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Old 2nd April 2004, 06:30 PM   #1
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Default GainClone Group Buy Feedback

I hope I don't start a war here or appear ungrateful for the Brian and Meredith's efforts but I wanted to give some constructive feedback and prompt others as well in the case this group buy happens again. This is an ideal first amp project.

My only wish was that the capacitors were farther back so I could use a clamp to mount the chip. This would probably result in the board being more square in shape.

My least favorite part of the assembly was mounting the feedback resistor. I made it a little easier by supergluing the resistor body to the chip but I was paranoid I was going to break off a lead. Would it alter performance much by providing a place to mount it on the board for those who want easier assembly at the expense of performance?
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Old 2nd April 2004, 06:52 PM   #2
roibm is offline roibm  Romania
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No offence ultra, but this is about the easiest DIY project ever! And clearly it is the easiest amp ever.

What do you need the clamps for?
Also, you could have soldered the NFB resistor on the back of the board. Would have been much easier, altho I can't complain about being hard to "mount" it.

PS: If I'm no beginner, then who is one?
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Old 2nd April 2004, 06:57 PM   #3
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Default spoiling resistor wires

I did some training of bending the wiris in the right shape with some scrap cut-off's from old resistors.

I had the same feeling before if you break the thing you are "lost"with such a nice Kit of Parts.

Exercise is everything.
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Old 2nd April 2004, 07:00 PM   #4
tiroth is offline tiroth  United States
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Try mounting the caps on the bottom then. For the feedback resistor, shortest possible feedback path is one of the central tenets of the GC faith. If you think mounting that one resistor was hard you should build some P2P gainclones.

As far as I am concerned Brian could write a book about how to do a group buy right. Cheap, easy ordering/payment, rapid shipping, good communication. Hard to imagine much room for improvement.

Brian, hope you enjoy your trip to the Royal Canadian Audio Museum and Gainclone Factory.
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Old 2nd April 2004, 07:11 PM   #5
BrianGT is offline BrianGT  United States
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Quote:
Originally posted by tiroth
Try mounting the caps on the bottom then. For the feedback resistor, shortest possible feedback path is one of the central tenets of the GC faith. If you think mounting that one resistor was hard you should build some P2P gainclones.

As far as I am concerned Brian could write a book about how to do a group buy right. Cheap, easy ordering/payment, rapid shipping, good communication. Hard to imagine much room for improvement.

Brian, hope you enjoy your trip to the Royal Canadian Audio Museum and Gainclone Factory.
Thanks for the complements!

As for the feedback resistor, the bottom of the board should be alright. I wouldn't couple it directly to the LM3875 chip, as I wouldn't want the resistor heating up too much (though, the caddock resistors have accuracy over a wide range of temperatures, so it might not be a problem). I like the appearance of the resistor in front of the chip. If you are using the thick insulators and the LM3875T, it will fit nicely on the back of the chip, even closer to the leads.

I am working on organizing the next phase of the group orders now. There will be a 2-5 week leadtime on the parts, since I bought all the existing stock of the Caddock resistors in the US and Canada in the 19k-22k range. I am also looking into getting a shipping account with the post office, so that I can print my own postage, rather than having Meredith wait in line every day for a week and a half with 20-30 packages, waiting for the lady to punch in postage for each one. Paypal has a feature that you can print address labels through them along with postage for the US orders.

I have no trip planned to visit PD, but Rodd mentioned that he is going up there with the Cardas stuff.

--
Brian
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Old 2nd April 2004, 07:36 PM   #6
tiroth is offline tiroth  United States
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Ack, I got the group buy wonder twins mixed up! My apologies!

That's what you get for being a smart***.
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Old 2nd April 2004, 07:44 PM   #7
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Don't get me wrong, I'm not complaining in the least. It was by far the easiest kit I've assembled. I was just brainstorming, if you will.

As far as the feedback resistor is concerned, it wasn't a problem for me but it would be annoying if I was doing a bunch of these. I have only a tiny dab of superglue holding the resistor, I should be able to pry it off easily. Did so once already when I SG'd the wrong resistor.

I'm building one GC with Brian's parts and another with RN60Ds, both with TFs. I'll build a third, point-to-point with RN60Ds and the T chip and see which sounds best.

I just like the clamp method. It may or may not make a difference with a gainclone but its elegance pleases me, nonetheless. Building audio gear for me is as much (or more) about expression as it is about sound. Additionally, I have some heatsinks that would be easier to use with the clamp method.

Clever idea, Tiroth. I should have thought of that.
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Old 2nd April 2004, 07:54 PM   #8
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Well since this is about feedback I would like to add my 2uF of feedback.

I have thanked Brian and Meridith before...but I still felt something had to be said. Your thread is providing me with that oppertunity.

This groupbuy was done in such a short time...so well and in a period that must have been very busy for Meredith and Brian...getting married and all. But still they did not complain...quite the opposite they were ENJOYING it....making me feel a lot better about the whole deal...then there was the photo's, the manual ...oh the manual..excellent...even with some history on gainclones..I mean this groupbuy was brilliant...the boards! Oh don't get me started..excellent quality. Did I mention the price allready? No charge for paypal! The paypal shopping cart...with the lovely chip logo! The bonus pcb I got...The gallery of finished gainclones being put up as we speak. I love this guy..I wish every diy' er was like this...

Meredith I'm sorry I'm no breaker of marriages...but .....but Brian...would you marry me?

Sure you can never ever be everything to everybody...This is not to start a war. But if you want to take part in a groupbuy you going to have a thing or two that are different to the way you would like it....if you don't agree with that you can do you own boards.

This groupbuy went so smooth and fast...It was an absolute dream to take part in. If all group buys would be like this..my credit card would be overloaded.

Brian and Meredith Thanks again!!!
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Old 2nd April 2004, 08:04 PM   #9
speaker is offline speaker  United States
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Quote:
Originally posted by roibm
What do you need the clamps for?
A clamp will put even pressure across the device & heat sink and therefore provide better heat transfer to the heat sink. A screw through the device puts the bulk of pressure around the hole the screw goes through. At the edges of the device you may have less contact. Based on everything I've read about the GC's, they seem to be pretty tame and I don't think you would get much more than a theoretical advantage with a clamp.

speaker
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Old 2nd April 2004, 08:08 PM   #10
BrianGT is offline BrianGT  United States
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Quote:
Originally posted by Bas Horneman
If all group buys would be like this..my credit card would be overloaded.
Thanks for the complements.

I would cancel your credit card soon, as there will be more group buys in the future that I will organize...

I urge everyone to start finishing the projects soon and begin mailing me pictures. I will be giving out a free pcb set for the first 20 people to e-mail me finished pictures of thier amplfiers built with the kits. Pictures must show a finished amplifier, showing an internal view, and a view of the finished unit. [between 2 and 12 pictures accepted] Please size pictures down to 800x600, so that my e-mail box doesn't get flooded with 20meg attachments.

(offer limited to 1 free pcb set per person participating in the group order)

Rafal 's amplifier is a good example of the bare minimum:
http://www.briangt.com/gallery/nigc-rafal
but the more pictures, the better!

Once I have a large number of entries, and an updated webpage, I will award a more substantial prize for what I feel is the best unit in the gallery (sorry Peter, your amps don't count, since they look too good, and might discourage competition)

--
Brian
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