[BUILD] 1176LN Rev D DIY

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Well-known member
Jun 3, 2004
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(Click for really big pics)
There didn't seem to be much interest in this when I raised the idea on another thread but I thought I would post my holiday DIY anyway. I started out simply putting the class A output stage in place of one on my version of Jakob's G1176 board but quickly decided to do a whole new layout, incorporating the discrete meter circuit of the earlier revisions as well (and all the earlier component designations).

I did a double-sided home etch, fixed a few minor errors and have it up and running into some CJ iron (through a capacitor to block the DC). Everything seems to work just fine. Just waiting on output transformers from Andrew at Purple so I can hook up the feedback and DC balance windings, but I don't anticipate any problems as the amplifier seems to be working well even without the transformer feedback.

I'll post some PDFs of the corrected layout if anyone is interested. Sorry, I tried to make it single-sided but it was just too hard for me. Anyway, the ground plane makes it nice and quiet, even outside of a case.

*edit: Some documentation including self-etch files can be found on my site.
Please download the 1176LN manual from the JBL Pro Site.
that looks great ! :shock:

it's nice to see another pcb designer slave end up with some
nice results ,

i feel ya on the one sidded board things ,
turns it into the greatest puzzel ever.

best of luck ,

Awesome!!! :green:

Thats an impressive holiday project. :shock:

[quote author="mnats"]There didn't seem to be much interest in this when I raised the idea on another thread [/quote]I must have missed that thread, coz this has my interest straight away!!!! :thumb:

I've completly missed this thread :sad:
If I knew, I would have wait some times before I order your G1176 Rev H !
They are not stuffed yet :wink:
This new board seems to be a nice comromise between G1176 and the now defunct Purple kit.
I hope you'll make your pcb available soon

Great job :thumb: :thumb:
definately ! very nice layout!

for the meter circuit I would go for a classic meter buffer as purple did that in their mc77

I recognize a small drop in output level when the 1176 is switched to +4 or +8
That's a damn neat design, dude. Congrats :thumb:

I'd be interested in a pair once you 've finished it as well.

May I also ask your help once my brother and I get this flexi-76 challenge working too? It could be more practical for we are using your other 76 board as prototype. We still have a wee while to finish it, though. Not so easy as it seems, a lot of mechanical work to be done for the servomotor positionings and adjustments and all.

Happy new year.

[quote author="Rob Flinn"]Greg

That looks really good ! Nice & compact.

One thing. I'm wondering why you didn't take the opportunity to use 25 turn trimmers, which make the 1176 much easier to set up?[/quote]

i second this idea. multiturn trimmers make a big difference; hopefully your new layout can accept a few kinds of trimpots. i would also change the selected (usually around 1k) GR meter calibration resistor to a 2kohm trimmer in series with a 100ohm resistor. this makes the GR meter calibration easier.

i don't suppose there is room for the pcb mount input transformer?

board looks very nice, btw.

everyone should realize that for max performance you'll need the specialized output transformer. a simple gapped 1:1 could probably substitute acceptably. purple will not be selling the output transformers after the new year, but i've posted the cinemag part number before. if there is enough interest, perhaps i can arrange some kind of group order.

...just got back from a Melbourne New Year - fireworks off the tops of buildings :shock: - didn't realize there was any interest in this project. Guess now that the Purple kits are over there might be more folks interested...

It's not too difficult to do a single-sided board but it would disturb some of my neatly placed components. I spent a lot of time getting things to look nice - my wife thinks it's a very strange obsession.

I made the physical layout of the board follow the drawing of the schematic very closely so the signal flow is very easy to visualize. Should make it easier to troubleshoot as well.

The trimmer footprints will all accept precision types as there are holes for almost every type. Didn't find it that difficult to do the adjustments though with cheap single twist ones.

And the trimmer across the diff pair in the meter driver is already done. I got frustrated when I didn't have a 1.68k resistor so I changed the layout to fit the trim pot.

I could make room for just about anything on the board including the input transformer, but thought it might be better to leave it off-board so there are more options. Now that I think of it though, if there is a standard transformer people are using and it has pins it might make contruction easier if there is a quick way to mount it.

What sort of iron are people using in their Purples?

I'm thinking of building a couple of G1176 based on boards from Mnats. But this thread is making me a bit confused. The current version for sale in the black market is the rev J and this new version is rev D? Why "D", am I missing something? In what way is this new version different?

I'm planning to use a older Lundahl LL4602 output tranformer for my build and possibly use a LL4601 as input transformer. (The LL4601 is not 100% pin compatible with the 1540, which would require some tweaking.) I'm also planning on building dual units in one box. Would you say that I'd be better of building from the rev J boards?

Last, I'm a new member of this forum and is impressed with all the creativity, knowledege and accomplishments of the members, inspiring!

[quote author="Rob Flinn"]I would guess that many people are using the iron that Andrew supplies with the kits.[/quote]
You are rough on a guy who just drove 700 kms. Right, the Altran C-3837-1. Can't find any info about it doing a search so maybe it's a custom job? Anyway, I'll probably forget about on-board transformer mounting - the board suits my purposes as is and it's not intended as a G1176 replacement by any stretch. This project will never have the sort of popularity as Jakob's G1176 I'm sure, but I'll post some layouts and have a small batch made just the same.

Thanks for the compliments on the layout, folks. I had a lot of fun doing it, aside from getting the pinout on the FETs wrong...

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