High Gain SLO Influenced Amplifier Build Log For misterwhizzy

[Toe-Knee]

I wasn't going to bother with this but misterwhizzy expressed interest in more pictures.

I didn't start taking pictures right at the beginning so I only have bits and bats so far.

First up is the preamp PCB thats populated with Mallory 150 Capacitors Vishay & Panasonic resistors & F&T Electrolytic capacitors.

Preamp PCB



Next up is the filament bridge (faux centre tap if your power transformer doesnt have one. This one does so it's just a bridging point for the filaments)

Filament Bridge


From there the filament/heater wires go around the inside of the chassis

Filament Wiring




Then it joins onto the Lamp/Power Indicator.
Lamp


It then comes out from the lamp and goes to V5 (Phase Invertor) pins 4/5 & 9

V5 connection


The heaters are then wired in a parallel fashion straight down pins 4/5 & 9 for each 12ax7.
Heater Bus


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That is all for now as I kinda neglected this today as I got some new pickups so spent most of the day playing guitar. I do however have four days off work now thanks to the queens Jubilee so I shall spend it building!

Also it is very dusty inside there currently. This will all be cleaned up before the preamp & power amp get installed.

Update 02/06/2012

I haven't really done much today because I wasted my day travelling to Farnell to find they were closed even though the website stated they were open.

This is the Filament/Heater bridge that I started on before but it now has the 6.3v 9A Filament Tap from the power transformer hooked up to it.

Filament Bridge


From here there are two wires that go on to the power valve sockets which heat the filaments. In this shot you can also see the bias test points and external adjustment pot which are what I will be working on next

Power Valve Heaters


Update 03/06/2012

This morning I've wired up the transformers mainly other than the High voltage tap as that connects to the power amp PCB.

Up first is the Impedance switch this is where the OT connects and also the depth mod and Slave out.

Impedance Switch


Next up is the Slave out.

There is a 47k resistor going to the 8ohm tap on the impedance connector which connects to the level control for the Slave Out which is for using a wet/dry setup and of course can be used for direct recording as it captures the entire amp then you can just stick some cab impulses on the track and you are good to go.

Slave Out


And then we have the power valve wiring that is now complete

Power Section


Then finally we have the power transformer wiring in it's current birds nest phase. This will all be neatened once the power & preamp boards are in and the wires are shortened to the correct length.

Birds Nest Phase Wiring


That's it for a few hours. I've got a massive headache from the solder fumes and a friend has come round so i'm going to go for a beer.

Right I had a longer break than expected but i've managed to get a bit more done

Here's the power amp PCB nothing to say about this really other than it has a lot of filtering which again is a bit part of the SLO sound.

Power Amp


From here now there's just the preamp, Pots & FX Loop to do but theyre all pretty minor so will only take a couple of hours. Then it's first power up and voltage testing time then time to come back and shorten a few wires.

Update 04/06/2012

Here's the initial pot wiring.

Pot Wiring


And going on from the pots you get to the Clean/Crunch & Bright switching section which I will add is an absolute pain to get looking presentable. I'm not 100% happy with this so I will probably end up redoing it once I know everything's 100% working.

Clean / Crunch & Bright / Normal Switches


And then finally for a few hours until I wire the preamp in here's a shot of the amp in a much tidier state than before but still not optimal.

Amp Top View No Pre


Update 05/06/2012

Hey guys! I finished this one very earlier but had too much fun playing it and also tweaking it a little.

Yesterday I said that I have the preamp to wire in.... here's the photo before

Angry Porcupine


Then from there all I had to do was connect each section of the preamp to the corresponding valve. here's V1 which is the input stages and the second and third gain stages.

V1/V2 wiring


From here I Continued on along the other 3 valves and also wired the grid stops to the power valves and connected the tonestack & other controls up

More Wiring


And then onto one of my least favourite parts of amp builds. The effects loop. It's so damn fiddly getting all of this done in such a small space.

Effects Loop


Then It's just a case of wiring up the footswitch hack and front panel toggle but those are boring so heres a top down pic.

Complete Wiring


And a final assembly even though it's not really final.

Complete Head

[Mr 9finger]

Where did you get the PCB and the build instructions? It's something I'd want to start off with for building my first, but it's a good possibility of something that I'd like to work up to.

[ErikH]

That's very cool. Please continue to share. The SLO is my favorite high gain amp so I'm naturally curious how this turns out.

[Toe-Knee]

Where did you get the PCB and the build instructions? It's something I'd want to start off with for building my first, but it's a good possibility of something that I'd like to work up to.

There aren't really any instructions so to speak. The SloClone forum has a schematic & layout and there's also a member on there who sells the PCB's but he has been absent for a few months now. Another alternative is www.c3amps.com His PCBs are really nice and i'm using those in the rebuild of my personal amp whenever i get around to it as you can use higher quality capacitors in the power amp.

