Asdains DIY Single Ended Amp Build (free beer and hot babes)

[Asdain]

Hello MLP nerds!

as threatened in Barnaby's LP Scratch Build thread, here is my amp-build thread

i have done a lot of planning lately and this is what i have so far:

The Schematic:

The Faceplate:


The Layout:



This is still in the planning stage, so things might still be far from optimum.
The basic design is something like a cross breed between a Ax84 SEL and a Trainwreck Express. This is not intended as a "CLONE" of the Trainwreck preamp in a Single Ended design.
I have quite a few parts lying around in my (small, ugly and under-equipped) workshop/basement. so i will survey what i have and take a few pics tomorrow.
For now i would be happy for any suggestions or corrections to my (so far-)design and layout.

The Arrangement of the control elements (see layout and faceplate)might strike you as odd, since it does not represent the actual signal flow and makes the wiring inside more complicated. I chose this layout just because i really like it and i want to keep it!
The "Boost" as well as the bright switch are optional at this point.

I hope for your suggestions, inspiration and interest
More info and pics will follow tomorrow!

PS:check out ax84.com, it's an awesome project and the P1 is a great build for beginners!

PPS: the promised Beer 'n' Babes :

[Cygnus X1]

Ahh, the St. Pauli Girl comes to life!

I'm really interested in seeing how this turns out.
I have looked at the TW combined with SEL circuits myself...just haven't done it.

My own is a variation of the SEL with a few tweaks here and there.

[White94RX]

Is it just me or were the pics REALLY small. Even when I clicked on them expecting full size, alas...they remained small.

[Asdain]

Originally Posted by Cygnus X1

Ahh, the St. Pauli Girl comes to life!

I'm really interested in seeing how this turns out.
I have looked at the TW combined with SEL circuits myself...just haven't done it.

My own is a variation of the SEL with a few tweaks here and there.

i wold be happy to learn what kind those tweaks are..

Originally Posted by White94RX

Is it just me or were the pics REALLY small. Even when I clicked on them expecting full size, alas...they remained small.

the faceplate and the layout work fine for me,.. but i screwed up with the image export for the schematic.
unfortunately i am not at home right now.. so i'll fix it on sunday! : )

[Quill]

Well that looks cool.

Can you explain a bit what's going on? Walk us through the signal path? What are the "clean" and "mean" controls doing? It looks like you can switch one tube in ("mean") and out ("clean") of the circuit; so are the pots then sitting between gain stages - it looks like it, kind of - or ... something else? - I shamelessly ask on behalf of those who are interested, but just can't quite read a schematic like it's a book, quite yet.

[Barnaby]

This looks sweet - I'll be watching this one for sure! A good, long look at the schematics suggests you're going with a D-cup. Nice chassis, too.

Here's a shout out from where I am:

[Asdain]

Originally Posted by Barnaby

This looks sweet - I'll be watching this one for sure! A good, long look at the schematics suggests you're going with a D-cup. Nice chassis, too.

Here's a shout out from where I am:

that's what i was waiting for!

[BillB1960]

Originally Posted by White94RX

Is it just me or were the pics REALLY small. Even when I clicked on them expecting full size, alas...they remained small.

Not just you.

[agejaded]

Originally Posted by White94RX

Is it just me or were the pics REALLY small. Even when I clicked on them expecting full size, alas...they remained small.

It's you. Hovver on the pop up pic and you get a taskbar appearing at the top - then click on the Zoom in and it enlarges the pic. Job done!

[BillB1960]

Originally Posted by agejaded

It's you. Hovver on the pop up pic and you get a taskbar appearing at the top - then click on the Zoom in and it enlarges the pic. Job done!

Didn't work for me

[Asdain]

Originally Posted by Quill

Well that looks cool.

Can you explain a bit what's going on? Walk us through the signal path? What are the "clean" and "mean" controls doing? It looks like you can switch one tube in ("mean") and out ("clean") of the circuit; so are the pots then sitting between gain stages - it looks like it, kind of - or ... something else? - I shamelessly ask on behalf of those who are interested, but just can't quite read a schematic like it's a book, quite yet.

i will do that in more detail later, for now just a quick description:

A 12AX7 (or ECC83 or 5751 or .... ) as many other preamp tube is actually two triodes in one glass envelope.

i am using 2 12AX7 preamp tubes and a 6L6GC power tube

that makes 4 triode stages in the preamp and a single Pentode as the power stage.
only three of of the triodes are wired as generic triode gain stages, the last one is connected as a cathode follower, which has a maximum possible gain of 1 (meaning it does not amplify the signal). It does however have a very distinct and smooth tonal characteristic and is also a lower impedance source than a normal gain stage, meaning it can drive heavier loads like tone stacks without as much signal loss.

at the current version its purely for the sound characteristics, as the tone stack is between the first and the second gain stage. ( i might change this though and put it after the cathode follower)

the Clean/Mean switch basically switches a third gain stage in and out before the cathode follower.

so it is:
Input-> Gain Stage1 -> Tonestack->"Clean" Pot->Gain Stage 2 -> ("Mean" Pot and Gain Stage 3 Switchable)-> Cathode Follower as 4th Stage -> Master Pot and Output tube


i hope that helps so far

[Asdain]

Originally Posted by BillB1960

Didn't work for me

i just double checked the pictures.. now it's all working properly for me.. : o

[BillB1960]

Originally Posted by Asdain

i just double checked the pictures.. now it's all working properly for me.. : o

Well...still not working for me. When I go to the photobucket site all I get are small pictures with no option to zoom.

