Constructing a SS Guitar Amp- Any Comments

[maurawkela]

Hello,

I am planning to build a ss guitar amplifier. The design I'm thinking of using is http://www.sound.westhost.com/project27.htm. Mainly due to fact that that the parts are easily available in India (where I'm from) and many seems to be recommending it. I am planning to use Eminence Legend 121A as this is the only guitar speaker i can find in India within my budget.

My questions are:
1. Whether it will be good to change the overdrive/distortion clipper diode as many has report the quality to be not so good, if so any idea?
2. The speaker is 8 ohms and the amplifier is rated for 100w for 4 Ohms. Whether there will be any discernible effect in the functioning. The load being a 150W at 8 Ohms.
3. Any general comments. (if its of any importance, I am planning to use TO3 can transistor due to easy availability of heat-sink for them).

Regarding electronics, i put myself between beginner and intermediate. I can read circuits, troubleshoot them and am a fair hand at soldering. What i cannot do is design circuits or modify intricate circuits as i am a self taught enthusiast.

[J M Fahey]

First of all, welcome to the Forum and to a beautiful hobby.
Your choice was good.
1) Leave the diodes as-is.
They are not "bad"; on the contrary, they are good, only that they don't distort too much, just enough for some edge on Rock'n Roll or Blues music.
Of course, Heavy Metal players don't find it strong enough, that does not mean it's bad.
Easy to solve, you can build a distortion pedal, there are many projects available on the Net, including the design for "ready to transfer" PCBs.
You can choose from an MXR Distortion+ to a very distorted Guv'nor clone.
2) No problem at all; it will give you 100W into 4 ohms; around 70W into 8 ohms, it's loud enough to play almost anywhere; the Legend high efficiency helps a lot; it's important that you used a good guitar speaker instead of a Hi Fi or Audio type (or, worst of all, a car type one)
In the future, whenever your Rupee box is filled again, you can add another box with a second Legend if you wish.
3) TO3 can transistors will be fine.
As a personal curiosity, I would like you to post here some pictures along the construction, showing how it goes.
I'm interested as how somebody out of the USA/Europe area builds such an amp from scratch, without the usual resources others give for granted.
I am in a similar situation, I am from Argentina and along the years had to build *everything*: chassis, PCBs, transformers, even the speakers.
Not that there are none available, far from it, but 99.99% are not meant for guitar use.
Good luck on your project.  :tu:

[maurawkela]

Dear Fahey,

Thanks for the quick reply. I am planning to play mostly country music and slow rock so the distortion does not really matters. What i am more worried about was that whether that part will have any effect on the clean channel.

I am ordering the Eminence from the India distributor and expecting it soon. Other than the speaker, quality components are easily available here in India, so there is no problem from that side. I expected that all my components will be ready by end of January and by early february, i should be able to start.

I definitely post stage by stage photos when i start.

Maurawkela

[joecool85]

I definitely post stage by stage photos when i start.

Maurawkela

I'm looking forward to it!

[askwho69]

this is nice : D im planning to build one too but need to find PCB Layout

[J M Fahey]

im planning to build one too but need to find PCB Layout 

Then get ready to grow a very looooong beard.
No, I'm just kidding.
You will have to roll your own.
It's not *that* difficult.
You won't find the best distribution on first try, even more if you have not experience, but it can be improved on and as much as you need.
1) draft it roughly on a piece of paper.
Put all parts first , in a logical way, meaning if a resistor goes connected to a capacitor, draw them somewhat close and so on, *but* leaving free space between them, say 1/4 to 1/3 inch, for the wiring.
Your first drawing will be *huge*, who cares?
2) start pencilling connecting lines, future tracks, connecting pin to pin as needed.
3) you can erase and redraw as needed.
4) the main goal is to connect everything, without tracks touching each other
5) go to sleep, next day with a fresh mind start compacting or rearranging it, until happy with results.
If some track proves impossible to solve, just use a piece of "floating" wire.
Redraw at will, if it gets messy redraw what you like on a new sheet of paper.
6) when you are satisfied with results, draw it professionally with some PCB program.
Bancika's Do it Yourself Layout Creator (search this Forum) is *excellent.
There are three versions: the original one (Windows only), the second (any platform) and the last one, still on trial.
I suggest you use the first one.
It's main advantage is that there are a lot of designs posted by users like you and me.
Browse through them, to see how others faced your same problems.

*OR*

Go the easy way and buy one of Rod Elliot's ready-to-solder boards; they are inexpensive and help him with his wonderful site's expenses.
I only ask you please do not post the drawing in the Internet, respect his efforts.
A PCB is easily shipped anywhere in the world inside a common mail envelope (ok, between two pieces of cardboard), plus his being "the real deal".
Good luck.

[DJPhil]

im planning to build one too but need to find PCB Layout 

5) go to sleep, next day with a fresh mind start compacting or rearranging it, until happy with results.

This part is very important.
It took me half a dozen boards before I discovered that things look very different after a night's sleep. I'd go from pulling my hair out to sorting out the two or three bugs that were hanging me up.
Also a very useful technique for troubleshooting that freshly built pedal that thinks it's supposed to be an AM radio.  xP

[askwho69]

Wow thank for the use full replies maybe ill get it a shot to find much easier design like chips LM3886 and TDA7293

but ill try:D