My new amp (solid state "mesa recto")

[Alexius II]

Hello!

I've been building a small amp for the past week... and now it is nearly finished (finaly) 
Here are some photos and comments


First I drilled the alu chasis (hammond 1444) according to my plan:



Then I designed the power supply and the jfet splitter (which I later ditched):



Assembled power supply:

(18V for the amp and 15V for the preamp, both regulated)


I then fiddled with the global layout and stuff:



Next was choosing a handle and wood type... and then drawing a plan in 3D (google sketchup):



This was the internal pcb layout...

...until I wired it and plugged it in 
There was just no way in hell my dr.Boogey would cooperate with my small dpdt switch. I used shielded&grounded wire, but the proximity of I/O wires at the switch caused it to oscilate. I then ditched the second preamp and wired the Boogey differently. It is now a "one trick pony" amp, but it sounds really good 
Also, I wired the volume from tonestack directly to amp input. I had some trouble with the splitter, I might try it again later.


This is from today's testing:


After three hours the heatsinks (scavenged from a dead PC PS) were just slightly warm. Transformer was a bit warmer, but still at lower than body temperature... yay  :tu:

Now I'll have to wait until monday for my wood to continue

Comments are as always most welcome!

[J M Fahey]

WOW !!Congratulations !! :tu:             :tu:             :tu:            :tu:             :tu:             :tu:

[techno-rachit]

Really nice! What its power rating??

[Alexius II]

Power amp is TDA2003 running at 18V, so it has approx. 5W into 8 ohm, according to datasheet. It was born as as a practice/recording amp and it does it nicely. Plugged into my 1x12 cab it reaches "max. bedroom level" at around half volume. Into my 4x12 with V30s it is loud enough to tear my ears of from a meter or so, hehe.

Just this moment the wood arrived, two days early! 



I will probably glue it together tomorrow  :tu:

[phatt]

Hello Alexius II,
                     Very tidy workmanship :tu:
Watch out Mr Fahey might have you working in his factory before you can blink
Phil.

[techno-rachit]

Lovely Work!!

[joecool85]

Very nice work.  I have to ask though, why did you regulate the voltage on the power amp chip?

[Alexius II]

Thanks!  :tu:

As for the regulation: I first intended to use a 12V transformer which would give me about the right voltage after smoothing caps... but then I decided to just use the 15V, 1A transformer, which I already had. And since the TDA2003 datasheet said 18V is the max. operating voltage - I regulated it down to that 

I'm still deciding about the wood though... to stain or not to stain 

[joecool85]

Thanks!  :tu:

As for the regulation: I first intended to use a 12V transformer which would give me about the right voltage after smoothing caps... but then I decided to just use the 15V, 1A transformer, which I already had. And since the TDA2003 datasheet said 18V is the max. operating voltage - I regulated it down to that 

I'm still deciding about the wood though... to stain or not to stain 

If you don't stain I would recommend using Linseed oil to finish it with.

[Alexius II]

Ha, I just found some "leftover" clear acrylic based lacquer for wood from a previous (non music) project :tu:
I have just about enough for a few coats... so I'll go with it 

Who said a "metal" amp should be black... it's gonna be bright and pretty

[J M Fahey]

Who said a "metal" amp should be black...

You are right, it can also be Red ..... dripping Blood Red, that is :grr

Attila the Hun, your friendly Death Doom Metal player.
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[joecool85]

You could always use a torch to darken it up a bit first, then put the laquer on.  I think the burnt look would be badass on a metal amp.

[Alexius II]

While dripping blood is not a bad idea  burnt look would be even better.
The only problem is... my wood won't do that. It is not a solid piece of wood, but is made from smaller (2 inch wide) parts glued together. I tried that yesterday on a small leftover piece to see if the glue would hold, but it does not 

Also, this spruce wood burns faster than I can say "fire extinguisher"

I also tried to stain it with my fountain pen ink and achieved a really nice effect so I'll try it on a larger piece to see if it works.

[teemuk]

Personally, I'm getting a bit tired in the generic hardwood cab -look but each to his own I guess. Too bad that the heat ruins the glue, as the burned wood -look wasn't such a bad idea. The burned wood effect looks nice also when you sand out the top layer, sort of brings out the wood grains like a stain would.


Nevertheless, looking forward seeing how that amp looks when finished.

[Alexius II]

Wow, this really looks good  :tu:
The trick might also be in the high flame temperature of that "torch"... what I have is more of a orange-ish flame "burner", so the wood (and glue) heats up too much before actually turning black.

Well, I've tried another of my inks which I like best so far.
After a rough sanding it with a small piece of wet-sanding paper, this spruce suddenly looks a bit older, half rotten and beaten up 
I believe this decadent look could be just dirty enough for the sounds coming out this amp 

Here is the sampled surface (lower left part):
(upper part is overburned and not sanded... don't mind that)