Assistence with M^3 part order

can't help but "saves project" and ugh where to buy PCB? I enjoy solderingz! lol

^ Huh?

This is really neatpicking but the resistors could have a better temperature coefficient, 50 ppm is common instead of 100, doubt it is a huge deal. If someone could chip in as to if it would be worth changing ? Also worth just rounding up to the nearest 10 or so, spares are handy for future use.

With the transistors, with fairly generic parts there will usually be several different manufacturers, then there may be different variants, packages and finally if it's loose, reel, tape, ammo box etc.

Different variants could be slightly different specs like lower noise, different gain, mil spec, there may be just a suffix for different packages, same for how it's packing type, straight or pre-bent leads, RoHs or not, different manufacturers may use different designations just to make life interesting and may offer different versions unique to them.

Just double check with the datasheet to be sure.

Quote:

Originally Posted by Groundzero 

Thanks for pointing that out splaz, I wasn't aware the ppm mattered. I'm noticing though that any resistors with 50/10/5ppm are all .25" long vs. .15". Does this matter?

Can you point out which resistor he's referring to?  I'm sure splaz must be referring to something that I'm not seeing.

As far as I can tell, other than your output power resistors, everything you've selected are Vishay-Dale RN/CM series.  The RN55's are as good as you're going to get for normal applications (non-SMD or "boutique").  In fact, you have several CM50's that can be replaced with RN55's if you do a little more searching.  For instance, I doubt seriously that Mouser is out of stock of RN55's in 1K - you should be able to find something in 1K besides a CM50.  The CM50's are the same thing, merely V-D's commercial grade and paradoxically, are more expensive(!).  The RN55's are military grade, mil-spec.  The commonly known secret on Head-Fi and elsewhere "in the know" is that RN55's rated at 1/8W are the very same resistors that are labeled CM50 for 1/4W.  You should be able to get RN55's in every commonly used ohm rating for 7 cents each.  You can't beat the quality for more money than that at 1/4W.
 

In fact, the V-D metal film power resistors you've selected are just fine (1R, 2W).  They're much better than metal oxides at that rating and power.  They add no color to the sound (unlike metal oxides), which is important at the power output positions.  We've used those series on the MAX/MiniMAX/MOSFET-MAX for years with great results.

Quote:

Originally Posted by tomb 

Can you point out which resistor he's referring to?  I'm sure splaz must be referring to something that I'm not seeing.

 

As far as I can tell, other than your output power resistors, everything you've selected are Vishay-Dale RN/CM series.  The RN55's are as good as you're going to get for normal applications (non-SMD or "boutique").  In fact, you have several CM50's that can be replaced with RN55's if you do a little more searching.  For instance, I doubt seriously that Mouser is out of stock of RN55's in 1K - you should be able to find something in 1K besides a CM50.  The CM50's are the same thing, merely V-D's commercial grade and paradoxically, are more expensive(!).  The RN55's are military grade, mil-spec.  The commonly known secret on Head-Fi and elsewhere "in the know" is that RN55's rated at 1/8W are the very same resistors that are labeled CM50 for 1/4W.  You should be able to get RN55's in every commonly used ohm rating for 7 cents each.  You can't beat the quality for more money than that at 1/4W.
 

In fact, the V-D metal film power resistors you've selected are just fine (1R, 2W).  They're much better than metal oxides at that rating and power.  They add no color to the sound (unlike metal oxides), which is important at the power output positions.  We've used those series on the MAX/MiniMAX/MOSFET-MAX for years with great results.

 

I blame Mouser and their lies!

They incorrectly list 100 ppm in the specs.

Doesn't help as I'm currently doing a BOM for something else from Farnell/element14 and had some vishay dale datasheets up for their generic cheap as chips resistors which happen to have that temperature coefficient.

Likely contributed to my error.

Lastly doesn't help I'm not really familiar with the RN55 series as they cannot be easily had here as far as I know, Farnell stock has huge gaping holes. Closest thing are some Welwyn or Tyco (TE) mil spec resistors but they are over $1 each.

Considering actually changing my BOM over to digikey/mouser as due to min quantites I've racked up about $40 on resistors alone and I only need a handful and these are just generic 1/4W 1% 50ppm metal film.

Anyway Groundzero, disregard what I said and tune into tomb.

Quote:

Originally Posted by Groundzero 

Thanks for the help guys, I switched all CM50s to RN55s and ordered everything. With any luck I won't be back asking why my amp doesn't work.  If anyone reading this is curious the total came to around $350 w/o an enclosure. 

Glad you sorted out, I think my mistake is a case in point, always double check the datasheets and try to familiarise yourself with certain series of parts so you know what is desirable it will make selecting parts much easier. The suppliers can get it wrong.

Quote:

Originally Posted by Groundzero 

Hah whoops, guess I should have specified. The $350 wasn't just the Mouser order, it includes everything needed from the AMB shop, the transformer, and all shipping charges. Regarding suppliers getting it wrong, I noticed quite a few resistors labeled as both 1/8th and 1/10th watt. I'm not sure if that's a mistake but it sure makes building a BOM more confusing. 

Yep.  Stay away from the 1/10W resistors, too - they're too expensive for very diminishing returns.

OK, this is probably a dumb question, but is there anywhere to get clear, step-by-step instructions on putting together an M^3? I'm not worried about the soldering, but I need clear instructions on what the hell I'm supposed to do, and I find the instructions on the AMB website to be clear as mud...

Any suggestions?

AMB has some of the best documentation I've ever seen... what exactly are you confused about?

When you don't find your way around Amb's instructions then an M3 is too big for you...

Quote:

Originally Posted by amcananey 

OK, this is probably a dumb question, but is there anywhere to get clear, step-by-step instructions on putting together an M^3? I'm not worried about the soldering, but I need clear instructions on what the hell I'm supposed to do, and I find the instructions on the AMB website to be clear as mud...

 

Any suggestions?

It's confusing? When it comes to electrical engineers, they just love to use jargons that a non-electrical engineering person might not understand. But Ti Kan really doesn't do that in his documentations when it comes to putting it together.

I'll post a guide with pictures as soon as I finish it. However, the guide is for my setup so yours may be different.

I may not be a fan of AMB's designs, but his documentation is excellent. As others have said, if you can't work out what to do from it you probably shouldn't be trying to do it.