, I guess I just wouldn't know where to start. Probably wise to try to build "block by block" and not be too fussy about lengths etc I suppose like you would on a PCB?

Hal Harvey said:
Some use https://diy-fever.com/software/diylc/ that @JohnnyCreepy mentioned.

I've used Visio too. It's O K.

But lately I just use Affinity Designer for EVERYTHING. I have it set for 1/4" grid. I can go from front panel graphics to chassis layout to turret boards and it's all in the same program which is handy AF. For turret boards I just have the few generic pieces as groups. Like a resistor. You can select it and drag while the alt key is down and it makes a copy. Double click the text on the label to edit it. Done. Odd dimension components that comes in Satan's system of measurement - you can just type in 25mm or whatever and it converts it to the measurement system of the document. I started getting fancy and I have octal socket graphics that are properly dimensioned etc.
Click to expand...
Hah ok. But there is no software like PCB softwares that make it fool proof by saying "hey you should have a connection here". Damn, needing brain cells makes everything complicated.
 
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