This was pretty much my first build ampwise. I'll try and document as much as possible as I go for reference.

[zzmoore]

That lamp is as nicely wired as any I have ever seen.
Are the caps really up off the PCB, or does it just look that way in the picture.?
Well Done

[Toe-Knee]

That lamp is as nicely wired as any I have ever seen.
Are the caps really up off the PCB, or does it just look that way in the picture.?
Well Done

I'm actually going to redo the lamp tomorrow to remove a bit of excess wire. Thanks for the feedback.

And yes theyre slightly raised from the PCB as the lead spacing is ever so slightly wider than the hole spacing on the PCB and well i'm a bit OCD so i also got them all straight whilst being secure and inline.

Another reason for this is it makes it easier to remove the caps at a later date without removing the PCB from the amp.

[zzmoore]

10-4.
That certainly makes sense.
I have not been inside of every amp in the world, but to my knowledge Mike Soldano is the only builder that runs his heaters like that. Just goes to show what theory is in play.....
Are you the guy that is using O'Netic tranny sets.?
Really Looking Good.

[misterwhizzy]

Dude, this is as sweet as it gets. Thanks for taking the time to do it. It looks flawless, and I'll bet it sounds brilliant as well. Please keep me posted. I appreciate it, and at some point in the future (probably distant), I'd like to do it for myself.

[Toe-Knee]

10-4.
That certainly makes sense.
I have not been inside of every amp in the world, but to my knowledge Mike Soldano is the only builder that runs his heaters like that. Just goes to show what theory is in play.....
Are you the guy that is using O'Netic tranny sets.?
Really Looking Good.

I usually use O'netics as they are really exceptional transformers.

In this build however I am using some custom wound transformers from an Italian winder.

The heater wiring is an interesting topic. I've had people criticise me for doing it this way rather than the traditional way of using twisted pairs all along as it is quieter.

When in fact There is little to no difference at all it's just more time consuming to do it all twisted and you end up using a lot more wire rather than doing it twisted up to the socket then bus bar straight down either side.

[Toe-Knee]

Dude, this is as sweet as it gets. Thanks for taking the time to do it. It looks flawless, and I'll bet it sounds brilliant as well. Please keep me posted. I appreciate it, and at some point in the future (probably distant), I'd like to do it for myself.

Just as soon as you do decide to I can hook you up with certain parts that I may be able to get cheaper than most.

Also I will of course help you as much as i can along the way.

[misterwhizzy]

Just as soon as you do decide to I can hook you up with certain parts that I may be able to get cheaper than most.

Also I will of course help you as much as i can along the way.

This is why I love this place.

[Mattr4president]

This is probably the cleanest amp I've seen. Amazing. Bravo. Your soldering skills = wizard level. Very clean.

[Toe-Knee]

This is probably the cleanest amp I've seen. Amazing. Bravo. Your soldering skills = wizard level. Very clean.

Thanks. I was hoping to get some teflon tubing so.i could try something a little different on the power valve wiring but farnell was closed. Oh well ill do it regularly.

I should have a few more pics later

[misterwhizzy]

Are the black squares the opto-relays?

[Toe-Knee]

Are the black squares the opto-relays?

Yes they are.

The ones that can be seen in the picture are face down due to the polarity required but the other 2 at the other side of the board are face up so you can see the markings and such.

I really like using Optos for channel switching as it's instant and has no noise at all.

Some people add an extra Opto in to make the channels completely isolated but in my opinion this makes the amp sound really sterile and takes away a lot of the detail in the midrange.

[zzmoore]

I usually use O'netics as they are really exceptional transformers.

In this build however I am using some custom wound transformers from an Italian winder.

The heater wiring is an interesting topic. I've had people criticise me for doing it this way rather than the traditional way of using twisted pairs all along as it is quieter.

When in fact There is little to no difference at all it's just more time consuming to do it all twisted and you end up using a lot more wire rather than doing it twisted up to the socket then bus bar straight down either side.

Yeah, guys think there is some kind of "magic" in a twisted pair. When, after all, it is just a Close and Consistent Proximity that aids in the hum-bucking.
Again..... Well Done

[Toe-Knee]

I've updated the first post with a couple more pictures.

I will probably do a bit more later but I'm going to relax for a bit and watch a film or something.

[misterwhizzy]

Some people add an extra Opto in to make the channels completely isolated but in my opinion this makes the amp sound really sterile and takes away a lot of the detail in the midrange.

There's a bit of bleed over from the clean to the overdrive channel in the default SLO configuration, right?

[Toe-Knee]

There's a bit of bleed over from the clean to the overdrive channel in the default SLO configuration, right?

Yeah. Some people make out like it's an absolutely massive amount but its really very small unless you run the clean channels master considerably higher than the lead channels.

It adds a bit of character into the sound that some people describe as being 3d. I just say it sounds better with it.

[Toe-Knee]

I've added a few new photos to the first post.

There isn't really too much left to do now.