Edit: Finally got it to work. It was taking me to that stupid Photobucket Mobile site which onlyu has the small pictures. Once I found the full site I could zoom.

[Cygnus X1]

Originally Posted by Asdain

i wold be happy to learn what kind those tweaks are..

Enough so I'd have to look again at the old SEL to figure it all out.
AX84 has some serious anomalies between their schems, parts lists, and layouts.
Don't misunderstand, I like their concept but the reason they recommend
some of those builds for "experienced" folks is largely due to those oddities.

I see a lot of my changes (I started the Cyg-7 in October 2007) were also built into Randy Faze's Daisycutter and a few other SEL related builds...at least the ones that sound good.
Power supply, tone mods, layout were notable differences.
Getting rid of the buzzbox fizziness was the largest improvement and I cannot remember exactly what my key was!
I just know I drew it up in Autocad so I have my designs down.
Never SPICED it (I should have), but let my ears do the tweaking.

[hipofutura]

Cyg, I got all excited about Spice when I first learned of it. But the glow didn't last long. I realized it really doesn't have much to offer that I find useful. We build things that sound good. We're not calculating the hyperbolic curve to the moon. Spice seems to be a lab tool useful to electrical engineers who are prototyping circuit designs or running simulations. That's not what we do. The book was written LONG ago that outlined the circuits we work with. Very little has changed in the last 70 years.

[hipofutura]

Asdain, can't wait to see this go from drawing board to youtube.

And please, MORE exciting women. Especially from you Barnaby! I have a soft spot for Asian women.

[BillB1960]

Originally Posted by hipofutura

And please, MORE exciting women. Especially from you Barnaby! I have a soft spot for Asian women.

They have a pill for that.

[Cygnus X1]

Almost forgot...

[FF_Pedals]

That's looking pretty cool. I did the same thing in my Champ with the power tube bias. What kind of pot were you going to use? I used a Clarostat rated at a few Watts. You'll have more current with 6L6 than I had with 6V6 though. The Clarostats are pretty expensive!

I disagree with Don about SPICE. It rules.

[Asdain]

Originally Posted by hipofutura

Cyg, I got all excited about Spice when I first learned of it. But the glow didn't last long. I realized it really doesn't have much to offer that I find useful. We build things that sound good. We're not calculating the hyperbolic curve to the moon. Spice seems to be a lab tool useful to electrical engineers who are prototyping circuit designs or running simulations. That's not what we do. The book was written LONG ago that outlined the circuits we work with. Very little has changed in the last 70 years.

i like spice, though i never use it for amp design..
i always roughly calculate the expected voltages by hand and bias points i do graphically from the spec-sheet.

Originally Posted by hipofutura

Asdain, can't wait to see this go from drawing board to youtube.

And please, MORE exciting women. Especially from you Barnaby! I have a soft spot for Asian women.

me neither ^^
though i will still need a little more planning, i don't want it to be doomed from the beginning.
right now the long signal wire from the first stage to the tonestack and pretty much all wires to the clean/mean switch are potentially bad lead-dress and can't even be shielded, because they carry high dc voltage.

i may move the tonestack after the cathode follower,... making the whole thing closer to the SEL...

i also might leave out the Clean/Mean Switch, as i usually only play one setting and use the guitar controls,.... leaving out the switch would save me a lot of work (and about 6 bucks for a good APEM 600 DPDT) and make the build much cleaner...

if i really change all that i will basically have an SEL, but with a better "Crunch" i guess..
the two gain knobs could be adjusted individually to get different distortion characteristics..

Another thing i might do is run the power tube (probably will change to an EL34) asymmetrically.. running it with 2.5k will go it into cutoff quicker than into grid conduction,.. giving it a sweet and compressive overdrive characteristic

Originally Posted by BillB1960

They have a pill for that.

Originally Posted by Cygnus X1

Almost forgot...

nice kegs

Originally Posted by FF_Pedals

That's looking pretty cool. I did the same thing in my Champ with the power tube bias. What kind of pot were you going to use? I used a Clarostat rated at a few Watts. You'll have more current with 6L6 than I had with 6V6 though. The Clarostats are pretty expensive!

I disagree with Don about SPICE. It rules.

i have a CTS 1k 5 Watts lying around in my parts box

[Asdain]

Update... i cleaned up my little workspace and sorted a few parts.. even took a few pics for you people^^ though i am not at home right now. i will upload them as soon as i get home and post another update, maybe a few different layout attempts,.. i think i will start the actual building on wendsday.

