28 February 2012

Laney... The Saga Continues

Hey,

So tonight (though things are in reality way more along than the last post... and I'm just doing some non-linear Tarantino style blogging) I decided to make a small change based on a page from this slice of literature...

Building Valve Amplifiers by Morgan Jones

On page eleventeen or whatever... there is a note about using a nice heavy bit of wire for the IEC Ground connection to avoid unwanted noise by offering a really nice path to ground for the chassis. I remembered how the wire I originally used was from a section of green/yellow wire I cut off the Power Transformer shield. The stranded core was actually kind of small, compared to what you get down a good 3 core mains cable.



So... I found a bit of mains flex I have lying around and just sliced out the earth wire. I compared the cores between this wire and the old ground wire and the new one is way bigger. I installed it, and hopefully even if it doesn't make an audible difference, it's still a good tip as well as good practice.

Laney Gut Project. End Days

YO.

So, It's been a while since I posted but I've been away doing this and that and working and all that good stuff. I say good, but that's questionable... alright it was mostly good.

Things with the amp have moved on a bit, so I'm going to try and catch up over the next few days with some retrospective bloggage. Below is the Power Supply board in its testing stage. The Yellow wires are just temporary for a ground connection for what requires one.



What you can see on that board (going front to back) is a good old full-wave rectifier made of UF5408 diodes. The original bias circuit. The faux centre tap and reference voltage source for the AC heaters. Then finally the basic DC heater circuit at the back.

Initial testing showed that I wired the Illuminated DPDT switch backwards, so it would light up as soon as the chord was placed in the IEC socket. That got fixed right away. Schoolboy error.

The bias circuit is dishing out around -30v to -60v if I can remember correctly.
The DC heaters read 3.6vDC at the sockets of V1 & v2, which is also fine. This type of DC heater circuit has a reduced voltage and higher power strain on the wind used to power it, but this power transformer can cope with 2x 12AX7 filaments. The reference for the AC elevation ended up being about 40v, which is awesome.

Elevated AC heat reduces the chances of getting filament hum in the preamp since the AC voltage won't really swing 'negative' in a way that will interfere with the normal operation of the valve. It also prolongs the life of Cathode Followers by reducing the possibility of arcing. That's a pretty basic way to sum it up, so I really suggest researching those ideas a bit if you want to know more.



I used some pretty decent Rifa and Rubycon caps for the main filters. They are pretty large values and super low ESR. They are actually 'snap in' types, meaning they have small but robust pins on the bottom, rather than solder tags. Well... the pins on these ones are robust!

You can also see the INGO soldano style transformers in that photo, and the tone stack module from a previous post poking out the new front panel made by JPF Amplification (Who incidentally make some great amps with a vintage vibe).

4 February 2012

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.