NDIYAD - New DIY Amp Day

[Dmoney]

So this is my latest build.

http://www.youtube.com/watch?v=AYaiyqxas8k

I'm playing (or attempting to play) my Edwards Les Paul with Nailbombs into it.
Its a JCM800 circuit with a Depth control. Basically this thing is pretty much a 50watt EL34 'crunch channel only' SLO100. The power supply/filtering is different though.

It's got the usual controls you'd find one something like this, plus bias test points at the back and a precision pot with a locking wheel for you to set the bias with opening the amp or needing a screwdriver.

I'm tempted to do 1 or 2 more tiny tweaks to it, but I'd say this is 99.9% done.
I suck a doing clips. The clip above has lots of photos.

[Twinfan]

Looks and sounds great - tasty!

[Telerocker]

Great tone. Well done. Looks nice in white tolex.

[Denim n Leather]

That amp looks beautiful.

[Dmoney]

cheers guys!
Toe-Knee have given me some tips on how to record with what I have a little bit better. Hopefully if I can get a chance over the weekend I can get some more clips done. The volume on this thing was probably barely on 1 or 1 and a half and it was late when I started. I think you can hear the traffic outside my window if you listen closely.

EDIT: just noticed the serious neck-bend at 3.01... haha. crazy move.

[Transcend]

As i said yesterday its good to see this working at long last.

Its been a while trying to figure that damn ticking!

I have also just noticed that you have almost stolen my colour scheme idea for my next amp!

Now all you need is a swish logo for it

[dave_mc]

very nice :)

[Dmoney]

I just had a little session with some tweaking ideas.

Its now pretty much the same as the Soldano X88r crunch channel. I attached the schem in case some people are interested.
In my amp the first coupling cap is 0.022uf, and the 3rd stage has a 1uf cathode bypass rather than 0.1uf shown on the schematic, and I'm using 1Meg pots gain and Master Vol. I also added a 10K grid stopper to the output of the gain pot.

The changes I made from the video above are as follows.
Originally... the 680K resistor on that schem was a 2.2M with 120pf in parallel
Originally... the 470K before the gain pot was unbypassed

One thing I have also tried a Splawn trick of putting a 47K resistor to ground between between the first 0.022uf and the 470K/470pf network. I don't recall if that is a 'OD' switch or a 'Gear' switch on the Splawn QR but in this, it adds some punch and take the sound away from that vintage marshall vibe. I took it back out again but I'm debating making that switchable. I quite like it but I haven't cranked the amp much since making these changes, and since I decreased that 2.2M resistor I'm a LITTLE worried about levels, stability, that kind of thing.

that said... I think it's going to be an improvement from what I've heard so far!

Any advice on what I've done is more than welcome.

[JacksonRR]

Just listened to it. The beginning had some very delicious light distortion. Looks like a pro job with the fit and finish as well.  :D

I've been messing around with the cold stage cathode resistor in my 5150 which is also a popular thing with the SLO dudes I guess. Took it down to 33K and it decreased the sharpness and aggressiveness. I decided I'm not playing that game anymore and installed a trim pot in series with the 33K. Adjusted to taste and ended up with 42K, so 3K more than the stock value felt good to me. Been that way for a few days and I'm digging it. If not, I never actually put the thing back together. Don't even know where the feet are......

[Dmoney]

I've been tempted to try and find a cheap used 5150 just to get stuck into.
when I made my little 30watt Avenger thing, I tried some of the slo forum mods on it but whatever I tried I didn't like. I think I might have tried the 33K at the cold stage but I didn't try going higher than 39K. I've tried the 39K slope resistor before and that is ok.

what have you done to your 5150? have you banged a choke in it or anything like that? I've done the bias mod on a 6505 but that is about it.

[forestcaver]

Nice!!! Need some gut shots though :-) Where did you get the faceplates from or did you make them as well ? Gotta love DIY amps.... The fear adds a little frisson to the first chord :-)

[Dmoney]

The faceplates are from our own JPF Amps, who resides on this forum from time to time.
The chassis is actually his Mk1 chassis for his range, so his amps faceplates are the same dimensions as the ones on this amp.

The front was originally white but now its that white on black stuff that Hiwatt uses. Traffolyte.

I'm going to try this 47K resistor switching between the first two stages, record it again now i've made some changes, tidy up from wiring. A mate is going to be buying this.

[JacksonRR]

My mangled 5150 has these changes:

Bias mod running two KT88s
Krank style midsweep added though I've been thinking of swapping it out for a Lee Jackson style 5 position. I think swapping caps may be more useful than a variable slope resistor. Damn. Typing this out has convinced me to do both now.
Have a little switch that dumps off some extra gain from the lead making it a different sounding crunch. Not footswitchable, just a thing to have and it sounds good.
Peavey coring circuit "noise gateish" thing added. Adjustable, but from the inside. There's only so many switches and knobs that can fit on the thing.
Swapped a lot of the 1/4 watt resistors for 1 watters.
Killed the clean channel. It sounded like it was dying anyways. From the ashes rose another lead channel and the clean/crunch is a crunch/lead button now.
Played with the preamp a whole lot, but what it boiled down to was knocking the bass and highs down and playing with the gain of each stage. I even had a few bits of help from people on here.
At this point I'm pretty sure I need to rack up on some push-pull pots if I wanna have some more controls.
Outside of the box I did add a clean channel. Sorta. A DIY amp selector pedal lets me bypass the 5150 pre and go straight into my first effect in my loop, which is stereo input, but only setup for mono output.

Good on ya for selling it! Not that you should get rid of it that is. More money for a new project.  :D

[Dmoney]

Nice.

I've recently seen a lot of talk about the lee jackson mod. is it just a rotary switch switch that cuts in various caps and slope resistors? That sounds kind of cool. With things like that though, I always feel like I'd end up stuck on one position and that puts me of installing something like that. If I had an amp that was a solid platform for testing stuff out one it sounds like it would be worth a go. I think the Splawn uses a rotary to increase gain in various ways.

The coring circuit... is that lifted from the JSX? or some other peavey I can't remember. I know FJA mods will install a noise gate into a 5150, but I have no idea how that works.

Your 5150 sounds like a BEAST

I'm tempted to find a thrashed Laney Pro Tube or GH100L.
I'd like to try a total rebuild with split bias and mixed valve output section and some really basic low insertion loss tone controls right at the front of the preamp, in addition the marshall stack at the end.

[JacksonRR]

Haha, thanks. She's a work in progress. Well, she progresses when I do. :)

FJA's noise gate mod is exactly that. The Peavey circuit, that is. FJA only solders his into the lead channel, while I have it elsewhere in shared circuitry because I have no clean channel to be affected negatively. I lifted it from the XXX, but the JSX has the same thing except with a pot instead of a static resistor. It's a three component circuit. I can look it up later, but I'm just home for a change of clothes and I'm going back out.

The Lee Jackson Six position mid-boost has 5 caps and then an off position. The caps are from 0.0047uF to 500pF so there is a lot of ground it will cover. It's an additional tone shaper, not  your standard mid control. I have his book, Ultimate Bench Warrior(which is sucky cept a few things). I'll draw it out if you want though. I'd prefer the lazy way of scanning, but posting a scanned page in a book seems like it's against some kind of rule or something.

I'd like to get more into variable filters throughout the preamp as well. If you could at least swap coupling caps on the fly there would be tons of responses available.

Dmoney....... this is a sickness. The smaller components are so cheap and I just can't help myself.