Dave's Custom Amp - None More Black! Updated: Thursday 8th March 2012

THIS AMP IS NOW FINISHED!

Well here is a little something i'm putting together for a friend of a friend!

So far all the pcbs are populated and the chassis & headshell are in which I am going to prepare for the final build steps this weekend.

The transformers should hopefully be here in the middle of next week.

The spec is as follows

50w
Sprague Orange Drops
Vishay CCF60/ Koa Speer & Panasonic Resistors
Sprague Atom, F&T, Nichicon Muse Electrolytics
Onetics Hi Def Output Transformer
Onetics Custom Power Transformer
Onetics 5H Choke
SLO style Chassis & Headshell - none more black.

And here are a few pictures of whats been done so far.

Resistors Populated Vishay CCF60 1% MF for ultra quiet operation.

Panasonic Power Resistors.

Full preamp resistor population shot.

F&T Electrolytic Capacitors added

Sprague Orange Drop 715p/225p Capacitors

Sprague Atom Electrolytic Capacitor

This one is pretty much the entire preamp populated

Power amp Using Nichicon Muse Series Electrolytics & UF5408 Diodes

Vactec VTL5C1 Optocouplers for Silent & Instantaneous channel switching

Recton DB101 Bridge Rectifier for the channel switching voltage rectification

The Headshell when it arrived

This headshell needs a little adjustment. The front grill sits about 11mm too far forward.

 

And that is all for now. I shall update this post as and when things happen which should be a fair amount over the coming week.

Update: Sunday 19th February

I started work drilling the chassis today should hopefully get the amp finished by the end of the week.

This one is a fairly boring update as not much went on as this part takes quite some time as I countersunk the holes by hand as I find it a lot easier to do it accurately this way.

The reason for countersinking all the board mounting holes is so that the transformers can sit flush against the chassis.

Transformer Drilling #1

Transformer Drilling #2

Update: Friday 24th February
I managed to get a good amount done today, the amp is mainly wired up im just waiting on the preamp & power amp valve sockets as the ones I had didn't quite fit the chassis or they were the wrong pin orientation for how I wanted to do the wiring.

All that's left to do now is wire up all the heaters/valve sockets and wiring the actual circuitry in.

The Pot Shot!

Faux Center Tap

Lamp Wiring #1

Lamp Wiring Close Up #1

Lamp Wiring Close Up #2

Clean/Crunch & Bright Switch Wiring. This part needs redoing.

Pot Wiring

 Transformers Mounted

Clean/ Crunch, Bright & Channel Switches

Power, Standby Switches & Lamp

Onetics Power Transformer Hookup Schematic 

Power Amp Wiring

Preamp Wiring #1

Preamp Wiring #2 In this photo you can also see a wire joining to the preamp PCB mounting post this is coming from an RF cap that is just an extra measure that I was made aware of by my co blogger Bob that just stops those annoying radio frequencies that can sometimes be picked up by guitar cables.

Pot Wiring & Effects Loop

 

Test Run #1

Final Assembly 

 Front Right. You can see in this picture that the front panel now perfectly lines up with the front of the chassis.

Rear Right 

Signature 

This one is just for the sake of it really. These two amps are practically the same circuit wise the main differences being mine (the white one) is running on JJ E34L and Daves is running on JJ 6l6GC so it's kinda the evil twin scenario!

And here is the final shot of the amp in my posession where it went through around 8 hours of constant play testing at a range of volumes (which my gerbils weren't too happy about when it got higher)

 

Dave is coming to pick up the amp this evening after a 6 hour tattooing session and is extremely excited.

The effects of capacitance on tone.

This is the first part of something that I was asked about on the MetalGuitarist forum.

In itself it can be quite awkward to explain but there are a few basic rules that apply and I will go through them in the simplest application there is to a guitarist.

The tone control. The main properies of a capacitor used in this application is to increase or decrease the high frequencies depending on how they are wired.

A common value that is used as a "tone" capacitor is 0.022uF if you increase this to say 0.1uF you will roll off a far larger amount of the high frequencies.

For a quick reference here are a few common capacitor values that are used in guitars

0.10uF - Darker sometimes described as a muddier sound (no good for metal imho)

0.047uF - Less dark, with a pleasant frequency curve through the travel of the pot.

0.022uF - This cap gives a brighter sound and does not roll off as much high end and also has a good frequency curve throughout the travel of the pot

Another point that i have seen come up on various forums is that a higher voltage capacitor will change/alter the sound. This is NOT true a using a 600v  Orange Drop will have the exact same effect as using a 100v Orange Drop as your guitar will never see 600v going through it and if it does there is something seriously wrong!

Also using a really low value capacitor will give the effect of reducing the low end frequencies when wired up with a pot this can be seen in an excellent post on the MetalGuitarist forum.

I shall do more of these in different applications if people request them.