Mauro Penasa's INV GC/REF GC group buy.

[Russ White]

Hey guys, a quick update on the PCBs for the group buy. I have 2 PCBs left. If you want to get in on this first round of PCBs this is your last chance until I can get some more ordered and do a second round.

Cheers!
Russ

 

[BrianDonegan]

If your parts kit has arrived, could you update the WIKI? I want to be sure everyone receives their kits, and am alos curious as to how well the various shipping methods are working outside the US.

 

[BrianDonegan]

Okay, some pics.

General layout:

An externally hosted image should be here but it was not working when we last tested it.

Power will be on left, in/out on the right. Sides and frint edge of the base plate will be trimmed down and squared up.

Grounding arrangement:

An externally hosted image should be here but it was not working when we last tested it.

If I experience and ground loop issues etc., I can simplt unplug it.

Groove in heatsink (shape is from profile of tablesaw blade):

An externally hosted image should be here but it was not working when we last tested it.

Arial view showing top HS threaded holes:

An externally hosted image should be here but it was not working when we last tested it.

Note the floating volume pot. All the currently messy wiring will be replaced and cleaned up.

 

[Russ White]

Looks like a winner Brian.

 

[awashi]

Brian, your shipment arrived today!
Perfect packaging! (really, haven't seen one that good until now)
Thanks alot!
Enough exclamation marks for now! 😉

What kind of transformer do you guys recommend? None of you seems to be using a torroid.

 

[BrianDonegan]

The one in my pics is from Parts Express in the US for $7USD. Might be expensive to ship.

 

[awashi]

The 25V/18V CT TRANSFORMER buyout for $5 i guess?
The big online shops i know around here only sell transformers with 18V and 30V secondaries for some reason, no 24V ones.
Might have to try parts express

Edit: Ah the 48V CT is $7

 

[Russ White]

The 25V/18V CT TRANSFORMER buyout for $5 i guess?
The big online shops i know around here only sell transformers with 18V and 30V secondaries for some reason, no 24V ones.
Might have to try parts express

Its the $7.00 48VCT. And I can confirm it works very well for Mauro's amp. Mine has 30+ hours on it.

 

[Russ White]

I just ordered 5 more of the PE trafos. Because I am building a few sponsored amps for my buddies at UT. 🙂 At $7 I don't see how they can last long.

 

[awashi]

Gathering stuff to order along with it to get the minimum $50.

Edit: Oops forgot they prolly have 110v primaries
Could try two 25V CTs?

 

[Russ White]

Lab tests successful. 🙂

I got my amp back from the lab with a clean bill of health. No oscillation, and what has been described to me as incredible low THD. 🙂 .06% average at 10V from 20hz to 20Khz. SNR was 97db!!! Thats the best any amp of mine has ever measured.

No oscillation at all. 🙂

Thanks for the design Mauro. It am fully confident my amp is a success! 😀

Cheers!
Russ

 

[Russ White]

Gathering stuff to order along with it to get the minimum $50.

Edit: Oops forgot they prolly have 110v primaries
Could try two 25V CTs?

A would never use a 110 rated trafo on 220. It's generally a bad idea.

 

[mauropenasa]

Hi Russ,
thanks, am happy that work all well.
Nearly all the THD is over the 10Khz for choice of project ( the second harmonic of 10khz is already not listing, over that little!).

Ciao

Mauro

 

[Russ White]

Sold out.

Unfortunately I have no more Revision A PCBs to sell. I still get a lot of requests for boards however.

If you are interested in a second round please email me.

Thanks to everyone for making this a huge success. I sincerely appreciate it.

Cheers!
Russ

 

[Russ White]

alpha pots

Brian, and anyone else using alpha pots for this amp may want to look at this:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=61645

Cheers!
Russ

 

[DcibeL]

If your parts kit has arrived, could you update the WIKI? I want to be sure everyone receives their kits, and am alos curious as to how well the various shipping methods are working outside the US.

What seems to be the parts have arrived today. I have to go to the post office tomorrow and pick them up. So from the 22nd to today is one week for shipping to Saskatchewan Canada, and I owe $10.12 for duties/taxes. Thanks again Brian for the parts GP.

 

[Russ White]

and I owe $10.12 for duties/taxes.

Geez, that sux.

 

[Ed LaFontaine]

I recieved a delivery today from Apex Jr. Included were Nichicon 12,000uf 35V caps that snap right into the boards.

Get this: 2/$1. If you haven't gotten your caps, or need more, consider them.
Now I have no excuses. The parts are here. The wife is away on Sunday. The kitchen table is MINE! The aroma of solder will fill the air.

Calmart, I haven't forgotten your question for a better understanding of the AXP caps article. I'll post a summary on Sunday, as well.

 

[Russ White]

I recieved a delivery today from Apex Jr. Included were Nichicon 12,000uf 35V caps that snap right into the boards.

Get this: 2/$1. If you haven't gotten your caps, or need more, consider them.
Now I have no excuses. The parts are here. The wife is away on Sunday. The kitchen table is MINE! The aroma of solder will fill the air.

Calmart, I haven't forgotten your question for a better understanding of the AXP caps article. I'll post a summary on Sunday, as well.

Hey Ed!

Glad to hear from you. Thanks so much for the care package. I will put that stuff to good use. 😉

Cheers! And happy solder sniffing. 😀

Russ

 

[Ed LaFontaine]

Russ,

You are most welcome.

If you become aware of Nashville area sources for DIY treasure be sure to let me know. I may run out of junk bins to scrounge through some day.