I'd be happy if the more experienced amp builders here could spare a minute to look over layout and schematic a little closer and check if there are any obvious errors or potential problems with it,.. i have built 3 amps ( not kits) so fa, but i'm still not very experienced when it comes to making the layout : /

now excuse me.. bbq and beer awaits... so do these gals:

[Cygnus X1]

I can't get the zoom to work either.
Check your PM's.

[BillB1960]

Originally Posted by Cygnus X1

I can't get the zoom to work either.
Check your PM's.

Click on the Go To Full Site link. The original links took me to the mobile site which doesn't have the zoom controls.

[eaglewolf]

Originally Posted by Cygnus X1

Almost forgot...

Now that's some serious, uh, well, yeah, um, some real serious... uh, beer. Yeah, that's it. I think I'll go have a beer.

This site is getting so NSFW!

David

[Asdain]

Ok i hope THIS fixes the zoom issue for all of you guys : )

Originally Posted by Asdain

The Schematic:

The Faceplate:


The Layout:

[Asdain]

as Promised, here are some pics of Parts i am going to use:

the Chassis:
its 365mm x 160mm x 80mm



Going to work it with these fine little buggers:




and just so you know what kept me busy:

more will follow tomorrow : )

[Cygnus X1]

OK, I got it.
In case the rest of you haven't caught on...replies need to include Beer and Babes.
Good way to rope others into the finer details of amp designing!

Remember, output impedance is very important.

[Asdain]

Originally Posted by Cygnus X1

OK, I got it.
In case the rest of you haven't caught on...replies need to include Beer and Babes.
Good way to rope others into the finer details of amp designing!

Remember, output impedance is very important.

Thx, Cygnus!

i think i will add a few posts about how tubes work and how the stages are designed and all that in between the actual building info too : )


here some more pics and Info
as you see, i will recycle a lot of parts from my old P1-extreme build.

I want to build a 1x12" Open Back Combo with this. The Chassis will be mounted to the back of the Cab, like in a fender deluxe. I am open to speaker suggestions here too ^^ right now i think an Eminence Wizard should work well... for testing purposes i have a Jensen C12Q here for now.

my old and battered test chassis holding a P1'ish amp,.. looks more like a piece of swiss cheese now


Gut-shot: (this new build will be a lot prettier, i promise )


a shot of my Parts Box:




(I actually have that poster on my fridge !)

[Asdain]

So you might have been thinking:
"HOW THE HECK DO TUBES WORK ANYWAY?"

The most common tube types are the Diode, the Triode and the Pentode

The Diode is the simplest form of vacuum tube and is used in rectification, common rectifier tubes combine two diodes in one envelope for full wave rectification.

The diode consists of three parts:
The heater (usually called filament), the cathode and the anode (often called plate)
The filament only serves to heat up the cathode. When the cathode is hot enough, electrons can leave the material (thermionic emission). If you now apply an electric field, by giving the anode a higher potential than the cathode ( so the Voltage between Anode and Cathode is positive), the free electrons will get "sucked" off by the anode. Ofc the cathode needs to be grounded for that, so new electrons can flow into it.
Giving the Anode a negative Voltage with respect to the cathode will not allow any current to flow.
Thats what a typical diode does, it lets current through only in one way!
diode.png
Remember that electric current is defined as the flow of positive particles, so while the electrons are flying from cathode to anode, the electric current is defined as from anode to cathode.

A Vacuum triode is basically a diode with an additional electrode called the gate.
The gate usually sits very close to the cathode. If the gate has a lower potential than the cathode (Voltage between Gate and Cathode is negative) it suppresses the electron flow to the anode somewhat. This is why we often talk about valves, because the gate acts like one, regulating the flow of electrons to from cathode to anode. Now if you would apply a sine wave of for example 1V, with a dc offset of -1.5V (all respect to the cathode) the current through the Valve would follow the sine wave. So when the Voltage of the sine wave rises, more current flows, because the grid gets less negative to the cathode and suppresses the electron flow less.
if the gate gets to the same or a higher potential than the cathode, it will start drawing current itself, which is called grid conduction.
if the gate gets Very negative, it might stop the electron flow completely, which is called cutoff (usually it won't stop it completely though, but just reduce it to very very small levels)

Triodes are the most common in preamp stages. The 12ax7 (or ECC83) and a bunch of other tubes are actually two triodes in one envelope.
triode.png

How do you actually amplify a signal with this ? Well i will leave that and the pentodes for later or tomorrow, but if you think about it and remember Ohms' Law, and maybe what you could use a capacitor for, you might get the idea all by yourself

PS: the illustrations were taken from ax84.com SEL theory document and edited by me

[Cygnus X1]

Careful about building the whole circuit on one board.
That's one of the things I changed for layout, splitting the filter cap side away from the preamp:


In fact it looks like your filter caps are going to be directly over the 12AX7's.
Yes, I would change that...
I looked at the layout/schematic and it looks OK.
Nothing jumped out at me as being seriously wrong.

Speaker?
For the SEL I like Celestion V30's.
Some people like Scumbacks.
Look at Daisycutter recommendations for other ideas.