[warplanegrey]

Hey gang,

So after finishing my first amp build (an Express circuit), I've definitely caught the amp building bug.

Instead of building an amp based off of a pre-made layout or design, I figured I would marry a preamp I love the sound of with a power section I love the sound of, while making a couple tweaks.

So I found schematics of the preamp, a cathode follower and EQ driver, and power amp, plunked them into photoshop, and put them all together in one package (hence the font differences).

Also, the schematic has component numbers assigned, but because of how the whole thing came together, I left them off the layout (but included the values). I left the heater wiring off for cleanliness.

The lead dress in the layout isn't what the end product would look like (I learned quite a bit about what to do and not to do on that front).

I took an initial run at converting the schematic to a DIYLC layout, but definitely made some errors. I posted over on EL34world and had a few guys offer some initial thoughts. I've also floated the schematic past a killer amp builder who makes a wide range of amps.

Would you guys be willing to have a look at the schematic and the layout, and let me know if you see any issues?

Thanks guys!

 

[WCGill]

I admire your ambition.

 

[warplanegrey]

I admire your ambition.

Haha thanks! The learning curve is a steep one, but this is how I figure things out…

 

[Rski]

The diagram shows an extra common cathode stage, essentially that configuration does add some soft compression, one circuitry author once written. The layout needs the power amp, not shown, in what was presented. Advice, go for star grounding of all ground nodes, at the point where the power supply grounds, poor grounding results in hum noise, is worth doing while building. Have colored wire for different points, green ground, red B+ , black for signal. Check your layout point to point, colored, make small pencil marks of each node, wiring configuration mistakes could possibly occur, good planning makes initial power up pleasing

 

[greco]

The layout needs the power amp, not shown, in what was presented

I think I see a power amp.
Admittedly, I have limited skills with this sort of thing.

 

[warplanegrey]

The diagram shows an extra common cathode stage, essentially that configuration does add some soft compression, one circuitry author once written. The layout needs the power amp, not shown, in what was presented. Advice, go for star grounding of all ground nodes, at the point where the power supply grounds, poor grounding results in hum noise, is worth doing while building. Have colored wire for different points, green ground, red B+ , black for signal. Check your layout point to point, colored, make small pencil marks of each node, wiring configuration mistakes could possibly occur, good planning makes initial power up pleasing

Yeah, the feedback regarding the wire colour is a good one. I’ll make that change tonight.

I’ll add more detailed grounding tonight as well.

Could you clarify the comment about the power amp?

 

[Rski]

I miss read the layout print, all six tubes are present. I take this might be a kit build? A word of advice about layout vs the diagram, lable the tube pins, small triode 1 - 9 and power tube 1 -8 via the layout to the schematic, this step, although seems demanding, it pays off in two ways. First, getting familiarize with the connection nodes, make circuitry checking clear. Secondly, lable the tube sockets once installed with a pencile (pin out) any mis step can easily be pin pointed. The diagram looks pretty normal as a marshal modified build, the small signal triodes on the front end, pins 3 or 8 (annode) the annode bypass capacitors are small value, this gives a upper response, to move away from muddy sound.

 

[warplanegrey]

I miss read the layout print, all six tubes are present. I take this might be a kit build? A word of advice about layout vs the diagram, lable the tube pins, small triode 1 - 9 and power tube 1 -8 via the layout to the schematic, this step, although seems demanding, it pays off in two ways. First, getting familiarize with the connection nodes, make circuitry checking clear. Secondly, lable the tube sockets once installed with a pencile (pin out) any mis step can easily be pin pointed. The diagram looks pretty normal as a marshal modified build, the small signal triodes on the front end, pins 3 or 8 (annode) the annode bypass capacitors are small value, this gives a upper response, to move away from muddy sound.

It's not a kit build, it's the marriage of the brown channel from a Bogner Fish and the power section from a 2204, so while they both exist in the world, they haven't been put together in a single unit, as far as any documentation out there goes.

I've updated the schematic and the layout. The layout has a depth control (because it was really easy to mock up) that's missing from the schematic.

Here's the updated layout: New item by Scott McGregor

here’s the latest schematic:

 

[Paul Running]

Are you using a 220KΩ pot for VR1?
What's your opinion on the sonic performance?

 

[warplanegrey]

Are you using a 220KΩ pot for VR1?
What's your opinion on the sonic performance?

It's currently a 1Meg audio, but someone on another forum had suggested dropping it to 220k for less resistive hiss

 

[warplanegrey]

Update:

board is populated, top of a chassis has been drilled out, and everything on the top has been dry fitted.

 

[warplanegrey]

once I have the front and back face plates from a local laser engraver, I will drill out front and back for the switches, Jacks, and pots

 

[Mark Brown]

I gotta get back to building amps. It is so much fun.

That is gorgeous though!

 

[warplanegrey]

I gotta get back to building amps. It is so much fun.

That is gorgeous though!

Thanks! I’ve been forced to take my time with this build, as I’ve been ordering parts a batch at a time.

I’m just hoping it turns on, doesn’t blow up, and makes guitar sounds.

 

[Mark Brown]

Thanks! I’ve been forced to take my time with this build, as I’ve been ordering parts a batch at a time.

I’m just hoping it turns on, doesn’t blow up, and makes guitar sounds.

I know that feeling!!

 

[Paul Running]

I’m just hoping it turns on, doesn’t blow up, and makes guitar sounds.

What's your plan to reduce the chance of that occurring?
I mean so that it does not blow-up.

 

[warplanegrey]

What's your plan to reduce the chance of that occurring?
I mean so that it does not blow-up.

not make stupid mistakes, like I did with my first build (wired a diode backwards).

I follow the initial power up steps outlined in this guide:https://el34world.com/Forum/index.php?action=dlattach;topic=22434.0;attach=67180

I have a lightbulb limiter I use when powering up amps for the first time or after they’ve been repaired substantially. Helps me make sure nothing is super wrong.

I was more being facetious about the not blowing up thing. I’m fairly confident in my ability to make an amp work haha.

 

[MarkM]

This is quite an undertaking, good luck with your build! Hope it is all that you want it to be.

 

[warplanegrey]

This is quite an undertaking, good luck with your build! Hope it is all that you want it to be.

thanks! I’ve never been one to shy away from a challenge