Neat & Tidy Gainclone Tips Anyone???

[Gcollier]

Well I finally built my first Gainclone and while the sound is definately sweet, the appearance is not. I'm calling it FrankenAMP .

What I'm hoping is that some of you can share your ideas on layout to keep these things as neat and tidy as possible (a la Peter Daniel). Also any PCB links would also be helpful.

Thanks everyone for all the help getting me this far!

[monguz]

Originally posted by Gcollier
What I'm hoping is that some of you can share your ideas on layout to keep these things as neat and tidy as possible (a la Peter Daniel). Also any PCB links would also be helpful.

By layout ideas I don't really know what exact help you mean, but the "This is not just another gainclone" thread will show you quite a few details.

As for the pcb, take a look at this one from JordanG:

http://www.diyaudio.com/forums/showt...?postid=122202

Regards,

monguz

PS. I've just finished my inverted gainclone test construction which is perhaps not a rats nest but still experimental. (I'm listening to it right now while typing and what can I tell, I just love it's sound!) Not boxed but stable enough to be portable as I wanted to make a few tests at my friends too. I don't think this could be of much help but tell me if you or anyone would like to look at a photo or two of how I made it.

Probably my final (ever?? ) version will be on a small pcb even for the few parts for the ease of reproduction by others.

[swirv]

I too am interested in tidy GC tips. I am about to start my GC and am worried it will turn into a mess. Of course I know it will look nothing like Peter Dainiel's work of amp art.

[Cradle22]

Hi!

One tip I can give: The real layout question is: Where to put those 1000uF (or another similar value) caps?

For me is seemed that there are three basic layouts (described with the IC mounted to a surface)
- one cap above and one cap beneath the IC
- one cap to the left, and the other to the right of the IC
- both caps above or beneath the IC

Chose what you like in accordance with how much space you have available (take into account the other connections to input and output you will have to make)

Break off the not used pins of the IC (twisting them up and down repeatedly), and bend the others according to the layout you chose

If the feedback resistor is small enough (for example a Welwyn RC55), you can solder it directly to the pins, UNDERNEATH the IC, therefore saving space for the parts on the other side

I found working with solid core wiring a lot easier and comfortable than with flexible cables, I actually used paper clips (shame on me), but you could always chose more expensive stuff, like solid core silver wiring (Peter said that solid silver wiring sounded too harsh on the LM3875, but you can always try...). Those solid core wires (not isolated in my case...) also fixes parts more firmly in place than normal cables would...

Try omitting the input coupling cap (measure DC offset, if it is below 100 mV, I would not use such a cap), you can save a lot of space that way - t6hat is, if you chose to use a "normal" cap like MKP, which can get quite big at 2.2 - 4.7 uF...

Although I would like to build such nice stuff like P. Daniels does, I simply lack the experience, knowledge, tools, and patience for those exquisite metalworks stuff, so I always use pre-fabricated housings, which often kind of dictate the overall layout...

Maybe someone else comes up with tips as well, normally it is all in the massive GC thread (good for me that I've been reading it since it started, so that I do not have to read all ~1600 posts at once...

Bye,

Arndt

[Gcollier]

Thanks for the suggestions. Right now I am using silver wire that I pulled out of an old amp. I've really got to get a bigger transformer since the one I am using is only delivering 16V AC (about +/- 18 VDC). This little guy is getting pretty hot as I'm sure the ampl load is much higher than what it is rated for. I'm looking to get a Plitron 750VA toroid to run 5 channels. My current version is using axial 100uF caps, which appear to be a real pain for a neat layout, I'll see how Radial caps work in my next version.

Also I have looked at Jordans PCB design, and may be using a similar version myself. Any idea where I can get some blank copper boards in Canada??

Anyway thanks and keep the suggestions coming.

[Nuuk]

I hope to be able to post some pictures of my effort very soon but one tip I will pass on is to try and get the LM3875 with the stepped pins. I found that it made soldering everything to the chip much easier than I had anticipated.

The case design I have used also makes for easy construction (and a fairly neat layout) as you will see when I can get the pictures up here.

[Gcollier]

Nuuk I can't wait to see the pictures. The chips I've got do have the stepped pins, so hopefully your layout will work for me. I'd also be interested in the order you attached your components. If I had years of building experience I'm sure I could whip one of these little beauties up in a few minutes, but I'm still an amateur when it comes to solder....but I can't think of a better project to learn on!

[Nuuk]

If I had years of building experience I'm sure I could whip one of these little beauties up in a few minutes

Actually Gcollier, it's not the years of experience that make for speed of construction, it's whether it is the first one you are doing or a subsequent version.

It took me all day just to assemble the two channels of the amp section as every step had to be planned, thought about, checked with subsequent steps etc etc. Obviously, the second channel took me much less time to build than the first!

So even when you become experienced, protoyping still takes a lot of time. That's one reason PCB's are popular for shortening construction times.

If I can borrow a digital camera today, I will try and get some 'in progress' shots up here. A full explanation of my Gainclone build including all the casing details will appear later on my website.

[Nuuk]

I can't believe how time-consuming something like this is - even though it's the same each time that I build something from scratch!

Anyway, I've taken a few pictures, very hurridly but I took the view that something is better than nothing. As I said before, I will eventually do a comprehensive write up on my Decibel Dungeon site as this is an ideal project for a beginner.

So here is the progress thus far...









I should really be out in this sunny weather

Briefly (for now), I started by removing the 'NC' pins from the LM3875. Then I soldered the two RC55 resistors between pins 3 and 8.

Next up were the decoupling caps which I first soldered together with their bypass caps, then to the pins of the chip.

Next was the resistor at the input (metal film), the coupling cap (Black Gate NXQ) and the 10K input resistor (carbon film).

Lastly, all the wiring for the power supply, earthing and grounds (0 volts). If you are really observant, you will see that I have yet to add the wires to the speaker terminals!

I agree that this sort of job is ten times easier using solid core wire (0.6mm2).

The case Well, it's a five inch length of plastic soil pipe veneered in cheerywood and with a mahogany face-plate. The amp is built on the rear plate.

There's plenty of room inside to add ballast like sand. The 'tubes' will rest on mahogany dowel at the front and a spike at the rear.

The 'holes' at the front are for the speaker terminals.

As you can see, they are designed to be used with a separate preamp.

As I said, more details to follow.

[Nuuk]

And a shot of part of the PSU.



I've designed it so that I can insert/remove the caps easily for comparisons.