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PCB order for Goldmun clone

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#81
I don't know where the boards currently stand, but may I suggest something?

I have bought from "group buys" before and have been happy for the most part. The problems I have run into in the past is where people from the Group Buy wanted special "options" on their PCB's like gold plate, solder mask, silkscreen printing, etc.

I strongly suggest that this be avoided as it adds quite a bit to the final price and really doesn't add to the quality of the PCB.
I suggest that the extra money be spent on thick copper traces and tin plate for the copper traces.
Silkscreen is not needed if you have a diagram where the parts go on the board. Just double check your work before parts are soldered in.

I was involved in a group buy where the majority of people wanted gold plating on the traces; probably because it looked nice. It was a total pain to get good solder joints on the board because of the gold.

Anyway, this is just my opinion... I would rather have my money spent on a good quality board with thick copper traces than all the "pretty extras" that can be had on PCB's.
Daniel
 
#82
Bigpanda - To me, silk screen printing is not that important. But I can see how it could be important to other builders, especially those not very familiar with this schematic. I would strongly prefer that the ground plane did not have any solder mask. I plan on soldering, most if not all ground points to it. And I'm sure many others will too. Goldmund solders all of their ground points to the ground plane. Having solder mask on the ground plane will make building this amplifier significantly more difficult. The solder mask is very tough and hard to clean off. Usually one has to scrape it off, making the circuit board very ugly. Is there any way that you can ask the PCB fabrication house if they can print the silk screen on the ground plane directly?

As for the electroless nickel plating, I no longer really care one way, or the other. I know Goldmund did NOT use electroless nickel plating. If no one else cares and we can save a few buck, we can do just a regular tin plated board. But again, I'm completely neutral on this matter.
 
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#84
NagysAudio said:
If no one else cares and we can save a few buck, we can do just a regular nickel plated board. But again, I'm completely neutral on this matter.
Click to expand...

I have never heard of nickel plating on a PCB. Nickel does not take solder easily. Are you sure you don't mean tin plating? Tin is put over the copper traces so the copper does not oxidize and turn color. Tin Plating gives the traces a "silver" look, similar to what nickel looks like.
Daniel
 
#87
Tyimo - Yes, you can only have a single pair of outputs if you choose to. Remember, the input stage will still need 40VAC. I'm not exactly sure how much voltage the output stage will need. I'm guessing you can leave +/- 60VDC. Goldmund does not describe a single pair version of the amplifier in their service notes. This is something you'll have to experiment. But one problem could be this: If you decide to feed the single pair of MOSFETS with less than +/-60VDC, you'll most likely need a separate transformer for the input stage and the output stage. Is there any reason why 2 pairs is too much for you? 2 pairs will give you a very standard 100 watt amplifier.
Thanks!
I need only ca.30W. 🙂
Greets:
Tyimo
Click to expand...
Click to expand...
 
#91
Tyimo said:
Hi NagysAudio!
Is it possible to operate the amp with only one complementer pair of MOSFETS?
Could you tell me the voltages and any other changes needed?
Greets:
Tyimo
Click to expand...

Hi,
You can operate this amp with only one pair of outputs or 2 pair, but remember, rail voltages will have to be decreased accordingly or you will blow the outputs.
Think of ohm's law... At +/- 80 volts, the voltage doesn't care if there is one pair of outputs or 10 pair, it's going to go through just the same. The on state of these devices is too low to limit current going through them so rail voltages will have to be adjusted. Calculate the rail voltages so the output's dissipation ratings are not exceeded.
Daniel
 
#92
bambadoo - Yes, you can use your 800VA, 2X42VAC transformer. Please see my post #51 in this thread.

800VA rating is meaningless, as it's completely overkill for this amplifier, so it makes no difference.

However, with 2X42VAC, you can expect the amplifier to be 100 watts (2-8ohms), 200 watts max at 3 ohms. I would also suggest you only use 2 pairs of MOSFETS and not 3 pairs.
 
#98
Here's the latest PCB layout from Alex. Everyone who's on the group buy list, please compare it against the original schematic (see attached) for mistakes.

I personally think this PCB is done. The only concern is the grounding scheme. Will everyone be satisfied with all ground points going to the ground plane?

If you see any mistakes, or want anything changed, please speak now.
 

Attachments

  • PCB REV 3.2.jpg
    PCB REV 3.2.jpg
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  • Goldmund Mimesis 9.2 Schematic.pdf
    Goldmund Mimesis 9.2 Schematic.pdf
    47.9 KB · Views: 403
#100
Looks as though the design has finally settle down.

Material : 1.6mm FR-4
Size : 238x119mm
Copper : Double side 2oz
Finish : Tin Plated
Silkscreen : Black on top layer
Resist : none
Cost : $35 / pair
Shipping : $6 / pair

If you found any information missing from the above, please notify me.


Local (HKSAR) members please state how you want the shipping done as to skip the shipping cost. Send me email with subject “delivery for Goldmun clone PCB”. Sorry for slightly overcharging the Asia-Pacific members (rather than local) for shipping.

If for any reason, you want to pull out of this or rectify the ordered quantity, please send me an email with subject “Cancel / rectify order for Goldmun clone PCB”. If it is because of the board design and / or the grounding issue, please state so. I might be coming back for the 2 boards design later. I cannot make a promise or can’t say when. At least I have to know if there are enough interest for another GB on that design.

I will be sending performa invoice to your email add. (the one you had as your paypal a/c, not the one you send me your order) on Nov 1. If you want any change in the order, please try to make it before then.

Krzysztof -- I haven't got your paypal a/c.
Aug -- please see if you have the right quantity.


Pls check the GB report for your own order. I have 2 columns of board charges so you can compare the 2 versions
 

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